ARDELYX, INC. (ARDX)

ITEM 7.    MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

You should read the following discussion and analysis of our financial condition and results of operations in conjunction with our financial statements and related notes included elsewhere in this report. This discussion and other parts of this report contain forward-looking statements that involve risk and uncertainties, such as statements of our plans, objectives, expectations and intentions. Our actual results could differ materially from those discussed in these forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed in the section of this report entitled “Risk Factors.” These forward-looking statements speak only as of the date hereof. Except as required by law, we assume no obligation to update or revise these forward-looking statements for any reason. Unless the context requires otherwise, the terms “Ardelyx,” “we,” “us,” “our” and “the Company” refer to Ardelyx, Inc.

EXECUTIVE SUMMARY AND FINANCIAL HIGHLIGHTS

We are a biopharmaceutical company founded with a mission to discover, develop and commercialize innovative, first-in-class medicines that meet significant unmet medical needs. We developed a unique and innovative platform that enabled the discovery of new biological mechanisms and pathways to develop potent and efficacious therapies that minimize the side effects and drug-drug interactions frequently encountered with traditional, systemically absorbed medicines. The first molecule we discovered and developed was tenapanor, a minimally absorbed, first-in-class, oral, small molecule therapy. Tenapanor, branded as IBSRELA®, is approved in the U.S. for the treatment of adults with IBS-C. Tenapanor, branded as XPHOZAH®, is approved in the U.S. to reduce serum phosphorus in adults with CKD on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy.

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Below is a summary of our product sales, net by product for the years ended December 31 and total cash, cash equivalents and short-term investments as of December 31:

IBSRELA and XPHOZAH product sales have continually grown since their respective commercial launches. IBSRELA net sales growth was attributed to patient demand for this first-in-class therapy as well as increased product awareness achieved through the IBSRELA field-based team. XPHOZAH’s commercial launch has been met with a strong response from the prescribing community and net sales continued to increase during 2024, the first full year of commercialization. As of January 1, 2025, we no longer receive reimbursement for XPHOZAH from Medicare Part D following the decision by the Centers of Medicare and Medicaid Services to eliminate Medicare Part D reimbursement to transition oral only therapies, including XPHOZAH, into the End Stage Renal Disease Prospective Payment System. Patient access to XPHOZAH remains through a prescription written by a qualifying healthcare provider through our ArdelyxAssist specialty pharmacy partner. Patients who do not have affordable access will be evaluated for eligibility to receive XPHOZAH fulfilled by our Ardelyx patient assistance program.

The increase in our cash, cash equivalents and short-term investment was attributed to higher product sales, net and incremental borrowings. During 2024, we amended the 2022 Loan Agreement with SLR and drew an additional $100.0 million in debt as discussed in Note 9. Borrowing. We expect that we will increasingly rely on cash generated from operations to fund our operating plan. We believe our existing cash, cash equivalents and short-term investments, and cash generated from operations will be sufficient to satisfy our anticipated cash needs for operations for at least the next few years. Our access to additional capital, including our ability to source cash from future equity sales and debt financing, provides us financial flexibility to execute our principal strategy as discussed below.

Strategy

We are committed to our mission of discovering, developing and commercializing first-in-class medicines that address unmet patient needs. Our principal strategy is to maintain our commercial momentum with our current products while identifying additional assets that leverage our core capabilities, including clinical, developmental and regulatory expertise and commercial excellence while maintaining a solid financial foundation, to support our future growth.

Our priorities include: (i) accelerating IBSRELA growth momentum; (ii) executing our XPHOZAH strategy to grow utilization; (iii) building a pipeline focused on areas of unmet patient need; and (iv) continuing to deliver strong commercial and financial performance.

RECENT ACCOUNTING PRONOUNCEMENTS

A summary of recent accounting pronouncements that we have adopted or may expect to adopt is included in Note 2. Summary Of Significant Accounting Policies in the notes to our financial statements, included in Part II, Item 8, of this Annual Report on Form 10-K.

CRITICAL ACCOUNTING POLICIES AND ESTIMATES

A detailed discussion of our significant accounting policies can be found in Note 2. Summary Of Significant Accounting Policies, in the notes to our financial statements, included in Part II, Item 8, of this Annual Report on Form 10-K. The preparation of financial statements requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities and the reported amounts of revenues and expenses. Our critical accounting policies are those that significantly affect our financial condition and results of operations and require the most difficult, subjective or complex judgments, often because of the need to make estimates about the effect of matters that are inherently uncertain.

While we believe that our estimates, assumptions and judgments are reasonable, they are based on information available when the estimate or assumption was made. Actual results may differ significantly. Additionally, changes in our assumptions, estimates or assessments due to unforeseen events or otherwise could have a material impact on our financial position or results of operations.

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Revenue Recognition

The application of ASC 606 Revenue from Contracts with Customers substantially impacts our reported results, particularly product sales, net, which requires certain estimates in determining the transaction price. Total revenues are recognized following a five-step model: (i) identify the customer contract; (ii) identify the contract’s performance obligations; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations; and (v) recognize revenue when or as a performance obligation is satisfied.

Product Sales, Net

GTN adjustments are primarily a function of sales volume, payor mix, contractual or legislative discounts and rebates. The transaction price for product sales, net is reduced for estimates of variable consideration related to GTN adjustments for discounts and chargebacks, rebates, wholesaler and GPO fees, copay assistance and returns. Except for certain wholesaler and GPO fees and discounts, which are based on contracts, these adjustments involve estimation and judgment. The GTN adjustments for rebates, copay assistance and chargebacks are impacted by our estimate of payor mix, which requires significant judgment. We consider legal interpretations of applicable laws and regulations, historical experience, current contract prices under applicable programs, unbilled claims, processing time lags and inventory levels in the distribution channel in determining our estimates. Estimates are assessed each period and adjusted as required to revise information or actual experience.

Discounts and chargebacks:

Our U.S. business participates in programs with government entities, the most significant of which are the U.S. Department of Defense and the U.S. Department of Veterans Affairs, and other parties, including covered entities under the 340B program, whereby pricing on products is extended below wholesaler list price to participating entities. These entities purchase products through wholesalers at the lower program price and the wholesalers then charge us the difference between their acquisition cost and the lower program price. Accounts receivable is reduced for the estimated amount of unprocessed chargeback claims attributable to a sale (typically within a two to four week time lag).

Our Customers may also receive prompt pay discounts for payment within a specified period, generally approximating two percent of the invoiced sales price. Our payment terms are generally 30 to 60 days. We expect discounts to be earned when offered and we deduct the full amount of these discounts from product sales when revenue is recognized.

Accounts receivable is reduced for the estimated amount of fees and cash discount at the time of sale and the discount is typically taken by the customer within contractual terms.

Rebates, wholesaler and GPO fees:

Our U.S. business participates in state government Medicaid and Medicare programs and other qualifying Federal and state government programs requiring discounts and rebates to participating state and local government entities. All discounts and rebates provided through these programs are included in our Medicaid and Medicare rebate accruals. Medicaid rebates have also been extended to drugs used in managed Medicaid plans. The estimated amount of unpaid or unbilled rebates and discounts is presented as a liability. Settlement of Medicare and Medicaid accruals can lag for multiple quarters due to extensive time delays between recording an accrual and subsequent receipt of an invoice. Due to this lag, adjustments can incorporate revision of several prior quarters. Through December 31, 2024, we paid a 70% discount to CMS when the Medicare Part D beneficiaries were in the coverage gap. Beginning in 2025, as part of the Medicare Part D redesign within the IRA, there is a $2,000 cap for out-of-pocket costs for Medicare Beneficiaries and manufacturers are responsible for 10% of costs up to the cap and 20% after the cap is reached.

Wholesaler and GPO administrative fees are a significant portion of our GTN adjustments, however, since they are based on contracts, they require inherently less estimation.

Copay assistance and returns:

Patients who have commercial insurance may receive copay assistance when product is dispensed by pharmacies to patients. We estimate the amount of copay assistance provided to eligible patients based on the terms of the program and redemption information provided by third-party claims processing organizations. We also estimate the amount of copay assistance that we will provide to patients associated with product we have sold but has not yet been dispensed to commercial patients, which requires significant estimation and judgment. Our estimates are recorded in accrued expenses and other current liabilities on the balance sheets.

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Considering the timing of our respective product launches, and limited experiences with returns, we are primarily reliant on historical sales returns of similar products, such as those within the same product line, similar therapeutic area, similar distribution model, estimated levels of inventory in the distribution channel and projected demand. We increasingly rely on our products’ actual returns history and other factors, including levels of our inventory in the distribution channel and estimated shelf life, to estimate our returns. Our estimates are recorded in accrued expenses and other current liabilities on the balance sheets.

Use of Information from External Sources:

Information from external sources is used to estimate GTN adjustments. Our estimate of inventory at the wholesalers is based on the historical inventory experience, as well as our analysis of third-party information, including written and oral information obtained from certain wholesalers with respect to their inventory levels and sell-through to customers and our internal information. The inventory information received from wholesalers is a product of their recordkeeping process and excludes inventory held by intermediaries to whom they sell, such as retailers and hospitals. We also use information from external sources to identify prescription trends, patient demand and average selling prices. Our estimates are subject to inherent limitations of estimates that rely on third-party information, as certain third-party information was itself in the form of estimates and reflect other limitations including lags between the date as of which third-party information is generated and the date on which we receive third-party information.

RESULTS OF OPERATIONS

Revenue

Our revenue to date has been generated primarily through a combination of product sales and payments in connection with license, research and development collaborative agreements with our various collaboration partners. In the future, we may generate revenue from a combination of our own product sales and payments in connection with our current or future collaborative partnerships, including license fees, other upfront payments, milestone payments, royalties and payments for drug product and/or drug substance. We expect that any revenue we generate will fluctuate in future periods as a result of many factors as described in Part I, Item 1A, “Risk Factors,” of this Annual Report on Form 10-K.

Below is a summary of our total revenues:

(a) Percent change is not meaningful.

Below is a summary of our product sales, net by product:

Product sales, net:

The increase in IBSRELA product sales, net in 2024 and 2023 was due to higher demand since its commercial launch in March 2022, reflecting continued increase in awareness and prescriber experience. In addition, the increase in 2024 was attributable to the completion of our field-base team expansion.

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The increase in XPHOZAH product sales, net in 2024 and 2023 was due to higher demand since its commercial launch in November 2023. As of January 1, 2025, we no longer receive reimbursement for XPHOZAH from Medicare Part D following the decision by the Centers of Medicare and Medicaid Services to eliminate Medicare Part D reimbursement to transition oral only therapies, including XPHOZAH, into the End Stage Renal Disease Prospective Payment System. Patient access to XPHOZAH remains through a prescription written by a qualifying healthcare provider through our ArdelyxAssist specialty pharmacy partner. Patients who do not have affordable access will be evaluated for eligibility to receive XPHOZAH fulfilled by our Ardelyx patient assistance program.

Product supply revenue:

The increase in product supply revenue in 2024 and 2023 was due to product supply shipments to our collaboration partners, primarily Kyowa Kirin, under our respective commercial supply agreements in support of non-US launches.

Licensing revenue:

Licensing revenue is primarily impacted by the timing of regulatory and commercial milestone achievements from our out-licensing partners, as well as sales-based royalties received from Knight. The 2023 licensing revenue included $30.0 million in payments received under the Kyowa Kirin Agreement, following Kyowa Kirin’s submission to the Japanese MHLW for the NDA for tenapanor in the improvement of hyperphosphatemia in adult patients with CKD on dialysis; and a $5.0 million payment under the Fosun Agreement, following the NDA acceptance by China’s Center for Drug Evaluation of the NMPA for tenapanor in the control of serum phosphorus in adult patients with CKD on hemodialysis and the U.S. FDA approval of XPHOZAH to reduce serum phosphorus in adults with CKD on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy.

Non-cash royalty revenue:

Non-cash royalty revenue in 2024 was attributable to royalties from Kyowa Kirin for sales of PHOZEVEL in Japan since its launch in February 2024, which we remitted to HCR upon receipt in accordance with the HCR Agreement.

GTN Adjustments

We recognize product sales net of GTN adjustments that are further described in Note 6. Revenue and the “Critical Accounting Policies and Estimates” caption in Part II, Item 7, “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” Reconciliation of gross product sales to product sales, net by GTN adjustment category is as follows:

GTN adjustments are primarily a function of sales volume, payor mix, contractual or legislative discounts and rebates. Adjustments to provisions for product sales made in prior periods due to changes in estimates were not significant for any of the years presented. The decrease in GTN adjustment percentage in 2024 was primarily due to a higher percentage of sales which had a more favorable GTN rate. The reduction was mainly due to lower sales subjected to copay assistance and contractual chargebacks which had higher GTN adjustment percentages. We expect GTN adjustment percentages to increase in the future due to unfavorable payor mix shifts associated with loss of XPHOZAH Medicare Part D reimbursement beginning January 1, 2025.

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The activities and ending reserve balances for each significant category of GTN adjustments on product sales, net, which constitute variable consideration, were as follows:

Adjustments to prior period provisions recorded in the current period were not material.

Expenses

Below is a summary of our cost of goods sold, operating expenses, interest expense, non-cash interest expense related to the sale of future royalties and other income, net:

Cost of Goods Sold

Cost of product sales consists of the cost of commercial goods sold to our Customers and includes the cost of materials, third-party contract manufacturing, third-party packaging services, freight, labor costs for personnel involved in the manufacturing process and indirect overhead costs. Other cost of revenue consists of the cost of materials sold to our international partners under product supply agreements, certain costs related to capacity expansion at current and future CMOs, as well as payments due to AstraZeneca based on sales of tenapanor. See the “AstraZeneca” caption in Note 7. Collaboration And Licensing Agreements for further detail.

Cost of product sales:

The increase in cost of product sales in 2024 and 2023 was due to higher product sales. A portion of the costs of IBSRELA and XPHOZAH units recognized as revenue during the years ended December 31, 2024 and 2023 were expensed as research and development expenses in periods prior to the commencement of capitalization of inventory costs for each respective product as discussed in Note 2. Summary Of Significant Accounting Policies. The cost associated with inventory sold but previously expensed as research and development was $6.3 million, $4.4 million and $1.9 million in 2024, 2023 and 2022, respectively. The value of inventory on hand as of December 31, 2024 and 2023 that was previously expensed as research and development was approximately $15.6 million and $21.8 million, respectively.

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Other cost of revenue:

The increase in other cost of revenue in 2024 and 2023 was primarily due to higher AstraZeneca royalties, driven by higher product sales, net of tenapanor. In 2023, AstraZeneca royalties attributed to licensing revenue had a greater impact on the obligation than royalties from product sales, net. Other cost of revenue related to the AstraZeneca Termination Agreement was $34.7 million, $12.4 million and $3.6 million in 2024, 2023 and 2022, respectively. The remaining future royalty obligation to AstraZeneca was $12.1 million as of December 31, 2024. In addition, the increase in other cost of revenue was due to higher product supply revenue and costs associated with that revenue.

Research and Development

Research and development activities include research and early discovery, preclinical and clinical development, drug formulation and medical support to marketed products. External R&D expenses include research and development expenses incurred under agreements with outside consultants, third-party CROs and investigative sites where a substantial portion of our clinical studies are conducted, and with CMOs where our clinical supplies are produced; employee-related expenses, which include salaries, bonuses, benefits, travel and stock-based compensation; expenses associated with supplies and materials consumed in connection with our research operations; and other allocated expenses, which include direct and allocated expenses for rent and maintenance of facilities, depreciation and amortization expense, information technology expense and other supplies.

Below is a summary of our research and development expenses:

The increase in R&D expenses in 2024, including other R&D expenses, primarily reflected increased medical engagement with scientific communities in the areas of gastroenterology and nephrology related to our marketed products. The increase in external R&D expenses was also attributable to clinical trial and pharmacovigilance activities. The increase in employee-related R&D expenses was the result of increases in headcount and personnel costs, including an increase in stock-based compensation expenses totaling $6.0 million and $0.4 million in 2024 and 2023, respectively.

