Protagonist Therapeutics, Inc (PTGX)

Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations

​

OVERVIEW

We are a discovery through late-stage development biopharmaceutical company focused on peptide therapeutics. Our clinical programs fall into two broad categories of diseases: (i) hematology and blood disorders, and (ii) inflammatory and immunomodulatory (“I&I”) diseases. Two novel peptides derived from our proprietary discovery technology platform, rusfertide and icotrokinra (formerly known as JNJ-2113), are currently in advanced Phase 3 clinical development, with New Drug Application (“NDA”) submissions to the U.S. Food and Drug Administration (“FDA”) potentially in 2025.

Rusfertide, an injectable mimetic of the natural hormone hepcidin, is currently in Phase 3 development for treatment of the rare blood disorder polycythemia vera (“PV”). Rusfertide is being co-developed and will be co-commercialized with Takeda Pharmaceuticals, Inc. (“Takeda”) and the Company remains primarily responsible for development through NDA filing. Icotrokinra is a first-in-class investigational targeted oral peptide that selectively blocks the Interleukin-23 receptor (“IL-23R”) and is licensed to J&J Innovative Medicines (“JNJ”), formerly Janssen Biotech, Inc. Following icotrokinra’s joint discovery by us and JNJ scientists pursuant to our IL-23R collaboration, we were primarily responsible for the development of icotrokinra through Phase 1, with JNJ assuming responsibility for development in Phase 2 and beyond.

We also have a number of pre-clinical stage oral drug discovery programs to address clinically and commercially validated targets, including IL-17 oral peptide antagonist PN-881, an oral metabolic/obesity peptide program, and an oral hepcidin mimetic/ferroportin blocker program.

Rusfertide

Rusfertide is currently in Phase 3 development for the treatment of PV. VERIFY (ClinicalTrials.gov identifier NCT05210790) is a global double-blind, placebo-controlled Phase 3 clinical trial of rusfertide in PV for approximately 250 patients. The trial evaluates the efficacy, symptom burden and safety of once-weekly, subcutaneously self-administered rusfertide in patients with uncontrolled hematocrit who are phlebotomy dependent despite standard of care treatment. The trial enrolled patients across North and South America, Europe, Asia and Australia. We expect to announce top-line data for the trial’s 32-week primary efficacy endpoint in March 2025, potentially leading to an NDA filing in the fourth quarter of 2025.

Our rusfertide Phase 2 clinical trials include the following:

Final results from the REVIVE trial presented at the American Society of Hematology (“ASH”) 2024 Annual Meeting in December 2024 showed that 54% of patients with PV experienced more than 2.5 years of durable hematocrit control (45%), decreased phlebotomy use, long-term tolerability and improvements in patient-reported outcomes.

62

Table of Contents

In January 2024, we entered into a worldwide license and collaboration agreement for rusfertide with Takeda (the “Takeda Collaboration Agreement”). We are primarily responsible for the development of rusfertide through a potential NDA filing. Under the terms of the agreement, we received a one-time, non-refundable upfront payment of $300.0 million in April 2024, and we are eligible to receive additional worldwide development, regulatory and commercial milestone payments for rusfertide of up to $330.0 million, inclusive of the following potential upcoming milestones:

We are also eligible to receive tiered royalties from 10% to 17% on ex-U.S. net sales of rusfertide and other specified second-generation injectable hepcidin memetic compounds (the “Licensed Products”). We and Takeda will also share equally in profits and losses (50% to us and 50% to Takeda) of the Licensed Products in the United States, if approved. See Note 3 to the consolidated financial statements included elsewhere in this Annual Report on Form 10-K for further details related to the agreement, including our right to opt-out of the 50:50 U.S. profit and loss sharing arrangement.

Icotrokinra

Our IL-23R antagonist compound icotrokinra, licensed to J&J, is an orally delivered drug that is designed to block biological pathways currently targeted by marketed injectable antibody drugs. Our orally stable peptide approach may offer a targeted therapeutic approach for gastrointestinal and systemic compartments as needed. We believe that, compared to antibody drugs, icotrokinra has the potential to provide clinical improvement in an oral medication with increased convenience and compliance and the opportunity for the earlier introduction of targeted oral therapy.

JNJ has initiated the following icotrokinra trials:

63

Table of Contents

In the fourth quarter of 2024, we announced positive topline results for the ICONIC-LEAD and ICONIC-TOTAL Phase 3 trials. In the ICONIC-LEAD trial, once daily icotrokinra showed significant skin clearance versus placebo in adults and adolescents with moderate to-severe plaque psoriasis. At week 16, nearly two-thirds (64.7%) of patients treated with icotrokinra achieved IGA scores of 0 or 1 and 49.6% achieved PASI-90, compared to 8.3% and 4.4% on placebo, respectively. In addition, topline results from the Phase 3 ICONIC-TOTAL trial showed that once daily icotrokinra met the primary endpoint of IGA scores of 0 or 1 at week 16 as compared to placebo. Comprehensive results from both ICONIC-LEAD and ICONIC-TOTAL are expected to be presented at upcoming medical congresses and shared with health authorities in planned submissions.

Topline results for the ANTHEM trial for icotrokinra in UC are expected in the first quarter of 2025. Topline results for the ICONIC-ADVANCE 1, ICONIC-ADVANCE 2, and pustular/erythrodermic psoriasis trials are expected in the second quarter of 2025.

On July 27, 2021, we entered into an Amended and Restated License and Collaboration Agreement with JNJ, which amended and restated the License and Collaboration Agreement, effective July 13, 2017, by and between the Company and JNJ, as amended by the first amendment, effective May 7, 2019 (together, the “JNJ License and Collaboration Agreement”) for the development and commercialization of icotrokinra. During the fourth quarter of 2023, we earned a $50.0 million milestone payment in connection with the dosing of the third patient in the ICONIC-TOTAL Phase 3 clinical trial of icotrokinra in patients with moderate-to-severe psoriasis and a $10.0 million milestone payment upon the dosing of the third patient in the ANTHEM Phase 2b trial in patients with moderately-to-severely active UC. The JNJ License and Collaboration Agreement was further amended in November 2024 to:

We earned the $165.0 million milestone payment described above during the fourth quarter of 2024. We have earned a total of $337.5 million in nonrefundable payments from JNJ from 2017 through December 31, 2024. We are eligible to receive up to $630.0 million in future development and sales milestone payments, inclusive of the following potential upcoming milestones:

We also remain eligible to receive upward tiering royalties on net product sales at percentages ranging from 6% percent to 10% percent, with 10% percent applicable for net sales over $4.0 billion. See Note 3 to the consolidated financial statements included elsewhere in this Annual Report on Form 10-K for additional information.

PN-881

In the fourth quarter of 2024, we announced the selection of PN-881, a potential best-in-class oral peptide IL-17 antagonist, as a development candidate for the treatment of immune-mediated skin diseases. PN-881 targets three IL-17 dimers (IL-17 AA, AF and FF), which may offer potential treatment options for hidradenitis suppurativa (“HS”), spondyloarthritis, plaque psoriasis and psoriatic arthritis (“PsA”). Investigational New Drug (“IND”), or foreign equivalent, enabling studies are ongoing, and we expect to initiate a PN-881 Phase 1 study in the fourth quarter of 2025.

64

Table of Contents

Discovery Platform

Our clinical and pre-clinical assets are all derived from our proprietary discovery platform. Our platform enables us to engineer novel, structurally constrained peptides that are designed to retain key advantages of both orally delivered small molecules and injectable antibody drugs while overcoming many of their limitations as therapeutic agents. Importantly, constrained peptides can be designed to potentially alleviate the fundamental instability inherent in traditional peptides to allow different delivery forms, such as oral, subcutaneous, intravenous, and rectal. Our discovery pipeline has strategically focused on (i) hematology and blood disorders, (ii) I&I diseases and (iii) metabolic diseases, including obesity.

We have a pre-clinical stage program to identify an orally administered hepcidin mimetic/ferroportin blocker, which we believe to be complementary to the injectable rusfertide for offering the best treatment options for PV and other potential erythropoietic and iron imbalance disorders, and we expect to nominate a development candidate in the fourth quarter of 2025. We also have an oral peptide-based metabolic/obesity program and expect to nominate a development candidate in the second quarter of 2025.

​

Risks and Uncertainties

​

We describe the respective risks, uncertainties and assumptions that could affect our business, financial condition and/or results of operations in Part I, Item 1A. “Risk Factors” herein.

Operations

We have incurred cumulative net losses from inception through December 31, 2024 of $340.5 million. Substantially all of our net losses have resulted from costs incurred in connection with our research and development programs and from general and administrative costs associated with our operations. We expect to continue to incur significant research and development expenses and other expenses related to our ongoing operations, product development, pre-clinical discovery programs and pre-commercialization activities. As a result, we may incur losses in the future as we continue the development of, and seek regulatory approval for, our product candidates.

Critical Accounting Polices and Estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). The preparation of these consolidated financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities at the date of the consolidated financial statements, as well as the reported revenue generated, and the expenses incurred during the reporting periods. Our estimates are based on our historical experience and on various other factors that we believe are reasonable under the circumstances, and the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions. We believe that the accounting policies discussed below are critical to understanding our historical and future performance, as these policies relate to the more significant areas involving management’s judgments and estimates.

Use of Estimates

The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, we evaluate our estimates, including those related to revenue recognition, accruals for research and development activities, stock-based compensation, income taxes, marketable securities and leases. Estimates related to revenue recognition include assumptions used to determine standalone selling price utilized to allocate the transaction price between distinct performance obligations, assumptions used to recognize revenue over time for certain performance obligations for which a cost-based input method is used as the measure of

65

Table of Contents

progress and estimates of whether contingent consideration should be included in the transaction price at each reporting period. We base these estimates on historical and anticipated results, trends and various other assumptions that we believe are reasonable under the circumstances, including assumptions as to forecasted amounts and future events. Actual results may differ materially from these estimates.

There has been uncertainty and disruption in the global economy and financial markets due to a number of factors, including geopolitical instability, inflationary pressures, high interest rates, a recessionary environment, domestic and global monetary and fiscal policy, changes in trade policies, including tariffs or other trade restrictions or the threat of such actions, banking and other financial institution instability and other factors. We have taken into consideration any known impacts in our accounting estimates to date and are not aware of any additional specific events or circumstances that would require any additional updates to our estimates or judgments or a revision of the carrying value of our assets or liabilities as of the date of the filing of this Annual Report on Form 10-K. These estimates may change as new events occur, circumstances change, and additional information is obtained. Actual results could differ materially from these estimates under different assumptions or conditions.

Revenue Recognition

Accounting Standards Codification Topic 606, Revenue from Contracts with Customers requires us to allocate the arrangement consideration on a relative standalone selling price basis for each performance obligation after determining the transaction price of the contract and identifying the performance obligations to which that amount should be allocated. The relative standalone selling price is defined as the price at which an entity would sell a promised good or service separately to a customer. If other observable transactions in which we have sold the same performance obligation separately are not available, we estimate the standalone selling price of each performance obligation. Key assumptions to determine the standalone selling price may include forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success.

Whenever we determine that goods or services promised in a contract should be accounted for as a combined performance obligation over time, we determine the period over which the performance obligations will be performed and revenue will be recognized. Revenue is recognized using the proportional performance method. Costs incurred or labor hours are typically used as the measure of performance. Management’s judgment is required in determining the level of effort required under an arrangement and the period over which we expect to complete our performance obligations. If we determine that the performance obligation is satisfied over time, any upfront payment received is initially recorded as deferred revenue on our consolidated balance sheets.

Research and Development Costs

Research and development costs are expensed as incurred, unless there is an alternate future use in other research and development projects or otherwise. Research and development costs include salaries and benefits, stock-based compensation expense, laboratory supplies and facility-related overhead, outside contracted services, including clinical and pre-clinical trial costs, manufacturing and process development costs for both clinical and preclinical materials, research costs, development milestone payments under license and collaboration agreements, and other consulting services.

We accrue for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of pre-clinical studies and clinical trials, and contract manufacturing activities. We record the estimated costs of research and development activities based upon the estimated services provided but not yet invoiced and we include these costs in accrued expenses and other payables in our consolidated balance sheets and within research and development expense in our consolidated statements of operations. We accrue for these costs based on various factors such as estimates of the work completed and in accordance with agreements established with our third-party service providers. As actual costs become known, we adjust our accrued liabilities. We have not experienced any material differences between accrued liabilities and actual costs incurred. However, the status and timing of actual services performed, number of patients enrolled, the rate of patient enrollment and the number and location of sites activated may vary from our estimates and may result in adjustments to our research and development expenses in future

66

Table of Contents

periods. Changes in these estimates that result in material changes to our accruals could materially affect the results of our operations.

Recent Accounting Pronouncements

Information regarding recent accounting pronouncements applicable to us is included in Note 2 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K.

Components of Our Results of Operations

License and Collaboration Revenue

Our license and collaboration revenue is derived from payments we receive under the Takeda Collaboration Agreement and the JNJ License and Collaboration Agreement. See Note 3 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

Research and Development Expenses

Research and development expenses represent costs incurred to conduct research, such as the discovery and development of our product candidates. We recognize all research and development costs as they are incurred unless there is an alternative future use in other research and development projects or otherwise. Non-refundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received, rather than when payment has been made. In instances where we enter into agreements with third parties to provide research and development services to us, costs are expensed as services are performed. Amounts due under such arrangements may be either fixed fee or fee for service and may include upfront payments, monthly payments, and payments upon the completion of milestones or the receipt of deliverables.

Research and development expenses consist primarily of the following:

We recognize the amounts related to our Australian research and development refundable tax offset that are not subject to refund provisions as a reduction in research and development expenses. The research and development tax offsets are recognized when there is reasonable assurance that the offset will be received, the relevant expenditure has been incurred and the amount of the consideration can be reliably measured. We evaluate our eligibility under the tax incentive program as of each balance sheet date and make accruals and related adjustments based on the most current and relevant data available. We may alternatively be eligible for a nonrefundable tax offset.

67

Table of Contents

We allocate direct and indirect costs incurred to product candidates when they enter clinical development. For product candidates in clinical development, direct costs consist primarily of clinical, pre-clinical, and drug discovery costs, costs of supplying drug substance and drug product for use in clinical and pre-clinical studies, including clinical manufacturing costs, contract research organization fees, and other contracted services pertaining to specific clinical and pre-clinical studies. Indirect costs allocated to our product candidates on a program-specific basis include research and development employee salaries, benefits, and stock-based compensation, and indirect overhead and other administrative support costs. Program-specific costs are unallocated when the related expenses are incurred for our early-stage research and drug discovery projects as our internal resources, employees and infrastructure are not tied to any one research or drug discovery project and are typically deployed across multiple projects. As such, we do not provide financial information regarding the costs incurred for early stage pre-clinical and drug discovery programs on a program-specific basis prior to the clinical development stage.

We expect our research and development expenses to increase in the near term as compared to prior year periods as we continue to focus our resources toward (i) progressing our rusfertide program into late stage clinical trials and preparing for regulatory filings and commercialization, and (ii) advancing our pre-clinical and drug discovery research programs, including progressing our recently nominated product development candidate PN-881 through IND-enabling studies, or foreign equivalents. We do not intend to dedicate further internal resources to clinical development or contract manufacturing activities for our PN-943 clinical program. The process of conducting research, identifying potential product candidates, conducting pre-clinical studies and clinical trials necessary to obtain regulatory approval and commencing pre-commercialization activities is costly and time intensive. We may never succeed in achieving marketing approval for our product candidates regardless of our costs and efforts. The probability of success of our product candidates may be affected by numerous factors, including pre-clinical data, clinical data, competition, manufacturing capability, our cost of goods to be sold, our ability to receive, and the timing of, regulatory approvals, market conditions, and our ability to successfully commercialize our products if they are approved for marketing. As a result, we are unable to determine the duration and completion costs of our research and development projects or when and to what extent we will be able to generate revenue from the commercialization and sale of any of our product candidates. Our research and development programs are subject to change from time to time as we evaluate our priorities and available resources.

General and Administrative Expenses

General and administrative expenses consist of personnel costs, allocated facilities costs and other expenses for outside professional services, including legal, human resources, audit and accounting services, IT and pre-commercialization expenses, including selling and marketing costs. Personnel costs consist of salaries, benefits and stock-based compensation. Allocated expenses consist of expenses for rent and maintenance of facilities, information technology, depreciation and amortization expense and other administrative supplies. We expect to continue to incur expenses to support our continued operations as a public company, including expenses related to compliance with the rules and regulations of the SEC and those of the national securities exchange on which our securities are traded, insurance expenses, investor relations expenses, audit fees, professional services and general overhead and administrative costs.

Interest Income

Interest income consists of interest earned on our cash, cash equivalents, and marketable securities, which is comprised of contractual interest, premium amortization and discount accretion.

Other Income (Expense), Net

Other income (expense), net consists primarily of amounts related to foreign exchange gains and losses and related items.

68

Table of Contents

Results of Operations

​

Comparison of the Years Ended December 31, 2024 and 2023

*Percentage not meaningful.

(1) Includes $20.9 million and $17.1 million of non-cash stock-based compensation expense for the years ended December 31, 2024 and 2023, respectively.

(2) Includes $16.6 million and $12.2 million of non-cash stock-based compensation expense for the years ended December 31, 2024 and 2023, respectively.

​

License and Collaboration Revenue

License and collaboration revenue was comprised of the following for the years presented:

*Percentage not meaningful.

​

License and collaboration revenue increased by $374.4 million from $60.0 million for the year ended December 31, 2023 to $434.4 million for the year ended December 31, 2024.

​

Takeda Collaboration Agreement revenue of $269.4 million for the year ended December 31, 2024 was comprised of (i) $254.1 million of the $300.0 million upfront cash payment allocated to the delivery of the rusfertide license to Takeda upon effectiveness of the agreement in March 2024, and (ii) $15.3 million allocated to development services provided by us during the period based on the cost input method. The remaining balance of $30.6 million was recorded as deferred revenue as of December 31, 2024, which will be recognized over time based on a measure of our efforts toward satisfying our performance obligation relative to the total expected efforts or inputs to satisfy the performance obligation (e.g. costs incurred compared to total budget).

​

JNJ License and Collaboration Agreement revenue represents the achievement of non-refundable milestone payments pursuant to the JNJ License and Collaboration Agreement, as amended in November 2024, of $165.0 million and $60.0 million for the years ended December 31, 2024 and 2023, respectively.

​

69

Table of Contents

We do not have any commercialized products, and our revenue is derived from licensing and collaboration agreements. Revenue from licensing and collaboration agreements, by its very nature, is highly variable and dependent upon factors such as the timing of when regulatory and sales milestones are achieved, if at all, and the accounting for any upfront payments and performance obligations associated with any existing or new agreements.

As discussed above, our revenue for the year ended December 31, 2024 was significantly higher than in prior years due to the partial recognition of an upfront payment of $300.0 million upon execution of the Takeda Collaboration Agreement and the achievement of a $165.0 million milestone pursuant to the terms of the JNJ License and Collaboration Agreement, as amended in November 2024. Our revenue for the year ended December 31, 2025 is expected to be comprised of (i) the proportionate recognition of the $30.6 million recorded in deferred revenue as of December 31, 2024, and (ii) any milestones achieved during the year, which are expected to be substantially lower than in 2024. Accordingly, revenue in 2025 is expected to reduce significantly, which will also impact our net income.

Research and Development Expenses

​

Research and development expenses increased $18.0 million, or 15%, from $120.2 million for the year ended December 31, 2023 to $138.1 million for the year ended December 31, 2024. The increase was primarily due to an increase of $19.0 million in pre-clinical and drug discovery research expense, including costs related to PN-881, our recently nominated IL-17 development candidate, partially offset by a decrease of $0.9 million in expenses for our PN-943 program as further development work was deprioritized in 2023.

We had 98 and 85 full-time equivalent research and development employees as of December 31, 2024 and 2023, respectively. Research and development personnel-related expenses for the year ended December 31, 2024 increased by $10.0 million as compared to the year ended December 31, 2023, including increases of $6.1 million in personnel-related expenses and $3.9 million in stock-based compensation expense.

General and Administrative Expenses

General and administrative expenses increased $10.0 million, or 30%, from $33.5 million for the year ended December 31, 2023 to $43.5 million for the year ended December 31, 2024. This increase was primarily due to a $4.6 million increase in advisory and legal fees related to the Takeda Collaboration agreement and a $4.4 million increase in stock-based compensation expense.

We had 28 and 27 full-time equivalent general and administrative employees as of December 31, 2024 and 2023, respectively.

Interest Income

Interest income increased $11.4 million, or 77%, from $14.9 million for the year ended December 31, 2023 to $26.3 million for the year ended December 31, 2024. This increase was primarily due to higher invested balances, including the $300.0 million one-time, nonrefundable upfront payment received under the Takeda Collaboration Agreement in April 2024.

​

​

​

70

Table of Contents

Income Tax Expense

​

Income tax expense was $4.2 million and $0 for the year ended December 31, 2024 and 2023, respectively. Income tax expense for the year ended December 31, 2024 was a result of taxable income from the recognition of revenue in connection with the Takeda Collaboration Agreement and the JNJ License and Collaboration Agreement. The effective tax rate was 1.5% and 0.0% for the years ended December 31, 2024 and 2023, respectively.