R&D expenses in 2023 remained relatively stable as compared to 2022, however, the focus of 2023 activities primarily shifted towards medical and pharmacovigilance efforts supporting our marketed products. Whereas, in 2022, activities focused more on clinical activities in preparation for the respective regulatory approvals.

Selling, General and Administrative

Selling, general and administrative expenses relate to sales and marketing, finance, human resources, legal and other administrative activities, including information technology investments. Selling, general and administrative expenses consist primarily of personnel costs, outside professional services, marketing, advertising and legal expenses, facilities costs not otherwise allocated to research and development and other general and administrative costs.

The increase in selling, general and administrative expenses in 2024 and 2023 was primarily due to increased commercialization and administrative costs to support net sales growth of IBSRELA and XPHOZAH and to support our strategy. The increases consisted of external spending for disease awareness initiatives, patient affordability, access support and related patient awareness, as well as increased commercial infrastructure and increased legal fees incurred related to the Company’s lawsuit against CMS in 2024. The increase was also attributable to increases in headcount and related personnel costs, including an increase in stock-based compensation expense totaling $17.8 million and $2.4 million in 2024 and 2023, respectively.

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Interest Expense

Interest expense represents the interest associated with our loan agreements.

The increase in interest expense in 2024 and 2023 was due to a higher loan balance resulting from the term loan draws in each respective year: $50.0 million for the Term D Loan in October 2024, $50.0 million for the Term C Loan in March 2024, and $22.5 million for the Term B Loan in October 2023.

Non-Cash Interest Expense Related to the Sale of Future Royalties

Non-cash interest expense related to the sale of future royalties represents the imputed interest expense on our deferred royalty obligation related to the sale of future royalties using the effective interest method. Non-cash interest expense is impacted by the outstanding balance of the deferred royalty obligation, which increases from milestone payments received from HCR under the sale of future royalties agreement and imputed interest accrued on the outstanding deferred royalty obligation, and decreases as royalties received from Kyowa Kirin related to the sale of tenapanor for cardiorenal indications in Japan are subsequently remitted to HCR. Refer to Note 8. Deferred Royalty Obligation Related To The Sale Of Future Royalties for further detail.

The increase in non-cash interest expense related to the sale of future royalties in 2024 and 2023 was due to the increasing outstanding balance of the deferred royalty obligation attributed to the upfront milestones received from HCR, including the $10.0 million upfront payment received in June 2022 and the $5.0 million milestone payment received in October 2023 as a result of Kyowa Kirin’s receipt of regulatory approval to market tenapanor for hyperphosphatemia in Japan in February 2024 and imputed interest accrued on the outstanding balance. In 2024, we began to receive royalties from Kyowa Kirin which were remitted to HCR, thereby reducing the outstanding deferred royalty obligation.

Other Income, Net

Other income, net consists of interest income earned on our cash, cash equivalents and short-term investments, the periodic revaluation of the exit fees related to our loan agreements, as well as currency exchange gains and losses.

The increase in other income, net in 2024 and 2023 primarily reflected higher income on our investments, resulting from both higher interest rates and larger investment balances throughout the periods.

Provision for Income Taxes

Our provision for income taxes includes current and deferred tax, including foreign withholding taxes paid on payments received from certain collaboration partners. Deferred income tax balances reflect the effects of temporary differences between the carrying amounts of assets and liabilities and their income tax bases, as well as from net operating loss and tax credit carryforwards. Our deferred tax assets continue to be fully offset by a valuation allowance, including deferred tax assets related to our net operating loss and tax credit carryforwards, which may be subject to annual limitations as a result of ownership changes that may have occurred or could occur in the future.

Refer to Note 2. Summary Of Significant Accounting Policies for further discussion of our significant accounting policies.

LIQUIDITY AND CAPITAL RESOURCES

Below is a summary of our cash, cash equivalents and short-term investments:

We regularly assess our cash position and our working capital needs to execute our strategy. Our primary uses of cash to date have been to fund research and development expenditures related to our development of tenapanor and to support the commercialization of our marketed products. We have funded our operations primarily from the sale of common stock, product sales, funds from our collaboration partnerships, funds from our loan agreements with SLR, as well as sales of future royalties to HCR. We expect that we will increasingly rely on cash generated from operations to fund our operating plan while maintaining financial flexibility from our ability to source cash from future equity sales and debt financing.

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Under a registration statement filed in 2020, we had the ability to sell up to $150.0 million of our common stock through Jefferies, as our sales agent. As of March 2023, we had received the maximum gross proceeds of $150.0 million at a weighted average share price of approximately $1.57.

In January 2023, we filed a registration statement on Form S-3, which became effective in January 2023, containing (i) a base prospectus for 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, warrants and/or units, from time to time in one or more offerings; and (ii) a prospectus supplement for the offering, issuance and sale by us of up to a maximum aggregate offering price of $150.0 million of our common stock that may be issued and sold, from time to time, under a sales agreement with Jefferies, deemed to be “at-the-market offerings” (2023 Open Market Sales Agreement). Pursuant to the 2023 Open Market Sales Agreement, Jefferies, as sales agent, may receive a commission of up to 3.0% of the gross sales price for shares of common stock sold under the 2023 Open Market Sales Agreement. As of December 31, 2024, we have completed sales pursuant to the 2023 Open Market Sales Agreement resulting in the issuance of 16.8 million shares of our common stock and receipt of gross proceeds of $70.0 million at a weighted average sales price of approximately $4.17.

We have a loan and security agreement (as amended, the 2022 Loan Agreement) with SLR. The 2022 Loan Agreement provides a total of $200.0 million, of which $150.0 million has been drawn as of December 31, 2024 to support our ongoing operations and the commercial launches of IBSRELA and XPHOZAH. The borrowings under the 2022 Loan Agreement bear interest at SOFR plus a spread based on our public debt rating. We classify outstanding borrowings under the 2022 Loan Agreement as long-term based on the maturity date of the loan. All the term loans mature on July 1, 2028. See Note 9. Borrowing for further discussion.

We believe our available cash, cash equivalents and short-term investments as of December 31, 2024 will be sufficient to fund our planned operations for at least a period of one year from the issuance of these financial statements. We have based this estimate on assumptions that may prove to be wrong and we could utilize our available capital resources sooner than we currently expect. In particular, our operating plan may change and we may require significant additional capital to fund our operations. There are no assurances that our efforts to meet our operating cash flow requirements will be successful. If our current cash, cash equivalents and short-term investments as well as our plans to meet our operating cash flow requirements are not sufficient to fund necessary expenditures and meet our obligations following the issuance of these financial statements, our liquidity, financial condition and business prospects will be materially affected.

Our future funding requirements will depend on many factors as described in Part I, Item 1A, “Risk Factors,” of this Annual Report on Form 10-K.

CASH FLOW ACTIVITIES

The following table summarizes our cash flows activities:

Cash Flows from Operating Activities

Net cash used in operating activities decreased in 2024 compared to 2023, primarily due to cash generated from higher product sales, net, partially offset by working capital cash uses to support our commercial growth. Net working capital cash outflows were driven primarily by increases in customer credit and inventory purchases, which were partially offset by increases in accounts payable and accruals.

Net cash used in operating activities increased in 2023 compared to 2022, primarily due to working capital cash uses to support our commercial launches, partially offset by cash generated from higher product sales, net from such launches. Net working capital cash outflows were driven primarily by increases in customer credit, upfront payments to CMOs for the commercial manufacturing of IBSRELA and XPHOZAH and increased prepaid selling and marketing spending.

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Cash Flows from Investing Activities

Net cash used in investing activities for 2024 and 2023 was primarily impacted by the timing of our investment maturities and purchases. In 2023, net investment purchases were significantly higher when compared to other reported periods. To a lesser extent, the 2024 cash used for investing activities included property, plant and equipment purchases associated with our new leased facility and build outs of existing facilities.

Cash Flows from Financing Activities

Net cash provided by financing activities decreased in 2024 compared to 2023, primarily due to $99.5 million net proceeds from the Term C Loan and Term D Loan and proceeds from the issuance of common stock under our equity incentive and stock purchase plans in 2024 which were less than $119.2 million received in 2023 from the issuance of common stock pursuant to at the market offerings. We have not received any proceeds under the 2021 Open Market Sales Agreement in 2024.

Net cash provided by financing activities increased in 2023 compared to 2022, primarily due to higher net proceeds from issuance of our common stock pursuant to the at the market offerings of $47.6 million, as well as net proceeds received of $22.4 million from drawing the Term B Loan as compared to net expenditure of $6.1 million in 2022 in conjunction with entering into the 2022 Loan Agreement and repaying the principal outstanding under the 2018 Loan. This increase was partially offset by lower net proceeds from the sale of future royalties to HCR of $5.0 million.

SMALLER REPORTING COMPANY AND LARGE ACCELERATED FILER STATUS

As a non-accelerated filer, we were not required to obtain an opinion of our independent auditors with respect to our internal controls over financial reporting for the year ended December 31, 2022. On June 30, 2023, our public float exceeded $700.0 million and therefore since January 1, 2024, we are considered a large accelerated filer. This Annual Report on Form 10-K includes an opinion of Ernst & Young LLP, our independent auditors with respect to our internal control over financial reporting as of December 31, 2024.

ITEM 7.    MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

You should read the following discussion and analysis of our financial condition and results of operations in conjunction with our financial statements and related notes included elsewhere in this report. This discussion and other parts of this report contain forward-looking statements that involve risk and uncertainties, such as statements of our plans, objectives, expectations and intentions. Our actual results could differ materially from those discussed in these forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed in the section of this report entitled “Risk Factors.” These forward-looking statements speak only as of the date hereof. Except as required by law, we assume no obligation to update or revise these forward-looking statements for any reason. Unless the context requires otherwise, the terms “Ardelyx”, “Company”, “we”, “us”, and “our” refer to Ardelyx, Inc.

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OVERVIEW

We are a biopharmaceutical company founded with a mission to discover, develop and commercialize innovative first-in-class medicines that meet significant unmet medical needs. We developed a unique and innovative platform that enabled the discovery of new biological mechanisms and pathways to develop potent, and efficacious therapies that minimize the side effects and drug-drug interactions frequently encountered with traditional, systemically absorbed medicines. The first molecule we discovered and developed was tenapanor, a minimally absorbed, first-in-class, oral, small molecule therapy. Tenapanor, branded as IBSRELA®, is approved in the U.S. for the treatment of adults with irritable bowel syndrome with constipation (IBS-C). Tenapanor, branded as XPHOZAH®, was approved by the U.S. Food and Drug Administration (U.S. FDA) on October 17, 2023, to reduce serum phosphorus in adults with chronic kidney disease (CKD) on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy. We also have a development stage asset, RDX013 for adult patients with CKD and/or heart failure with hyperkalemia, or elevated serum potassium, and a discovery phase asset, RDX020 for adult patients with metabolic acidosis, a serious electrolyte disorder, in patients with CKD.

Since commencing operations in October 2007, substantially all our efforts have been dedicated to our research and development (R&D) activities, including developing tenapanor and developing our proprietary drug discovery and design platform, as well as commercialization activities, including the marketing and sales of IBSRELA and XPHOZAH. We realized our first product sales of IBSRELA in March 2022 and realized our first product sales of XPHOZAH in November 2023. As of December 31, 2023, we had an accumulated deficit of $846.2 million.

We expect to continue to incur operating losses for the foreseeable future as we invest in the commercialization of IBSRELA and XPHOZAH, incur manufacturing and development cost for tenapanor, and incur R&D costs related to potential new product candidates. To date, we have funded our operations from the sale and issuance of common stock and convertible preferred stock, funds from our collaboration partnerships, which includes license fees, milestones and product supply revenue, funds from our loan agreement with SLR Investment Corp. (SLR), as amended on August 1, 2022, February 9, 2023 and October 17, 2023 (collectively, the 2022 Loan Agreement), as well as from sales of IBSRELA and XPHOZAH.

Our Commercial Products

IBSRELA for IBS-C

Our unique discovery platform and deep understanding of the primary mechanism of sodium transport in the intestine resulted in our discovery and development of IBSRELA, a first-in-class, U.S. FDA approved, sodium hydrogen exchange 3 (NHE3) inhibitor for the treatment of IBS-C in adults. IBSRELA acts locally in the gut and is minimally absorbed. IBS-C is a gastrointestinal (GI) disorder characterized by both abdominal pain and altered bowel habits. IBS-C is associated with significantly impaired quality of life, reduced productivity, and substantial economic burden.

We recognized our first sales of IBSRELA in the U.S. in March 2022. For our commercial launch of IBSRELA, we designed a market-responsive commercial strategy and built a commercial organization highly experienced in launching novel therapies into specialty areas. The dynamics of the IBS-C market reflect an established patient base, limited number of competitors all confined to a single mechanism of action, concentrated number of prescribers, and recognized unmet need. In addition, market research indicated a favorable response to the IBSRELA product profile as a novel mechanism therapy. These dynamics enabled a targeted promotional focus on patients currently being managed for IBS-C by the approximately 9,000 high-writing healthcare providers who account for approximately 50% of IBS-C prescriptions. Central to our go to market strategy for IBSRELA has been our highly experienced specialty sales force, many with existing relationships across their GI target base, and omnichannel digital initiatives.

We expect competition for IBSRELA will come largely from the three prescription products indicated for IBS-C: Linzess (linaclotide), Amitiza (lubiprostone) and Trulance (plecanatide). Generic lubiprostone is also available in the U.S. Additionally, over-the-counter products and prescription therapies, not indicated for IBS-C are commonly used to treat the constipation component of IBS-C, alone and in combination with the IBS-C-indicated prescription therapies.

We have established commercial agreements with Shanghai Fosun Pharmaceutical Industrial Development Co. Ltd. (Fosun Pharma) in China and Knight Therapeutics, Inc. (Knight) in Canada for IBSRELA for IBS-C. Knight is currently marketing IBSRELA in Canada. In October 2023, we announced that Fosun Pharma received approval from the Hong Kong Department of Health for the marketing application for tenapanor for the treatment of irritable bowel syndrome with constipation (IBS-C).

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XPHOZAH to Reduce Serum Phosphorus in Adults with CKD on dialysis as Add-on Therapy in Patients who have an Inadequate Response to Phosphate Binders or who are Intolerant of any Dose of Phosphate Binder Therapy

On October 17, 2023, XPHOZAH, a first-in-class phosphate absorption inhibitor, received approval from the U.S. FDA to market XPHOZAH in the U.S. to reduce serum phosphorus in adults with chronic kidney disease (CKD) on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy. XPHOZAH has a differentiated mechanism of action and acts locally in the gut to inhibit NHE3. This results in the tightening of the epithelial cell junctions, thereby significantly reducing paracellular uptake of phosphate, the primary pathway of phosphate absorption. It is estimated that there are more than 550,000 adult patients with CKD on dialysis in the U.S. and approximately eighty percent of those patients are being treated with phosphate lowering therapies. On average during 2020 through 2023, approximately seventy percent of patients treated with phosphate binders to treat hyperphosphatemia were unable to consistently maintain phosphorous levels =5.5 mg/dL over a six-month period. XPHOZAH is the first therapy for phosphate management that blocks phosphate absorption at the primary site of uptake.

We recognized our first sales of XPHOZAH in the U.S. in November 2023. For our commercial launch of XPHOZAH, we designed a market-responsive commercial strategy and built a commercial organization highly experienced and knowledgeable of the nephrology market. The dynamics of the hyperphosphatemia market reflect an established patient base, limited number of competitors all confined to a single mechanism of action, concentrated number of prescribers, and recognized unmet need. In addition, market research indicated a high level of awareness, interest and intent to adopt XPHOZAH upon approval and favorable response to the XPHOZAH product profile as a novel mechanism therapy. These dynamics enabled a targeted promotional focus on patients currently being managed for hyperphosphatemia by the approximately 8,000 nephrology healthcare providers who write approximately 80% of phosphate lowering therapy prescriptions. Central to our go to market strategy for XPHOZAH is our highly experienced specialty sales force, many with existing relationships across their nephrology target base, and innovative omnichannel digital initiatives.