​

Comparison of the Years Ended December 31, 2023 and 2022

See Part II, Item 7—Results of Operations—Comparison of the Years Ended December 31, 2023 and 2022 in our Annual Report on Form 10-K for the year ended December 31, 2023, filed on February 17, 2024, for a discussion of our results of operations for the year ended December 31, 2023 compared to the year ended December 31, 2022.

​

Liquidity and Capital Resources

Sources of Liquidity

Historically we have funded our operations primarily from net proceeds from the sale of shares of our common stock and receipt of payments under collaboration agreements.

Proceeds from Sales of Our Common Stock

​

In April 2023, we completed an underwritten public offering of 5,000,000 shares of our common stock at a public offering price of $20.00 per share and issued an additional 750,000 shares of common stock at a price of $20.00 per share following the underwriters’ exercise of their option to purchase additional shares. Net proceeds, after deducting underwriting commissions and offering costs paid by us, were approximately $107.8 million.

​

In August 2022, we entered into an Open Market Sale AgreementSM , pursuant to which we may offer and sell up to $100.0 million shares of our common stock from time to time in “at-the-market” offerings (the “2022 ATM Facility”). During the year ended December 31, 2023, we sold 1,749,199 shares of our common stock under the 2022 ATM Facility for net proceeds of $24.3 million, after deducting issuance costs. There were no sales of our common stock under the 2022 ATM Facility during the years ended December 31, 2024 and 2022.

​

Pre-Funded Warrants

​

In August 2018, we entered into a Securities Purchase Agreement with certain accredited investors (each, an “Investor” and, collectively, the “Investors”), pursuant to which we sold an aggregate of 2,750,000 shares of our common stock at a price of $8.00 per share for aggregate net proceeds of $21.7 million, after deducting offering expenses payable by us. In a concurrent private placement, we issued the Investors warrants to purchase an aggregate of 2,750,000 shares of our common stock (each, a “Warrant” and, collectively, the “Warrants”). Each Warrant was exercisable from August 8, 2018 through August 8, 2023. Warrants to purchase 1,375,000 shares of our common stock had an exercise price of $10.00 per share and Warrants to purchase 1,375,000 shares of our common stock had an exercise price of $15.00 per share.

​

In August 2023, prior to the expiration of the Warrants, we entered into certain agreements with the Investors and their affiliates under which we agreed to allow the Warrants to be exercised in exchange for pre-funded warrants representing the same number of Warrant Shares underlying the Warrants with an exercise price of $0.001 per share (the “Pre-Funded Warrants”). Subsequent to the execution of the agreements and prior to the expiration of the Warrants, all outstanding Warrants were exercised for gross proceeds of $34.4 million in exchange for 44,748 shares of our common stock and Pre-Funded Warrants to purchase 2,705,252 shares of common stock (subject to adjustment in the event of any stock dividends and splits, reverse stock split, recapitalization, reorganization or similar transaction, as described in the Pre-Funded Warrants) with an exercise price of $0.001 per share. The Pre-Funded Warrants will expire upon the day they are exercised in full. The Pre-Funded Warrants are exercisable at any time prior to expiration except that the Pre-Funded Warrants cannot be exercised by the Investors if, after giving effect thereto, the Investors would beneficially

71

Table of Contents

own more than 9.99% of our common stock, subject to certain exceptions. The common stock and Pre-Funded Warrants met the criteria for equity classification and the net proceeds from the transaction were recorded as a credit to additional paid-in capital. In accordance with Accounting Standards Topic 260, Earnings Per Share, outstanding Pre-Funded Warrants are included in the computation of basic net loss per share because the exercise price is negligible, and they are fully vested and exercisable after the original issuance date. During the year ended December 31, 2024, Pre-Funded Warrants to purchase 1,205,252 shares were net exercised, resulting in the issuance of 1,205,225 shares of common stock. As of December 31, 2024, Pre-Funded Warrants to purchase 1,500,000 shares of common stock remained outstanding.

Receipt of Payments Under Collaboration Agreements

​

In March 2024, we earned a $300.0 million one-time, nonrefundable upfront payment from Takeda upon the closing of the Takeda Collaboration Agreement, which we received in April 2024.

​

Pursuant to the Takeda Collaboration Agreement, we may be eligible to receive clinical development, regulatory and sales milestones, if and when achieved. Upcoming potential development milestones under the Takeda Collaboration Agreement include:

​

Under the JNJ License and Collaboration Agreement, we earned a $50.0 million milestone payment upon the dosing of the third patient in the ICONIC-TOTAL Phase 3 trial in late October 2023, which we received in December 2023. We earned a $10.0 million milestone payment upon the dosing of the third patient in the ANTHEM Phase 2b trial in patients with UC in December 2023, which we received in January 2024. The JNJ License and Collaboration Agreement was further amended in November 2024 to:

We earned the $165.0 million milestone payment described above during the fourth quarter of 2024. We earned a total of $337.5 million in nonrefundable payments from JNJ from 2017 through December 31, 2024. We have also received payments for services provided under the collaboration agreement and we may make in-kind payment reimbursements to JNJ for certain costs they have incurred pursuant to the cost sharing terms of the agreement.

Pursuant to the JNJ License and Collaboration Agreement, we may be eligible to receive clinical development, regulatory and sales milestones, if and when achieved. Upcoming potential development milestones under the JNJ License and Collaboration Agreement include:

72

Table of Contents

Capital Requirements

As of December 31, 2024, we had $559.2 million of cash, cash equivalents and marketable securities and an accumulated deficit of $340.5 million. Our capital expenditures were $1.4 million, $0.6 million and $0.8 million for the years ended December 31, 2024, 2023 and 2022, respectively. Our primary uses of cash are to fund our operating expenses, including our research and development expenditures and general and administrative costs. We expect that our existing cash, cash equivalents and marketable securities will be sufficient to fund our operations for at least the next twelve months from the date of this Annual Report on Form 10-K based on current operating plans and financial forecasts.

We may require additional funding to advance our early discovery pipeline and to develop, acquire, or in-license other potential product candidates. Our future funding requirements will depend on many factors, including:

Such additional funding may come from various sources, including raising additional capital, seeking access to debt, and seeking additional collaborative or other arrangements with partners, but such funding may not be available on terms acceptable to us, if at all. As discussed in Part I, Item 1A, “Risk Factors,” we are currently operating in a period of economic uncertainty and capital markets disruption, which has been significantly impacted by domestic and global monetary and fiscal policy, changes in trade policies, including tariffs or other restrictions or the threat of such actions, geopolitical instability, inflationary pressures, high interest rates and banking and other financial institution instability, among other factors. A future recession or market correction, including those due to significant geopolitical or macroeconomic events, could materially affect our business and our access to credit and financial markets.

73

Table of Contents

Any failure to raise capital as and when needed could have a negative impact on our financial condition and on our ability to pursue our business plans and strategies. Further, our operating plans may change, and we may need additional funds to meet operational needs and capital requirements for clinical trials, other research and development activities and pre-commercialization costs. If we do raise additional capital through public or private equity offerings or convertible debt securities, the ownership interest of our existing stockholders could be diluted, and the terms of these securities could include liquidation or other preferences that could adversely affect our stockholders’ rights. If we raise additional capital through debt financing, we could be subject to covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. Because of the numerous risks and uncertainties associated with the development and commercialization of our product candidates, we are unable to fully estimate the amounts of increased capital outlays and operating expenditures associated with our current and anticipated product development programs. For additional information, see Part I, Item 1A, “Risk Factors — Risks Related to our Financial Position and Capital Requirements.”

The following table summarizes our cash flows for the periods indicated:

​

Cash Provided by (Used in) Operating Activities

Cash provided by operating activities for the year ended December 31, 2024 was $184.2 million and consisted primarily of our net income of $275.2 million and certain non-cash items, including $37.6 million of stock-based compensation, partially offset by a net change of $122.6 million in net operating assets and liabilities. The change in net operating assets and liabilities was driven primarily by a change of $155.0 million in receivable from a collaboration partner related to a milestone payment under the JNJ License and Collaboration Agreement, partially offset by a change of $30.6 million in deferred revenue related to the Takeda Collaboration Agreement. The $254.4 million increase in cash provided by operating activities during the year ended December 31, 2024, as compared to the year ended December 31, 2023, was primarily due to the receipt of a $300.0 million one-time, non-refundable upfront payment related to the Takeda Collaboration Agreement.

Cash used in operating activities for the year ended December 31, 2023 was $70.2 million and consisted primarily of our net loss of $79.0 million and a net change of $19.5 million in net operating assets and liabilities, partially offset by certain non-cash items, including $29.2 million of stock-based compensation expense. The $37.9 million decrease in cash used in operating activities for the year ended December 31, 2023, as compared to the year ended December 31, 2022, was primarily due to a $48.4 million decrease in our net loss and a $5.1 million increase in stock-based compensation expense, partially offset by a $4.0 million decrease in accretion of discount on marketable securities and an $11.7 million net change in net operating assets and liabilities.

Cash (Used in) Provided by Investing Activities

Cash used in investing activities for the year ended December 31, 2024 was $299.5 million and consisted of purchases of securities of $621.7 million and purchases of property and equipment of $1.4 million, partially offset by proceeds from maturities of marketable securities of $323.6 million. The $260.2 million increase in cash used in investing activities for the year ended December 31, 2024, as compared to the year ended December 31, 2023, was primarily due to the investment made with a portion of the proceeds from the $300.0 million payment from the Takeda Collaboration Agreement. Purchases of property and equipment were primarily related to purchases of leasehold improvements and laboratory equipment.

74

Table of Contents

Cash used in investing activities for the year ended December 31, 2023 was $39.3 million and consisted of purchases of marketable securities of $191.1 million and purchases of property and equipment of $0.6 million, partially offset by proceeds from maturities of marketable securities of $152.4 million. The $130.7 million decrease in cash provided by investing activities for the year ended December 31, 2023, as compared to the year ended December 31, 2022, was primarily related to a decrease in the net activity of purchases and maturities of marketable securities. Purchases of property and equipment were primarily related to purchases of laboratory and computer equipment.

Cash Provided by Financing Activities

Cash provided by financing activities for the year ended December 31, 2024 was $25.9 million and consisted of net cash proceeds of $26.5 million from the issuance of common stock upon exercises of stock options and purchases of stock under our employee stock purchase plan (“ESPP”), partially offset by $0.6 million in tax withholding payments related to the net settlement of restricted stock units. The $144.6 million decrease in cash provided by financing activities for year ended December 31, 2024, as compared to the year ended December 31, 2023, was primarily due to $107.8 million of proceeds received from a public offering of our common stock in April 2023, $24.3 million of proceeds from ATM sales of our common stock in 2023, and $34.3 million in proceeds from exercises of warrants in 2023 in exchange for Pre-Funded Warrants and common stock. These changes were partially offset by a $21.7 million increase in proceeds from the issuance of common stock upon exercise of options and purchases of common stock under our ESPP.

Cash provided by financing activities for the year ended December 31, 2023 was $170.5 million and consisted primarily of net cash proceeds of $107.8 million from the April 2023 public offering of our common stock, $24.3 million from sales of our common stock under the 2022 ATM Facility, $34.4 million from the exercise of the Warrants in exchange for issuance of Pre-Funded Warrants and common stock, and $4.8 million in proceeds from the issuance of common stock upon exercise of stock options and purchases of common stock under our ESPP. The $151.6 million increase in cash provided by financing activities for the year ended December 31, 2023, as compared to the year ended December 31, 2022, was primarily due to a $107.8 million increase in net cash proceeds from the April 2023 public offering, a $9.7 million increase in cash proceeds from ATM sales and a $34.4 million increase in net cash proceeds from the exercise of the Warrants.

Contractual Obligations and Other Commitments

In the normal course of business, we enter into agreements with contract service providers to assist in the performance of our research and development activities and clinical and commercial manufacturing activities. Subject to the required notice periods and our obligations under certain binding commitments, we can elect to discontinue the work under these agreements at any time. However, the financial terms of some of these agreements may include non-refundable upfront payments, payments by us for options to acquire certain rights, contingent obligations by us for potential development and regulatory milestone payments and/or sales-based milestone payments and royalty payments. These obligations are recorded in our consolidated statements of operations as incurred, which is generally when the corresponding events become probable. Certain payments are contingent upon the occurrence of various future events that have a high degree of uncertainty. We expect to enter into additional clinical development, contract research, clinical and commercial manufacturing, supplier and collaborative research agreements in the future, which may require upfront payments and long-term commitments of capital resources.

​

Our contractual obligations include minimum lease payments under our operating lease obligations. In May 2024, we entered into a third amendment to our facility lease agreement dated as of March 2017 to extend the lease term for our existing office and laboratory space from one to 66 months and to lease approximately 17,700 rentable square feet of additional office space. See Note 8 to the Consolidated Financial Statements elsewhere in this Annual Report on Form 10-K for additional information.

​

Under the Takeda Collaboration Agreement, we may share with Takeda certain development, manufacturing and commercialization costs. The actual amounts that we may pay Takeda or that Takeda may pay us will depend on a number of factors, some of which are outside of our control and some of which are contingent upon the success, if

75

Table of Contents

achieved, of certain development and regulatory activities. See Note 3 to the Consolidated Financial Statements elsewhere in this Annual Report on Form 10-K for additional information.

In January 2020, we initiated arbitration proceedings with the International Court of Arbitration of the International Chamber of Commerce against Zealand Pharma A/S (“Zealand”) related to a collaboration agreement we and Zealand entered into in 2012 and terminated in 2014. The agreement provides for certain post-termination payment obligations to Zealand with respect to compounds related to the collaboration that we elect to further develop and that meet specified conditions. In August 2021, we and Zealand agreed to resolve the dispute and reached an Arbitration Resolution Agreement. Under the Arbitration Resolution Agreement, we recognized $4.0 million in development milestone payments to Zealand in the third quarter of 2021 and are obligated to pay Zealand certain milestone and royalty payments for rusfertide. The potential future payments include (i) up to $2.75 million in future development milestone payments, (ii) a low single digit royalty on worldwide net sales, and (iii) sales milestones for achievement of annual net sales amounts in specific geographies. See Note 7 and Note 9 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

​

Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations

​

Overview

We are a biopharmaceutical company with peptide-based new chemical entities rusfertide and JNJ-2113 (formerly PN-235) in advanced stages of development, both derived from our proprietary peptide technology platform. Our clinical programs fall into two broad categories of diseases: (i) hematology and blood disorders, and (ii) inflammatory and immunomodulatory (“I&I”) diseases.

Rusfertide

​

Our most advanced clinical asset, rusfertide (generic name for PTG-300), is an injectable hepcidin mimetic in development for the potential treatment of polycythemia vera (“PV”) and other blood disorders. Hepcidin is a key hormone in regulating iron equilibrium and is critical to the proper development of red blood cells (“RBCs”). Rusfertide mimics the effect of the natural hormone hepcidin, but with greater potency, solubility and stability. Data from our rusfertide Phase 2 clinical trials presented at medical conferences from 2021 through 2023 provided evidence regarding the potential of rusfertide for managing hematocrit, reducing thrombotic risk and improving iron deficiency symptoms. Rusfertide has a unique mechanism of action in the potential treatment of PV, which may enable it to specifically decrease and maintain hematocrit levels within the range of recommended clinical guidelines without causing the iron deficiency that can occur with frequent phlebotomy. Our rusfertide Phase 2 clinical trials include the following:

​

​

​

​

In March 2023, we announced positive topline results from the blinded, placebo-controlled, randomized withdrawal portion of the REVIVE trial. Subjects receiving rusfertide achieved statistically significant improvements versus placebo in the trial’s primary endpoint. The double-blind, placebo-controlled, 12-week randomized withdrawal portion was included as Part 2 of the REVIVE trial to evaluate rusfertide in PV patients with frequent phlebotomy requirements. In the REVIVE trial, subjects were initially enrolled in the 28-week open label dose-titration and efficacy evaluation Part 1 of the study, followed by 1:1 randomization of 53 subjects to placebo versus rusfertide therapy for a subsequent duration of 12 weeks. More subjects receiving rusfertide during the blinded randomized withdrawal portion of the REVIVE trial were responders compared with placebo (69.2% versus 18.5%, p=0.0003). A trial subject was defined as a responder if the subject completed 12 weeks of double-blind treatment while maintaining hematocrit control without phlebotomy eligibility and without phlebotomy. During the 12 weeks of the blinded randomized withdrawal, 92.3% of subjects on rusfertide (24 out of 26) were not phlebotomized.

​

Data from the REVIVE trial presented at the European Hematology Association Congress in June 2023 suggested that rusfertide treatment results in highly statistically significant reduction in the need for therapeutic phlebotomy in phlebotomy-dependent patients, leading to rapid, sustained and durable control of hematocrit levels below 45%. Rusfertide was well tolerated, with localized injection site reactions (“ISRs”) comprising the majority of adverse events.

​

Long-term follow up data from the REVIVE trial presented at the American Society of Hematology (“ASH”) Annual Meeting in December 2023 showed durable hematocrit control, decreased phlebotomy use, long-term tolerability, and no new safety signals in patients with PV. An analysis of the PACIFIC Phase 2 trial was also presented that indicated rusfertide improves markers of iron deficiency in patients with PV. In addition, data was presented

56

Table of Contents

regarding the prevalence of thromboembolic events and secondary cancers in PV patients not treated with rusfertide. In February 2024, the full Phase 2 REVIVE trial results, including efficacy and safety data, were published in the New England Journal of Medicine.

We have initiated VERIFY, a global double-blind, placebo-controlled Phase 3 clinical trial of rusfertide in PV for approximately 250 patients. We expect enrollment completion by the end of the first quarter of 2024. By the end of 2024, we expect to receive the results of our ongoing two-year study evaluating the carcinogenicity potential of rusfertide when administered once weekly to rats.

​

In January 2024, we entered into a worldwide license and collaboration agreement for the development and commercialization of rusfertide with Takeda, which is yet to become effective. Under the terms of the agreement, we expect to receive an upfront payment of $300 million and to be eligible to receive additional worldwide development, regulatory and commercial milestone payments of up to $330 million, as well as tiered royalties from 10% to 17% on ex-U.S. net sales. We expect to be responsible for research and development through the completion of the Phase 3 VERIFY trial and U.S. regulatory approval. Takeda is expected to have rights for ex-U.S. development and to be responsible for leading global commercialization activities. We and Takeda expect to also share equally in U.S. profits and losses (50% to us and 50% to Takeda).

Further details related to the agreement, including our right to opt-out of the 50:50 U.S. profit and loss sharing arrangement in exchange for enhanced economics, are available in our Current Report on Form 8-K filed on January 31, 2024 with the U.S. Securities and Exchange Commission (the “SEC”). The effectiveness of the agreement is dependent on and subject to the termination or expiration of any applicable waiting periods under the Hart-Scott-Rodino Act (the “HSR Act”).

JNJ-2113 (formerly PN-235)

​

Our partnered Interleukin-23 receptor (“IL-23R”) antagonist compound JNJ-2113 is an orally delivered investigational drug that is designed to block biological pathways currently targeted by marketed injectable antibody drugs. Our orally stable peptide approach may offer a targeted therapeutic approach for gastrointestinal (“GI”) and systemic compartments as needed. We believe that, compared to antibody drugs, JNJ-2113 has the potential to provide clinical improvement in an oral medication with increased convenience and compliance and the opportunity for the earlier introduction of targeted oral therapy.

​

In May 2017, we entered into a worldwide license and collaboration agreement with JNJ, formerly Janssen, to co-develop and co-detail our IL-23R antagonist compounds, including PTG-200 (JNJ-67864238) and certain related compounds for all indications, including inflammatory bowel disease (“IBD”). PTG-200 was a first-generation investigational, orally delivered, IL-23R antagonist for the treatment of IBD. The agreement with JNJ was amended in May 2019 to expand the collaboration by supporting efforts towards second-generation IL-23R antagonists; and in July 2021 to, among other things, enable JNJ to independently research and develop collaboration compounds for multiple indications in the IL-23 pathway and further align our financial interests.

​

Following completion of a Phase 1 trial in the fourth quarter of 2021, a decision was made by JNJ to advance second-generation product candidate JNJ-2113 (JNJ-77242113) based on its superior potency and overall pharmacokinetic and pharmacodynamic profile.

​

In February 2022, JNJ initiated FRONTIER 1, a 255-patient Phase 2b clinical trial of JNJ-2113 in moderate-to-severe plaque psoriasis, which was completed in December 2022. FRONTIER 1 was a randomized, multicenter, double-blind, placebo-controlled trial that evaluated three once-daily dosages and two twice-daily dosages of JNJ-2113 taken orally. The primary endpoint of the trial was the proportion of patients achieving PASI-75 (a 75% improvement in skin lesions as measured by the Psoriasis Area and Severity Index (“PASI”)) at 16 weeks. In July 2023, we announced updated positive topline results from the trial, which were presented by JNJ at the World Congress of Dermatology in Singapore. JNJ-2113 achieved the trial’s primary and secondary efficacy endpoints. A statistically significant greater proportion of patients who received JNJ-2113 achieved PASI-75 as well as PASI-90 and PASI-100 (90% and 100% improvement, respectively, in skin lesions as measured by the PASI) responses compared to placebo at week 16 in all

57

Table of Contents

five of the trial’s treatment groups. A clear dose response was observed across an eight-fold dose range. Treatment was well tolerated, with no meaningful difference in frequency of adverse events across treatment groups versus placebo.

JNJ has initiated five additional JNJ-2113 trials, including:

All of the trials in the ICONIC program will use the once-daily, immediate release formulation of JNJ-2113 from the previously completed FRONTIER 1 study. The estimated primary completion date for the ICONIC-LEAD and ICONIC-TOTAL trials is November 2024 (see NCT06095115 and NCT06095102, respectively, at clinicaltrials.gov). The estimated primary completion dates for the ICONIC-ADVANCE 1 and ICONIC-ADVANCE 2 trials are March 2025 and April 2025, respectively (see NCT06143878 and NCT06220604, respectively, at clinicaltrials.gov). The estimated primary completion date for the ANTHEM-UC trial is May 2025 (see NCT06049017 at clinicaltrials.gov). Other Phase 2 trials of JNJ-2113 include the SUMMIT trial for the treatment of moderate-to-severe plaque psoriasis and FRONTIER 2, a long-term extension study, both of which were completed by JNJ in 2023.

We earned a $50.0 million milestone payment upon dosing of the third patient in the ICONIC-TOTAL Phase 3 trial in late October 2023, which we received in December 2023. We earned a $10.0 million milestone payment upon the dosing of the third patient in the ANTHEM Phase 2b trial in UC in December 2023, which we received in January 2024. To date, we have earned $172.5 million in nonrefundable payments from JNJ. We remain eligible for up to approximately $795.0 million in future development and sales milestone payments, inclusive of the potential milestones listed below:

58

Table of Contents

We also remain eligible to receive upward tiering royalties on net product sales at percentages ranging from six percent to ten percent, with ten percent applicable for net sales over $4.0 billion.

At JNJ’s Enterprise Business Review in December 2023, JNJ highlighted JNJ-2113 as a potential first- and best-in class targeted oral IL-23 peptide antagonist with potential across multiple indications, including plaque psoriasis, psoriatic arthritis and IBD, with potential peak year sales projection of $5.0 billion plus. JNJ IL-23 monoclonal antibody (“mAb”) drugs Stelara and Tremfya generated $14.0 billion in revenues in 2023.

In February 2024, the JNJ-2113 Phase 2b FRONTIER 1 trial results in adults living with moderate-to-severe plaque psoriasis were published in the New England Journal of Medicine.

PN-943

​

PN-943 is a wholly owned investigational orally delivered gut-restricted alpha 4 beta 7 specific integrin antagonist for IBD. We completed a Phase 2 trial of PN-943 in patients with moderate to severe UC in early 2023. We do not intend to dedicate further internal resources to clinical development or contract manufacturing activities for our PN-943 clinical program.

​

Discovery Platform

​

Our clinical assets are all derived from our proprietary discovery platform. Our platform enables us to engineer novel, structurally constrained peptides that are designed to retain key advantages of both orally delivered small molecules and injectable antibody drugs in an effort to overcome many of their limitations as therapeutic agents. Importantly, constrained peptides can be designed to potentially alleviate the fundamental instability inherent in traditional peptides to allow different delivery forms, such as oral, subcutaneous, intravenous, and rectal. Our discovery pipeline has strategically focused on i) hematology and blood disorders and ii) I&I diseases. For example, we have a pre-clinical stage program to identify an orally active hepcidin mimetic, which we believe to be complementary to the injectable rusfertide for offering the best treatment options for PV, hereditary hemochromatosis and other potential erythropoietic and iron imbalance disorders.

​

In January 2024, we announced a new oral Interleukin-17 (“IL-17”) peptide antagonist program targeting three IL-17 dimers (IL-17 AA, AF and FF) which may offer potential treatment options for hidradenitis suppurativa (“HS”), spondyloarthritis (“SpA”), plaque psoriasis and psoriatic arthritis. Our preliminary results showed similar or better in vitro potency than the currently approved drugs Cosentyx® and Taltz®. We expect to nominate a development candidate by the end of 2024.

​

Business Update

​

We are currently operating in a period of economic uncertainty and capital markets disruption, which has been impacted by domestic and global monetary and fiscal policy, geopolitical instability, ongoing military conflicts, including between Russia and Ukraine and in Israel and surrounding areas, rising tensions between China and Taiwan, a recessionary environment, historically high domestic and global inflation, high interest rates and instability in banks and other financial institutions. Our future results of operations and liquidity could be adversely impacted by outbreaks of disease, epidemics and pandemics, including potential further delays in existing and planned clinical trials, difficulty in recruiting patients for these clinical trials, delays in manufacturing and collaboration activities and supply chain disruptions. The conflict in Ukraine has exacerbated market disruptions, including significant volatility in commodity prices, as well as supply chain interruptions, and has contributed to record inflation globally. The U.S. Federal Reserve and other central banks may be unable to contain inflation through more restrictive monetary policy and inflation may increase or continue for a prolonged period of time. Inflationary factors, such as increases in the cost of clinical supplies, interest rates, overhead costs and transportation costs may adversely affect our operating results. Also, the failure of Silicon Valley Bank and other regional banks in the United States during the first half of 2023 has given rise to uncertainty in the security of amounts in deposit accounts uninsured by the Federal Deposit Insurance Corporation. We continue to monitor these events and the potential impact on our business. Although we do not believe that inflation has had a material adverse impact on our financial position or results of operations to date, our financial position or results of

59

Table of Contents

operations may be adversely affected in the future due to numerous factors, including domestic and global monetary and fiscal policy, supply chain constraints, consequences associated with ongoing military conflicts, including between Russia and Ukraine and in Israel and surrounding areas, and other factors, and such factors may lead to increases in the cost of manufacturing our product candidates and delays in initiating trials.

Operations

We have incurred net losses in each year since inception and we do not anticipate achieving sustained profitability in the foreseeable future. Our net losses were $79.0 million, $127.4 million and $125.6 million for the years ended December 31, 2023, 2022 and 2021, respectively. As of December 31, 2023, we had an accumulated deficit of $615.7 million. Substantially all of our net losses have resulted from costs incurred in connection with our research and development programs and from general and administrative costs associated with our operations. We expect to continue to incur significant research and development expenses and other expenses related to our ongoing operations, product development, and pre-commercialization activities. As a result, we expect to continue to incur losses in the future as we continue our development of, and seek regulatory approval for, our product candidates.

JNJ License and Collaboration Agreement

On July 27, 2021, we entered into an Amended and Restated License and Collaboration Agreement (the “Restated Agreement”) with JNJ, which amended and restated the License and Collaboration Agreement, effective July 13, 2017, by and between us and JNJ (the “Original Agreement”), as amended by the first amendment, effective May 7, 2019 (the “First Amendment”). Prior to January 1, 2023, JNJ was a related party to us as Johnson & Johnson Innovation - JJDC, Inc. was a significant (greater than 5%) stockholder of the Company, and both companies are subsidiaries of Johnson & Johnson. Upon the effectiveness of the Original Agreement, we received a non-refundable, upfront cash payment of $50.0 million from JNJ. Upon the effectiveness of the First Amendment, we received a $25.0 million payment from JNJ in 2019. In the first quarter of 2020, we received a $5.0 million payment triggered by the successful nomination of a second-generation IL-23R antagonist development compound. In the fourth quarter of 2021, we received a $7.5 million milestone payment from JNJ triggered by completion of the data collection for JNJ-2113 Phase 1 activities. In the second quarter of 2022, we received a $25.0 million milestone payment in connection with the dosing of a third patient in FRONTIER 1 during the first quarter of 2022. In the fourth quarter of 2023, we received a $50.0 million milestone payment from JNJ in connection with the dosing of the third patient in the ICONIC-LEAD Phase 3 clinical trial of JNJ-2113 in patients with moderate-to-severe psoriasis. In the first quarter of 2024, we received a $10.0 million milestone payment from JNJ in connection with the dosing of the third patient in connection with the ANTHEM Phase 2b clinical trial of JNJ-2113 in patients with UC in the fourth quarter of 2023. We have earned a total of $172.5 million in non-refundable payments from JNJ since the inception of the Restated Agreement in 2017 through the date of this report. See Note 3 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

Takeda Collaboration Agreement

In January 2024, we entered into a worldwide license and collaboration agreement for the development and commercialization of rusfertide with Takeda (the “Takeda Collaboration Agreement”), which is yet to become effective. See Note 15 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

Critical Accounting Polices and Estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). The preparation of these consolidated financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities at the date of the consolidated financial statements, as well as the reported revenue generated, and the expenses incurred during the reporting periods. Our estimates are based on our historical experience and on various other factors that we believe are reasonable under the circumstances, and the results of which form the basis for making judgments about the carrying

60

Table of Contents

value of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions. We believe that the accounting policies discussed below are critical to understanding our historical and future performance, as these policies relate to the more significant areas involving management’s judgments and estimates.

Use of Estimates

The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, we evaluate our estimates, including those related to revenue recognition, accruals for research and development activities, stock-based compensation, income taxes, marketable securities and leases. Estimates related to revenue recognition include actual costs incurred versus total estimated costs of our deliverables to determine percentage of completion in addition to the application and estimates of potential revenue constraints in the determination of the transaction price under our license and collaboration agreements. We base these estimates on historical and anticipated results, trends and various other assumptions that we believe are reasonable under the circumstances, including assumptions as to forecasted amounts and future events.

There has been uncertainty and disruption in the global economy and financial markets due to a number of factors, including geopolitical instability, inflationary pressures, high interest rates, instability in banks and other financial institutions and domestic and global monetary and fiscal policy. We have taken into consideration any known impacts of these factors in our accounting estimates to date and are not aware of any additional specific events or circumstances that would require any additional updates to our estimates or judgments or a revision of the carrying value of our assets or liabilities as of the date of the filing of this Annual Report on Form 10-K. These estimates may change as new events occur, circumstances change, and additional information is obtained. Actual results could differ materially from these estimates under different assumptions or conditions.

Revenue Recognition

Under Accounting Standards Codification Topic 606, Revenue from Contracts with Customers (“ASC 606”), we recognize revenue when our customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. To determine revenue recognition for arrangements that we determine are within the scope of ASC 606, we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) we satisfy a performance obligation. We apply the five-step model to contracts when it is probable that we will collect the consideration we are entitled to in exchange for the goods or services we transfer to the customer. At contract inception, we assess the goods or services promised within each contract, determine those that are performance obligations, and assess whether each promised good or service is distinct. We then recognize as revenue the amount of the transaction price that is allocated to the respective performance obligations when (or as) the performance obligations are satisfied. We constrain our estimate of the transaction price up to the amount (the “variable consideration constraint”) that a significant reversal of recognized revenue is not probable.

Licenses of intellectual property: If a license to our intellectual property is determined to be distinct from the other performance obligations identified in an arrangement, we recognize revenue from non-refundable, upfront fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, we utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring proportional performance for purposes of recognizing revenue from non-refundable, upfront fees. We evaluate the measure of proportional performance for each reporting period and, if necessary, adjust the measure of performance and related revenue recognition.

Milestone payments: At the inception of each arrangement or amendment that includes development, regulatory or commercial milestone payments, we evaluate whether the milestones are considered probable of being reached and

61

Table of Contents

estimate the amount to be included in the transaction price. ASC 606 suggests two alternatives to use when estimating the amount of variable consideration: the expected value method and the most likely amount method. Under the expected value method, an entity considers the sum of probability-weighted amounts in a range of possible consideration amounts. Under the most likely amount method, an entity considers the single most likely amount in a range of possible consideration amounts. Whichever method is used should be consistently applied throughout the life of the contract; however, it is not necessary for us to use the same approach for all contracts. We expect to use the most likely amount method for development and regulatory milestone payments. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within our control or the control of the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. If there is more than one performance obligation, the transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis. We recognize revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, we re-evaluate the probability or achievement of each such milestone and any related constraint, and if necessary, adjust our estimates of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment.

Any potential milestone payments that we determine are not associated with performance obligations as defined under the contract are excluded from the transaction price and are recognized as the triggering event occurs.

Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, where the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

Upfront payments and fees are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until we perform our obligations under these arrangements. Amounts payable to us are recorded as accounts receivable when our right to consideration is unconditional. Amounts payable to us and not yet billed to the collaboration partner are recorded as contract assets. We do not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less.

Contractual cost sharing payments made to a customer or collaboration partner are accounted for as a reduction to the transaction price if such payments are not related to distinct goods or services received from the customer or collaboration partner.

Contracts may be amended to account for changes in contract specifications and requirements. Contract modifications exist when the amendment either creates new, or changes existing, enforceable rights and obligations. When contract modifications create new performance obligations and the increase in consideration approximates the standalone selling price for goods and services related to such new performance obligations, as adjusted for specific facts and circumstances of the contract, the modification is considered to be a separate contract and revenue is recognized prospectively. If a contract modification is not accounted for as a separate contract, we account for the promised goods or services not yet transferred at the date of the contract modification (the remaining promised goods or services) prospectively, as if it were a termination of the existing contract and the creation of a new contract, if the remaining goods or services are distinct from the goods or services transferred on or before the date of the contract modification. We account for a contract modification as if it were a part of the existing contract if the remaining goods or services are not distinct and, therefore, form part of a single performance obligation that is partially satisfied at the date of the contract modification. In such case the effect that the contract modification has on the transaction price, and on the entity’s measure of progress toward complete satisfaction of the performance obligation, is recognized as an adjustment to revenue (either as an increase in or a reduction of revenue) at the date of the contract modification (the adjustment to revenue is made on a cumulative catch-up basis).

62

Table of Contents

Research and Development Costs

Research and development costs are expensed as incurred, unless there is an alternate future use in other research and development projects or otherwise. Research and development costs include salaries and benefits, stock-based compensation expense, laboratory supplies and facility-related overhead, outside contracted services, including clinical trial costs, manufacturing and process development costs for both clinical and pre-clinical materials, research costs, development milestone payments under license and collaboration agreements, and other consulting services.

We accrue for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of pre-clinical studies and clinical trials, and contract manufacturing activities. We record the estimated costs of research and development activities based upon the estimated services provided but not yet invoiced and we include these costs in accrued expenses and other payables in our consolidated balance sheets and within research and development expense in our consolidated statements of operations. We accrue for these costs based on various factors such as estimates of the work completed and in accordance with agreements established with our third-party service providers. As actual costs become known, we adjust our accrued liabilities. We have not experienced any material differences between accrued liabilities and actual costs incurred. However, the status and timing of actual services performed, number of patients enrolled, the rate of patient enrollment and the number and location of sites activated may vary from our estimates and may result in adjustments to our research and development expenses in future periods. Changes in these estimates that result in material changes to our accruals could materially affect the results of our operations.

Recent Accounting Pronouncements

Information regarding recent accounting pronouncements applicable to us is included in Note 2 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K.

Components of Our Results of Operations

License and Collaboration Revenue

Our license and collaboration revenue is derived from payments we receive under the JNJ License and Collaboration Agreement. See Note 3 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information. For the year ended December 31, 2024, we expect to recognize license and collaboration revenue from payments we are eligible to receive under the Takeda Collaboration Agreement, which is yet to become effective. The effectiveness of the agreement and our receipt of payments thereunder is dependent on and subject to the termination or expiration of any applicable waiting periods under the HSR Act. See Note 15 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

Research and Development Expenses

Research and development expenses represent costs incurred to conduct research, such as the discovery and development of our product candidates. We recognize all research and development costs as they are incurred unless there is an alternative future use in other research and development projects or otherwise. Non-refundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received, rather than when payment has been made. In instances where we enter into agreements with third parties to provide research and development services to us, costs are expensed as services are performed. Amounts due under such arrangements may be either fixed fee or fee for service and may include upfront payments, monthly payments, and payments upon the completion of milestones or the receipt of deliverables.

Research and development expenses consist primarily of the following:

63

Table of Contents

We recognize the amounts related to our Australian research and development refundable cash tax incentive that are not subject to refund provisions as a reduction in research and development expenses. The research and development tax incentives are recognized when there is reasonable assurance that the incentives will be received, the relevant expenditure has been incurred and the amount of the consideration can be reliably measured. We evaluate our eligibility under the tax incentive program as of each balance sheet date and make accruals and related adjustments based on the most current and relevant data available. We may alternatively be eligible for a taxable credit in the form of a non-cash tax incentive. We recognize the amounts from grants under government programs as a reduction of research and development expenses when the related research costs are incurred.

We allocate direct and indirect costs incurred to product candidates when they enter clinical development. For product candidates in clinical development, direct costs consist primarily of clinical, pre-clinical, and drug discovery costs, costs of supplying drug substance and drug product for use in clinical and pre-clinical studies, including clinical manufacturing costs, contract research organization fees, and other contracted services pertaining to specific clinical and pre-clinical studies. Indirect costs allocated to our product candidates on a program-specific basis include research and development employee salaries, benefits, and stock-based compensation, and indirect overhead and other administrative support costs. Program-specific costs are unallocated when the clinical expenses are incurred for our early-stage research and drug discovery projects as our internal resources, employees and infrastructure are not tied to any one research or drug discovery project and are typically deployed across multiple projects. As such, we do not provide financial information regarding the costs incurred for early stage pre-clinical and drug discovery programs on a program-specific basis prior to the clinical development stage.

We expect our research and development expenses to increase in the near term as compared to prior year periods as we continue to focus our resources toward progressing our rusfertide program into later stage clinical trials and preparing for commercialization. We do not intend to dedicate further internal resources to clinical development or contract manufacturing activities for our PN-943 clinical program. The process of conducting research, identifying potential product candidates and conducting pre-clinical studies and clinical trials necessary to obtain regulatory approval and commencing pre-commercialization activities is costly and time intensive. We may never succeed in achieving marketing approval for our product candidates regardless of our costs and efforts. The probability of success of our product candidates may be affected by numerous factors, including pre-clinical data, clinical data, competition, manufacturing capability, our cost of goods to be sold, our ability to receive, and the timing of, regulatory approvals, market conditions, and our ability to successfully commercialize our products if they are approved for marketing. As a result, we are unable to determine the duration and completion costs of our research and development projects or when and to what extent we will be able to generate revenue from the commercialization and sale of any of our product candidates. Our research and development programs are subject to change from time to time as we evaluate our priorities and available resources.

​

General and Administrative Expenses

General and administrative expenses consist of personnel costs, allocated facilities costs and other expenses for outside professional services, including legal, human resources, audit and accounting services, and pre-commercialization expenses, including selling and marketing costs. Personnel costs consist of salaries, benefits and

64

Table of Contents

stock-based compensation. Allocated expenses consist of expenses for rent and maintenance of facilities, information technology, depreciation and amortization expense and other administrative supplies. We expect to continue to incur expenses to support our continued operations as a public company, including expenses related to compliance with the rules and regulations of the SEC and those of the national securities exchange on which our securities are traded, insurance expenses, investor relations expenses, audit fees, professional services and general overhead and administrative costs.

Interest Income

Interest income consists of interest earned on our cash, cash equivalents, and marketable securities, which is comprised of contractual interest, premium amortization and discount accretion.

Other Expense, Net

Other expense, net consists primarily of amounts related to foreign exchange gains and losses and related items.

Results of Operations

​

Comparison of the Years Ended December 31, 2023 and 2022

(1) Includes $17.1 million and $14.7 million of non-cash stock-based compensation expense for the years ended December 31, 2023 and 2022, respectively.

(2) Includes $12.2 million and $9.5 million of non-cash stock-based compensation expense for the years ended December 31, 2023 and 2022, respectively.

​

License and Collaboration Revenue

License and collaboration revenue increased $33.4 million, or 126%, from $26.6 million for the year ended December 31, 2022 to $60.0 million for the year ended December 31, 2023. The increase in revenue was primarily due to milestone payments earned under our license and collaboration agreement with JNJ during the fourth quarter of 2023, including a $50.0 million milestone payment upon dosing of the third patient in the ICONIC-LEAD Phase 3 trial of JNJ-2113 in patients with moderate-to-severe psoriasis, and a $10.0 million milestone payment upon the dosing of the third patient in the ANTHEM-UC Phase 2b trial in UC. License and collaboration revenue for the year ended December 31, 2022 was primarily related to the transaction price under the license and collaboration agreement with JNJ recognized based on proportional performance. We completed our performance obligation under the license and collaboration agreement with JNJ as of June 30, 2022.

65

Table of Contents

Research and Development Expenses

​

Research and development expenses decreased $6.0 million, or 5%, from $126.2 million for the year ended December 31, 2022 to $120.2 million for the year ended December 31, 2023. The decrease was primarily due to (i) a decrease of $35.8 million in expenses for the PN-943 program, and (ii) a decrease of $2.8 million in expenses related to pre-clinical and drug discovery research expense, partially offset by (iii) an increase of $33.3 million in rusfertide clinical and contract manufacturing expenses primarily for the Phase 3 VERIFY clinical trial. We completed a Phase 2 trial of PN-943 in patients with moderate to severe UC in early 2023, following which we de-prioritized further development work.