XPHOZAH is indicated to reduce serum phosphorus in adults with chronic kidney disease (CKD) on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy. The various types of phosphate binders commercialized in the U.S. include the following: Calcium acetate (several prescription brands including PhosLo and Phoslyra); Lanthanum carbonate (Fosrenol); Sevelamer hydrochloride (Renagel); Sevelamer carbonate (Renvela); Sucroferric oxyhydroxide (Velphoro); and Ferric citrate (Auryxia). All of the listed phosphate binders are available as generics in the U.S., with the exception of Velphoro and Auryxia. Additionally, over-the-counter calcium carbonate, such as Tums and Caltrate, is also used to bind phosphorus.

In addition to the currently available phosphate binders, we are aware of at least four other binders in development, including fermagate (Alpharen), an iron-based binder in Phase 3 being developed by Opko Health, Inc., PT20, an iron-based binder in Phase 3 being developed by Shield Therapeutics, AP-301 in Phase 2 being developed by Alebund Pharmaceutical (Hong Kong) Limited, and Oxylanthanum Carbonate (OLC), which has demonstrated pharmacodynamic bioequivalence to Fosrenol. OLC is being developed by Unicycive Therapeutics, which has announced its plans to seek U.S. FDA approval via the 505(b)(2) pathway. Additionally, Chugai and Alebund are developing EOS789, an inhibitor of phosphate transporters NaPi-2b, PiT-1, and PiT-2, thus far studied in a phase 1 clinical trial.

In November 2023, XPHOZAH was granted orphan drug designation by the U.S. FDA for the treatment of pediatric hyperphosphatemia.

We have established commercial agreements with Kyowa Kirin, Co. Ltd. (Kyowa Kirin) in Japan, Fosun Pharma in China and Knight in Canada for tenapanor for hyperphosphatemia. In July 2023, we announced that a New Drug Application (NDA) for tenapanor had been accepted for review by China’s Center for Drug Evaluation of the National Medical Products Administration (NMPA) for the control of serum phosphorus in adult patients with CKD on hemodialysis. In September 2023, we announced that Kyowa Kirin received approval from the Japanese Ministry of Health, Labour and Welfare (MHLW) for the NDA for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis.

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Discovery and Developmental Assets

We have a small molecule potassium secretagogue program, RDX013, for the potential treatment of hyperkalemia, or elevated serum potassium. Hyperkalemia is a common problem in patients with heart and kidney disease, particularly in patients taking customary blood pressure medications known as renin-angiotensin-aldosterone system (RAAS) inhibitors. RDX013 is a novel mechanism agent designed to target the underlying biological mechanisms of potassium secretion to lower elevated potassium. We have completed a Phase 2 dose ranging clinical trial evaluating the safety and efficacy of RDX013 for the treatment of hyperkalemia in CKD patients who are not on dialysis. While the results of the study demonstrated an acceptable safety and tolerability profile for RDX013 and supported proof of concept in its ability to lower serum potassium levels, with statistically significant reductions compared to placebo after eight days of treatment, the study did not meet its primary endpoint of significantly reducing serum potassium levels compared to placebo after four weeks of treatment.

We have a discovery program targeting the inhibition of the chloride bicarbonate exchanger for the treatment of metabolic acidosis, a highly prevalent comorbidity in CKD patients that is strongly correlated with disease progression and adverse outcomes. We have identified lead compounds that are potent, selective and proprietary inhibitors of bicarbonate secretion.

We do not currently expect to meaningfully advance either of these two assets until such time as we have determined our available resources can support additional activities after prioritization of the commercialization of IBSRELA and XPHOZAH.

Collaboration Partners

We have exclusive rights to tenapanor in the U.S. and we have established agreements with Kyowa Kirin in Japan, Fosun Pharma in China and Knight in Canada for the development and commercialization of tenapanor for certain indications in their respective territories.

In March 2018, we entered into an exclusive license agreement with Knight (Knight Agreement) for the development, commercialization and distribution of tenapanor in Canada for hyperphosphatemia and IBS-C. In March 2021, Knight announced the commercial availability of IBSRELA in Canada, following its approval by Health Canada in April 2020. Under the terms of the Knight Agreement, Knight paid us a $2.3 million non-refundable, one-time payment in March 2018. We may also be eligible to receive approximately CAD 22.2 million for development and commercialization milestones, or approximately $16.7 million at the currency exchange rate on December 31, 2023, of which $0.7 million has been received and recognized as revenue as of December 31, 2023. We are also eligible to receive royalties throughout the term of the agreement, and a transfer price for manufacturing services.

In November 2017, we entered into an exclusive license agreement with Kyowa Kirin (2017 Kyowa Kirin Agreement) for the development, commercialization and distribution of tenapanor in Japan for cardiorenal indications. Under the terms of the 2017 Kyowa Kirin Agreement, we received a $30.0 million upfront payment from Kyowa Kirin, and we may be entitled to receive up to $55.0 million in total development and regulatory milestones, of which $35.0 million has been recognized as revenue and received as of December 31, 2023. We may also be eligible to receive approximately ¥8.5 billion for commercialization milestones, or approximately $60.3 million at the currency exchange rate on December 31, 2023, as well as reimbursement of costs plus a reasonable overhead for the supply of product and royalties on net sales throughout the term of the agreement. As discussed in Note 8. Deferred Royalty Obligation Related to the Sale of Future Royalties, the future royalties and commercial milestone payments we may receive under the 2017 Kyowa Kirin Agreement will be remitted to HealthCare Royalty Partners IV, L.P. pursuant to a Royalty and Sales Milestone Interest Acquisition Agreement.

On April 11, 2022, we entered into a second amendment to the 2017 Kyowa Kirin Agreement (2022 Amendment). Under the terms of the 2022 Amendment, we and Kyowa Kirin agreed to a reduction in the royalty rate payable to us by Kyowa Kirin upon net sales of tenapanor in Japan. The royalty rate was reduced from the high teens to low double digits for a two-year period of time following the first commercial sale in Japan, and then to mid-single digits for the remainder of the royalty term. As discussed in Note 8. Deferred Royalty Obligation Related to the Sale of Future Royalties, the future royalties we may receive under the 2017 Kyowa Kirin Agreement will be remitted to HealthCare Royalty Partners IV, L.P. pursuant to a Royalty and Sales Milestone Interest Acquisition Agreement. As consideration for the reduction in the royalty rate, Kyowa Kirin agreed to pay us up to an additional $40.0 million which has been received and recognized as revenue as of September 2023 as described below.

In October 2022, we announced that Kyowa Kirin submitted an NDA to the Japanese MHLW for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis, which resulted in payment to us from Kyowa Kirin for an aggregate of $35.0 million for milestone payments and payments under the 2022 Amendment.

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In September 2023, we announced that Kyowa Kirin received approval from the Japanese MHLW for the NDA for tenapanor for the improvement of hyperphosphatemia in adult patients with chronic kidney disease on dialysis, which resulted in payment to us from Kyowa Kirin for an aggregate of $30.0 million for milestone payments and payments under the 2022 Amendment.

In December 2017, we entered into an exclusive license agreement with Fosun Pharma (Fosun Agreement) for the development and commercialization of tenapanor in China for both hyperphosphatemia and IBS-C. Under the terms of the Fosun Agreement, Fosun paid us a $12.0 million upfront license fee. In July 2023, we announced that an NDA for tenapanor had been accepted for review by China’s Center for Drug Evaluation of the NMPA for the control of serum phosphorus in adult patients with chronic kidney disease on hemodialysis. This acceptance triggered a $2.0 million milestone payment to us under the terms of the Fosun Agreement, which we received in the third quarter of 2023.

In October 2023, we announced that the U.S. FDA has approved XPHOZAH to reduce serum phosphorus in adults with CKD on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy. This triggered an additional $3.0 million milestone payment to us under the terms of the Fosun Agreement, which was received during the first quarter of 2024. Also, in October 2023, we announced that Fosun Pharma received approval from the Hong Kong Department of Health for the marketing application for tenapanor for the treatment of irritable bowel syndrome with constipation (IBS-C). We may be entitled to receive development and commercialization milestones of up to $113.0 million, of which $8.0 million has been recognized as revenue and $5.0 million has been received as of December 31, 2023 and $3.0 million was received in January 2024, as well as reimbursement of cost plus a reasonable overhead for the supply of product and tiered royalties on net sales ranging from the mid-teens to 20%.

FINANCIAL OPERATIONS OVERVIEW

Revenue

Our revenue to date has been generated primarily through a combination of product sales and payments in connection with license, research and development collaborative agreements with our various collaboration partners. We realized our first commercial product sales of IBSRELA beginning in March 2022 and our first commercial product sales of XPHOZAH in November 2023. In the future, we may generate revenue from a combination of our own product sales and payments in connection with our current or future collaborative partnerships, including license fees, other upfront payments, milestone payments, royalties and payments for drug product and/or drug substance. We expect that any revenue we generate will fluctuate in future periods as a result of, among other factors: the extent to which we are successful in our commercialization of IBSRELA and XPHOZAH; our ability to obtain and sustain an adequate level of coverage and reimbursement for IBSRELA and XPHOZAH by third-party payors; whether and the extent to which we are successful in our commercialization of XPHOZAH; whether or when XPHOZAH, along with other oral ESRD-related drugs without an injectable or intravenous equivalent, are bundled into the end stage renal disease prospective payment system (ESRD PPS), and the manner in which such introduction into the ESRD PPS may occur, including the length of any applicable Transitional Drug Add-on Payment Adjustment (TDAPA) period, the amount of the add-on payment available during the TDAPA period and whether, and the extent to which, the ESRD PPS base rate is adjusted following any applicable TDAPA period; the timing and progress of goods and services provided pursuant to our current or future collaborative partnerships; our collaborators’ achievement of clinical, regulatory or commercialization milestones, to the extent achieved; the timing and amount of any payments to us relating to the aforementioned milestones; addressing any competing technological and market developments; maintaining, protecting and expanding our portfolio of intellectual property rights, including patents, trade secrets, and know-how, and our ability to develop, manufacture and commercialize our product candidates and products without infringing intellectual property rights of others; attracting, hiring, and retaining qualified personnel; and the extent to which tenapanor or other licensed products are approved and successfully commercialized by a collaboration partner. If our current collaboration partners or any future collaboration partners fail to obtain regulatory approval for tenapanor or other licensed products, our ability to generate future revenue from our collaborative arrangements, and our results of operations and financial position, would be materially and adversely affected. Our past revenue performance is not necessarily indicative of results to be expected in future periods.

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Cost of Goods Sold

Cost of product sales consists of the cost of commercial goods sold to our Customers. Other cost of revenue consists of the cost of materials sold to our international partners under product supply agreements, as well as payments due to AstraZeneca AB (AstraZeneca) based on sales of tenapanor. We capitalize inventory costs associated with the production of our products after regulatory approval or when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Otherwise, such costs are expensed as research and development. A portion of the costs of IBSRELA and XPHOZAH units recognized as revenue during the years ended December 31, 2023 and 2022 were expensed in periods prior to the commencement of capitalization of inventory costs for each respective product. We believe our cost of goods sold for the years ended December 31, 2023 and 2022 would have been $4.4 million and $1.9 million higher, respectively, if we had not previously expensed certain material and production costs with respect to the units sold. As of December 31, 2023 and December 31, 2022, we had approximately $21.8 million and $28.0 million, respectively, of inventory on hand that was previously expensed as research and development expense and will not be reported as cost of goods sold in future periods when sales of IBSRELA and XPHOZAH are recognized as revenue.

Other cost of revenue includes payments due to AstraZeneca, which under the terms of a termination agreement entered into in 2015 (AstraZeneca Termination Agreement) is entitled to (i) future royalties at a rate of 10% of net sales of tenapanor or other NHE3 products by us or our licensees, and (ii) 20% of non-royalty revenue received from our collaboration partners in connection with the development and commercialization of tenapanor or other NHE3 products. We have agreed to pay AstraZeneca up to a maximum of $75.0 million in the aggregate for (i) and (ii). We recognize these expenses as other cost of revenue when we recognize the corresponding revenue that gives rise to payments due to AstraZeneca. To date, we have recognized an aggregate of $27.6 million as other cost of revenue under the AstraZeneca Termination Agreement. See details in Note 7, Collaboration and Licensing Agreements, under AstraZeneca, in the notes to our financial statements, included in Part II, Item 8, of this Annual Report on Form 10-K.

Research and Development

We recognize all R&D expenses as they are incurred to support the discovery, research, development and manufacturing of our product candidates. R&D expenses include, but are not limited to, the following:

•external research and development expenses incurred under agreements with consultants, third-party contract research organizations (CROs) and investigative sites where a substantial portion of our clinical studies are conducted, and with contract manufacturing organizations where our clinical supplies are produced;

•expenses associated with supplies and materials consumed in connection with our research operations;

•expenses associated with producing XPHOZAH prior to U.S. FDA approval;

•expenses associated with producing discovery and developmental assets prior to U.S. FDA approval;

•other costs associated with research, clinical development and regulatory activities;

•employee-related expenses, which include salaries, bonuses, benefits, travel and stock-based compensation; and

•facilities and other allocated expenses, which include direct and allocated expenses for rent and maintenance of facilities, depreciation and amortization expense, information technology expense and other supplies.

Selling, General and Administrative

Selling, general and administrative expenses relate to sales and marketing, finance, human resources, legal and other administrative activities, including information technology investments. Selling, general and administrative expenses consist primarily of personnel costs, outside professional services, marketing, advertising and legal expenses, facilities costs not otherwise allocated to research and development and other general and administrative costs.

Interest Expense

Interest expense represents the interest associated with on our 2022 Loan Agreement.

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Non-cash interest expense related to the sale of future royalties

Non-cash interest expense related to the sale of future royalties represents the imputed interest expense on our deferred royalty obligation related to the sale of future royalties using the effective interest method. As further described in Note 8. Deferred Royalty Obligation Related to the Sale of Future Royalties, in June 2022, we and HealthCare Royalty Partners IV, L.P. (HCR) entered into a Royalty and Sales Milestone Interest Acquisition Agreement (HCR Agreement). Under the terms of the HCR Agreement, HCR agreed to pay us up to $20.0 million in exchange for the royalty payments and commercial milestone payments (collectively the Royalty Interest Payments) that we may receive under our 2017 License Agreement with Kyowa Kirin based upon Kyowa Kirin's net sales of tenapanor in Japan for hyperphosphatemia. As part of the HCR Agreement, we have received a $10.0 million upfront payment and a $5.0 million milestone payment from HCR, which we recorded as a deferred royalty obligation on our balance sheet. Non-cash interest expense will be recognized over the life of the HCR Agreement using the effective interest method based on the imputed interest rate derived from estimated amounts and timing of future royalty payments to be received from Kyowa Kirin.

Other Income, net

Other income, net consists of interest income earned on our cash, cash equivalents and available-for-sale investments, the periodic revaluation of the exit fee related to our 2022 Loan Agreement, gains on sales of property and equipment, and currency exchange gains and losses.

Provision for Income Taxes

Our provision for income taxes includes current and deferred tax, including foreign withholding taxes paid on payments received from certain collaboration partners. Deferred income taxes reflect the tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Our deferred tax assets continue to be fully offset by a valuation allowance, including deferred tax assets related to our net operating loss carryforwards, which may be subject to annual limitations as a result of ownership changes that may have occurred or could occur in the future.

CRITICAL ACCOUNTING POLICIES AND ESTIMATES

A detailed discussion of our significant accounting policies can be found in Note 2, Summary of Significant Accounting Policies, in the notes to our financial statements, included in Part II, Item 8, of this Annual Report on Form 10-K. Critical accounting policies are those that require significant judgment and/or estimates by management at the time that financial statements are prepared such that materially different results might have been reported if other assumptions had been made. These estimates form the basis for making judgments about the carrying values of assets and liabilities. We base our estimates and judgments on experience and on various other assumptions that we believe to be reasonable under the circumstances. Actual results could differ materially from these estimates.

We consider certain accounting policies related to revenue recognition, inventory, accrued research and development expenses to be critical policies to understanding the judgments and estimates applied in our reported financial results.