We had 85 and 82 full-time equivalent research and development employees as of December 31, 2023 and 2022, respectively. Research and development personnel-related expenses for the year ended December 31, 2023 increased by $1.1 million as compared to the year ended December 31, 2022 primarily due to an increase of $2.3 million in stock-based compensation expense, partially offset by a decrease of $1.2 million of other personnel-related expenses.

General and Administrative Expenses

General and administrative expenses increased $1.8 million, or 6%, from $31.7 million for the year ended December 31, 2022 to $33.5 million for the year ended December 31, 2023 primarily due to an increase in stock-based compensation expense during the current year period, partially offset by one-time costs incurred during the first quarter of 2022.

We had 27 and 23 full-time equivalent general and administrative employees as of December 31, 2023 and 2022, respectively.

Interest Income

Interest income increased $10.8 million, or 267%, from $4.1 million for the year ended December 31, 2022 to $14.9 million for the year ended December 31, 2023. This increase was primarily due to higher invested balances and higher yields due to increased interest rates compared to the prior year period.

​

Comparison of the Years Ended December 31, 2022 and 2021

See Part II, Item 7—Results of Operations—Comparison of the Years Ended December 31, 2022 and 2021 in our Annual Report on Form 10-K for the year ended December 31, 2022, filed on March 15, 2023, for a discussion of our results of operations for the year ended December 31, 2022 compared to the year ended December 31, 2021.

​

66

Table of Contents

Liquidity and Capital Resources

Sources of Liquidity

Historically we have funded our operations primarily from net proceeds from the sale of shares of our common stock and receipt of payments under collaboration agreements.

Proceeds from Sales of Our Common Stock

​

In April 2023, we completed an underwritten public offering of 5,000,000 shares of our common stock at a public offering price of $20.00 per share and issued an additional 750,000 shares of common stock at a price of $20.00 per share following the underwriters’ exercise of their option to purchase additional shares. Net proceeds, after deducting underwriting commissions and offering costs paid by us, were approximately $107.8 million.

​

In August 2022, we entered into an Open Market Sale AgreementSM , pursuant to which we may offer and sell up to $100.0 million shares of our common stock from time to time in “at-the-market” offerings (the “2022 ATM Facility”). During the three months ended March 31, 2023, we sold 1,749,199 shares of our common stock under the 2022 ATM Facility for net proceeds of $24.3 million, after deducting issuance costs. There were no sales of our common stock under the 2022 ATM Facility during the three months ended June 30, 2023, September 30, 2023 or December 31, 2023. There were no sales of our common stock under the 2022 ATM Facility during the year ended December 31, 2022.

​

In August 2018, we entered into a Securities Purchase Agreement with certain accredited investors (each, an “Investor” and, collectively, the “Investors”), pursuant to which we sold an aggregate of 2,750,000 shares of our common stock at a price of $8.00 per share for aggregate net proceeds of $21.7 million, after deducting offering expenses payable by us. In a concurrent private placement, we issued the Investors warrants to purchase an aggregate of 2,750,000 shares of our common stock (each, a “Warrant” and, collectively, the “Warrants”). Each Warrant was exercisable from August 8, 2018 through August 8, 2023. Warrants to purchase 1,375,000 shares of our common stock had an exercise price of $10.00 per share and Warrants to purchase 1,375,000 shares of our common stock had an exercise price of $15.00 per share. The exercise price and number of shares of our common stock issuable upon the exercise of the Warrants (the “Warrant Shares”) were subject to adjustment in the event of any stock dividends and splits, reverse stock split, recapitalization, reorganization or similar transaction, as described in the Warrants. Under certain circumstances, the Warrants were exercisable on a “cashless” basis. In connection with the issuance and sale of the common stock and Warrants, we granted the Investors certain registration rights with respect to the Warrants and the Warrant Shares. The common stock and Warrants met the criteria for equity classification, and the net proceeds from the transaction were recorded as a credit to additional paid-in capital.

​

In August 2023, prior to the expiration of the Warrants, we entered into certain agreements with the Investors and their affiliates under which we agreed to allow the Warrants to be exercised in exchange for pre-funded warrants representing the same number of Warrant Shares underlying the Warrants with an exercise price of $0.001 per share (the “Pre-Funded Warrants”). Subsequent to the execution of the agreements and prior to the expiration of the Warrants, all outstanding Warrants were exercised for gross proceeds of $34.4 million in exchange for 44,748 shares of our common stock and Pre-Funded Warrants to purchase 2,705,252 shares of common stock (subject to adjustment in the event of any stock dividends and splits, reverse stock split, recapitalization, reorganization or similar transaction, as described in the Pre-Funded Warrants) with an exercise price of $0.001 per share. The Pre-Funded Warrants will expire upon the day they are exercised in full. The Pre-Funded Warrants are exercisable at any time prior to expiration except that the Pre-Funded Warrants cannot be exercised by the Investors if, after giving effect thereto, the Investors would beneficially own more than 9.99% of our common stock, subject to certain exceptions. The common stock and Pre-Funded Warrants met the criteria for equity classification and the net proceeds from the transaction were recorded as a credit to additional paid-in capital. In accordance with Accounting Standards Codification Topic 260, Earnings Per Share, outstanding Pre-Funded Warrants are included in the computation of basic net loss per share because the exercise price is negligible, and they are fully vested and exercisable after the original issuance date. As of December 31, 2023, none of the Pre-Funded Warrants have been exercised.

67

Table of Contents

Receipt of Payments Under Collaboration Agreements

​

We have earned $172.5 million in non-refundable payments from JNJ since the inception of the Restated Agreement in 2017 through the date of this Annual Report on Form 10-K as follows:

​

We have also received payments for services provided under the collaboration agreement and we may make in-kind payment reimbursements to JNJ for certain costs they have incurred pursuant to the cost sharing terms of the agreement.

Pursuant to the Restated Agreement, we may be eligible to receive clinical development, regulatory and sales milestones, if and when achieved. Upcoming potential development milestones for second-generation products include:

Capital Requirements

As of December 31, 2023, we had $341.6 million of cash, cash equivalents and marketable securities and an accumulated deficit of $615.7 million. Our capital expenditures were $0.6 million, $0.8 million and $1.1 million for the years ended December 31, 2023, 2022 and 2021, respectively. Our primary uses of cash are to fund our operating

68

Table of Contents

expenses, primarily related to our research and development expenditures and general and administrative costs. We expect that our existing cash, cash equivalents and marketable securities will be sufficient to fund our operations for at least the next twelve months from the date of this Annual Report on Form 10-K based on current operating plans and financial forecasts.

​

In January 2024, we entered into a worldwide license and collaboration agreement for the development and commercialization of rusfertide with Takeda, which is yet to become effective. See Note 15 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

We may require additional funding to advance our early discovery pipeline and to develop, acquire, or in-license other potential product candidates. Our future funding requirements will depend on many factors, including:

Such additional funding may come from various sources, including raising additional capital, seeking access to debt, and seeking additional collaborative or other arrangements with partners, but such funding may not be available on terms acceptable to us, if at all. As discussed in Part I, Item 1A,”Risk Factors,” we are currently operating in a period of macroeconomic uncertainty and capital markets disruption, which has been significantly impacted by domestic and global monetary and fiscal policy, geopolitical instability, inflationary pressures, high interest rates and banking and other financial institution instability, among other factors. A future recession or market correction, including those due to significant geopolitical or macroeconomic events, could materially affect our business and our access to credit and financial markets.

69

Table of Contents

Any failure to raise capital as and when needed could have a negative impact on our financial condition and on our ability to pursue our business plans and strategies. Further, our operating plans may change, and we may need additional funds to meet operational needs and capital requirements for clinical trials, other research and development activities and pre-commercialization costs. If we do raise additional capital through public or private equity offerings or convertible debt securities, the ownership interest of our existing stockholders could be diluted, and the terms of these securities could include liquidation or other preferences that could adversely affect our stockholders’ rights. If we raise additional capital through debt financing, we could be subject to covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. Because of the numerous risks and uncertainties associated with the development and commercialization of our product candidates, we are unable to fully estimate the amounts of increased capital outlays and operating expenditures associated with our current and anticipated product development programs. For additional information, see Part I, Item 1A, “Risk Factors — Risks Related to our Financial Position and Capital Requirements.”

The following table summarizes our cash flows for the periods indicated:

​

Cash Used in Operating Activities

Cash used in operating activities for the year ended December 31, 2023 was $70.2 million, consisting primarily of our net loss of $79.0 million and a net change of $19.5 million in net operating assets and liabilities, partially offset by certain non-cash items, including $29.2 million of stock-based compensation expense. The $37.9 million decrease in cash used in operating activities for the year ended December 31, 2023, as compared to the year ended December 31, 2022, was primarily due to a $48.4 million decrease in our net loss and a $5.1 million increase in stock-based compensation expense, partially offset by a $4.0 million decrease in accretion of discount on marketable securities and an $11.7 million net change in net operating assets and liabilities.

Cash used in operating activities for the year ended December 31, 2022 was $108.1 million, consisting primarily of our net loss of $127.4 million and a net change of $7.8 million in net operating assets and liabilities, partially offset by certain non-cash items, including $24.2 million of stock-based compensation expense. The $0.3 million increase in cash used in operating activities for the year ended December 31, 2022, as compared to the year ended December 31, 2021, was primarily due to a $1.8 million increase in our net loss, a $4.5 million net change in net operating assets and liabilities and a $1.8 million net change in other non-cash items, partially offset by a $7.8 million increase in stock-based compensation expense.

Cash (Used in) Provided by Investing Activities

Cash used in investing activities for the year ended December 31, 2023 was $39.3 million, consisting of purchases of marketable securities of $191.1 million and purchases of property and equipment of $0.6 million, partially offset by proceeds from maturities of marketable securities of $152.4 million. The $130.7 million decrease in cash provided by investing activities for the year ended December 31, 2023, as compared to the year ended December 31, 2022, was primarily related to a decrease in the net activity of purchases and maturities of marketable securities. Purchases of property and equipment were primarily related to purchases of laboratory and computer equipment.

Cash provided by investing activities for the year ended December 31, 2022 was $91.5 million, consisting of proceeds from maturities of marketable securities of $307.1 million, partially offset by purchases of marketable securities of $214.9 million and purchases of property and equipment of $0.8 million. The $107.3 million increase in cash provided by investing activities for the year ended December 31, 2022, as compared to the year ended December

70

Table of Contents

31, 2021, was primarily related to a decrease of $71.7 million in purchases of marketable securities and an increase of $35.3 million in proceeds from maturities of marketable securities. Purchases of property and equipment were primarily related to purchases of laboratory and computer equipment.

Cash Provided by Financing Activities

Cash provided by financing activities for the year ended December 31, 2023 was $170.5 million, consisting primarily of net cash proceeds of $107.8 million from the April 2023 public offering of our common stock, $24.3 million from sales of our common stock under the 2022 ATM Facility, $34.4 million from the exercise of the Warrants in exchange for issuance of Pre-Funded Warrants and common stock, and $4.8 million in proceeds from the issuance of common stock upon exercise of stock options and purchases of common stock under our employee stock purchase plan. The $151.6 million increase in cash provided by financing activities for the year ended December 31, 2023, as compared to the year ended December 31, 2022, was primarily due to a $107.8 million increase in net cash proceeds from the April 2023 public offering, a $9.7 million increase in cash proceeds from ATM sales and a $34.4 million increase in net cash proceeds from the exercise of the Warrants.

Cash provided by financing activities for the year ended December 31, 2022 was $18.8 million, consisting primarily of net cash proceeds of $14.6 million from sales under the 2019 ATM Facility and proceeds from the issuance of common stock upon the exercise of stock options and purchases of common stock under our employee stock purchase plan of $4.4 million. The $111.1 million decrease in cash provided by financing activities for the year ended December 31, 2022, as compared to the year ended December 31, 2021, was primarily due to a $123.8 million decrease in cash proceeds from our public offerings of common stock and a $1.8 million decrease in proceeds from the issuance of common stock upon exercise of stock options and purchases of common stock under our employee stock purchase plan. These decreases were partially offset by a $14.6 million increase in cash proceeds from ATM sales.

Contractual Obligations and Other Commitments

In the normal course of business, we enter into agreements with contract service providers to assist in the performance of our research and development activities and clinical and commercial manufacturing activities. Subject to the required notice periods and our obligations under certain binding commitments, we can elect to discontinue the work under these agreements at any time. We expect to enter into additional clinical development, contract research, clinical and commercial manufacturing, supplier and collaborative research agreements in the future, which may require upfront payments and long-term commitments of capital resources.

​

Our contractual obligations include minimum lease payments under our operating lease obligations. In July 2021, we entered into a second amendment to our facility lease agreement dated as of March 2017 to lease approximately 15,000 square feet of additional office space in Newark, California. See Note 8 to the Consolidated Financial Statements elsewhere in this Annual Report on Form 10-K for additional information.

​

Under the Restated Agreement, we share with JNJ certain development, regulatory and compound supply costs. The actual amounts that we pay JNJ or that JNJ pays us will depend on a number of factors, some of which are outside of our control and some of which are contingent upon the success, if achieved, of certain development and regulatory activities. See Note 3 to the Consolidated Financial Statements elsewhere in this Annual Report on Form 10- K for additional information.

In January 2024, we entered into the Takeda Collaboration Agreement, which is yet to become effective. See Note 15 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

In June 2012, we entered into the Zealand Agreement to identify, optimize and develop novel disulfide-rich peptides to discover a hepcidin mimetic. We amended the Zealand Agreement in February 2014, at which point we assumed responsibility for the development program. In January 2020, we initiated arbitration proceedings with the International Court of Arbitration of the International Chamber of Commerce against Zealand. In August 2021, we and

71

Table of Contents

Zealand agreed to resolve the dispute and reached an Arbitration Resolution Agreement. See Note 7 and Note 9 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

​

Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations

​

Overview

We are a biopharmaceutical company with peptide-based new chemical entities rusfertide and JNJ-2113 (formerly known as PN-235) in different stages of development, all derived from our proprietary discovery technology platform. Our clinical programs fall into two broad categories of diseases; (i) hematology and blood disorders, and (ii) inflammatory and immunomodulatory diseases.

Rusfertide

​

Our most advanced clinical asset, rusfertide (generic name for PTG-300), is an injectable hepcidin mimetic in development for the potential treatment of erythrocytosis, iron overload and other blood disorders and is wholly owned. Hepcidin is a key hormone in regulating iron equilibrium and is critical to the proper development of red blood cells. Rusfertide mimics the effect of the natural hormone hepcidin, but with greater potency, solubility and stability. Data from our rusfertide Phase 2 clinical trials presented at medical conferences in 2021 and 2022 provided evidence regarding the potential of rusfertide for managing hematocrit, reducing thrombotic risk and improving iron deficiency symptoms. Rusfertide has a unique mechanism of action in the potential treatment of the blood disorder polycythemia vera (“PV”), which may enable it to specifically decrease and maintain hematocrit levels within the range of recommended clinical guidelines without causing the iron deficiency that can occur with frequent phlebotomy. Our rusfertide Phase 2 clinical trials include the following:

​

​

​

At the June 2022 American Society of Clinical Oncology (“ASCO”) Annual Meeting, we presented updated interim results for REVIVE and PACIFIC demonstrating the effects of dosing interruption and resumption. Rusfertide dosing interruption led to loss of effect, including increased phlebotomy rate and increases in hematocrit and red blood cells. Rusfertide restart restored therapeutic benefits. Following the brief clinical hold described below, over 90% of patients in the REVIVE trial provided reconsent and returned to rusfertide treatment after dosing interruption and reinitiation. At the June 2022 European Hematology Association Congress, we presented interim data as of May 2022 showing that rusfertide treatment interruption reverses hematologic gains and re-initiation of treatment restores therapeutic benefits in patients with PV. At the December 2022 American Society of Hematology meeting, we presented data as of October 2022 related to rusfertide, including a subgroup of analyses of the adverse event profile from the REVIVE trial. These preliminary results indicated that 84% of treatment-emergent adverse events (“TEAEs”) were Grade 2 or below. 16% of patients experienced Grade 3 TEAEs and there were no Grade 4 TEAEs.

​

On March 15, 2023, we announced positive topline results from the blinded, placebo-controlled, randomized withdrawal portion of the REVIVE trial. Subjects receiving rusfertide achieved statistically significant improvements versus placebo in the trial’s primary endpoint.

​

The double-blind, placebo-controlled, 12-week randomized withdrawal portion was included as Part 2 of the REVIVE trial study to evaluate rusfertide in PV patients with frequent phlebotomy requirements. In the REVIVE trial, subjects were initially enrolled in the 28-week open label dose-titration and efficacy evaluation Part 1 of the study, followed by 1:1 randomization of 53 subjects to placebo versus rusfertide therapy for a subsequent duration of 12 weeks.

54

​

Table of Contents

More subjects receiving rusfertide during the blinded randomized withdrawal portion of the REVIVE trial were responders compared with placebo (69.2% versus 18.5%, p=0.0003). A study subject was defined as a responder if the subject completed 12 weeks of double-blind treatment while maintaining hematocrit control without phlebotomy eligibility and without phlebotomy. During the 12 weeks of the blinded randomized withdrawal, only 2 of 26 subjects on rusfertide were phlebotomized.

​

VERIFY, a global Phase 3 clinical trial of rusfertide in PV for approximately 250 patients, was initiated in the first quarter of 2022. Significant efforts have been taken toward the goal of full enrollment and a high degree of interest has been observed from physicians and patient communities. We expect enrollment completion in the fourth quarter of 2023.

​

On September 16, 2021, the U.S. Food and Drug Administration (“FDA”) placed a clinical hold on our then ongoing rusfertide clinical trials following our submission to the FDA of findings in a 26-week rasH2 transgenic mouse carcinogenicity study. In October 2021, we submitted a Complete Response to the FDA related to the clinical hold, and the FDA removed the clinical hold on October 8, 2021. In our Complete Response, we provided the individual patient clinical safety reports the FDA requested for human cancers observed in rusfertide clinical trials, updated the investigator brochure and patient informed consent forms for ongoing rusfertide trials, proposed new safety and stopping rules in trial protocols for our ongoing rusfertide clinical trials, and performed a comprehensive review of our rusfertide safety database. Dosing of patients and enrollment in ongoing clinical trials with rusfertide resumed in the fourth quarter of 2021.

​

The FDA granted orphan drug designation for rusfertide for the treatment of PV in June 2020, and Fast Track designation for rusfertide for the treatment of PV in December 2020. The EMA granted orphan drug designation for rusfertide for treatment of PV in October 2020. The FDA granted Breakthrough Therapy Designation for rusfertide for the treatment of PV in June 2021. In April 2022, we received a letter from the FDA indicating the FDA’s intent to rescind Breakthrough Therapy Designation for rusfertide in PV. In June 2022, we voluntarily withdrew our Breakthrough Therapy Designation following correspondence with FDA and based on our internal analysis of the relative utility of Breakthrough Therapy Designation for Phase 3 trials and beyond. The FDA correspondence relating to the Breakthrough Therapy designation does not address the rusfertide Fast Track Designation, which remains active.

​

In keeping with our organizational prioritization of rusfertide in PV, plans to initiate trials of rusfertide in additional disease indications have been paused. This decision was influenced in part by the enactment of the Inflation Reduction Act (“IRA”) in the United States and includes previously planned trials of rusfertide in the subset of hereditary hemochromatosis patients with chronic arthropathy.

​

JNJ-2113 (formerly known as PN-235)

​

Our partnered Interleukin-23 receptor (“IL-23R”) antagonist compound JNJ-2113 is an orally delivered investigational drug that is designed to block biological pathways currently targeted by marketed injectable antibody drugs. Our orally stable peptide approach may offer a targeted therapeutic approach for gastrointestinal (“GI”) and systemic compartments as needed. We believe that, compared to antibody drugs, JNJ-2113 has the potential to provide clinical improvement in an oral medication with increased convenience and compliance and the opportunity for the earlier introduction of targeted oral therapy.

​

In May 2017, we entered into a worldwide license and collaboration agreement with Janssen Biotech, Inc. (“Janssen”), a Johnson & Johnson company, to co-develop and co-detail our IL-23R antagonist compounds, including PTG-200 (JNJ-67864238) and certain related compounds for all indications, including inflammatory bowel disease (“IBD”). PTG-200 was a first-generation investigational, orally delivered, IL-23R antagonist for the treatment of IBD. The agreement with Janssen was amended in May 2019 to expand the collaboration by supporting efforts towards second-generation IL-23R antagonists; and in July 2021 to, among other things, enable Janssen to independently research and develop collaboration compounds for multiple indications in the IL-23 pathway and further align our financial interests.

​

55

​

Table of Contents

During the fourth quarter of 2021, following a pre-specified interim analysis criteria, a portfolio decision was made by Janssen to advance second-generation product candidate JNJ-2113 (JNJ-77242113) based on its superior potency and overall pharmacokinetic and pharmacodynamic profile. A JNJ-2113 Phase 1 trial was completed in the fourth quarter of 2021.