Product Sales, Net

We account for our commercial product sales, net in accordance with Topic 606 – Revenue from Contracts with Customers. We received approval from the FDA to market IBSRELA in the U.S. in September 2019 and to market XPHOZAH in the U.S. in October 2023. We began selling IBSRELA and XPHOZAH in the U.S. in March 2022 and November 2023, respectively. We distribute IBSRELA principally through major wholesalers, specialty pharmacies and group purchasing organizations (GPOs) (collectively, our IBSRELA Customers). XPHOZAH is principally distributed through a specialty wholesaler (XPHOZAH Customer) to select specialty pharmacies (collectively, IBSRELA Customers and XPHOZAH Customers, “Customers”). Our Customers subsequently sell IBSRELA and XPHOZAH to pharmacies and patients. Separately, we enter into arrangements with third parties that provide for government-mandated rebates, chargebacks and discounts. Revenue from product sales is recognized when our performance obligations are satisfied, which is when Customers obtain control of our product and occurs upon delivery.

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Reserves for Variable Consideration

Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration which may be settled in the form of off-invoice discounts, chargebacks, or rebates. Variable consideration includes discounts to customers and government programs, wholesaler fees, group purchasing organization administrative fees, patient copay assistance, and estimated product returns. These estimates are based on the amounts earned or to be claimed for related sales and are classified as reductions of gross accounts receivable if settlement is expected to occur through a reduction in the amounts paid by our Customers or a current liability if settlement is expected to occur through a payment from us. Where appropriate, these estimates are based on factors such as industry data and forecasted customer buying and payment patterns, our experience, current contractual and statutory requirements, specific known market events and trends. These reductions to gross sales reflect our best estimates of the amount of consideration to which we are entitled based on the terms of the contract. Variable consideration is included in the transaction price only to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Actual amounts of consideration ultimately received may differ from our estimates. If actual results in the future vary from our estimates, we adjust these estimates, which would affect product revenue and earnings in the period such variances become known. As we gain more experience, estimates will be more heavily based on the expected utilization from historical data we have accumulated since the IBSRELA and XPHOZAH product launches. Changes in estimates recorded through December 31, 2023 have not been material.

Rebates: Rebates include wholesaler fees, GPO fees, as well as mandated discounts under the Medicaid Drug Rebate Program (Medicaid) and the Medicare Coverage Gap Program (Medicare). Estimates for rebates are recorded in the same period the related gross revenue is recognized, resulting in a reduction of product revenue. We estimate our Medicaid and Medicare rebates based upon the estimated payor mix, and statutory discount rates. Our estimates for payor mix are guided by payor information received from specialty pharmacies, expected utilization for wholesaler sales to pharmacies, and available industry payor information and therefore require the most estimation and judgment of our gross to net deductions.

Chargebacks: Chargebacks are discounts that occur when certain contracted purchasers purchase directly from our wholesalers at a discounted price. The wholesaler, in turn, charges back the difference between the price initially paid to us by the wholesaler and the discounted price paid to the wholesaler by the contracted purchaser. Amounts for estimated chargebacks are established in the same period that the related gross revenue is recognized, resulting in a reduction of product revenue and accounts receivable. The accrual for wholesaler chargebacks is estimated based on known chargeback rates, known sales to wholesalers, and known sales from wholesalers to their chargeback-eligible customers.

Discounts and Fees: Our payment terms are generally 30 to 60 days. Wholesalers, GPOs and specialty pharmacies are offered various forms of consideration, including off-invoice discounts which may be paid to GPOs and specialty pharmacies. Wholesalers and GPOs may also receive prompt pay discounts for payment within a specified period. We expect discounts to be earned when offered and therefore, we deduct the full amount of these discounts from product sales when revenue is recognized, resulting in a reduction of product revenue and accounts receivable.

Other Reserves: Patients who have commercial insurance may receive copay assistance when product is dispensed by pharmacies to patients. We estimate the amount of copay assistance provided to eligible patients based on the terms of the program, and redemption information provided by third-party claims processing organizations. We also estimate the amount of copay assistance that will be provided to patients associated with product which we have sold but which has not yet been dispensed to commercial patients, which requires significant estimation and judgment. Our estimates are recorded in accounts payable and accrued expenses and other current liabilities on the balance sheets. Other reserves include estimated product returns which are recorded in the same period the related gross revenue is recognized, resulting in a reduction of product revenue as well as accounts receivable. We estimate our product returns reserve based upon our experience and specific known market events and trends. As we have experienced limited product returns, establishing the appropriate level of product returns reserve require estimation and judgment.

Collaboration Revenue Recognition

We generate collaboration revenue primarily from research and collaboration and license agreements with customers. Goods and services in the agreements may include the grant of licenses for the use of our technology, the provision of services associated with the research and development of product candidates, manufacturing services, and participation in joint steering committees. The terms of these arrangements typically include payment to us of one or more of the following: non-refundable, up-front license fees; research, development, regulatory and commercial milestone payments; reimbursement of research and development services; option payments; reimbursement of certain costs; payments for manufacturing supply services; and future royalties on net sales of licensed products.

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As part of the accounting for contracts with customers, we develop assumptions that require judgment to determine whether promised goods and services represent distinct performance obligations and the standalone selling price for each performance obligation identified in the contract. Determining the standalone selling price for performance obligations requires significant judgment, and when an observable price of a promised good or service is not readily available, we consider relevant assumptions to estimate the standalone selling price, including, as applicable, market conditions, development timelines, probabilities of technical and regulatory success, reimbursement rates for personnel costs, forecasted revenues, potential limitations to the selling price of the product and discount rates. We also use judgment to evaluate whether the milestones are considered probable of being reached and estimate the amount to be included in the transaction price using the most likely amount method. At the end of each subsequent reporting period, we re-evaluate the probability of achievement of such development milestones and any related constraints, and if necessary, adjust our estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect earnings in the period of adjustment.

Inventory

We capitalize inventory costs associated with the production of our products after regulatory approval or when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Otherwise, such costs are expensed as research and development. Prior to the regulatory approval of drug product candidates, we incurred expenses for the manufacture of drug product that could potentially be available to support the commercial launch of our products or could be sold to our international partners under product supply agreements. We began to capitalize inventory costs associated with IBSRELA during the fourth quarter of 2021, when our intent to commercialize IBSRELA was established and we commenced preparation for the commercial launch of IBSRELA, which was when it was determined that the inventory had a probable future economic benefit. We began to capitalize inventory costs associated with XPHOZAH during the fourth quarter of 2023, following approval by the U.S. FDA to market XPHOZAH in the U.S., which was when it was determined that the inventory had a probable future economic benefit.

Inventory is stated at the lower of cost or estimated net realizable value with cost determined under the specific identification method. Inventory costs include the cost of materials, third-party contract manufacturing, third-party packaging services, freight, labor costs for personnel involved in the manufacturing process, and indirect overhead costs. We primarily use actual costs to determine the cost basis for inventory, and therefore there is limited estimation or judgment involved. The determination of whether inventory costs will be realizable requires management review of the expiration dates of IBSRELA and XPHOZAH compared to our forecasted sales. If actual market conditions are less favorable than projected by management, write-downs of inventory may be required, which would be recorded as cost of revenue in the statement of operations and comprehensive loss. As of December 31, 2023, we have not recorded any write-downs for excess and obsolete inventory.

Accrued Expenses

As part of the process of preparing our financial statements, we are required to estimate our accrued expenses. This process involves reviewing open contracts and purchase orders, communicating with our personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of the actual cost. The majority of our service providers invoice us monthly in arrears for services performed or when contractual milestones are met. We make estimates of our accrued expenses as of each balance sheet date in our financial statements based on facts and circumstances known to us at that time. We periodically confirm the accuracy of our estimates with our service providers and make adjustments if necessary.

In accruing service fees, we estimate the time period over which each component of a service will be performed, and estimate, with vendor input if appropriate. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrued or prepaid expense balance accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differ from the actual status and timing of services performed, we may report amounts that are too high or too low in any particular period.

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RESULTS OF OPERATIONS

Comparison of the Years Ended December 31, 2023, 2022 and 2021

Revenue

Below is a summary of our total revenue (dollars in thousands):

Below is a summary of our net product sales by product (dollars in thousands):

Fiscal 2023 compared to 2022:

The increase in product sales, net during the year ended December 31, 2023 as compared to the same period in 2022 is primarily attributable to increased net product sales for IBSRELA and is primarily volume based as 2023 was a full year of sales while IBSRELA sales commenced in March of 2022. IBSRELA sales volumes increased in 2023 as awareness and prescriber experience with the product continued to grow following its commercial launch in March 2022. Commercial sales of XPHOZAH commenced in November 2023.

Licensing revenue during the year ended December 31, 2023 was comparable to the same period in 2022. During the year ended December 31, 2023, we earned an aggregate of $30.0 million for milestones under the 2017 Kyowa Kirin Agreement and payments under the 2022 Kyowa Kirin Amendment upon approval from the Japanese MHLW for the NDA for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis. We also earned an aggregate of $5.0 million in milestones under the terms of the Fosun Agreement upon acceptance of the NDA for tenapanor by China’s Center for Drug Evaluation of the NMPA for the control of serum phosphorus in adult patients with CKD on hemodialysis and the U.S. FDA approval of XPHOZAH to reduce serum phosphorus in adults with CKD on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy.

The increase in product supply revenue during the year ended December 31, 2023 as compared to the same periods in 2022 is attributable to increased product supply revenue to Kyowa Kirin.

Fiscal 2022 compared to 2021:

The increase in product sales, net during the year ended December 31, 2022 as compared to the same period in 2021 is attributable to net product sales for IBSRELA that commenced in March 2022.

The increase in licensing revenue during the year ended December 31, 2022 as compared to the same period in 2021 is attributable to an aggregate of $35.0 million in milestone payments and payments under the second amendment to the 2017 KKC Agreement which we earned upon Kyowa Kirin's submission of a New Drug Application to the Japanese MLHW for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis.

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The decrease in collaborative development revenue during the year ended December 31, 2022 as compared to the same period in 2021 is attributable to the full recognition of collaborative development revenue for upfront payments associated with the 2019 Kyowa Kirin Agreement through the end of 2021.

The increase in product supply revenue during the year ended December 31, 2022 as compared to the same period in 2021 is attributable to increased product supply revenue in connection with the 2017 Kyowa Kirin Agreement.

Cost of Goods Sold

Below is a summary of our cost of goods sold (dollars in thousands):

Fiscal 2023 compared to 2022:

The increase to cost of product sales for the year ended December 31, 2023 as compared to the same period in 2022 is primarily attributable to cost of goods sold for increased net product sales of IBSRELA.

The increase to other cost of revenue for the year ended December 31, 2023 as compared to the same period in 2022 is primarily attributable to payments due to AstraZeneca under the AstraZeneca Termination Agreement, which include a percentage of milestones earned, as well as cost of goods sold for increased product supply sold to our international partners.

Fiscal 2022 compared to 2021:

The increase to cost of product sales for the year ended December 31, 2022 as compared to the same period in 2021 was primarily attributable to $0.5 million for the cost of goods sold for product sales of IBSRELA during year ended December 31, 2022.

The increase in other cost of revenue for the year ended December 31, 2022 as compared to the same period in 2021 was primarily attributable to payments due to AstraZeneca under the AstraZeneca Termination Agreement for IBSRELA product sales, net and for the milestone payment we received under the second amendment to the 2017 Kyowa Kirin Agreement, which we earned upon Kyowa Kirin's submission of a NDA to the Japanese MHLW for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis.

Operating Expenses

Below is a summary of our operating expenses (dollars in thousands):

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Research and Development

Below is a summary of our research and development expenses (dollars in thousands):

Fiscal 2023 compared to 2022:

The change in our R&D expenses for the year ended December 31, 2023 as compared to the same period in 2022 is primarily the result of clinical trial and pharmacovigilance activities related to IBSRELA.

Fiscal 2022 compared to 2021:

The decrease in our external R&D expenses for the year ended December 31, 2022 as compared to the same period in 2021 was primarily the result of lower clinical study costs following the completion of the OPTIMIZE study, lower tenapanor manufacturing expense as we began to capitalize costs associated with the production of IBSRELA to inventory, and lower expenses for research following the elimination of our internal research organization in the fourth quarter of 2021. The decrease in our employee-related expenses for the year ended December 31, 2022 is due to lower compensation and benefits expenses for our research and development workforce following restructuring actions in 2021. Similarly, the decrease in facilities, equipment and depreciation expenses is primarily due to a smaller proportion of such expenses being attributed to R&D following the restructuring in 2021. The increase in other expenses is primarily related to disease-related education grants during the year ended December 31, 2022.

Selling, General and Administrative

Fiscal 2023 compared to 2022:

The increase in selling, general and administrative expenses for the year ended December 31, 2023 as compared to the same period in 2022 is primarily due to increased costs associated with the commercial launches of IBSRELA and XPHOZAH and increases in expenses associated with administrative support functions as our company has grown in headcount and activity level. The increases consisted of headcount and related personnel costs and external spending for disease awareness initiatives, commercial infrastructure and strategy.

Fiscal 2022 compared to 2021:

The increase in selling, general and administrative expenses for the year ended December 31, 2022 as compared to the same period in 2021 was primarily due to increased costs associated with the commercial launch of IBSRELA. The changes consisted of headcount and related personnel costs and external spending for disease awareness initiatives, commercial infrastructure and strategy. These increases were partially offset by a reduction in ongoing costs as a result of the restructuring action carried out during the third quarter of 2021.

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Interest Expense

Below is a summary of our interest expense (dollars in thousands):

Fiscal 2023 compared to 2022:

The increase in interest expense for the year ended December 31, 2023 as compared to the same period in 2022 is due to a higher variable interest rate applied to our loan balance primarily resulting from market fluctuations, as well as a larger loan balance outstanding following the draw of an additional $22.5 million for the Term B Loan in October 2023.

Fiscal 2022 compared to 2021:

The decrease in interest expense for the year ended December 31, 2022 as compared to the same period in 2021 was due to lower principal outstanding on our loan payable in 2022 than in 2021 due to principal payments made on our 2018 Loan during the fourth quarter of 2021 through February 2022. In February 2022, we repaid the remaining outstanding principal balance of the 2018 Loan in the amount of $25.0 million and entered into the new 2022 Loan in the amount of $27.5 million.

Non-Cash Interest Expense Related to the Sale of Future Royalties

Below is a summary of our non-cash interest expense related to the sale of future royalties (dollars in thousands):

Fiscal 2023 compared to 2022:

Non-cash interest expense related to the sales of future royalties for the year ended December 31, 2023 is accrued on the deferred royalty obligation that we recorded following the receipt of the $10.0 million upfront payment and the $5.0 million milestone payment received from HCR during June 2022 and October 2023, respectively. We recognized a full twelve months of expense during the year ended December 31, 2023 compared to approximately six months of expense during the year ended December 31, 2022.

Fiscal 2022 compared to 2021:

Non-cash interest expense related to the sale of future royalties reflects the recognized amortization of the deferred royalty obligation that we recorded following the receipt of the $10.0 million upfront payment from HCR in June 2022.

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Other Income, net

Below is a summary of our other income, net (dollars in thousands):

Fiscal 2023 compared to 2022:

The increase in other income, net for the year ended December 31, 2023 as compared to the same period in 2022 is primarily due to increased income on our investments resulting from both higher interest rates and larger investment balances throughout the period.

Fiscal 2022 compared to 2021:

The increase in other income, net for the year ended December 31, 2022 as compared to the same period in 2021 was primarily due to sales of certain lab equipment and supplies for a net gain of $1.5 million and increased investment income during the year ended December 31, 2022. Partially offsetting these increases were fluctuations related to revaluation of our exit fees.

LIQUIDITY AND CAPITAL RESOURCES

Below is a summary of our cash, cash equivalents and short-term investments (in thousands):

As of December 31, 2023, we had cash, cash equivalents and short-term investments of approximately $184.3 million.

In August 2021, we filed a prospectus supplement under a Registration Statement which was filed in July 2020 for the offering, issuance and sale by us of up to a maximum aggregate offering price of $150.0 million of our common stock that was authorized for issuance and sale, from time to time, under a sales agreement (2021 Open Market Sales Agreement) we entered into with Jefferies LLC (Jefferies), pursuant to which we, from time to time, sold up to $150.0 million in shares of our common stock through Jefferies. Pursuant to the 2021 Open Market Sales Agreement, Jefferies, as our sales agent, received a commission of up to 3.0% of the gross sales price for shares of common stock sold under the 2021 Open Market Sales Agreement. As of March 2023, we had received the maximum gross proceeds of $150.0 million under the 2021 Open Market Sales Agreement at a weighted average share price of approximately $1.57 per share, which included 15.5 million shares of our common stock for which we received gross proceeds of $51.9 million at a weighted average share price of approximately $3.35 during the quarter ended March 31, 2023.

In January 2023, we filed a Form S-3 Registration Statement, which became effective in January 2023 (2023 Registration Statement), containing (i) a base prospectus for 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, warrants and/or units, from time to time in one or more offerings; and (ii) a prospectus supplement for the offering, issuance and sale by us of up to a maximum aggregate offering price of $150.0 million of our common stock that may be issued and sold, from time to time, under a sales agreement with Jefferies, deemed to be “at-the-market offerings” (2023 Open Market Sales Agreement). Pursuant to the 2023 Open Market Sales Agreement, Jefferies, as sales agent, may receive a commission of up to 3.0% of the gross sales price for shares of common stock sold under the 2023 Open Market Sales Agreement. During the year ended December 31, 2023, we completed sales pursuant to the 2023 Open Market Sales Agreement resulting in the issuance of 16.8 million shares of our common stock and receipt of gross proceeds of $70.0 million at a weighted average sales price of approximately $4.17 per share.

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In February 2022, we entered into a loan and security agreement (2022 Loan Agreement) with SLR Investment Corp (SLR). The 2022 Loan Agreement was subsequently amended on August 1, 2022 and February 9, 2023. The 2022 Loan Agreement as amended through February 9, 2023 provides for a senior secured term loan facility, with $27.5 million funded at closing (the Term A Loan) and an additional $22.5 million that we could borrow on or prior to December 20, 2023; provided that (i) we received approval by the U.S. FDA for our NDA for XPHOZAH by November 30, 2023 and (ii) we achieved certain product revenue milestone targets described in the 2022 Loan Agreement (the Term B Loan).

The initial funding of $27.5 million was used to repay the 2018 Loan and is funding our ongoing operations. We had $25.0 million principal from the 2018 Loan outstanding as of the closing date, as well as the 2018 Exit Fee in the amount of $1.5 million. We paid the 2018 Exit Fee in October 2023 following approval from the U.S. FDA for XPHOZAH to reduce serum phosphorus in adults with chronic kidney disease (CKD) on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy. As discussed in Note 10. Derivative Liabilities, in connection with entering into the 2022 Loan Agreement, we entered into the 2022 Exit Fee agreement, as amended, whereby we agreed to pay an exit fee in the amount of 2% of the amounts funded for the Term A Loan and Term B Loan by SLR if certain conditions are met. Notwithstanding the prepayment or termination of the 2022 Loan, the 2022 Exit Fee will expire on February 23, 2032.

In October 2023, we entered into a Third Amendment (the Third Amendment) to the 2022 Loan Agreement by and between us and the 2022 Lenders. As discussed in Note 9. Borrowing, the Third Amendment, among other things, (1) provides us with the option to draw an additional $50.0 million of committed capital by March 15, 2024 (the Term C Loan); (2) provides us with the option to draw up to an additional $50.0 million of uncommitted capital, subject to approval by the Agent's investment committee (the Term D Loan); and (3) extends the interest-only period for the Four Loans to December 31, 2026, effective upon our decision to draw the Term B Loan in the amount of $22.5 million. In October 2023, we provided the Agent with notice of our decision to draw the Term B Loan to support the commercial launch of XPHOZAH and received the proceeds of the Term B Loan. We expect to provide the Agent with notice of our decision to draw the Term C Loan prior to the expiry of the option on March 15, 2024 to further support the commercial launch of XPHOZAH.

In October 2022, we announced that our collaboration partner, Kyowa Kirin, submitted an NDA to the Japanese MHLW for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis. In accordance with the terms of the 2022 Amendment, Kyowa Kirin paid an aggregate of $35.0 million to us in milestone payments and payments associated with the 2022 Amendment during the quarter ended December 31, 2022.

In September 2023, we announced that Kyowa Kirin received approval from the Japanese MHLW for the NDA for tenapanor for the improvement of hyperphosphatemia in adult patients with chronic kidney disease on dialysis, which resulted in payment to us from Kyowa Kirin for an aggregate of $30.0 million for milestone payments and payments under the 2022 Amendment and entitled us to a $5.0 million payment under the terms of the HCR Agreement. We received these payments in October 2023.

We have incurred operating losses since inception in 2007 and our accumulated deficit as of December 31, 2023 is $846.2 million. Our primary sources of cash have been from the sale and issuance of common stock (in both public offerings and private placements), private placements of convertible preferred stock, funds from our collaboration partnerships, funds from our 2018 Loan Agreement, as amended, and 2022 Loan Agreement, as amended, as well as from sales of IBSRELA and XPHOZAH. Our primary uses of cash have been to fund operating expenses, including research and development expenditures, pre-commercial and commercial expenses. Cash used to fund operating expenses is impacted by the timing of when we pay these expenses, as reflected in the change in our outstanding accounts payable and accrued expenses.

Between December 31, 2021 and September 30, 2023, our liquidity position raised substantial doubt about our ability to continue as a going concern. We have addressed our operating cash flow requirements through cash generated from product sales of IBSRELA and XPHOZAH, proceeds from the sale of shares of our common stock under our at-the-market offering, from the receipt of milestones payments from our collaboration partners and payments from Kyowa Kirin under the 2022 Amendment to our License Agreement, which were received in October 2023, and from proceeds of the Term B Loan. We believe our available cash, cash equivalents and short-term investments as of December 31, 2023 will be sufficient to fund our planned operations for at least a period of one year from the issuance of these financial statements. We have based this estimate on assumptions that may prove to be wrong, and we could utilize our available capital resources sooner than we currently expect. In particular, our operating plan may change and we may require significant additional capital to fund our operations. There are no assurances that our efforts to meet our operating cash flow requirements will be successful. If our current cash, cash equivalents and short-term investments as well as our plans to meet our operating cash flow requirements are not sufficient to fund necessary expenditures and meet our obligations following the issuance of these financial statements, our liquidity, financial condition and business prospects will be materially affected.

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Our future funding requirements will depend on many factors, including, but not limited to:

•the extent to which we are able to generate product revenue from sales of IBSRELA and XPHOZAH;

•the availability of adequate third-party reimbursement for IBSRELA and XPHOZAH;

•the manufacturing, selling and marketing costs associated with IBSRELA and XPHOZAH;

•whether or when XPHOZAH, along with other oral ESRD-related drugs without an injectable or intravenous equivalent, are bundled into the ESRD prospective payment system (ESRD PPS), the manner in which such introduction into the ESRD PPS may occur, including the length of any applicable TDAPA period and the amount of the add-on payment available during the TDAPA period and whether, and the extent to which, the ESRD PPS base rate is adjusted following any applicable TDAPA period;

•our ability to maintain our existing collaboration partnerships and to establish additional collaboration partnerships, in-license/out-license, joint ventures or other similar arrangements and the financial terms of such agreements;

•the timing, receipt and amount of any milestones that may be received from our collaboration partners in connection with tenapanor, if any;

•the timing, receipt, and amount of royalties we may receive as a result of sales of tenapanor by our collaboration partners in China, and Canada, if any;

•the cash requirements for the discovery and/or development of other potential product candidates, including RDX013 and RDX020;

•the time and cost necessary to respond to technological and market developments;

•the costs of filing, prosecuting, maintaining, defending, and enforcing any patent claims and other intellectual property rights, including litigation costs and the outcome of such litigation, and costs of defending any claims of infringement brought by others in connection with the development, manufacture or commercialization of tenapanor or any of our product candidates; and

•the payment of interest and principal related to the 2022 Loan Agrememt, as amended to date.

Please see the risk factors set forth in Part I, Item 1A, Risk Factors, in this Annual Report on Form 10-K for additional risks associated with our capital requirements.

CASH FLOW ACTIVITIES

The following table summarizes our cash flows for the periods indicated (in thousands):

Cash Flows from Operating Activities

Fiscal 2023 compared to 2022:

Net cash used in operating activities during the year ended December 31, 2023 increased by $19.7 million as compared to the same period in 2022 primarily as a result of changes in our working capital, including a $13.8 million increase in prepaid expenses primarily related to the timing of upfront payments to contract manufacturing organizations for the commercial manufacturing for the production of IBSRELA and XPHOZAH.

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Fiscal 2022 compared to 2021:

Net cash used in operating activities during the year ended December 31, 2022 decreased as compared to the same period in 2021 by $82.5 million primarily as a result of decreased spending on research and development expenses during the year ended December 31, 2022 as compared to the year ended December 31, 2021, as well net product sales of IBSRELA and $35.0 million of milestone payments and payments under the 2022 Amendment, which we earned in 2022 upon Kyowa Kirin's submission of a New Drug Application to the Japanese Ministry of Health, Labour and Welfare for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis. Partially offsetting the net loss improvement were changes to our operating assets and liabilities related to expenditures for commercial manufacturing and inventory for the production of IBSRELA.

Cash Flows from Investing Activities

Fiscal 2023 compared to 2022:

Net cash provided by investing activities during the year ended December 31, 2023 decreased as compared to the same period in 2022 by $149.7 million primarily due to increased investment purchases during 2023, as we invested higher levels of cash as compared to the same period in 2022. The decrease due to investment purchases of $215.3 million was partially offset by investment maturities and redemptions of $84.3 million,

Fiscal 2022 compared to 2021:

Net cash provided by investing activities during the year ended December 31, 2022 decreased as compared to the same period in 2021 by $32.5 million due to lower investment balances and the timing of our investment maturities, which was partially offset by $1.8 million proceeds from sale of laboratory equipment and supplies during the year ended December 31, 2022.

Cash Flows from Financing Activities

Fiscal 2023 compared to 2022:

Net cash provided by financing activities during the year ended December 31, 2023 increased by $71.0 million as compared to the same period in 2022 primarily due to net proceeds from issuance of our common stock pursuant to the at the market offerings of $119.2 million during the year ended December 31, 2023 compared to $71.6 million during the year ended December 31, 2022, as well as net proceeds received of $22.4 million from drawing the Term B Loan as compared to net expenditure of $6.1 million during the year ended December 31, 2022 in conjunction with entering into the 2022 Loan and repaying the principal outstanding under the 2018 Loan. In addition we received net proceeds of $5.0 million from the sale of future royalties to HCR during the year ended December 31, 2023 as compared to $10.0 million during the year ended December 31, 2022.

Fiscal 2022 compared to 2021:

Net cash provided by financing activities during the year ended December 31, 2022 decreased as compared to the same period in 2021 by $7.7 million primarily due to $29.5 million lower proceeds from issuance of common stock under at-the-market offerings and well as increased payments in the amount of $13.6 million to repay the principal outstanding on the 2018 Loan. Partially offsetting these amounts were $27.0 million net proceeds received from the 2022 Loan and $9.6 million net proceeds from the sales of future royalties during the year ended December 31, 2022.

SMALLER REPORTING COMPANY AND LARGE ACCELERATED FILER STATUS

As a non-accelerated filer, we were not required to obtain an opinion of our independent auditors with respect to our internal controls over financial reporting for the year ended December 31, 2022. On June 30, 2023, our public float exceeded $700.0 million and therefore, as of January 1, 2024, we are considered a large accelerated filer and we will be required to reflect the determination that we are no longer a smaller reporting company in our Quarterly Report on Form 10-Q for the fiscal quarter ending March 31, 2024. This Annual Report on Form 10-K includes an opinion of Ernst & Young LLP, our independent auditors with respect to our internal control over financial reporting as of December 31, 2023.

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ITEM 7.    MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

You should read the following discussion and analysis of our financial condition and results of operations in conjunction with our financial statements and related notes included elsewhere in this report. This discussion and other parts of this report contain forward-looking statements that involve risk and uncertainties, such as statements of our plans, objectives, expectations and intentions. Our actual results could differ materially from those discussed in these forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed in the section of this report entitled “Risk Factors. ” These forward-looking statements speak only as of the date hereof. Except as required by law, we assume no obligation to update or revise these forward-looking statements for any reason. Unless the context requires otherwise, the terms “Ardelyx”, “Company”, “we”, “us”, and “our” refer to Ardelyx, Inc.

OVERVIEW

We are a biopharmaceutical company founded with a mission to discover, develop and commercialize innovative first-in-class medicines that meet significant unmet medical needs. We developed a unique and innovative platform that enabled the discovery of new biological mechanisms and pathways to develop potent, and efficacious therapies that minimize the side effects and drug-drug interactions frequently encountered with traditional, systemically absorbed medicines. The first molecule we discovered and developed was tenapanor, a targeted, first-in-class, oral, small molecule therapy. Tenapanor, branded as IBSRELA, is approved in the U.S. for the treatment of adults with irritable bowel syndrome with constipation (“IBS-C”). Tenapanor is in development for the control of serum phosphorus, or hyperphosphatemia, in adult patients with chronic kidney disease (“CKD”) on dialysis under the brand name XPHOZAH. We also have a development stage asset, RDX013 for adult patients with CKD and/or heart failure with hyperkalemia, or elevated serum potassium, and a discovery stage asset, RDX020, for adult patients with metabolic acidosis, a serious electrolyte disorder, in patients with CKD.

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Since commencing operations in October 2007, substantially all our efforts have been dedicated to our research and development (“R&D”) activities, including developing tenapanor and developing our proprietary drug discovery and design platform. We realized our first product sales of IBSRELA® (tenapanor) in March 2022. As of December 31, 2022, we had an accumulated deficit of $780.1 million.

We expect to continue to incur substantial operating losses for the foreseeable future as we invest in the commercialization of IBSRELA, seek to gain approval in the U.S. for XPHOZAH® (tenapanor); prepare for and commercialize XPHOZAH in the U.S., if approved; and incur manufacturing and development cost for tenapanor. To date, we have funded our operations from the sale and issuance of common stock and convertible preferred stock, funds from our collaboration partnerships, which includes license fees, milestones and product supply revenue, funds from our loan agreements with our lenders, as well as from sales of IBSRELA.

OUR COMMERCIAL PRODUCT

IBSRELA for IBS-C

Our unique discovery platform and deep understanding of the primary mechanism of sodium transport in the intestine resulted in our discovery and development of IBSRELA, a first-in-class, U.S. Food and Drug Administration (“FDA") approved, sodium hydrogen exchange 3 ("NHE3") inhibitor for the treatment of IBS-C in adults. IBSRELA acts locally in the gut and is minimally absorbed. IBS-C is a gastrointestinal ("GI") disorder characterized by both abdominal pain and altered bowel movements, and is estimated to affect 12 million people in the U.S. IBS-C is associated with significantly impaired quality of life, reduced productivity, and substantial economic burden.

We recognized our first sales of IBSRELA in the U.S. in March 2022. For our commercial launch of IBSRELA, we designed a market-responsive commercial strategy and built a commercial organization highly experienced in launching novel therapies into specialty areas. The dynamics of the IBS-C market reflect an established patient base, limited number of competitors all confined to a single mechanism of action, concentrated number of prescribers, and recognized unmet need. In addition, market research indicated a favorable response to the IBSRELA product profile as a novel mechanism therapy. These dynamics enabled a targeted promotional focus on patients currently being managed for IBS-C by the approximately 9,000 high-writing healthcare providers that account for 50% of IBS-C prescriptions. Central to the go to market strategy for IBSRELA is a highly experienced specialty sales force, many with existing relationships across their GI target base, full company engagement, and innovative peer-to-peer and digital initiatives.

We expect competition for IBSRELA will come largely from the three prescription products indicated for IBS-C: Linzess (linaclotide), Amitiza (lubiprostone) and Trulance (plecanatide). Generic lubiprostone is also available in the U.S. Additionally, over-the-counter products, not indicated for IBS-C are commonly used to treat the constipation component of IBS-C, alone and in combination with the IBS-C-indicated prescription therapies.