​

In February 2022, Janssen initiated FRONTIER1, a 255-patient Phase 2b clinical trial of JNJ-2113 in moderate-to-severe plaque psoriasis, which was completed in December 2022. FRONTIER1 was a randomized, multicenter, double-blind, placebo-controlled study that evaluated three once-daily dosages and two twice-daily dosages of JNJ-2113 taken orally. The primary endpoint of the study is the proportion of patients achieving PASI-75 (a 75% improvement in skin lesions as measured by the Psoriasis Area and Severity Index) at 16 weeks. In March 2023, we announced positive topline results from the trial. JNJ-2113 achieved the study's primary efficacy endpoint, with a statistically significant greater proportion of patients who received JNJ-2113 achieving PASI-75 responses compared to placebo at Week 16 in all five of the study’s treatment groups. A clear dose response was observed across an eight-fold dose range. Treatment was well tolerated, with no meaningful difference in frequency of adverse events across treatment groups versus placebo. It is our expectation that JNJ-2113 will progress into a Phase 3 registrational study in plaque psoriasis on the strength of the FRONTIER1 data. Advancement of JNJ-2113 into a Phase 3 study and meeting the primary endpoint in that study would qualify us for milestone payments of $50 million and $115 million, respectively. Data will be presented from various pre-clinical and clinical studies on JNJ-2113 at medical conferences beginning in the second quarter of 2023.

​

Other Phase 2 studies of JNJ-2113 that Janssen has initiated include the SUMMIT study of JNJ-2113 for the treatment of moderate-to-severe plaque psoriasis expected to be completed in the second quarter of 2023 and FRONTIER2, a long-term extension study. A Phase 1 trial of an immediate release formulation of JNJ-2113 in healthy Japanese and Chinese adult participants is currently recruiting. Following the completion of Phase 2 studies of JNJ-2113 in plaque psoriasis, we expect Janssen to initiate a separate Phase 2 trial of JNJ-2113 in a second indication. Additional indications may include any or all of psoriatic arthritis, UC and CD.

​

During the fourth quarter of 2021, we received a $7.5 million milestone payment from Janssen triggered by the completion of data collection for JNJ-2113 Phase 1 activities. In the second quarter of 2022, we received a $25.0 million milestone payment in connection with the dosing of a third patient in FRONTIER1 during the first quarter of 2022. We will be eligible to receive a $10.0 million milestone payment in connection with the dosing of a third patient in the second Phase 2 trial of a second-generation candidate, a $50 million milestone upon dosing of a third patient in a Phase 3 trial for a second-generation compound for any indication, and a $115.0 million milestone payment upon a Phase 3 clinical trial for a second-generation compound for any indication meeting its primary clinical endpoint.  We remain eligible for up to approximately $855.0 million in future development and sales milestone payments, in addition to the $112.5 million in nonrefundable payments from Janssen received to date. We also remain eligible to receive tiered royalties on net product sales at percentages ranging from mid-single digits to ten percent.

PN-943

​

PN-943 is a wholly owned, investigational, orally delivered, gut-restricted alpha 4 beta 7 (“α4β7”) specific integrin antagonist for IBD. During the second quarter of 2020, we initiated IDEAL, a 159 patient Phase 2 trial evaluating the safety, tolerability and efficacy of PN-943 in patients with moderate to severe UC. Enrollment in IDEAL was completed during the first quarter of 2022. The trial includes a 12-week induction period, which has been completed, and a 40-week extended treatment period. With the exception of completing the 40-week extended treatment period for eligible patients in the IDEAL trial, which is expected to be completed in the first quarter of 2023, we do not intend to dedicate further internal resources to clinical development or contract manufacturing activities for our PN-943 clinical program.

​

Discovery Platform

​

Our clinical assets are all derived from our proprietary discovery platform. Our platform enables us to engineer novel, structurally constrained peptides that are designed to retain key advantages of both orally delivered small molecules and injectable antibody drugs in an effort to overcome many of their limitations as therapeutic agents.

56

​

Table of Contents

Importantly, constrained peptides can be designed to potentially alleviate the fundamental instability inherent in traditional peptides to allow different delivery forms, such as oral, subcutaneous, intravenous, and rectal. We continue to use our peptide technology platform to discover product candidates against targets in disease areas with significant unmet medical needs. For example, we have a pre-clinical stage program to identify an orally active hepcidin mimetic, which we believe will be complementary to the injectable rusfertide for offering the best treatment options for PV, hereditary hemochromatosis and other potential erythropoietic and iron imbalance disorders.

​

Business Outlook

​

We are subject to risks and uncertainties as a result of the prolonged nature of the COVID-19 pandemic and emergent variants with increased transmissibility, even in those who are fully vaccinated. Some of the workforce trends starting during the pandemic have continued to lead to staffing shortages in settings such as clinical trial sites and healthcare offices. The future impact of COVID-19 on our activities will depend on a number of factors, including, but not limited to, the scope and magnitude of any resurgences in the outbreak and the spread of COVID-19 variants; the timing, extent, effectiveness and durability of COVID-19 vaccine programs or other treatments; and new travel and other restrictions and public health measures. We have experienced delays in our existing and planned clinical trials due to the worldwide impacts of the pandemic. Our future results of operations and liquidity could be adversely impacted by further delays in existing and planned clinical trials, continued difficulty in recruiting patients for these clinical trials, delays in manufacturing and collaboration activities, supply chain disruptions and the ongoing impact on our operating activities and employees. In addition, a recession or market correction related to or amplified by COVID-19 could materially affect our business.

We are currently operating in a period of economic uncertainty and capital markets disruption, which has been impacted by domestic and global monetary and fiscal policy, geopolitical instability, the ongoing military conflict between Russia and Ukraine and the rising tensions between China and Taiwan, a recessionary environment and historically high domestic and global inflation. In particular, the conflict in Ukraine has exacerbated market disruptions, including significant volatility in commodity prices, as well as supply chain interruptions, and has contributed to record inflation globally. The U.S. Federal Reserve and other central banks may be unable to contain inflation through more restrictive monetary policy and inflation may increase or continue for a prolonged period of time. Inflationary factors, such as increases in the cost of clinical supplies, interest rates, overhead costs and transportation costs may adversely affect our operating results. Also, the failure of Silicon Valley Bank and other banks in the United States in March 2023 has given rise to uncertainty in the security of amounts in deposit accounts uninsured by the Federal Deposit Insurance Corporation. We continue to monitor these events and the potential impact on our business. Although we do not believe that inflation has had a material impact on our financial position or results of operations to date, we may be adversely affected in the future due to domestic and global monetary and fiscal policy, supply chain constraints, consequences associated with COVID-19 and the ongoing conflict between Russia and Ukraine, and such factors may lead to increases in the cost of manufacturing our product candidates and delays in initiating trials.

Operations

We have incurred net losses in each year since inception and we do not anticipate achieving sustained profitability in the foreseeable future. Our net losses were $127.4 million, $125.6 million and $66.2 million for the years ended December 31, 2022, 2021 and 2020, respectively. As of December 31, 2022, we had an accumulated deficit of $536.8 million. Substantially all of our net losses have resulted from costs incurred in connection with our research and development programs and from general and administrative costs associated with our operations. We expect to continue to incur significant research and development expenses and other expenses related to our ongoing operations, product development, and pre-commercialization activities. As a result, we expect to continue to incur losses in the future as we continue our development of, and seek regulatory approval for, our product candidates.

57

​

Table of Contents

Janssen License and Collaboration Agreement

On July 27, 2021, we entered into the Restated Agreement with Janssen, which amends and restates the Original Agreement, as amended by the First Amendment. Janssen is a related party to us as Johnson & Johnson Innovation - JJDC, Inc., a significant stockholder of ours, and Janssen are both subsidiaries of Johnson & Johnson. Upon the effectiveness of the Original Agreement, we received a non-refundable, upfront cash payment of $50.0 million from Janssen. Upon the effectiveness of the First Amendment, we received a $25.0 million payment from Janssen in 2019. In the first quarter of 2020, we received a $5.0 million payment triggered by the successful nomination of a second-generation IL-23R antagonist development compound. In the fourth quarter of 2021, we received a $7.5 million milestone payment from Janssen triggered by completion of the data collection for JNJ-2113 Phase 1 activities. In the second quarter of 2022, we received a $25.0 million milestone payment in connection with the dosing of a third patient in FRONTIER1 during the first quarter of 2022. See Note 3 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

Critical Accounting Polices and Estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with United States generally accepted accounting principles. The preparation of these consolidated financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities at the date of the consolidated financial statements, as well as the reported revenue generated, and the expenses incurred during the reporting periods. Our estimates are based on our historical experience and on various other factors that we believe are reasonable under the circumstances, and the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions. We believe that the accounting policies discussed below are critical to understanding our historical and future performance, as these policies relate to the more significant areas involving management’s judgments and estimates.

Use of Estimates

The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, we evaluate our estimates, including those related to revenue recognition, accruals for research and development activities, stock-based compensation, income taxes, marketable securities and leases. Estimates related to revenue recognition include actual costs incurred versus total estimated costs of our deliverables to determine percentage of completion in addition to the application and estimates of potential revenue constraints in the determination of the transaction price under its license and collaboration agreements. We base these estimates on historical and anticipated results, trends and various other assumptions that we believe are reasonable under the circumstances, including assumptions as to forecasted amounts and future events.

Due to the COVID-19 pandemic, military conflict between Ukraine and Russia, rising tensions between China and Taiwan and inflationary pressures, among other factors, there has been uncertainty and disruption in the global economy and financial markets. We have taken into consideration any known impacts in our accounting estimates to date and are not aware of any additional specific events or circumstances that would require any additional updates to our estimates or judgments or a revision of the carrying value of our assets or liabilities as of the date of the filing of this Annual Report on Form 10-K. These estimates may change as new events occur and additional information is obtained. Actual results could differ materially from these estimates under different assumptions or conditions.

Revenue Recognition

Under Accounting Standards Codification Topic 606, Revenue from Contracts with Customers (“ASC 606”), we recognize revenue when our customer obtains control of promised goods or services, in an amount that reflects the

58

​

Table of Contents

consideration which we expect to receive in exchange for those goods or services. To determine revenue recognition for arrangements that we determine are within the scope of ASC 606, we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) we satisfy a performance obligation. We apply the five-step model to contracts when it is probable that we will collect the consideration we are entitled to in exchange for the goods or services we transfer to the customer. At contract inception, we assess the goods or services promised within each contract, determine those that are performance obligations, and assess whether each promised good or service is distinct. We then recognize as revenue the amount of the transaction price that is allocated to the respective performance obligations when (or as) the performance obligations are satisfied. We constrain our estimate of the transaction price up to the amount (the “variable consideration constraint”) that a significant reversal of recognized revenue is not probable.

Licenses of intellectual property: If a license to our intellectual property is determined to be distinct from the other performance obligations identified in an arrangement, we recognize revenue from non-refundable, upfront fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, we utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring proportional performance for purposes of recognizing revenue from non-refundable, upfront fees. We evaluate the measure of proportional performance each reporting period and, if necessary, adjust the measure of performance and related revenue recognition.

Milestone payments: At the inception of each arrangement or amendment that includes development, regulatory or commercial milestone payments, we evaluate whether the milestones are considered probable of being reached and estimate the amount to be included in the transaction price. ASC 606 suggests two alternatives to use when estimating the amount of variable consideration: the expected value method and the most likely amount method. Under the expected value method, an entity considers the sum of probability-weighted amounts in a range of possible consideration amounts. Under the most likely amount method, an entity considers the single most likely amount in a range of possible consideration amounts. Whichever method is used should be consistently applied throughout the life of the contract; however, it is not necessary for us to use the same approach for all contracts. We expect to use the most likely amount method for development and regulatory milestone payments. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within our control or the control of the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. If there is more than one performance obligation, the transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis. We recognize revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, we re-evaluate the probability or achievement of each such milestone and any related constraint, and if necessary, adjust our estimates of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment.

Any potential milestone payments that we determine are not associated with performance obligations as defined under the contract are excluded from the transaction price and are recognized as the triggering event occurs.

Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, where the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

Upfront payments and fees are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until we perform our obligations under these arrangements. Amounts payable to us are recorded as accounts receivable when our right to consideration is unconditional. Amounts payable to us and not yet billed to the collaboration partner are recorded as contract assets. We do not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less.

59

​

Table of Contents

Contractual cost sharing payments made to a customer or collaboration partner are accounted for as a reduction to the transaction price if such payments are not related to distinct goods or services received from the customer or collaboration partner.

Contracts may be amended to account for changes in contract specifications and requirements. Contract modifications exist when the amendment either creates new, or changes existing, enforceable rights and obligations. When contract modifications create new performance obligations and the increase in consideration approximates the standalone selling price for goods and services related to such new performance obligations, as adjusted for specific facts and circumstances of the contract, the modification is considered to be a separate contract and revenue is recognized prospectively. If a contract modification is not accounted for as a separate contract, we account for the promised goods or services not yet transferred at the date of the contract modification (the remaining promised goods or services) prospectively, as if it were a termination of the existing contract and the creation of a new contract, if the remaining goods or services are distinct from the goods or services transferred on or before the date of the contract modification. We account for a contract modification as if it were a part of the existing contract if the remaining goods or services are not distinct and, therefore, form part of a single performance obligation that is partially satisfied at the date of the contract modification. In such case the effect that the contract modification has on the transaction price, and on the entity’s measure of progress toward complete satisfaction of the performance obligation, is recognized as an adjustment to revenue (either as an increase in or a reduction of revenue) at the date of the contract modification (the adjustment to revenue is made on a cumulative catch-up basis).

Research and Development Costs

Research and development costs are expensed as incurred, unless there is an alternate future use in other research and development projects or otherwise. Research and development costs include salaries and benefits, stock-based compensation expense, laboratory supplies and facility-related overhead, outside contracted services, including clinical trial costs, manufacturing and process development costs for both clinical and pre-clinical materials, research costs, development milestone payments under license and collaboration agreements, and other consulting services.

We accrue for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of pre-clinical studies and clinical trials, and contract manufacturing activities. We record the estimated costs of research and development activities based upon the estimated services provided but not yet invoiced and we include these costs in accrued expenses and other payables in our consolidated balance sheets and within research and development expense in our consolidated statements of operations. We accrue for these costs based on various factors such as estimates of the work completed and in accordance with agreements established with our third-party service providers. As actual costs become known, we adjust our accrued liabilities. We have not experienced any material differences between accrued liabilities and actual costs incurred. However, the status and timing of actual services performed, number of patients enrolled, the rate of patient enrollment and the number and location of sites activated may vary from our estimates and may result in adjustments to our research and development expenses in future periods. Changes in these estimates that result in material changes to our accruals could materially affect our results of operations.

Recent Accounting Pronouncements

Information regarding recent accounting pronouncements applicable to us is included in Note 2 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K.

Components of Our Results of Operations

License and Collaboration Revenue

Our license and collaboration revenue is derived from payments we receive under the Janssen License and Collaboration Agreement. See Note 3 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

60

​

Table of Contents

Research and Development Expenses

Research and development expenses represent costs incurred to conduct research, such as the discovery and development of our product candidates. We recognize all research and development costs as they are incurred unless there is an alternative future use in other research and development projects or otherwise. Non-refundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received, rather than when payment has been made. In instances where we enter into agreements with third parties to provide research and development services to us, costs are expensed as services are performed. Amounts due under such arrangements may be either fixed fee or fee for service and may include upfront payments, monthly payments, and payments upon the completion of milestones or the receipt of deliverables.

Research and development expenses consist primarily of the following:

We recognize the amounts related to our Australian research and development refundable cash tax incentive that are not subject to refund provisions as a reduction of research and development expenses. The research and development tax incentives are recognized when there is reasonable assurance that the incentives will be received, the relevant expenditure has been incurred and the amount of the consideration can be reliably measured. We evaluate our eligibility under the tax incentive program as of each balance sheet date and make accruals and related adjustments based on the most current and relevant data available. We may alternatively be eligible for a taxable credit in the form of a non-cash tax incentive. We recognize the amounts from grants under government programs as a reduction of research and development expenses when the related research costs are incurred.

We allocate direct and indirect costs incurred to product candidates when they enter clinical development. For product candidates in clinical development, direct costs consist primarily of clinical, pre-clinical, and drug discovery costs, costs of supplying drug substance and drug product for use in clinical and pre-clinical studies, including clinical manufacturing costs, contract research organization fees, and other contracted services pertaining to specific clinical and pre-clinical studies. Indirect costs allocated to our product candidates on a program-specific basis include research and development employee salaries, benefits, and stock-based compensation, and indirect overhead and other administrative support costs. Program-specific costs are unallocated when the clinical expenses are incurred for our early-stage research and drug discovery projects as our internal resources, employees and infrastructure are not tied to any one research or drug discovery project and are typically deployed across multiple projects. As such, we do not provide financial information regarding the costs incurred for early stage pre-clinical and drug discovery programs on a program-specific basis prior to the clinical development stage.

61

​

Table of Contents

We expect our research and development expenses to decrease in the near term as we continue to de-prioritize our PN-943 clinical program and streamline certain discovery programs to focus our resources toward progressing our rusfertide program into later stage clinical trials and preparing for commercialization. The process of conducting research, identifying potential product candidates and conducting pre-clinical and clinical trials necessary to obtain regulatory approval and commencing pre-commercialization activities is costly and time intensive. We may never succeed in achieving marketing approval for our product candidates regardless of our costs and efforts. The probability of success of our product candidates may be affected by numerous factors, including pre-clinical data, clinical data, competition, manufacturing capability, our cost of goods to be sold, our ability to receive, and the timing of, regulatory approvals, market conditions, and our ability to successfully commercialize our products if they are approved for marketing. As a result, we are unable to determine the duration and completion costs of our research and development projects or when and to what extent we will generate revenue from the commercialization and sale of any of our product candidates. Our research and development programs are subject to change from time to time as we evaluate our priorities and available resources. With the exception of completing the 40-week extended treatment period for eligible patients in the Phase 2 IDEAL trial, which we expect to be completed in the first quarter of 2023, we do not intend to dedicate further internal resources to clinical development or contract manufacturing activities for our PN-943 clinical program. We will continue to explore out-licensing opportunities globally.

​

General and Administrative Expenses

General and administrative expenses consist of personnel costs, allocated facilities costs and other expenses for outside professional services, including legal, human resources, audit and accounting services, and pre-commercialization expenses, including selling and marketing costs. Personnel costs consist of salaries, benefits and stock-based compensation. Allocated expenses consist of expenses for rent and maintenance of facilities, information technology, depreciation and amortization expense and other administrative supplies. We expect to continue to incur expenses supporting our continued operations as a public company, including expenses related to compliance with the rules and regulations of the SEC and those of the national securities exchange on which our securities are traded, insurance expenses, investor relations expenses, audit fees, professional services and general overhead and administrative costs.

Interest Income

Interest income consists of interest earned on our cash, cash equivalents, and marketable securities, which is comprised of contractual interest, premium amortization and discount accretion.

Interest Expense

Interest expense consists of interest recognized on our long-term debt, which is comprised of contractual interest, amortization of origination fees and other issuance costs, and accretion of final payment fees.

Loss on Early Repayment of Debt

Loss on early repayment of debt consists of prepayment and final payment fees paid upon the early repayment of our long-term debt.

Other Expense, Net

Other expense, net consists primarily of amounts related to foreign exchange gains and losses and related items.

​

62

​

Table of Contents

Results of Operations

(1) Includes $14.7 million and $9.0 million of non-cash stock-based compensation expense for the years ended December  31, 2022 and 2021, respectively.

(2) Includes $9.5 million and $7.4 million of non-cash stock-based compensation expense for the years ended December  31, 2022 and 2021, respectively.

​

*Percentage not meaningful

​

License and Collaboration Revenue

License and collaboration revenue decreased $0.8 million, or 3%, from $27.4 million for the year ended December  31, 2021 to $26.6 million for the year ended December 31, 2022. The decrease in revenue was primarily due to a decrease in services under the Janssen License and Collaboration Agreement recognized based on proportional performance. We completed our performance obligation pursuant to the collaboration as of June 30, 2022.

We determined that the final transaction price of the initial performance obligation under the Restated Agreement is $131.7 million as of December 31, 2022, an increase of $25.2 million from the transaction price of $106.5 million as of December 31, 2021. In order to determine the transaction price, we evaluated all payments to be received during the duration of the contract, net of development costs reimbursement expected to be payable to Janssen. The transaction price as of December 31, 2022 includes $112.5 million of nonrefundable payments received as of June 30, 2022, $17.9  million of reimbursement from Janssen for services performed for IL-23 receptor antagonist compound research and other services, and variable consideration consisting of $8.2 million of development cost reimbursement from Janssen, partially offset by $6.9 million of net cost reimbursement due to Janssen for services performed.

Research and Development Expenses

63

​

Table of Contents

​

We had 82 and 92 full-time equivalent research and development employees as of December 31, 2022 and 2021, respectively. Research and development expenses for the year ended December 31, 2022 included increases of $5.7  million in stock-based compensation expense and $4.7 million of other personnel-related expenses compared to the year ended December 31, 2021.