We have established commercial agreements with Shanghai Fosun Pharmaceutical Industrial Development Co. Ltd. ("Fosun Pharma") in China and Knight Therapeutics, Inc. ("Knight") in Canada for IBSRELA for IBS-C. Knight is currently marketing IBSRELA in Canada.

OUR PRODUCT PIPELINE

Development Candidate XPHOZAH: A Potential New Approach for the Control of Serum Phosphorus in Adult Patients with CKD on Dialysis

XPHOZAH (tenapanor) is a first-in-class medicine being developed for the control of serum phosphorus, or hyperphosphatemia, in adult patients with CKD on dialysis. XPHOZAH has a unique mechanism of action and acts locally in the gut to inhibit NHE3. This results in the tightening of the epithelial cell junctions, thereby significantly reducing paracellular uptake of phosphate, the primary pathway of phosphate absorption. It is estimated that there are more than 550,000 adult patients with CKD on dialysis in the U.S. and approximately 80% of those patients are being treated with phosphate lowering therapies. Seventy-seven percent of patients treated with phosphate binders to treat hyperphosphatemia were unable to consistently maintain phosphorous levels =5.5 mg/dL over a six-month period. If approved, XPHOZAH would be the first therapy for phosphate management that blocks phosphorus absorption at the primary site of uptake. It is not a phosphate binder.

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In June 2020, we submitted a new drug application ("NDA") to the FDA for XPHOZAH. The NDA was supported by three Phase 3 trials involving more than 1,200 adult patients that evaluated the use of tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis, with two trials evaluating tenapanor as monotherapy and one trial evaluating tenapanor as part of a dual mechanism approach with phosphate binders. All three Phase 3 trials met their primary and key secondary endpoints.

On July 28, 2021, we received a Complete Response Letter ("CRL") from the FDA’s Division of Cardiology and Nephrology ("the Division") regarding our NDA for XPHOZAH. In December 2021 we submitted a Formal Dispute Resolution Request ("FDRR") to the Office of Cardiology, Hematology, Endocrinology and Nephrology ("OCHEN"). At the request of the FDA’s Office of New Drugs ("OND"), as part of our second level of appeal of the CRL, a Cardiovascular and Renal Drug Advisory Committee meeting on was held on November 16, 2022 with the committee voting that the benefits of XPHOZAH outweigh its risks nine to four as a monotherapy and ten to two, with one abstention, in combination with phosphate binder therapy. In December 2022, the OND granted our appeal to the CRL for the NDA for XPHOZAH and directed the Division to work with us to develop an appropriate label for the commercialization of XPHOZAH. We believe that a label could reflect an indication for patients whose hyperphosphatemia is insufficiently managed on binder therapy. On February 13, 2023, we participated in a Type A meeting with the Division where we discussed the resubmission of the NDA, and the information to be contained in the resubmitted NDA. We currently expect to resubmit the NDA for XPHOZAH early in the second quarter of 2023. Within thirty (30) days of resubmitting the NDA, we expect to receive notification from the Division as to the classification of the resubmission (Class 1 or Class 2) at which point the expected timing for review will also be known (2-months for a Class 1 and 6-months for a Class 2) as well as a goal review date. We currently that the FDA will act upon the XPHOZAH NDA in the second half of 2023, and that, if approved, we will launch XPHOZAH in the second half of 2023.

We have established commercial agreements with Kyowa Kirin, Co. Ltd. ("KKC") in Japan, Fosun Pharma in China and Knight in Canada for tenapanor for hyperphosphatemia. In October 2022, KKC submitted an NDA to the Japanese Ministry of Health, Labour and Welfare for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis.

Discovery and Developmental Assets

We have a small molecule potassium secretagogue program, RDX013, for the potential treatment of hyperkalemia, or elevated serum potassium. Hyperkalemia is a common problem in patients with heart and kidney disease, particularly in patients taking customary blood pressure medications known as renin-angiotensin-aldosterone system ("RAAS") inhibitors. RDX013 is a novel mechanism agent designed to target the underlying biological mechanisms of potassium secretion to lower elevated potassium. We have completed a Phase 2 dose ranging clinical trial evaluating the safety and efficacy of RDX013 for the treatment of hyperkalemia in CKD patients who are not on dialysis. While the results of the study demonstrated an acceptable safety and tolerability profile for RDX013 and supported proof of concept in its ability to lower serum potassium levels, with statistically significant reductions compared to placebo after eight days of treatment, the study did not meet its primary endpoint of significantly reducing serum potassium levels compared to placebo after four weeks of treatment.

We have a discovery program targeting the inhibition of bicarbonate exchange inhibitor for the treatment of metabolic acidosis, a highly prevalent comorbidity in CKD patients that is strongly correlated with disease progression and adverse outcomes. We have identified lead compounds that are potent, selective and proprietary inhibitors of bicarbonate secretion.

We do not currently expect to meaningfully advance either of these two assets until such time as we have determined our available resources can support additional activities after prioritization of the commercialization of IBSRELA and, if approved, XPHOZAH.

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FINANCIAL OPERATIONS OVERVIEW

Revenue

Our revenue to date has been generated primarily through license, research and development collaborative agreements with various collaboration partners. We realized our first commercial product sales of IBSRELA beginning in March 2022. In the future, we may generate revenue from a combination of our own product sales and payments in connection with our current or future collaborative partnerships, including license fees, other upfront payments, milestone payments, royalties and payments for drug product and/or drug substance. We expect that any revenue we generate will fluctuate in future periods as a result of, among other factors: the extent to which we are successful in our commercialization of IBSRELA; whether we are able to gain approval from the FDA for our NDA for XPHOZAH; our ability to obtain and sustain an adequate level of coverage and reimbursement for IBSRELA by third-party payors; whether and the extent to which we are successful in our commercialization of XPHOZAH, if approved; the timing and progress of goods and services provided pursuant to our current or future collaborative partnerships; our or our collaborators’ achievement of clinical, regulatory or commercialization milestones, to the extent achieved; the timing and amount of any payments to us relating to the aforementioned milestones; addressing any competing technological and market developments; maintaining, protecting and expanding our portfolio of intellectual property rights, including patents, trade secrets, and know-how, and our ability to develop, manufacture and commercialize our product candidates and products without infringing intellectual property rights of others; attracting, hiring, and retaining qualified personnel; and the extent to which tenapanor is approved and successfully commercialized by a collaboration partner. If our current collaboration partners or any future collaboration partners fail to obtain regulatory approval for tenapanor, our ability to generate future revenue from our collaborative arrangements, and our results of operations and financial position, would be materially and adversely affected. Our past revenue performance is not necessarily indicative of results to be expected in future periods.

Cost of Revenue

Cost of revenue consists of the cost of commercial goods sold to our Customers and international partners under product supply agreements, as well as royalty expense based on sales of tenapanor. We capitalize inventory costs associated with the production of our products after regulatory approval or when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Otherwise, such costs are expensed as research and development. A portion of the costs of IBSRELA units recognized as revenue during the twelve months ended December 31, 2022 were expensed prior to the fourth quarter of 2021, at which time our intent to commercialize IBSRELA was established and we commenced preparation for the commercial launch of IBSRELA. We believe our cost of revenue for the year ended December 31, 2022 would have been $1.9 million higher if we had not previously expensed certain material and production costs with respect to the units sold. As of December 31, 2022, we had approximately $28.0 million of inventory on hand that was previously expensed as research and development expense and will not be reported as cost of revenue sold in future periods when sales of IBSRELA are recognized as revenue.

Cost of revenue includes payments due to AstraZeneca AB (“AstraZeneca”), which under the terms of a termination agreement entered into in 2015 (“AZ Termination Agreement”) is entitled to (i) future royalties at a rate of 10% of net sales of tenapanor or other NHE3 products by us or our licensees, and (ii) 20% of non-royalty revenue received from our collaboration partners in connection with the development and commercialization of tenapanor or certain other NHE3 inhibitors. We have agreed to pay AstraZeneca up to a maximum of $75.0 million in the aggregate for (i) and (ii). We recognize these expenses as cost of revenue when we recognize the corresponding revenue that gives rise to payments due to AstraZeneca. To date, we have recognized an aggregate of $15.3 million as cost of revenue under the AZ Termination Agreement. See details in Note 7, Collaboration and Licensing Agreements, under AstraZeneca, in the notes to our financial statements, included in Part II, Item 8, of this Annual Report on Form 10-K.

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Research and Development

Pursuant to the October 2021 restructuring plan, we eliminated our internal research organization and we do not currently expect to meaningfully advance our discovery efforts with respect to our discovery and developmental assets until such time as we have determined our available resources can support additional activities after prioritization of the commercialization of IBSRELA and, if approved, XPHOZAH. We recognize all research and development expenses as they are incurred to support the discovery, research, development and manufacturing of our product candidates. Research and development expenses include, but are not limited to, the following:

•external research and development expenses incurred under agreements with consultants, third-party contract research organizations (“CROs”) and investigative sites where a substantial portion of our clinical studies are conducted, and with contract manufacturing organizations where our clinical supplies are produced;

•expenses associated with supplies and materials consumed in connection with our research operations;

•expenses associated with producing XPHOZAH prior to FDA approval;

•expenses associated with producing discovery and developmental assets prior to FDA approval;

•other costs associated with research, clinical development and regulatory activities;

•employee-related expenses, which include salaries, bonuses, benefits, travel and stock-based compensation; and

•facilities and other allocated expenses, which include direct and allocated expenses for rent and maintenance of facilities, depreciation and amortization expense, information technology expense and other supplies.

Selling, General and Administrative

Selling, general and administrative expenses relate to sales and marketing, finance, human resources, legal and other administrative activities, including information technology investments. Selling, general and administrative expenses consist primarily of personnel costs, outside professional services, marketing, advertising and legal expenses, facilities costs not otherwise allocated to research and development and other general and administrative costs.

Interest Expense

Interest expense represents the interest paid on our loan payable.

Non-cash interest expense related to the sale of future royalties

Non-cash interest expense related to the sale of future royalties represents the imputed interest expense on our deferred royalty obligation related to the sale of future royalties using the effective interest method. As further described in Note 8. Deferred Royalty Obligation Related to the Sale of Future Royalties, in June 2022, we and HealthCare Royalty Partners IV, L.P. (“HCR”) entered into a Royalty and Sales Milestone Interest Acquisition Agreement (“HCR Agreement”). Under the terms of the HCR Agreement, HCR agreed to pay us up to $20.0 million in exchange for the royalty payments and commercial milestone payments (collectively the “Royalty Interest Payments”) that we may receive under our 2017 License Agreement with KKC based upon KKC's net sales of tenapanor in Japan for hyperphosphatemia. As part of the HCR Agreement, we received a $10.0 million upfront payment from HCR in June 2022 and recorded it as a deferred royalty obligation on our balance sheet. Non-cash interest expense will be recognized over the life of the HCR Agreement using the effective interest method based on the imputed interest rate derived from estimated amounts and timing of future royalty payments to be received from KKC.

Other Income, net

Other income, net consists of interest income earned on our cash and cash equivalents and available-for-sale investments, the periodic revaluation of the exit fee related to our loan, gains on sales of property and equipment, and currency exchange gains and losses.

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Provision for Income Taxes

Our provision for income taxes includes current and deferred tax, including foreign withholding taxes paid on payments received from certain collaboration partners. Deferred income taxes reflect the tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Our deferred tax assets continue to be fully offset by a valuation allowance, including deferred tax assets related to our net operating loss carryforwards, which may be subject to annual limitations as a result of ownership changes that may have occurred or could occur in the future.

CRITICAL ACCOUNTING POLICIES AND ESTIMATES

A detailed discussion of our significant accounting policies can be found in Note 2, Summary of Significant Accounting Policies, in the notes to our financial statements, included in Part II, Item 8, of this Annual Report on Form 10-K. Critical accounting policies are those that require significant judgment and/or estimates by management at the time that financial statements are prepared such that materially different results might have been reported if other assumptions had been made. These estimates form the basis for making judgments about the carrying values of assets and liabilities. We base our estimates and judgments on experience and on various other assumptions that we believe to be reasonable under the circumstances. Actual results could differ materially from these estimates.

We consider certain accounting policies related to revenue recognition, accrued research and development expenses and stock-based compensation to be critical policies to understanding the judgments and estimates applied in our reported financial results.

Product Sales, Net

We account for our commercial product sales, net in accordance with Topic 606–- Revenue from Contracts with Customers. We received approval from the FDA in September 2019 to market IBSRELA in the U.S. We began selling IBSRELA in the U.S. in March 2022. We distribute IBSRELA principally through major wholesalers, specialty pharmacies and group purchasing organizations ("GPOs") (collectively, our "Customers"). Our Customers subsequently sell IBSRELA to pharmacies and patients. Separately, we enter into arrangements with third parties that provide for government-mandated rebates, chargebacks and discounts. Revenue from product sales is recognized when our performance obligations are satisfied, which is when Customers obtain control of our product and occurs upon delivery.

Reserves for Variable Consideration

Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration which may be settled in the form of off-invoice discounts, chargebacks, or rebates. Variable consideration includes discounts to customers and government programs, wholesaler fees, group purchasing organization administrative fees, patient copay assistance, and estimated product returns. These estimates are based on the amounts earned or to be claimed for related sales and are classified as reductions of gross accounts receivable if settlement is expected to occur through a reduction in the amounts paid by our Customers or a current liability if settlement is expected to occur through a payment from us. Where appropriate, these estimates are based on factors such as industry data and forecasted customer buying and payment patterns, our experience, current contractual and statutory requirements, specific known market events and trends. These reductions to gross sales reflect our best estimates of the amount of consideration to which we are entitled based on the terms of the contract. Variable consideration is included in the transaction price only to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Actual amounts of consideration ultimately received may differ from our estimates. If actual results in the future vary from our estimates, we adjust these estimates, which would affect product revenue and earnings in the period such variances become known. As we gain more experience, estimates will be more heavily based on the expected utilization from historical data we have accumulated since the IBSRELA product launch.

Rebates: Rebates include wholesaler fees, GPO fees, as well as mandated discounts under the Medicaid Drug Rebate Program ("Medicaid") and the Medicare Coverage Gap Program ("Medicare"). Estimates for rebates are recorded in the same period the related gross revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability which is included in accrued expenses on the balance sheets. We estimate our Medicaid and Medicare rebates based upon the estimated payor mix, and statutory discount rates. Our estimates for payor mix are guided by payor information received from specialty pharmacies, expected utilization for wholesaler sales to pharmacies, and available industry payor information.

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Chargebacks: Chargebacks are discounts that occur when certain contracted purchasers purchase directly from our wholesalers at a discounted price. The wholesaler, in turn, charges back the difference between the price initially paid to us by the wholesaler and the discounted price paid to the wholesaler by the contracted purchaser. Amounts for estimated chargebacks are established in the same period that the related gross revenue is recognized, resulting in a reduction of product revenue and accounts receivable. The accrual for wholesaler chargebacks is estimated based on known chargeback rates, known sales to wholesalers, and estimated utilization by types of contracted purchasers.

Discounts and Fees: Our payment terms are generally 30 to 60 days. Wholesalers, GPOs and specialty pharmacies are offered various forms of consideration, including off-invoice discounts which may be paid to GPOs and specialty pharmacies. Wholesalers and GPOs may also receive prompt pay discounts for payment within a specified period. We expect discounts to be earned when offered and therefore, we deduct the full amount of these discounts from product sales when revenue is recognized, resulting in a reduction of product revenue and accounts receivable.

Other Reserves: Patients who have commercial insurance may receive copay assistance when product is dispensed by pharmacies to patients. We estimate the amount of copay assistance provided to eligible patients based on the terms of the program and redemption information provided by third-party claims processing organizations and are recorded in accounts payable and accrued expenses and other current liabilities on the balance sheets. Other reserves include estimated product returns which are recorded in the same period the related gross revenue is recognized, resulting in a reduction of product revenue as well as accounts receivable. We estimate our product returns reserve based upon our experience, and specific known market events and trends.

Collaboration Revenue Recognition

We generate collaboration revenue primarily from research and collaboration and license agreements with customers. Goods and services in the agreements may include the grant of licenses for the use of our technology, the provision of services associated with the research and development of product candidates, manufacturing services, and participation in joint steering committees. The terms of these arrangements typically include payment to us of one or more of the following: non-refundable, up-front license fees; research, development, regulatory and commercial milestone payments; reimbursement of research and development services; option payments; reimbursement of certain costs; payments for manufacturing supply services; and future royalties on net sales of licensed products.

When two or more contracts are entered into with the same customer at or near the same time, we evaluate the contracts to determine whether the contracts should be accounted for as a single arrangement. Contracts are combined and accounted for as a single arrangement if one or more of the following criteria are met: (i) the contracts are negotiated as a package with a single commercial objective; (ii) the amount of consideration to be paid in one contract depends on the price or performance of the other contract; or (iii) the goods or services promised in the contracts (or some goods or services promised in each of the contracts) are a single performance obligation.

In determining the appropriate amount of revenue to be recognized as we fulfill our obligations under each of our agreements, management performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including any constraints on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) we satisfy each performance obligation. As part of the accounting for contracts with customers, we develop assumptions that require judgment to determine whether promised goods and services represent distinct performance obligations and the standalone selling price for each performance obligation identified in the contract. This evaluation is subjective and requires us to make judgments about the promised goods and services and whether those goods and services are separable from other aspects of the contract. Further, determining the standalone selling price for performance obligations requires significant judgment, and when an observable price of a promised good or service is not readily available, we consider relevant assumptions to estimate the standalone selling price, including, as applicable, market conditions, development timelines, probabilities of technical and regulatory success, reimbursement rates for personnel costs, forecasted revenues, potential limitations to the selling price of the product and discount rates.

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We apply judgment in determining whether a combined performance obligation is satisfied at a point in time or over time, and, if over time, concluding upon the appropriate method of measuring progress to be applied for purposes of recognizing revenue. We evaluate the measure of progress each reporting period and, as estimates related to the measure of progress change, related revenue recognition is adjusted accordingly. Changes in our estimated measure of progress are accounted for prospectively as a change in accounting estimate. We recognize collaboration revenue by measuring the progress toward complete satisfaction of the performance obligation using an input measure. In order to recognize revenue over the research and development period, we measure actual costs incurred to date compared to the overall total expected costs to satisfy the performance obligation. Revenues are recognized as the program costs are incurred. We will re-evaluate the estimate of expected costs to satisfy the performance obligation each reporting period and make adjustments for any significant changes. Amounts received prior to satisfying the revenue recognition criteria are recorded as contract liabilities in our balance sheets. If the related performance obligation is expected to be satisfied within the next twelve months, this will be classified in current liabilities. Amounts recognized as revenue prior to receipt are recorded as contract assets in our balance sheets. If we expect to have an unconditional right to receive the consideration in the next twelve months, this will be classified in current assets. A net contract asset or liability is presented for each contract with a customer.

Milestone Payments: At the inception of each arrangement that includes research and development milestone payments, we evaluate whether the milestones are considered probable of being reached and estimate the amount to be included in the transaction price using the most likely amount method. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. Milestone payments that are not within the control of us or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative standalone selling price basis, for which 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 of achievement of such development milestones and any related constraints, and if necessary, adjust our estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect earnings in the period of adjustment.

Manufacturing supply services: Arrangements that include a promise for the future supply of drug substance or drug product for either clinical development or commercial supply at the customer’s discretion are generally considered as options. We assess if these options provide a material right to the licensee and if so, they are accounted for as separate performance obligations. If we are entitled to additional payments when the customer exercises these options, any payments are recorded in product supply revenue when the customer obtains control of the goods, which is upon delivery.

Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and 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). To date, royalty revenue resulting from licensing arrangements has not been material.

Licenses of intellectual property: If a license granted to a customer to use our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenue from consideration allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, we apply 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, to conclude upon the appropriate method of measuring progress for purposes of recognizing revenue related to consideration allocated to the performance obligation.

Options: Customer options, such as options granted to allow a licensee to choose to research, develop and commercialize licensed compounds are evaluated at contract inception in order to determine whether those options provide a material right (i. e., an optional good or service offered for free or at a discount) to the customer. If the customer options represent a material right, the material right is treated as a separate performance obligation at the outset of the arrangement. We allocate the transaction price to material rights based on the standalone selling price, and revenue is recognized when or as the future goods or services are transferred or when the option expires. Customer options that are not material rights do not give rise to a separate performance obligation, and as such, the additional consideration that would result from a customer exercising an option in the future is not included in the transaction price for the current contract. Instead, the option is deemed a marketing offer, and additional option fee payments are recognized or being recognized as revenue when the licensee exercises the option. The exercise of an option that does not represent a material right is treated as a separate contract for accounting purposes.

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Contract modifications: Contract modifications, defined as changes in the scope or price (or both) of a contract that are approved by the parties to the contract, such as a contract amendment, exist when the parties to a contract approve a modification that either creates new or changes existing enforceable rights and obligations of the parties to the contract. Depending on facts and circumstances, we account for a contract modification as one of the following: (i) a separate contract; (ii) a termination of the existing contract and a creation of a new contract; or (iii) a combination of the preceding treatments. A contract modification is accounted for as a separate contract if the scope of the contract increases because of the addition of promised goods or services that are distinct and the price of the contract increases by an amount of consideration that reflects our standalone selling prices of the additional promised goods or services. When a contract modification is not considered a separate contract and 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 the contract modification as a termination of the existing contract and a creation of a new contract. When a contract modification is not considered a separate contract and the remaining goods or services are not distinct, we account for the contract modification as an add-on to the existing contract and as an adjustment to revenue on a cumulative catch-up basis.

We receive payments from our licensees as established in each contract. 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. Where applicable, amounts are recorded as unbilled revenue when our right to consideration is unconditional. We do not assess whether a contract with a customer has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less.

Inventory

We capitalize inventory costs associated with the production of our products after regulatory approval or when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Otherwise, such costs are expensed as research and development. Prior to the regulatory approval of drug product candidates, we incurred expenses for the manufacture of drug product that could potentially be available to support the commercial launch of our products or could be sold to our international partners under product supply agreements. We began to capitalize inventory costs associated with IBSRELA during the fourth quarter of 2021, when our intent to commercialize IBSRELA was established and we commenced preparation for the commercial launch of IBSRELA, which was when it was determined that the inventory had a probable future economic benefit.

Inventory is stated at the lower of cost or estimated net realizable value with cost determined under the first-in first-out method. Inventory costs include the cost of materials, third-party contract manufacturing, third-party packaging services, freight, labor costs for personnel involved in the manufacturing process, and indirect overhead costs. We primarily use actual costs to determine the cost basis for inventory. The determination of whether inventory costs will be realizable requires management review of the expiration dates of IBSRELA compared to our forecasted sales. If actual market conditions are less favorable than projected by management, write-downs of inventory may be required, which would be recorded as cost of revenue in the statement of operations and comprehensive loss. As of December 31, 2022, we have not recorded any write-offs for excess and obsolete inventory. The portion of inventory that represents product that is not expected to be sold or used within the next 12 months is classified as non-current on our balance sheets.

Accrued Research and Development Expenses

As part of the process of preparing our financial statements, we are required to estimate our accrued expenses. This process involves reviewing open contracts and purchase orders, communicating with our personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of the actual cost. The majority of our service providers invoice us monthly in arrears for services performed or when contractual milestones are met. We make estimates of our accrued expenses as of each balance sheet date in our financial statements based on facts and circumstances known to us at that time. We periodically confirm the accuracy of our estimates with our service providers and make adjustments if necessary. Examples of estimated accrued research and development expenses include fees paid to:

•CROs in connection with clinical studies;

•investigative sites in connection with clinical studies;

•vendors related to product manufacturing, development and distribution of clinical supplies; and

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•vendors in connection with preclinical development activities.

We record expenses related to clinical studies and manufacturing development activities based on our estimates of the services received and efforts expended pursuant to contracts with our CROs and manufacturing vendors that conduct and manage these activities on our behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract, and may result in uneven payment flows. There may be instances in which payments made to our vendors will exceed the level of services provided and result in a prepayment of the expense. Payments under some of these contracts depend on factors such as the successful enrollment of subjects and the completion of clinical trial milestones. In accruing service fees, we estimate the time period over which each component of a service will be performed, and estimate, with vendor input if appropriate, the resulting level of completion of each component of the service, with such estimates often involving drivers that provide a surrogate measurement of completion such as number of enrolled subjects and/or number of sites activated in the calculation of clinical trial fee accruals. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrued or prepaid expense balance accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differ from the actual status and timing of services performed, we may report amounts that are too high or too low in any particular period.

Stock-Based Compensation

We estimate the fair value of stock options and Employee Stock Purchase Plan (“ESPP”) shares using the Black-Scholes valuation model. The Black-Scholes model requires the input of highly subjective assumptions which determine the fair value of stock-based awards. These assumptions include:

Expected Term—We have limited historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for our stock-option grants. As such, the expected term is estimated using the simplified method whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the option. Beginning in 2021, we estimate the expected term of our options based upon historical exercises and post-vesting termination behavior, which has not resulted in a material difference as compared to using the simplified method.

Expected Volatility—We use the historic volatility of our own stock over the retrospective period corresponding to the expected remaining term of the options, or the period since our shares were first quoted on The Nasdaq Global Market, if that is shorter, to compute our expected stock price volatility.

Risk-Free Interest Rate—The risk-free interest rate assumption is based on zero-coupon U.S. Treasury instruments on the date of grant with a maturity date consistent with the expected term of our stock option grants.

Expected Dividend— To date, we have not declared or paid any cash dividends and do not have any plans to do so in the future. Therefore, we use an expected dividend yield of zero.

As required, we review our valuation assumptions at each grant date and, as a result, we are likely to change our valuation assumptions used to value employee stock-based awards granted in future periods. Employee and director stock-based compensation costs are to be recognized over the vesting period of the award, and we have elected to use the straight-line attribution method. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. We estimate forfeitures based on historical experience.

Restricted stock units ("RSUs") are measured at the fair value of our common stock on the date of grant and expensed over the period of vesting using the straight-line attribution approach.

Performance-based RSUs ("PRSUs") are valued at grant-date fair market value. The vesting of the PRSUs is based on performance conditions. Performance conditions include: (i) a specific performance criteria and (ii) the employee’s continuous employment by the company for a stated period of time in order to earn the right to the related PRSUs to vest. We recognize compensation cost with respect to the vesting of the PRSUs on a ratable basis over the requisite service period, upon the performance conditions being deemed probable of achievement.

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Restructuring

We recognize restructuring charges related to reorganization plans that have been committed to by management when liabilities have been incurred. In connection with these activities, we record restructuring charges at fair value for, (a) contractual employee termination benefits when obligations are associated to services already rendered, rights to such benefits have vested, and payment of benefits is probable and can be reasonably estimated, (b) one-time employee termination benefits when management has committed to a plan of termination, the plan identifies the employees and their expected termination dates, the details of termination benefits are complete, it is unlikely changes to the plan will be made or the plan will be withdrawn and communication to such employees has occurred, and (c) contract termination costs when a contract is terminated before the end of its term.

One-time employee termination benefits are recognized in their entirety when communication has occurred and future services are not required. If future services are required, the costs are recorded ratably over the remaining period of service. Contract termination costs to be incurred over the remaining contract term without economic benefit are recorded in their entirety when the contract is canceled.

RESULTS OF OPERATIONS

Comparison of the Years Ended December 31, 2022, 2021 and 2020

Revenue

Below is a summary of our total revenue (dollars in thousands):

Fiscal 2022 compared to 2021: The increase to total revenues was primarily attributable to $15.6 million of net product sales for IBSRELA to our Customers, as well as aggregate of $35.0 million in milestone payments and payments under the second amendment to the 2017 KKC Agreement which we earned upon KKC's submission of a New Drug Application to the Japanese Ministry of Health, Labour and Welfare for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis. We also realized increased product supply revenue in connection with the 2017 KKC Agreement. Partially offsetting these increases was the full recognition of collaborative development revenue for upfront payments associated with the 2019 KKC Agreement through the end of 2021. There were no product sales during 2021 and 2020.

Fiscal 2021 compared to 2020: The increase to total revenues was primarily attributable to a $5.0 million development milestone which we earned and recognized as licensing revenue during the twelve months ended December 31, 2021 upon the initiation by KKC of Phase 3 clinical studies in Japan to evaluate tenapanor for hyperphosphatemia. The increase was partially offset by lower collaborative development revenue and product supply revenue from KKC during the same period.

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Operating Expenses

Below is a summary of our operating expenses (dollars in thousands):

Cost of Revenue

Fiscal 2022 compared to 2021: The increase in cost of revenue was primarily attributable to payments due to AstraZeneca under the AZ Termination Agreement for IBSRELA product sales, net and for the milestone payment we received under the second amendment to the 2017 KKC Agreement, which we earned upon KKC's submission of a New Drug Application to the Japanese Ministry of Health, Labour and Welfare for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis. We also incurred $0.5 million for the cost of product shipped for product sales of IBSRELA during the twelve months ended December 31, 2022.

Fiscal 2021 compared to 2020: The increase in cost of revenue was attributable to payment to AstraZeneca under the AZ Termination Agreement related to the development milestone we earned upon the initiation by KKC of Phase 3 clinical studies in Japan to evaluate tenapanor for hyperphosphatemia.

Research and Development

Below is a summary of our research and development expenses (dollars in thousands):

Fiscal 2022 compared to 2021: The decrease in our external R&D expenses was primarily the result of lower clinical study costs following the completion of the OPTIMIZE study, lower tenapanor manufacturing expense as we have begun to capitalize costs associated with the production of IBSRELA to inventory, and lower expenses for research following the elimination of our internal research organization in the fourth quarter of 2021. The decrease in our employee-related expenses for the twelve months ended December 31, 2022 is due to lower compensation and benefits expenses for our research and development workforce following restructuring actions in 2021. Similarly, the decrease in facilities, equipment and depreciation expenses is primarily due to a smaller proportion of such expenses being attributed to R&D following the restructuring in 2021. The increase in other expenses is primarily related to disease-related education grants during the twelve months ended December 31, 2022.

Fiscal 2021 compared to 2020: The increase in our external R&D expenses was the result of tenapanor manufacturing costs as well as clinical study costs from the advancement of our OPTIMIZE study which were partially offset by lower costs for the PHREEDOM clinical study. The increase in our employee-related expenses was related to compensation and benefits expenses for our research and development workforce. Employee-related expenses for twelve months ended December 31, 2021 include $2.7 million of severance payments and other employee-related costs as discussed in Note 14 - Restructuring to the financial statements included elsewhere in this Annual Report.

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Selling, General and Administrative

Fiscal 2022 compared to 2021: The increase in selling, general and administrative expenses for the twelve months ended December 31, 2022 was primarily due to increased costs associated with the commercial launch of IBSRELA during 2022. The changes consisted of headcount and related personnel costs and external spending for disease awareness initiatives, commercial infrastructure and strategy. These increases were partially offset by a reduction in ongoing and one-time costs as a result of the restructuring action carried out during the third quarter of 2021.

Fiscal 2021 compared to 2020: The increase in general and administrative expenses was primarily due to increased costs associated with building and staffing our commercial infrastructure and teams as we prepared for a potential U.S. launch of XPHOZAH. The increase consisted of headcount and related personnel costs and an increase in external spending for disease awareness initiatives, commercial infrastructure and strategy. Selling, general and administrative expenses for the twelve months ended December 31, 2021 include $3.5 million severance payments and other employee-related costs as discussed in Note 14 - Restructuring to the financial statements included elsewhere in this Annual Report.

Interest Expense

Below is a summary of our interest expense (dollars in thousands):

Fiscal 2022 compared to 2021: The decrease in interest expense was due to lower principal outstanding on our loan payable in 2022 than in 2021 due to principal payments made on our 2018 Loan during the fourth quarter of 2021 through February 2022. In February 2022, we repaid the remaining outstanding principal balance of the 2018 Loan in the amount of $25.0 million and entered into the new 2022 Loan in the amount of $27.5 million which has an interest-only payment period through March 31, 2024.