General and Administrative Expenses

General and administrative expenses increased $4.5 million, or 17%, from $27.2 million for the year ended December 31, 2021 to $31.7 million for the year ended December 31, 2022, primarily due to increases of $2.2 million in personnel-related expenses and $2.3 million in other expenses to support the growth of our business. The increase in personnel-related expenses was primarily due to an increase of $2.1 million in stock-based compensation expense.

We had 23 and 26 full-time equivalent general and administrative employees as of December 31, 2022 and 2021, respectively.

Interest Income

Interest income increased $3.6 million, from $0.4 million for the year ended December 31, 2021 to $4.1 million for the year ended December 31, 2022. This increase was primarily due to higher yields on invested balances during a period of increasing interest rates compared to the prior year period.

​

Comparison of the Years Ended December 31, 2021 and 2020

(1) Includes $9.0 million and $4.1 million of non-cash stock-based compensation expense for the years ended December  31, 2021 and 2020, respectively.

(2) Includes $7.4 million and $3.8 million of non-cash stock-based compensation expense for the years ended December  31, 2021 and 2020, respectively.

License and Collaboration Revenue

License and collaboration revenue decreased $1.3 million, or 4%, from $28.6 million for the year ended December  31, 2020 to $27.4 million for the year ended December 31, 2021. The decrease in license and collaboration revenue was primarily related to a decrease in services provided under the Janssen License and Collaboration Agreement recognized based on proportional performance, partially offset by an $8.0 million cumulative catch-up amount recognized during the year ended December 31, 2021. This cumulative catch-up was primarily the result of an

64

​

Table of Contents

acceleration of our cumulative performance completed, following the execution of the Restated Agreement, which reduced our remaining performance obligation. Revenue for the year ended December 31, 2020 included an update in the amounts forecasted for future services remaining to be performed under the Janssen License and Collaboration Agreement which correspondingly increased our overall cumulative percentage of completion of our performance obligation during year ended December 31, 2020, along with continued performance and delivery of services under the Janssen License and Collaboration Agreement.

We determined that the transaction price of the initial performance obligation under the Restated Agreement was $106.5 million as of December 31, 2021, an increase of $7.9 million from the transaction price of $98.6 million as of December 31, 2020, under the Original Agreement. In order to determine the transaction price, we evaluated all payments expected to be received during the duration of the contract, net of development costs reimbursement expected to be payable to Janssen. We determined that the transaction price included $87.5 million of nonrefundable payments received as of December 31, 2021, $17.9 million of reimbursement from Janssen for services performed for IL-23 receptor antagonist compound research and other services and estimated variable consideration consisting of $8.2  million of development cost reimbursement from Janssen, partially offset by $7.1 million of net cost reimbursement due to Janssen for services performed. The increase in transaction price from December 31, 2020 to December 31, 2021 was due primarily to reductions in both the remaining services to be performed by us under the Restated Agreement and the remaining shared development costs under the Restated Agreement.

Research and Development Expenses

*Percentage not meaningful

Research and development expenses increased $51.5 million, or 69%, from $74.5 million for the year ended December 31, 2020 to $126.0 million for the year ended December 31, 2021. The increase was primarily due to an increase of $23.0 million in rusfertide clinical trial and development costs as clinical trials have enrolled and progressed, including the ongoing REVIVE and PACIFIC Phase 2 trials in PV, which began in December 2019 and the first quarter of 2021, respectively, and HH, which began in early 2020, and clinical and contract manufacturing activities incurred in 2021 in support of the REVIVE and PACIFIC Phase 2 trials and planned VERIFY global Phase 3 clinical trial of rusfertide in PV; an increase of $14.3 million in PN-943 clinical trial and development costs and contract manufacturing costs primarily related to the Phase 2 IDEAL trial in UC initiated during the second quarter of 2020; an increase of $6.5  million in preclinical and drug discovery research expenses; an increase of $4.5 million of clinical trial and development costs for the Phase 1 JNJ-2113 initiated in December 2020; an increase of $4.0 million of expenses related to milestone payments and obligations under the Zealand Agreement for rusfertide pursuant to the resolution of related arbitration; and an increase of $2.0 million of clinical trial and development costs for the Phase 1 PN-232 study initiated in May 2021. These increases were partially offset by a $1.7 million increase in grant and accrued refundable cash tax incentives and a decrease of $0.9 million in PTG-200 clinical trial and development expenses under the Janssen License

65

​

Table of Contents

and Collaboration Agreement due to our delivery of substantially all agreed-upon services for the PTG-200 Phase 2 clinical trial prior to 2021.

We had 92 and 59 full-time equivalent research and development employees as of December 31, 2021 and 2020, respectively. Research and development expenses for the year ended December 31, 2021 included increases of $4.9  million in stock-based compensation expense and $5.3 million of other personnel-related expenses compared to the year ended December 31, 2020.

General and Administrative Expenses

General and administrative expenses increased $8.6 million, or 46%, from $18.6 million for the year ended December 31, 2020 to $27.2 million for the year ended December 31, 2021, primarily due to increases of $5.2 million in personnel-related expenses, $1.6 million in consulting expenses, $0.9 million in market research expenses, $0.5 million in recruiting expenses to support the growth of our business, and $0.3 million in insurance expense. The increase in personnel-related expenses was primarily due to an increase of $3.6 million in stock-based compensation expense and $1.6 million in wages and salaries.

We had 26 and 20 full-time equivalent general and administrative employees as of December 31, 2021 and 2020, respectively.

Interest Income

Interest income decreased $0.5 million, or 51%, from $0.9 million for the year ended December 31, 2020 to $0.4  million for the year ended December 31, 2021. This decrease was primarily due to the low interest rate environment in 2021 and a change in the mix of marketable securities compared to the prior year period, despite higher interest-earning asset balances.

Interest Expense

Interest expense of $0.6 million for the year ended December 31, 2020 was comprised of interest expense on our long-term debt under our term credit facility. We prepaid our outstanding long-term debt under our term credit facility during the second quarter of 2020. We executed a payoff letter to release all obligations under the term credit facility during the third quarter of 2021.

Loss on Early Repayment of Debt

Loss on early repayment of debt of $0.6 million for the year ended December 31, 2020 was comprised of prepayment and final payment fees paid in connection with the early repayment of our term loan in June 2020. We had no debt outstanding at December 31, 2021.

Other Expense, Net

Other expense, net was $0.1 million for the year ended December 31, 2021 compared to zero for the year ended December 31, 2020. The change was due primarily to an increase in foreign exchange losses.

Income Tax Expense

Income tax expense decreased $1.3 million, or 100%, from $1.3 million for the year ended December 31, 2020 to zero for the year ended December 31, 2021. Our effective income tax rate was 0% for the year ended December 31, 2021 as compared to 2.0% for the year ended December 31, 2020. Our effective income tax rate differed from our federal statutory rate of 21% primarily because our losses could not be benefited due to our full valuation allowance position. During the second quarter of 2020, our Australia subsidiary sold beneficial rights to discovery intellectual property to our U.S. entity, and the U.S. entity reimbursed the Australia subsidiary for certain direct development costs.

66

​

Table of Contents

Upon completion of the sale, we analyzed tax planning strategies and future income and concluded that a valuation allowance was necessary for our Australia subsidiary. Income tax expense for the year ended December 31, 2020 reflected the sale of intellectual property rights, cost reimbursements and related adjustments to the deferred tax asset, establishment of a valuation allowance and certain uncertain tax position liabilities. We maintained a full valuation allowance on our tax position at December 31, 2021.

Liquidity and Capital Resources

Liquidity and Capital Expenditures

Sources of Liquidity

Historically, we have funded our operations primarily from net proceeds from the sale of shares of our common stock and receipt of payments under collaboration agreements.

In August 2022, we entered into an Open Market Sale AgreementSM (the “Sales Agreement”), pursuant to which we may offer and sell up to $100.0 million of shares of our common stock from time to time in “at-the-market” offerings (the “2022 ATM Facility”). As of December 31, 2022, no sales were made under the 2022 ATM Facility.

​

In June 2021, we completed an underwritten public offering of 3,046,358 shares of common stock at a public offering price of $37.75 per share and issued an additional 456,953 shares of common stock at a public offering price of $37.75 per share following the underwriters’ exercise of their option to purchase additional shares. Net proceeds, after deducting underwriting commission and offering costs paid by us, were $123.8 million.

​

In December 2020, we completed an underwritten public offering of 4,761,904 shares of common stock at a public offering price of $21.00 per share and issued an additional 714,285 shares of our common stock at a price of $21.00 per share following the underwriters’ exercise of their option to purchase additional shares. Net proceeds, after deducting underwriting commissions and offering costs paid by us, were $107.6 million.

​

In May 2020, we completed an underwritten public offering of 7,000,000 shares of our common stock at a public offering price of $14.00 per share, and we issued an additional 1,050,000 shares of our common stock at a price of $14.00 per share following the underwriters’ exercise of their option to purchase additional shares. Net proceeds, after deducting underwriting commissions and offering costs paid by us, were $105.3 million.

In November 2019, we entered into an Open Market Sale AgreementSM (the “Prior Sales Agreement”), pursuant to which we could offer and sell up to $75.0 million of shares of our common stock from time to time in “at-the-market” offerings (the “2019 ATM Facility”). During the year ended December 31, 2020, we sold 2,483,719 shares under the 2019 ATM Facility for net proceeds of $41.9 million. No shares were sold under the 2019 ATM Facility during the year ended December 31, 2021. During the year ended December 31, 2022, we sold 422,367 shares of our common stock under the 2019 ATM Facility for net proceeds of $14.6 million. The Prior Sales Agreement was terminated in connection with and replaced by the Sales Agreement in August 2022.

​

We have received a total of $112.5 million in non-refundable payments from Janssen since the inception of the Janssen License and Collaboration Agreement in 2017 through December 31, 2022, as follows:

​

67

​

Table of Contents

We also expect to receive payments for services provided under the collaboration agreement and we may make in-kind payment reimbursements to Janssen for certain costs they have incurred pursuant to the cost sharing terms of the agreement.

Pursuant to the Restated Agreement, we may be eligible to receive clinical development, regulatory and sales milestones, if and when achieved. Upcoming potential development milestones for second-generation products include:

Capital Requirements

As of December 31, 2022, we had $237.4 million of cash, cash equivalents and marketable securities and an accumulated deficit of $536.8 million. Our capital expenditures were $0.8 million, $1.1 million and $0.5 million for the years ended December 31, 2022, 2021 and 2020, respectively. Our primary uses of cash are to fund our operating expenses, primarily related to our research and development expenditures, general and administrative costs and pre-commercialization costs. Cash used in operating activities is impacted by the timing of when we pay these expenses. As of the date of this filing, we believe, based on our current operating plan and assumptions that our existing cash, cash equivalents and marketable securities will be sufficient to meet our anticipated operating and capital expenditure requirements for at least the next 12 months. We have based this estimate on assumptions that may prove to be wrong. We could utilize our available capital resources sooner than we currently expect if, for instance, our planned pre-clinical and clinical trials are successful or expanded, our product candidates enter new and more advanced stages of clinical development, we experience significant delays or difficulties in commencing, enrolling or completing clinical studies, our newer product clinical trials advance beyond the discovery stage, or various other factors. We expect that our cash burn will be lower in 2023 due to our research and development expenses decreasing in the near term as we continue to de-prioritize our PN-943 clinical program and streamline certain discovery programs to focus our resources toward progressing our rusfertide program into later stage clinical trials and preparing for commercialization.

​

68

​

Table of Contents

We anticipate that we will need to raise substantial additional funding to advance rusfertide through clinical development and toward potential regulatory approval and to develop, acquire, or in-license other potential product candidates. Our future funding requirements will depend on many factors, including:

Such additional funding may come from various sources, including raising additional capital, seeking access to debt, and seeking additional collaborative or other arrangements with partners, but such funding may not be available on terms acceptable to us, if at all. As discussed in Part I, Item1A.“Risk Factors”, we are currently operating in a period of economic uncertainty and capital markets disruption, which has been significantly impacted by domestic and global monetary and fiscal policy, and geopolitical instability, among other factors. A future recession or market correction related to COVID-19 or due to other factors, including significant geopolitical or macroeconomic events, could materially affect our business and our access to credit and financial markets.

Any failure to raise capital as and when needed could have a negative impact on our financial condition and on our ability to pursue our business plans and strategies. Further, our operating plans may change, and we may need additional funds to meet operational needs and capital requirements for clinical trials, other research and development activities and pre-commercialization costs. If we do raise additional capital through public or private equity offerings or convertible debt securities, the ownership interest of our existing stockholders could be diluted, and the terms of these securities

69

​

Table of Contents

could include liquidation or other preferences that could adversely affect our stockholders’ rights. If we raise additional capital through debt financing, we could be subject to covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. Because of the numerous risks and uncertainties associated with the development and commercialization of our product candidates, we are unable to fully estimate the amounts of increased capital outlays and operating expenditures associated with our current and anticipated product development programs. For additional information, see Part I, Item 1A, Risk Factors—“Risks Related to our Financial Position and Capital Requirements”.

The following table includes our cash flow data for the periods indicated (in thousands):

​

Cash Used in Operating Activities

Cash used in operating activities during the year ended December 31, 2022, was $108.1 million, consisting primarily of our net loss of $127.4 million and a net change of $7.8 million in net operating assets and liabilities, partially offset by certain non-cash items, including $24.2 million of stock-based compensation expense. The $0.3  million increase in cash flow used in operating activities during the year ended December 31, 2022, as compared to the year ended December 31, 2021, was primarily due to a $1.8 million increase in our net loss, a $4.5 million net change in net operating assets and liabilities, and a $1.8 million net change in other non-cash items, partially offset by a $7.8 million increase in stock-based compensation expense.

Cash used in operating activities during the year ended December 31, 2021, of $107.9 million consisted primarily of our net loss of $125.6 million, partially offset by certain non-cash items including $16.4 million of stock-based compensation expense. The $35.4 million increase in cash flow used in operating activities during the year ended December 31, 2021, as compared to the year ended December 31, 2020, was primarily due to a $59.4 million increase in our net loss, partially offset by certain non-cash items including an increase of $8.5 million of stock-based compensation expense, and a $14.2 million change in decrease in deferred revenue.

Cash Provided by (Used in) Investing Activities

Cash provided by investing activities for the year ended December 31, 2022, was $91.5 million, consisting of proceeds from maturities of marketable securities of $307.1 million, partially offset by purchases of marketable securities of $214.9 million and purchases of property and equipment of $0.8 million. The $107.3 million increase in cash provided by investing activities for the year ended December 31, 2022, as compared to the year ended December 31, 2021, was primarily related to a decrease of $71.7 million in purchases of marketable securities and an increase of $35.3 million in proceeds from maturities of marketable securities. Purchases of property and equipment were primarily related to purchases of laboratory and computer equipment.

Cash used in investing activities for the year ended December 31, 2021, was $15.9 million, consisting of purchases of marketable securities of $286.6 million and purchases of property and equipment of $1.1 million, partially offset by proceeds from maturities of marketable securities of $271.8 million. The $75.1 million decrease in cash used in investing activities for the year ended December 31, 2021, as compared to the year ended December 31, 2020, was primarily due to an increase of $82.3 million in proceeds from maturities of marketable securities. Purchases of property and equipment were primarily related to purchases of laboratory equipment, furniture and computer equipment.

70

​

Table of Contents

Cash Provided by Financing Activities

Cash provided by financing activities for the year ended December 31, 2022, was $18.8 million, consisting primarily of net cash proceeds from sales of $14.6 million under the 2019 ATM Facility and proceeds from the issuance of common stock upon the exercise of stock options and purchases of common stock under our employee stock purchase plan of $4.4 million. The $111.1 million decrease in cash provided by financing activities for the year ended December 31, 2022, as compared to the year ended December 31, 2021, was primarily due to a $123.8 million decrease in cash proceeds from our public offerings of common stock, and a $1.8 million decrease in proceeds from the issuance of common stock upon exercise of stock options and purchases of common stock under our employee stock purchase plan. These decreases were partially offset by $14.6 million increase in cash proceeds from ATM sales.

Cash provided by financing activities for the year ended December 31, 2021, was $129.9 million, consisting primarily of cash proceeds from our public offerings of common stock of $123.8 million and proceeds from the issuance of common stock upon the exercise of stock options and purchases of common stock under our employee stock purchase plan of $6.3 million. The $117.7 million decrease in cash provided by financing activities for the year ended December 31, 2021, as compared to the year ended December 31, 2020, was primarily due to an $89.5 million decrease in cash proceeds from our public offerings of common stock, a $42.1 million decrease in cash proceeds from ATM sales. These decreases were partially offset by $10.5 million related to the early repayment of long-term debt in 2020 and a $3.5  million increase in proceeds from the issuance of common stock upon exercise of stock options and purchases of common stock under our employee stock purchase plan.

Contractual Obligations and Other Commitments

In the normal course of business, we enter into agreements with contract service providers to assist in the performance of our research and development activities and clinical and commercial manufacturing activities. Subject to required notice periods and our obligations under binding commitments, we can elect to discontinue the work under these agreements at any time. We expect to enter into additional clinical development, contract research, clinical and commercial manufacturing, supplier agreements and collaborative research agreements in the future, which may require upfront payments and long-term commitments of capital resources.

​

Our contractual obligations include minimum lease payments under our operating lease obligations. On July 2,  2021, we entered into a second amendment to our facility lease agreement dated as of March 2017, to lease approximately 15,000 square feet of additional office space in Newark, California. See Note 10 to the Consolidated Financial Statements elsewhere in this Annual Report on Form 10-K for additional information.

​

Under the Restated Agreement, we share with Janssen certain development, regulatory and compound supply costs. The actual amounts that we pay Janssen or that Janssen pays us will depend on numerous factors, some of which are outside of our control and some of which are contingent upon the success, if achieved, of certain development and regulatory activities. See Note 3 to the Consolidated Financial Statements elsewhere in this Annual Report on Form 10- K for additional information.

In June 2012, we entered into the Zealand Agreement to identify, optimize and develop novel disulfide-rich peptides to discover a hepcidin mimetic. We amended the Zealand Agreement on February 28, 2014, at which point we assumed responsibility for the development program. On January 23, 2020, we initiated arbitration proceedings with the International Court of Arbitration of the International Chamber of Commerce against Zealand. On August 4, 2021, we and Zealand agreed to resolve the dispute and reached an Arbitration Resolution Agreement. See Note 7 and Note 11 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

​

71

​

Table of Contents

Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations

​

Overview

We are a biopharmaceutical company with multiple peptide-based new chemical entities in different stages of development, all derived from the Company's proprietary technology platform. Our clinical programs address two broad categories of diseases; (i) hematology and blood disorders, and (ii) inflammatory and immunomodulatory diseases.

Our most advanced clinical asset, rusfertide (generic name for PTG-300), is an injectable hepcidin mimetic in development for the potential treatment of erythrocytosis, iron overload and other blood disorders. Hepcidin is a key hormone in regulating iron equilibrium and is critical to the proper development of red blood cells. Rusfertide mimics the effect of the natural hormone hepcidin, but with greater potency, solubility and stability. We initiated REVIVE, a Phase 2 proof of concept (“POC”) study in the blood disorder polycythemia vera (“PV”), in the third quarter of 2019. We initiated a Phase 2 POC study in hereditary hemochromatosis (“HH”) in January 2020, which was completed during the fourth quarter of 2021. During the first quarter of 2021, we initiated PACIFIC, another Phase 2 study for rusfertide in up to 20 patients diagnosed with PV and with routinely elevated hematocrit levels (48%).

​

In June 2021, we presented updated Phase 2 data supporting the long-term efficacy of rusfertide in PV during an oral presentation at the European Hematology Association (“EHA”) 2021 Virtual Congress. An abstract highlighting positive preliminary data from our Phase 2 study of rusfertide in HH was orally presented at The Liver Meeting® 2021, hosted by the American Association for the Study of Liver Diseases (“AASLD”), which took place virtually in November 2021. In December 2021, two abstracts highlighting positive updated data from our REVIVE and PACIFIC Phase 2 studies of rusfertide in PV were orally presented at the American Society of Hematology (“ASH”) 2021 Annual Meeting, in addition to three poster presentations on rusfertide in PV and HH. These results provided evidence regarding the potential of rusfertide for managing hematocrit, reducing thrombotic risk and improving iron deficiency symptoms. Rusfertide has a unique mechanism of action in the potential treatment of PV, which may enable it to specifically decrease and maintain hematocrit levels within the range of recommended clinical guidelines without causing the iron deficiency that can occur with frequent phlebotomy.

​

On September 16, 2021, the FDA placed a clinical hold on our rusfertide clinical studies following our submission to the FDA of findings in a 26-week rasH2 transgenic mouse carcinogenicity study. In October 2021, we submitted a Complete Response to the FDA related to the clinical hold, and the FDA removed the clinical hold on October 8, 2021. In our Complete Response, we provided the individual patient clinical safety reports the FDA requested for human cancers observed in rusfertide clinical trials, updated the investigator brochure and patient informed consent forms for ongoing rusfertide trials, proposed new safety and stopping rules in clinical study protocols of our ongoing rusfertide clinical trials, and performed a comprehensive review of our rusfertide safety database. Dosing of patients and enrollment in ongoing clinical trials with rusfertide resumed in the fourth quarter of 2021.

​

We enrolled 63 patients in the ongoing REVIVE Phase 2 clinical trial of rusfertide in PV prior to the clinical hold, and we are currently enrolling approximately 20 patients to target approximately 50 patients enrolled through the end of a three-year open label extension. Based on ongoing end of Phase 2 feedback provided by the FDA’s Division of Nonmalignant Hematology and written comments from the European Medicines Agency (“EMA”), we expect to initiate VERIFY, a global Phase 3 clinical trial of rusfertide in PV in the first quarter of 2022. Patient enrollment into VERIFY is expected to be completed in the first half of 2023. In addition, we completed our Phase 2 POC study in HH, our second indication, during the fourth quarter of 2021.

55

Table of Contents

​

To date we have received the following designations for rusfertide in PV:

​

​

Our alpha-4-beta-7 (“α4β7”) antagonist PN-943 and our Interleukin-23 receptor (“IL-23R”) antagonist compound PN-235 are orally delivered investigational drugs that are designed to block biological pathways currently targeted by marketed injectable antibody drugs. Our orally stable peptide approach may offer a targeted therapeutic approach for GI and systemic compartments as needed. We believe that, compared to antibody drugs, these product candidates have the potential to provide improved safety due to minimal exposure in the blood, increased convenience and compliance due to oral delivery, and the opportunity for the earlier introduction of targeted oral therapy.

PN-943 is an investigational, orally delivered, gut-restricted α4β7 specific integrin antagonist for inflammatory bowel disease (“IBD”). We submitted a U.S. Investigational New Drug application with the FDA for PN-943 in December 2019, which took effect in January 2020. During the second quarter of 2020 we initiated IDEAL, a 150 patient Phase 2 trial evaluating the safety, tolerability and efficacy of PN-943 in patients with moderate to severe UC. This trial includes a 12-week induction period and a 40-week open label extension. Patient enrollment in IDEAL was completed during the first quarter of 2022, and topline data from the study, including the 12-week induction period, is expected in the second quarter of 2022.

In May 2017, we entered into a worldwide license and collaboration agreement with Janssen Biotech, Inc. (“Janssen”), a Johnson & Johnson company, to co-develop and co-detail our IL-23R antagonist compounds, including PTG-200 (JNJ-67864238) and certain related compounds for all indications, including IBD. PTG-200 was a first-generation investigational, orally delivered, IL-23R antagonist for the treatment of IBD. The agreement with Janssen was amended in May 2019 to expand the collaboration by supporting efforts towards second-generation IL-23R antagonists; and in July 2021 to, among other things, enable Janssen to independently research and develop collaboration compounds for multiple indications in the IL-23 pathway and further align our financial interests.

In October 2020, we and Janssen announced the selection of two second-generation IL23-R antagonists for advancement into clinical development, PN-232 (JNJ-75105186) and PN-235 (JNJ-77242113). During the fourth quarter of 2021, following a pre-specified interim analysis criteria, a portfolio decision was made by Janssen to stop further development of both PTG-200 and PN-232 favor of advancing PN-235, based on its superior potency and overall pharmacokinetic and pharmacodynamic profile. A PN-235 Phase 1 study was completed in Q4 2021. Janssen initiated FRONTIER 1, a Phase 2b clinical study of PN-235 in moderate-to-severe plaque psoriasis, in early 2022, and is expected to initiate a separate Phase 2 study of PN-235 in IBD in the second half of 2022.

​

During the fourth quarter of 2021, we received a $7.5 million milestone payment from Janssen triggered by the completion of data collection for PN-235 Phase 1 activities. We expect to earn a $25.0 million milestone in connection with the dosing of a third patient in the first Phase 2 study of a second-generation candidate, and a $10.0 million milestone in connection with the dosing of a third patient in the second Phase 2 study of a second-generation candidate. We remain eligible for up to approximately $900.0 million in development-related milestone payments, in addition to the $87.5 million in milestones already received.

Our clinical assets are all derived from our proprietary discovery platform. Our platform enables us to engineer novel, structurally constrained peptides that are designed to retain key advantages of both orally delivered small molecules and injectable antibody drugs in an effort to overcome many of their limitations as therapeutic agents. Importantly, constrained peptides can be designed to potentially alleviate the fundamental instability inherent in traditional peptides to allow different delivery forms, such as oral, subcutaneous, intravenous, and rectal. We continue to use our peptide technology platform to discover product candidates against targets in disease areas with significant unmet medical needs.

56

Table of Contents

COVID-19 Business Impact

​

We are subject to risks and uncertainties as a result of the ongoing COVID-19 pandemic. We are continuing to closely monitor the impact of the COVID-19 pandemic on our business and have taken and continue to take proactive efforts to protect the health and safety of our patients, study investigators, clinical research staff and employees, and to maintain business continuity. The extent of the impact of the COVID-19 pandemic on our activities is highly uncertain and difficult to predict, as the response to the pandemic is ongoing and information continues to evolve. Capital markets and economies worldwide have been significantly impacted by the COVID-19 pandemic and may be further impacted in the future. Such economic disruption could have a material adverse effect on our business. Policymakers around the globe have responded with fiscal policy actions to support the healthcare industry and economy as a whole. The magnitude and overall effectiveness of these actions remains uncertain.

The severity of the impact of the COVID-19 pandemic on our activities will depend on a number of factors, including, but not limited to, the duration and severity of the pandemic, including the severity of any additional periods of increases or spikes in the number of cases in the areas we, our suppliers and our manufacturers operate and areas where our clinical trial sites are located; the development and spread of COVID-19 variants; the timing, extent, effectiveness and durability of COVID-19 vaccine programs or other treatments; and new or continuing travel and other restrictions and public health measures, such as social distancing, business closures or disruptions. Accordingly, the extent and severity of the impact on our existing and planned clinical trials, manufacturing, collaboration activities and operations is uncertain and cannot be fully predicted. We have experienced delays in our existing and planned clinical trials due to the worldwide impacts of the pandemic. Our future results of operations and liquidity could be adversely impacted by further delays in existing and planned clinical trials and collaboration activities, continued difficulty in recruiting patients for these clinical trials, delays in manufacturing and collaboration activities, supply chain disruptions, the ongoing impact on our operating activities and employees, and the ongoing impact of any initiatives or programs that we may undertake to address financial and operational challenges. As of the date of issuance of this Annual Report on Form 10-K, the extent to which the COVID-19 pandemic may materially impact our future financial condition, liquidity or results of operations is uncertain.

Operations

We have incurred net losses in each year since inception and we do not anticipate achieving sustained profitability in the foreseeable future. Our net losses were $125.6 million, $66.2 million and $77.2 million for the years ended December 31, 2021, 2020 and 2019, respectively. As of December 31, 2021, we had an accumulated deficit of $409.4 million. Substantially all of our net losses have resulted from costs incurred in connection with our research and development programs and from general and administrative costs associated with our operations. We expect to continue to incur significant research, development and other expenses related to our ongoing operations, product development, and pre-commercialization activities. As a result, we expect to continue to incur losses in the future as we continue our development of, and seek regulatory approval for, our product candidates.

Janssen License and Collaboration Agreement

On July 27, 2021, we entered into an amended and restated License and Collaboration Agreement (“Restated Agreement”) with Janssen. The Restated Agreement amends and restates the License and Collaboration Agreement, dated May 26, 2017, by and between us and Janssen (as amended by the First Amendment thereto, effective May 7, 2019, the “Original Agreement”). Janssen is a related party to us as Johnson & Johnson Innovation - JJDC, Inc., a significant stockholder of ours, and Janssen are both subsidiaries of Johnson & Johnson. The Original Agreement became effective on July 13, 2017. Upon the effectiveness of the Original Agreement, we received a non-refundable, upfront cash payment of $50.0 million from Janssen. Upon the effectiveness of the First Amendment, we received a $25.0 million payment from Janssen in 2019. We received a $5.0 million payment triggered by the successful nomination of a second-generation IL-23R antagonist development compound during the first quarter of 2020. In the fourth quarter of 2021, we received a $7.5 million milestone payment from Janssen triggered by data collection activities for the first Phase 1 clinical trial of a second-generation compound during the fourth quarter of 2021. See Note 3 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

57

Table of Contents

Critical Accounting Polices and Estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with United States generally accepted accounting principles. The preparation of these consolidated financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities at the date of the consolidated financial statements, as well as the reported revenue generated, and expenses incurred during the reporting periods. Our estimates are based on our historical experience and on various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions. We believe that the accounting policies discussed below are critical to understanding our historical and future performance, as these policies relate to the more significant areas involving management’s judgments and estimates.

Use of Estimates

Due to the ongoing COVID-19 pandemic, there has been uncertainty and disruption in the global economy and financial markets. We have taken into consideration any known COVD-19 impacts in our accounting estimates to date and are not aware of any additional specific events or circumstances that would require any additional updates to our estimates or judgments or a revision of the carrying value of our assets or liabilities as of the date of issuance of this Annual Report on Form 10-K. These estimates may change as new events occur and additional information is obtained. Actual results could differ materially from these estimates under different assumptions or conditions.

Revenue Recognition

Under Accounting Standards Codification Topic 606, Revenue from Contracts with Customers (“ASC 606”), we recognize revenue when our customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. To determine revenue recognition for arrangements that we determine are within the scope of ASC 606, we perform the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) we satisfy a performance obligation. We apply the five-step model to contracts when it is probable that we will collect the consideration we are entitled to in exchange for the goods or services we transfer to the customer. At contract inception, we assess the goods or services promised within each contract, determine those that are performance obligations, and assess whether each promised good or service is distinct. We then recognize as revenue the amount of the transaction price that is allocated to the respective performance obligations when (or as) the performance obligations are satisfied. We constrain our estimate of the transaction price up to the amount (the “variable consideration constraint”) that a significant reversal of recognized revenue is not probable.

Licenses of intellectual property: If a license to our intellectual property is determined to be distinct from the other performance obligations identified in an arrangement, we recognize revenue from non-refundable, upfront fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, we utilize judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring proportional performance for purposes of recognizing revenue from non-refundable, upfront fees. We evaluate the measure of proportional performance each reporting period and, if necessary, adjust the measure of performance and related revenue recognition.

Milestone payments: At the inception of each arrangement or amendment that includes development, regulatory or commercial milestone payments, we evaluate whether the milestones are considered probable of being reached and estimate the amount to be included in the transaction price. ASC 606 suggests two alternatives to use when estimating the amount of variable consideration: the expected value method and the most likely amount method. Under the expected value method, an entity considers the sum of probability-weighted amounts in a range of possible consideration amounts. Under the most likely amount method, an entity considers the single most likely amount in a range of possible

58

Table of Contents

consideration amounts. Whichever method is used, it should be consistently applied throughout the life of the contract; however, it is not necessary for us to use the same approach for all contracts. We expect to use the most likely amount method for development and regulatory milestone payments. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within our control or the control of the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. If there is more than one performance obligation, the transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis. We recognize revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, we re-evaluate the probability or achievement of each such milestone and any related constraint, and if necessary, adjust our estimates of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment.

Any potential milestone payments that we determine are not associated with performance obligations as defined under the contract are excluded from the transaction price and are recognized as the triggering event occurs.

Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, we recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

Upfront payments and fees are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until we perform our obligations under these arrangements. Amounts payable to us are recorded as accounts receivable when our right to consideration is unconditional. Amounts payable to us and not yet billed to the collaboration partner are recorded as contract assets. We do not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less.

Contractual cost sharing payments made to a customer or collaboration partner are accounted for as a reduction to the transaction price if such payments are not related to distinct goods or services received from the customer or collaboration partner.

Contracts may be amended to account for changes in contract specifications and requirements. Contract modifications exist when the amendment either creates new, or changes existing, enforceable rights and obligations. When contract modifications create new performance obligations and the increase in consideration approximates the standalone selling price for goods and services related to such new performance obligations as adjusted for specific facts and circumstances of the contract, the modification is considered to be a separate contract and revenue is recognized prospectively. If a contract modification is not accounted for as a separate contract, we account for the promised goods or services not yet transferred at the date of the contract modification (the remaining promised goods or services) prospectively, as if it were a termination of the existing contract and the creation of a new contract, if the remaining goods or services are distinct from the goods or services transferred on or before the date of the contract modification. We account for a contract modification as if it were a part of the existing contract if the remaining goods or services are not distinct and, therefore, form part of a single performance obligation that is partially satisfied at the date of the contract modification. In such case the effect that the contract modification has on the transaction price, and on the entity’s measure of progress toward complete satisfaction of the performance obligation, is recognized as an adjustment to revenue (either as an increase in or a reduction of revenue) at the date of the contract modification (the adjustment to revenue is made on a cumulative catch-up basis).

The period between when we transfer control of promised goods or services and when we receive payment is expected to be one year or less, which is consistent with our historical experience. Upfront payment contract liabilities resulting from our license and collaboration agreements do not represent a financing component as the payment is not financing the transfer of goods and services, and the technology underlying the licenses granted reflects research and development expenses already incurred by us. As such, we do not adjust our revenues for the effects of a significant financing component.

59

Table of Contents

Research and Development Costs

Research and development costs are expensed as incurred, unless there is an alternate future use in other research and development projects or otherwise. Research and development costs include salaries and benefits, stock-based compensation expense, laboratory supplies and facility-related overhead, outside contracted services including clinical trial costs, manufacturing and process development costs for both clinical and pre-clinical materials, research costs, development milestone payments under license and collaboration agreements, and other consulting services.

We accrue for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of pre-clinical studies and clinical trials, and contract manufacturing activities. We record the estimated costs of research and development activities based upon the estimated services provided but not yet invoiced and includes these costs in accrued expenses and other payables in the consolidated balance sheets and within research and development expense in the consolidated statements of operations. We accrue for these costs based on factors such as estimates of the work completed and in accordance with agreements established with its third-party service providers. As actual costs become known, we adjust our accrued liabilities. We have not experienced any material differences between accrued liabilities and actual costs incurred. However, the status and timing of actual services performed, number of patients enrolled, the rate of patient enrollment and number and location of sites activated may vary from our estimates, resulting in adjustments to expense in future periods. Changes in these estimates that result in material changes to our accruals could materially affect our results of operations.

Recent Accounting Pronouncements

Information regarding recent accounting pronouncements applicable to us is included in Note 2 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K.

Components of Our Results of Operations

License and Collaboration Revenue

Our license and collaboration revenue is derived from payments we receive under the Janssen License and Collaboration Agreement. See Note 3 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

Research and Development Expenses

Research and development expenses represent costs incurred to conduct research, such as the discovery and development of our product candidates. We recognize all research and development costs as they are incurred, unless there is an alternative future use in other research and development projects or otherwise. Non-refundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received rather than when payment has been made. In instances where we enter into agreements with third parties to provide research and development services to us, costs are expensed as services are performed. Amounts due under such arrangements may be either fixed fee or fee for service and may include upfront payments, monthly payments, and payments upon the completion of milestones or the receipt of deliverables.

Research and development expenses consist primarily of the following:

60

Table of Contents

We recognize the funds from grants under government programs as a reduction of research and development expenses when the related research costs are incurred. In addition, we recognize the funds related to our Australian research and development refundable cash tax incentive that are not subject to refund provisions as a reduction of research and development expenses. The research and development tax incentives are recognized when there is reasonable assurance that the incentives will be received, the relevant expenditure has been incurred and the amount of the consideration can be reliably measured. We evaluate our eligibility under the tax incentive program as of each balance sheet date and make accruals and related adjustments based on the most current and relevant data available. We may alternatively be eligible for a taxable credit in the form of a non-cash tax incentive.

We allocate direct costs and indirect costs incurred to product candidates when they enter clinical development. For product candidates in clinical development, direct costs consist primarily of clinical, pre-clinical, and drug discovery costs, costs of supplying drug substance and drug product for use in clinical and pre-clinical studies, including clinical manufacturing costs, contract research organization fees, and other contracted services pertaining to specific clinical and pre-clinical studies. Indirect costs allocated to our product candidates on a program specific basis include research and development employee salaries, benefits, and stock-based compensation, and indirect overhead and other administrative support costs. Program-specific costs are unallocated when the clinical expenses are incurred for our early-stage research and drug discovery projects; our internal resources, employees and infrastructure are not tied to any one research or drug discovery project and are typically deployed across multiple projects. As such, we do not provide financial information regarding the costs incurred for early stage pre-clinical and drug discovery programs on a program-specific basis prior to the clinical development stage.

The following table summarizes our research and development expenses incurred during the periods indicated:

​

We expect our research and development expenses will increase as we progress our product candidates into later stage clinical trials, add to the number of ongoing clinical trials, advance our discovery research projects into the pre-clinical stage, continue our early-stage research and prepare for the commercialization of our product candidates. The process of conducting research, identifying potential product candidates and conducting pre-clinical and clinical trials necessary to obtain regulatory approval and commencing pre-commercialization activities is costly and time intensive. We may never succeed in achieving marketing approval for our product candidates regardless of our costs and efforts. The probability of success of our product candidates may be affected by numerous factors, including pre-clinical data, clinical data, competition, manufacturing capability, our cost of goods to be sold, our ability to receive, and the timing of, regulatory approvals, market conditions, and our ability to successfully commercialize our products if they are

61

Table of Contents

approved for marketing. As a result, we are unable to determine the duration and completion costs of our research and development projects or when and to what extent we will generate revenue from the commercialization and sale of any of our product candidates. Our research and development programs are subject to change from time to time as we evaluate our priorities and available resources.

General and Administrative Expenses

General and administrative expenses consist of personnel costs, allocated facilities costs and other expenses for outside professional services, including legal, human resources, audit and accounting services, and pre-commercialization expenses, including selling and marketing costs. Personnel costs consist of salaries, benefits and stock-based compensation. Allocated expenses consist of expenses for rent and maintenance of facilities, information technology, depreciation and amortization expense and other supplies. We expect to continue to incur expenses to support our continued operations as a public company, including expenses related to existing and future compliance with rules and regulations of the SEC and those of the national securities exchange on which our securities are traded, insurance expenses, investor relations, audit fees, professional services and general overhead and administrative costs.

Interest Income

Interest income consists of interest earned on our cash, cash equivalents, and marketable securities, which is comprised of contractual interest, premium amortization and discount accretion.

Interest Expense

Interest expense consists of interest recognized on our long-term debt, which is comprised of contractual interest, amortization of origination fees and other issuance costs, and accretion of final payment fees.

Loss on Early Repayment of Debt

Loss on early repayment of debt consists of prepayment and final payment fees paid upon the early repayment of our long-term debt.

Other Expense, Net

Other expense, net consists primarily of amounts related to foreign exchange gains and losses and related items.

62

Table of Contents

Results of Operations

Comparison of the Year ended December 31, 2021 and 2020

(1) Includes $9.0 million and $4.1 million of non-cash stock-based compensation expense for the years ended December 31, 2021 and 2020, respectively.

(2) Includes $7.4 million and $3.8 million of non-cash stock-based compensation expense for the years ended December 31, 2021 and 2020, respectively.

​

License and Collaboration Revenue

License and collaboration revenue decreased $1.3 million, or 4%, from $28.6 million for the year ended December 31, 2020 to $27.4 million for the year ended December 31, 2021. The decrease in license and collaboration revenue was primarily related to a decrease in services provided under the Janssen License and Collaboration Agreement recognized based on proportional performance, partially offset by an $8.0 million cumulative catch-up amount recognized during the year ended December 31, 2021 following the amendment of our collaboration agreement for the development of IL-23R assets with Janssen. This cumulative catch-up was primarily the result of an acceleration of our cumulative performance completed under our obligation, following the amendment to the collaboration which reduced the remaining services that we are responsible to provide. Revenue for the year ended December 31, 2020 included an update in the amounts forecast for future services remaining to be performed under the Janssen License and Collaboration Agreement which correspondingly increased our overall cumulative percentage of completion of our performance obligation during year ended December 31, 2020, coupled with continued performance and delivery of services under the Janssen License and Collaboration Agreement.

We have determined that the transaction price of the initial performance obligation under the Restated Janssen License and Collaboration Agreement was $106.5 million as of December 31, 2021, an increase of $7.9 million from the transaction price of $98.6 million as of December 31, 2020 under the Original Agreement. In order to determine the transaction price, we evaluated all payments expected to be received during the duration of the contract, net of development costs reimbursement expected to be payable to Janssen. We determined that the transaction price includes $87.5 million of nonrefundable payments received to date, $17.9 million of reimbursement from Janssen for services performed for IL-23R antagonist compound research costs and other services and estimated variable consideration consisting of $8.2 million of development cost reimbursement receivable from Janssen, partially offset by $7.1 million of net cost reimbursement due to Janssen for services performed. The increase in transaction price from December 31, 2020 to December 31, 2021 was due primarily to reductions in both the remaining services to be performed by the Company under the agreement and the Company’s remaining shared development costs following the Second Amendment to the Janssen License and Collaboration Agreement. We re-evaluate the transaction price each reporting period and as uncertain events are resolved or other changes in circumstances occur.

63

Table of Contents

Research and Development Expenses

*Percentage not meaningful

​

Research and development expenses increased $51.5 million, or 69%, from $74.5 million for the year ended December 31, 2020 to $126.0 million for the year ended December 31, 2021. The increase was primarily due to an increase of $23.0 million in rusfertide clinical trial and development costs as clinical trials have enrolled and progressed, including the ongoing REVIVE and PACIFIC Phase 2 trials in PV, which began in December 2019 and the first quarter of 2021, respectively, and HH, which began in early 2020, and clinical and contract manufacturing activities incurred in 2021 in support of the REVIVE and PACIFIC Phase 2 trials and planned VERIFY global Phase 3 clinical trial of rusfertide in PV; $14.3 million in PN-943 clinical trial and development costs and contract manufacturing costs primarily related to the Phase 2 IDEAL trial in UC initiated during the second quarter of 2020; an increase of $6.5 million in preclinical and drug discovery research expenses; $4.5 million of clinical trial and development costs for the Phase 1 PN-235 initiated in December 2020; $4.0 million of expenses related to milestone payments and obligations under the Zealand Agreement for rusfertide pursuant to the resolution of related arbitration; and $2.0 million of clinical trial and development costs for the Phase 1 PN-232 study initiated in May 2021. These increases were partially offset by a $1.7 million increase in grant and accrued refundable cash tax incentives and a decrease of $0.9 million in PTG-200 clinical trial and development expenses under the Janssen License and Collaboration Agreement due to our delivery of substantially all agreed-upon services for the PTG-200 Phase 2 clinical trial prior to 2021.

We had 92 and 59 full-time equivalent research and development employees at December 31, 2021 and 2020, respectively. Research and development expenses for the year ended December 31, 2021 included increases of $4.9 million in stock-based compensation expense and $5.3 million of other personnel-related expenses compared to the year ended December 31, 2020.

General and Administrative Expenses

General and administrative expenses increased $8.6 million, or 46%, from $18.6 million for the year ended December 31, 2020 to $27.2 million for the year ended December 31, 2021, primarily due to increases of $5.2 million in personnel-related expenses; $1.6 million in consulting expenses, $0.9 million in market research expenses, $0.5 million in recruiting expenses to support the growth of our business; and $0.3 million increase in insurance expense. The increase in personnel-related expenses was primarily due to an increase of $3.6 million in stock-based compensation expense and $1.6 million in wages and salaries.

We had 26 and 20 full-time equivalent general and administrative employees as of December 31, 2021 and 2020, respectively.

64

Table of Contents

Interest Income

Interest income decreased $0.5 million, or 51%, from $0.9 million for the year ended December 31, 2020 to $0.4 million for the year ended December 31, 2021. This decrease was primarily due to the recent record low interest rate environment and a change in the mix of marketable securities compared to the prior year period, despite higher interest-earning asset balances.

Interest Expense

Interest expense of $0.6 million for the year ended December 31, 2020 was comprised of interest expense on our long-term debt under our term credit facility. We prepaid our outstanding long-term debt under our term credit facility during the second quarter of 2020. We executed a payoff letter to release all obligations under the term credit facility during the third quarter of 2021.

Loss on Early Repayment of Debt

Loss on early repayment of debt of $0.6 million for the year ended December 31, 2020 was comprised of prepayment and final payment fees paid in connection with the early repayment of our term loan in June 2020. We had no debt outstanding as of December 31, 2021.

Other Expense, Net

Other expense, net was $0.1 million for the year ended December 31, 2021 compared to zero for the year ended December 31, 2020. The change was due primarily to an increase in foreign exchange losses.

Income Tax Expense

Income tax expense decreased $1.3 million, or 100%, from $1.3 million for the year ended December 31, 2020 to zero for the year ended December 31, 2021. Our effective income tax rate was 0% for the year ended December 31, 2021 as compared to 2.0% for the year ended December 31, 2020. Our effective income tax rate differs from our federal statutory rate of 21% primarily because our losses cannot be benefited due to our full valuation allowance position. During the second quarter of 2020, our Australia subsidiary sold beneficial rights to discovery intellectual property to our U.S. entity, and the U.S. entity reimbursed the Australia subsidiary for certain direct development costs. Upon completion of the sale, we analyzed tax planning strategies and future income and concluded that a valuation allowance is necessary for our Australia subsidiary. Income tax expense for year ended December 31, 2020 reflects this sale of intellectual property rights, cost reimbursements and related adjustments to the deferred tax asset, establishing a valuation allowance and certain uncertain tax position liabilities. We maintained a full valuation allowance on our tax position as of December 31, 2021.

65

Table of Contents

Comparison of the Years ended December 31, 2020 and 2019

(1) Includes $4.1 million and $4.4 million of non-cash stock-based compensation expense for the years ended December 31, 2020 and 2019, respectively.

(2) Includes $3.8 million and $4.0 million of non-cash stock-based compensation expense for the years ended December 31, 2020 and 2019, respectively.

*Percentage not meaningful

License and Collaboration Revenue

License and collaboration revenue increased $28.4 million from $0.2 million for the year ended December 31, 2019 to $28.6 million for the year ended December 31, 2020. The increase in license and collaboration revenue was primarily due to an update in the amounts forecast for future services remaining to be performed under the Janssen License and Collaboration Agreement, correspondingly increasing our overall cumulative percentage of completion of our performance obligation during year ended December 31, 2020, coupled with continued performance and delivery of services under the ongoing Janssen License and Collaboration Agreement. The increase in license and collaboration revenue for the year ended December 31, 2020 also included the impact of a one-time cumulative adjustment related to the application of revenue recognition principles following the May 2019 amendment of the Janssen License and Collaboration Agreement that reduced 2019 revenue by $9.4 million. The contract modification resulted in an increase in the transaction price and additional deliverables under the initial performance obligation, leading to an overall corresponding decrease in the cumulative percentage of completion of our performance obligation for the Janssen License and Collaboration Agreement during the second quarter of 2019.

We determined that the transaction price of the Janssen License and Collaboration Agreement was $98.6 million as of December 31, 2020, a decrease of $14.3 million from the transaction price of $112.9 million at December 31, 2019. In order to determine the transaction price, we evaluated all payments expected to be received during the duration of the contract, net of development costs reimbursement expected to be payable to Janssen. We determined that the transaction price includes the $50.0 million upfront payment, the $25.0 million payment received upon the effectiveness of the First Amendment, the $5.0 million payment triggered by the successful nomination of a second-generation compound, $17.9 million of reimbursement from Janssen for services performed for PTG-200 Phase 2 and for second-generation compound research costs and other services, and estimated variable consideration consisting of a $7.5 million milestone payment subject to the completion of a Phase 1 study for a second-generation compound, offset by $6.8 million of net cost reimbursement to Janssen for services performed. The decrease in transaction price from December 31, 2019 to December 31, 2020 was due primarily to a decrease in the forecast of remaining services to be provided under the initial performance obligation. We re-evaluate the transaction price each reporting period and as uncertain events are resolved or other changes in circumstances occur.

66

Table of Contents

Research and Development Expenses

*Percentage not meaningful

Research and development expenses increased $9.5 million, or 15%, from $65.0 million for the year ended December 31, 2019 to $74.5 million for the year ended December 31, 2020. The increase included a $14.3 million increase in pre-clinical and discovery research expenses, including pre-clinical costs related to our second-generation research collaboration efforts with Janssen, a $2.4 million increase in PN-943 clinical trial and development expenses following the initiation of the Phase 2 trial in UC in 2020, a $2.1 million increase in rusfertide clinical trial and development expenses, including the ongoing Phase 2 trials in PV and HH, and $0.3 million of Phase 1 clinical trial and development expenses for PN-235. These increases were partially offset by a decrease of $8.5 million for PTG-200 clinical trial and development expenses under the Janssen License and Collaboration Agreement due to timing of deliverables and related cost sharing arrangements, and the impact of a $1.3 million reversal of previously recorded reductions to research and development expenses in connection with the tax incentive from Australia in 2019. Research and development expenses for the year ended December 31, 2020 included increased personnel costs due to an increase in research and development headcount from 54 full-time equivalent employees at December 31, 2019 to 59 full-time equivalent employees at December 31, 2020.

General and Administrative Expenses

General and administrative expenses increased $2.9 million, or 18%, from $15.7 million for the year ended December 31, 2019 to $18.6 million for the year ended December 31, 2020 primarily due to increases of $1.4 million in compensation-related expenses to support the growth of our operations, $1.3 million in legal expenses and $0.8 million in insurance expense, partially offset by a $0.6 million decrease in other expenses, including accounting fees, market research, recruiting fees and travel expense.

Interest Income

Interest income decreased $1.9 million, or 68%, from $2.8 million for the year ended December 31, 2019 to $0.9 million for the year ended December 31, 2020. This decrease was primarily due to the declining interest rate environment and a change in the mix of marketable securities compared to the prior year period, despite higher interest-earning asset balances.

Interest Expense

Interest expense increased $0.4 million, or 254%, from $0.2 million for the year ended December 31, 2019 to $0.6 million for the year ended December 31, 2020. Interest expense reflects contractual interest, amortization of origination fees and other issuance costs, and accretion of final payment fees on our term loan that funded in October 2019 and was repaid in full in June 2020.

67

Table of Contents

Income Tax Expense

Income tax expense increased by $2.0 million, or 289%, from an income tax benefit of $0.7 million for the year ended December 31, 2019 to income tax expense of $1.3 million for the year ended December 31, 2020. Our effective income tax rate was (2.0)% for the year ended December 31, 2020 as compared to 0.9% for the year ended December 31, 2019. Our effective income tax rate differs from our federal statutory rate of 21% primarily because our losses cannot be benefited due to our full valuation allowance position. During the second quarter of 2020, our Australia subsidiary sold beneficial rights to discovery intellectual property to our U.S. entity, and the U.S. entity reimbursed the Australia subsidiary for certain direct development costs. Upon completion of the sale, we analyzed tax planning strategies and future income and concluded that a valuation allowance is necessary for our Australia subsidiary. Income tax expense for year ended December 31, 2020 reflects this sale of intellectual property rights, cost reimbursements and related adjustments to the deferred tax asset, establishing a valuation allowance and certain uncertain tax position liabilities. Income tax benefit for the year ended December 31, 2019 included a discrete tax benefit of approximately $1.1 million for the 2017 Australia refundable R&D tax offset.

Liquidity and Capital Resources

Liquidity and Capital Expenditures

Sources of Liquidity

Historically, we have funded our operations primarily from net proceeds from the sale of shares of our common stock and payments under collaboration agreements.

In December 2020, we filed an automatic registration statement on Form S-3ASR and an accompanying prospectus (File No. 333-251254), pursuant to which we completed an underwritten public offering of 4,761,904 shares of common stock at a public offering price of $21.00 per share and issued an additional 714,285 shares of our common stock at a price of $21.00 per share following the underwriters’ exercise of their option to purchase additional shares. Net proceeds, after deducting underwriting commissions and offering costs paid by us, were $107.6 million. In June 2021, pursuant to the Form S-3ASR (File No. 333-251254), we completed an underwritten public offering of 3,046,358 shares of common stock at a public offering price of $37.75 per share and issued an additional 456,953 shares of common stock at a public offering price of $37.75 per share following the underwriters’ exercise of their option to purchase additional shares. Net proceeds, after deducting underwriting commission and offering costs paid by us, were $123.8 million. This Form S-3ASR expires in December 2023.

​

In October 2019, we filed a registration statement on Form S-3 (File No. 333-234414) that was declared effective as of November 22, 2019 and permits the offering, issuance, and sale by us of up to a maximum aggregate offering price of $250.0 million of our common stock, preferred stock, debt securities and warrants (the “2019 Form S-3”). Up to a maximum of $75.0 million of the maximum aggregate offering price of $250.0 million may be issued and sold pursuant to an ATM financing facility under a sales agreement we entered into on November 27, 2019 (the “2019 Sales Agreement”). In May 2020, we completed an underwritten public offering of 7,000,000 shares of common stock at a public offering price of $14.00 per share, and we issued an additional 1,050,000 shares of our common stock at a price of $14.00 per share following the underwriters’ exercise of their option to purchase additional shares. Net proceeds, after deducting underwriting commissions and offering costs paid by us, were $105.3 million. During the year ended December 31, 2020, we issued 2,483,719 shares under our ATM facility for net proceeds of $41.9 million. No shares were issued under the ATM facility during the year ended December 31, 2021. As of December 31, 2021, a total of $94.2 million of common stock remained available for sale under the 2019 Form S-3, $31.9 million of which remained available for sale under the ATM financing facility. This Form S-3 expires in October 2022.

We have received $87.5 million in non-refundable payments from Janssen since the inception of the Janssen License and Collaboration Agreement in 2017 through December 31, 2021, as follows:

​

68

Table of Contents

We also receive payments for services provided under the collaboration agreement and in-kind reimburses Janssen for certain costs they have incurred based on the cost sharing terms of the agreement.

Pursuant to the amended and restated License and Collaboration Agreement with Janssen executed July 27, 2021 (the “Restated Agreement”), we will be eligible to receive clinical development, regulatory and sales milestones, if and as achieved. Upcoming potential development milestones for second-generation products include:

Capital Requirements

As of December 31, 2021, we had $326.9 million of cash, cash equivalents and marketable securities and an accumulated deficit of $409.4 million. Our capital expenditures were $1.1 million, $0.5 million and $1.0 million for the years ended December 31, 2021, 2020 and 2019, respectively. Our primary uses of cash are to fund operating expenses, primarily our research and development expenditures, general and administrative costs and pre-commercialization costs. Cash used to fund operating expenses is impacted by the timing of when we pay these expenses. We believe, based on our current operating plan and expected expenditures, that our existing cash, cash equivalents and marketable securities will be sufficient to meet our anticipated operating and capital expenditure requirements for at least the next 12 months from the date of this filing. We have based this estimate on assumptions that may prove to be wrong. We could utilize our available capital resources sooner than we currently expect if our planned pre-clinical and clinical trials are successful or expanded, our product candidates enter new and more advanced stages of clinical development or our newer product clinical trials or advance beyond the discovery stage. We expect to require additional financing to advance our product candidates through clinical development and toward potential regulatory approval and to develop, acquire or in-license other potential product candidates. Such additional funding may come from raising additional capital, seeking access to debt, and additional collaborative or other arrangements with corporate sources, but such funding may not be available at terms acceptable to us, if at all.

​

We anticipate that we will need to raise substantial additional funding, the requirements of which will depend on many factors, including:

69

Table of Contents

Adequate additional funding may not be available to us on acceptable terms, or at all. Any failure to raise capital as and when needed could have a negative impact on our financial condition and on our ability to pursue our business plans and strategies. Further, our operating plans may change, and we may need additional funds to meet operational needs and capital requirements for clinical trials, other research and development activities and pre-commercialization costs. If we do raise additional capital through public or private equity offerings or convertible debt securities, the ownership interest of our existing stockholders will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect our stockholders’ rights. If we raise additional capital through debt financing, we may be subject to covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. Because of the numerous risks and uncertainties associated with the development and commercialization of our product candidates, we are unable to fully estimate the amounts of increased capital outlays and operating expenditures associated with our current and anticipated product development programs.

The following table includes our cash flow data for the periods indicated (in thousands):

​

70

Table of Contents

Cash Used in Operating Activities

Cash used in operating activities during the year ended December 31, 2021 of $107.9 million consisted primarily of our net loss of $125.6 million, partially offset by certain non-cash items including $16.4 million of stock-based compensation expense. The $35.4 million increase in cash flow used in operating activities during the year ended December 31, 2021, as compared to the year ended December 31, 2020, was primarily due to a $59.4 million increase in our net loss, partially offset by certain non-cash items including an increase of $8.5 million of stock-based compensation expense, and a $14.2 million change in decrease in deferred revenue.

Cash used in operating activities for the year ended December 31, 2020 of $72.5 million consisted primarily of our net loss of $66.2 million and net changes of $19.0 million in net operating assets and liabilities, partially offset by certain non-cash items including $7.9 million of stock-based compensation expense and a $1.4 million decrease in deferred tax asset. Changes in net operating assets and liabilities included a $27.1 million decrease in deferred revenue, partially offset by a $5.8 million increase in accrued expenses and other payables and a $4.3 decrease in receivable from collaboration partner. The $31.0 million increase in cash flow used in operating activities during the year ended December 31, 2020, as compared to the year ended December 31, 2019, was primarily due to a $60.4 million change in decrease in deferred revenue, partially offset by an $11.0 million decrease in our net loss, a $15.2 million net increase due to changes in other operating assets and liabilities, and a $2.2 million change in decrease in deferred tax asset.

Cash Used in Investing Activities

Cash used in investing activities for the year ended December 31, 2021 was $15.9 million, consisting of purchases of marketable securities of $286.6 million and purchases of property and equipment of $1.1 million, partially offset by proceeds from maturities of marketable securities of $271.8 million. The $75.1 million decrease in cash used in investing activities for the year ended December 31, 2021, as compared to the year ended December 31, 2020, was primarily due to an increase of $82.3 million in proceeds from maturities of marketable securities. Purchases of property and equipment were primarily related to purchases of laboratory equipment, furniture and computer equipment.

Cash used in investing activities for the year ended December 31, 2020 was $91.0 million, consisting of purchases of marketable securities of $280.0 million and purchases of property and equipment of $0.5 million, partially offset by proceeds from maturities of marketable securities of $189.5 million. The $37.3 million increase in cash used in investing activities for the year ended December 31, 2020, as compared to the year ended December 31, 2019, was primarily due to an increase of $113.0 million in purchases of marketable securities, partially offset by an increase of $75.3 million of proceeds from maturities of marketable securities. Purchases of property and equipment were primarily related to purchases of laboratory equipment, furniture and computer equipment.

Cash Provided by Financing Activities

Cash provided by financing activities for the year ended December 31, 2021 was $129.9 million, consisting primarily of cash proceeds from our public offerings of common stock of $123.8 million and proceeds from the issuance of common stock upon exercise of stock options and purchases of common stock under our employee stock purchase plan of $6.3 million. The $117.7 million decrease in cash provided by financing activities for the year ended December 31, 2021, as compared to the year ended December 31, 2020, was primarily due to an $89.5 million decrease in cash proceeds from our public offerings of common stock, a $42.1 million decrease in cash proceeds from ATM sales, and a $3.5 million decrease in proceeds from the issuance of common stock upon exercise of stock options and purchases of common stock under our employee stock purchase plan. These decreases were partially offset by $10.5 million related to the early repayment of long-term debt in 2020.

Cash provided by financing activities for the year ended December 31, 2020 was $247.6 million, consisting primarily of cash proceeds from our public offerings of common stock of $213.3 million, cash proceeds from ATM sales of $42.1 million, and proceeds from the issuance of common stock upon exercise of stock options and purchases of common stock under our employee stock purchase plan of $2.8 million, partially offset by early repayment of long-term debt of $10.5 million. The $201.6 million increase in cash provided by financing activities for the year ended December 31, 2020, as compared to the year ended December 31, 2019, was primarily due to an increase of $213.3 million in cash

71

Table of Contents

proceeds from our public offerings of common stock and a $7.6 million increase in cash proceeds from ATM sales, and a decrease of $9.8 million in proceeds received from the issuance of long-term debt, partially offset by $10.5 million related to the repayment of long-term debt in 2021.

Contractual Obligations and Other Commitments

In the normal course of business, we enter into agreements with contract service providers to assist in the performance of our R&D and clinical and commercial manufacturing activities. Subject to required notice periods and our obligations under binding commitments, we can elect to discontinue the work under these agreements at any time. We expect to enter into additional clinical development, contract research, clinical and commercial manufacturing, supplier and collaborative research agreements in the future, which may require upfront payments and long-term commitments of capital resources.

​

Our contractual obligations include minimum lease payments under our operating lease obligations. On July 2, 2021, we entered into an amendment to our facility lease agreement dated as of March 2017, as amended, to lease approximately 15,000 square feet of additional office space in Newark, California. See Note 10 to the consolidated financial statements elsewhere in this Annual Report on Form 10-K for additional information.

​

On July 27, 2021, we entered into an amended and restated License and Collaboration Agreement with Janssen. The Restated Agreement amends and restates the License and Collaboration Agreement, dated May 26, 2017, by and between the Company and Janssen (as amended by the First Amendment thereto, effective May 7, 2019). Under the Janssen License and Collaboration Agreement, we share with Janssen certain development, regulatory and compound supply costs. The actual amounts that we pay Janssen or that Janssen pays us will depend on numerous factors, some of which are outside of our control and some of which are contingent upon the success of certain development and regulatory activities. See Note 3 to the consolidated financial statements elsewhere in this Annual Report on Form 10-K for additional information.

In June 2012, we entered into a Research Collaboration and License Agreement with Zealand Pharma A/S to identify, optimize and develop novel disulfide-rich peptides to discover a hepcidin mimetic. We amended this agreement on February 28, 2014, at which point Protagonist assumed responsibility for the development program. On January 23, 2020, we initiated arbitration proceedings with the International Court of Arbitration of the International Chamber of Commerce against Zealand Pharma A/S. On August 4, 2021, we and Zealand agreed to resolve the dispute and reached an Arbitration Resolution Agreement. See Note 7 and Note 11 to the Consolidated Financial Statements included elsewhere in this Annual Report on Form 10-K for additional information.

​