Fiscal 2021 compared to 2020: The decrease in interest expense was primarily due to lower interest rates on our variable-rate term loan.

Non-Cash Interest Expense Related to the Sale of Future Royalties

Below is a summary of our non-cash interest expense related to the sale of future royalties (dollars in thousands):

Fiscal 2022 compared to 2021: Non-cash interest expense related to the sale of future royalties reflects the recognized amortization of the deferred royalty obligation that we recorded following the receipt of the $10.0 million upfront payment from HCR in June 2022.

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Other Income, net

Below is a summary of our other income (expense), net (dollars in thousands):

Fiscal 2022 compared to 2021: The increase in other income, net was primarily due to sales of certain lab equipment and supplies for a net gain of $1.5 million and increased investment income during the twelve months ended December 31, 2022. Partially offsetting these increases were fluctuations related to revaluation of our exit fees.

Fiscal 2021 compared to 2020: The changes in other income, net were primarily due to lower income earned on our investments, which was largely offset by the revaluation of our exit fee related to our term loan agreement following receipt of the FDA CRL on July 28, 2021.

LIQUIDITY AND CAPITAL RESOURCES

Below is a summary of our cash, cash equivalents and short-term investments (in thousands):

As of December 31, 2022, we had cash and short-term investments of approximately $123.9 million. We have incurred operating losses since inception in 2007 and our accumulated deficit as of December 31, 2022 is $780.1 million. Our current level of cash and short-term investments alone is not sufficient to meet our plans for the next twelve months following the filing of these financial statements on March 2, 2023. These factors raise substantial doubt regarding our ability to continue as a going concern for a period of one year from the issuance of these financial statements. We plan to address our operating cash flow requirements with our current cash and short-term investments, cash generated from product sales of IBSRELA, and if approved, cash generated from sales of XPHOZAH, the potential receipt of anticipated milestone payments from our collaboration partners, the potential receipt of anticipated payments from KKC under the 2022 Amendment, with additional financing sources and through the implementation of cash preservation activities to reduce or defer discretionary spending.

There are no assurances that our efforts to meet our operating cash flow requirements will be successful. If our current cash and short-term investments as well as our plans to meet our operating cash flow requirements are not sufficient to fund necessary expenditures and meet our obligations for at least the next twelve months following the issuance of these financial statements, our liquidity, financial condition and business prospects will be materially affected. These financial statements have been prepared on a going concern basis and do not include any adjustments to the amounts and classification of assets and liabilities that may be necessary in the event that we can no longer continue as a going concern.

In July 2020, we filed a Form S-3 registration statement, which became effective in August 2020 ("2020 Registration Statement"), containing (i) a base prospectus for 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, warrants and/or units, from time to time in one or more offerings; and (ii) a prospectus supplement for the offering, issuance and sale by us of up to a maximum aggregate offering price of $100.0 million of our common stock that may be issued and sold, from time to time, under an Open Market Sales Agreement with Jefferies LLC ("Jefferies"), as sales agent, deemed to be “at the market offerings” "2020 Open Market Sales Agreement"). Pursuant to the 2020 Open Market Sales Agreement, Jefferies received a commission of up to 3.0% of the gross sales price for shares of common stock sold under the 2020 Open Market Sales Agreement. As of December 31, 2021, we had sold 23.3 million shares and received the maximum gross proceeds of $100.0 million pursuant to the 2020 Open Market Sales Agreement.

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In August 2021, we filed an additional prospectus supplement under the 2020 Registration Statement for the offering, issuance and sale by us of up to a maximum aggregate offering price of $150.0 million of our common stock that may be issued and sold, from time to time, under an additional sales agreement we entered into with Jefferies ("2021 Open Market Sales Agreement"), pursuant to which we may, from time to time, sell up to $150.0 million in shares of our common stock through Jefferies. We are not required to sell shares under the 2021 Open Market Sales Agreement. Pursuant to the 2021 Open Market Sales Agreement, Jefferies, as our sales agent, receives a commission of up to 3.0% of the gross sales price for shares of common stock sold under the 2021 Open Market Sales Agreement. As of December 31, 2022 we have sold 79.8 million shares and received gross proceeds of $98.1 million at a weighted average sales price of approximately $1.23 per share under the 2021 Open Market Sales Agreement. Subsequent to December 31, 2022, we received additional gross proceeds of $20.0 million for the sale of an additional 7.7 million shares which were settled between January 1, 2023 to January 12, 2023 and were sold at a weighted average sales price of approximately $2.60 per share under the 2021 Open Market Sales Agreement. There have been no other sales under the 2021 Open Market Sales Agreement after the January 12, 2023 settlement date.

In January 2023, we filed a Form S-3 registration statement, which became effective in January 2023 ("2023 Registration Statement"), containing (i) a base prospectus for 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, warrants and/or units, from time to time in one or more offerings; and (ii) a prospectus supplement for the offering, issuance and sale by us of up to a maximum aggregate offering price of $150.0 million of our common stock that may be issued and sold, from time to time, under a sales agreement with Jefferies, deemed to be “at-the-market offerings” ("2023 Open Market Sales Agreement"). Pursuant to the 2023 Open Market Sales Agreement, Jefferies, as sales agent, may receive a commission of up to 3.0% of the gross sales price for shares of common stock sold under the 2023 Open Market Sales Agreement. There have been no sales of our common stock under the 2023 Open Market Sales Agreement.

In February 2022, we entered into a loan and security agreement (“2022 Loan Agreement”) with SLR Investment Corp ("SLR"). The 2022 Loan Agreement provides for a senior secured term loan facility, with $27.5 million funded at closing and an additional $22.5 million that we may borrow on or prior to July 25, 2023; provided that (i) we had received approval by the FDA for our NDA for XPHOZAH by December 31, 2022, and (ii) we have achieved certain product revenue milestone targets described in the 2022 Loan Agreement. In August 2022, we entered into an amendment to the 2022 Loan Agreement with SLR that extended the date by which we must receive approval by the FDA for our NDA for XPHOZAH in order to borrow the additional $22.5 million from December 31, 2022 to March 31, 2023. In February 2023, we further amended the 2022 Loan Agreement (“2023 Amendment”) such that, we may borrow the additional $22.5 million under the 2022 Loan Agreement until December 20, 2023; provided that (i) we have received FDA approval for our NDA for XPHOZAH by November 30, 2023, or (ii) we have achieved certain product revenue milestone targets described in the 2023 Amendment.

The initial funding of $27.5 million was used to repay the 2018 Loan and is funding our ongoing operations. We had $25.0 million principal from the 2018 Loan outstanding as of the closing date. In connection with entering into the 2022 Loan Agreement, we entered into an agreement, whereby we agreed to pay an exit fee in the amount of 2% of the 2022 Loan funded (“2022 Exit Fee”) upon (i) any change of control transaction or (ii) our achievement of net revenue from the sale of any products equal to or greater than $100.0 million, measured on a six (6) months basis ("Revenue Milestone"), tested monthly at the end of each month. Notwithstanding the prepayment or termination of the 2022 Loan, the 2022 Exit Fee will expire on February 23, 2032. We concluded that the 2022 Exit Fee is a freestanding derivative which should be accounted for at fair value on a recurring basis. The estimated fair value of the 2022 Exit Fee is recorded as a derivative liability and included in accrued expenses and other current liabilities on the accompanying balance sheets.

In October 2022, we announced that our collaboration partner, KKC, submitted a New Drug Application to the Japanese Ministry of Health, Labour and Welfare for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis. In accordance with the terms of the 2022 Amendment, KKC paid an aggregate of $35.0 million to us in milestone payments and payments associated with the 2022 Amendment during the quarter ended December 31, 2022.

Our primary sources of cash have been from the sale and issuance of common stock (in both public offerings and private placements), private placements of convertible preferred stock, funds from our collaboration partnerships, funds from our 2018 Loan Agreement and 2022 Loan Agreement, as well as from sales of IBSRELA.

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Our primary uses of cash have been to fund operating expenses, primarily research and development expenditures, as well as pre-commercial and commercial expenses. Cash used to fund operating expenses is impacted by the timing of when we pay these expenses, as reflected in the change in our outstanding accounts payable and accrued expenses.

Our future funding requirements will depend on many factors, including, but not limited to:

•the extent to which we are able to generate product revenue from sales of IBSRELA;

•whether we are successful in securing approval for our NDA for XPHOZAH, and the time and cost associated with securing such approval;

•the availability of adequate third-party reimbursement for IBSRELA and, if approved, the sales price and the availability of adequate third-party reimbursement for XPHOZAH;

•The manufacturing, selling and marketing costs associated with IBSRELA and, if approved, XPHOZAH;

•our ability to maintain our existing collaboration partnerships and to establish additional collaboration partnerships, in-license/out-license, joint ventures or other similar arrangements and the financial terms of such agreements;

•the timing, receipt and amount of any milestones that may be received from our collaboration partners in connection with tenapanor, if any

•the timing, receipt, and amount of revenue, if any, that may be received by KKC in connection with the 2022 KKC Amendment;

•the timing, receipt, and amount of royalties we may receive as a result of sales of tenapanor by our collaboration partners in China and Canada, if any;

•the cash requirements for the discovery and/or development of other potential product candidates, including RDX013 and RDX020;

•the time and cost necessary to respond to technological and market developments;

•the costs of filing, prosecuting, maintaining, defending and enforcing any patent claims and other intellectual property rights, including litigation costs and the outcome of such litigation, including costs of defending any claims of infringement brought by others in connection with the development, manufacture or commercialization of tenapanor or any of our product candidates; and

•the payment of interest and principal related to our loan and security agreement entered into with SLR Investment Corp. in February 2022.

CASH FLOW ACTIVITIES

The following table summarizes our cash flows for the periods indicated (in thousands):

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Cash Flows from Operating Activities

Fiscal 2022 compared to 2021: Net cash used in operating activities during the twelve months ended December 31, 2022 decreased by $82.5 million primarily as a result of decreased spending on research and development expenses during the twelve months ended December 31, 2022 as compared to the twelve months ended December 31, 2021, as well net product sales of IBSRELA and $35.0 million of milestone payments and payments under the second amendment to the 2017 KKC Agreement which we earned in 2022 upon KKC's submission of a New Drug Application to the Japanese Ministry of Health, Labour and Welfare for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis. Partially offsetting the net loss improvement were changes to our operating assets and liabilities related to expenditures for commercial manufacturing and inventory for the production of IBSRELA.

Fiscal 2021 compared to 2020: Net cash used in operating activities during the year ended December 31, 2021 increased by $71.1 million as a result of our increased net loss for the period. The increased net loss was primarily driven by costs associated with building and staffing our commercial infrastructure and teams as we prepared for the anticipated U.S. launch of XPHOZAH. In addition to the increased net loss, cash flows related to our operating assets and liabilities increased in the amount of $8.7 million.

Cash Flows from Investing Activities

Fiscal 2022 compared to 2021: Net cash provided by investing activities decreased by $32.5 million due to lower investment balances and the timing of our investment maturities, which was partially offset by $1.8 million proceeds from sale of laboratory equipment and supplies during the twelve months ended December 31, 2022.

Fiscal 2021 compared to 2020: Net cash provided by investing activities increased by $82.4 million as our investment maturities increased to exceed the cost to purchase investments.

Cash Flows from Financing Activities

Fiscal 2022 compared to 2021: Net cash provided by financing activities decreased by $7.7 million primarily due to $29.5 million lower proceeds from issuance of common stock under at-the-market offerings and well as increased payments in the amount of $13.6 million to repay the principal outstanding on the 2018 Loan. Partially offsetting these amounts were $27.0 million net proceeds received from the 2022 Loan and $9.6 million net proceeds from the sales of future royalties during the twelve months ended December 31, 2022

Fiscal 2021 compared to 2020: Net cash provided by financing activities increased by $60.2 million due to net proceeds from issuance of our common stock pursuant to our at-the-market offerings, which were partially offset by principal repayments for our 2018 Loan.

SMALLER REPORTING COMPANY AND NON-ACCELERATED FILER STATUS

On June 28, 2018, the SEC adopted amendments that raise the thresholds in the smaller reporting company ("SRC") definition, whereby we were determined to qualify as a SRC. On March 12, 2020, the SEC amended its rules to allow SRCs that have less than $100.0 million in annual revenue and a public float of less than $700.0 million to qualify as a non-accelerated filer. As a non-accelerated filer, we were not required to obtain an opinion of our independent auditors with respect to our internal controls over financial reporting as of December 31, 2020.

On June 30, 2022, our public float did not exceed $700.0 million and we had less than $100.0 million in annual revenue, thereby allowing us to qualify as a SRC and a non-accelerated filer as of December 31, 2022. We have determined to avail ourselves of most of the SRC scaled disclosure accommodations and we were not required to obtain an opinion of our independent auditors with respect to our internal controls over financial reporting for the period ended December 31, 2022.

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ITEM 7.    MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

You should read the following discussion and analysis of our financial condition and results of operations in conjunction with our financial statements and related notes included elsewhere in this report. This discussion and other parts of this report contain forward-looking statements that involve risk and uncertainties, such as statements of our plans, objectives, expectations and intentions. Our actual results could differ materially from those discussed in these forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed in the section of this report entitled “Risk Factors. ” These forward-looking statements speak only as of the date hereof. Except as required by law, we assume no obligation to update or revise these forward-looking statements for any reason. Unless the context requires otherwise, the terms “Ardelyx”, “Company”, “we”, “us”, and “our” refer to Ardelyx, Inc.

OVERVIEW

We are a biopharmaceutical company founded with a mission to discover, develop and commercialize innovative first-in-class medicines that meet significant unmet medical needs. This includes adult patients with irritable bowel syndrome with constipation (“IBS-C”), adult patients with chronic kidney disease (“CKD”) on dialysis suffering from elevated serum phosphorus, or hyperphosphatemia; and adult patients with CKD and/or heart failure with elevated serum potassium, or hyperkalemia.

Since commencing operations in October 2007, substantially all our efforts have been dedicated to our research and development (“R&D”) activities, including developing tenapanor and developing our proprietary drug discovery and design

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platform. We have not generated any revenues from product sales. As of December 31, 2021, we had an accumulated deficit of $712.9 million.

We expect to continue to incur substantial operating losses for the foreseeable future as we prepare for commercialization of IBSRELA® (tenapanor) in April of this year, seek to gain approval for XPHOZAH® (tenapanor) for the control of serum phosphorus in adult patients with CKD on dialysis; prepare for the potential commercialization of XPHOZAH, if approved; incur manufacturing and development cost for, tenapanor; and incur development costs for RDX013. To date, we have funded our operations from the sale and issuance of common stock and convertible preferred stock, funds from our collaboration partnerships, which includes license fees, milestones and product supply revenue, as well as funds from our loan agreements with our lenders.

On February 28, 2022, we received a letter from Nasdaq indicating that we have failed to comply with the minimum bid price requirement of Nasdaq Listing Rule 5550(a)(2). Nasdaq Listing Rule 5550(a)(2) requires that companies listed on the Nasdaq Capital Market maintain a minimum closing bid price of at least $1.00 per share. Under Nasdaq Listing Rule 5810(c)(3)(A), we have a 180 calendar day grace period to regain compliance by meeting the continued listing standard. To regain compliance, the closing bid price of the Company’s common stock must meet or exceed $1.00 per share for a minimum of ten consecutive business days during this grace period. We are monitoring the bid price of our common stock and will consider options available to us to achieve compliance. There can be no assurances that we will be successful in restoring our compliance with the Nasdaq listing requirements.

OUR PRODUCT PIPELINE

IBSRELA for IBS-C

Our unique discovery platform and deep understanding of the primary mechanism of sodium transport in the intestine resulted in our discovery and development of IBSRELA, a first-in-class, FDA approved, sodium hydrogen exchanger 3 ("NHE3") inhibitor for the treatment of IBS-C in adults. IBSRELA acts locally in the gut and is minimally absorbed. By inhibiting NHE3, IBSRELA exerts a triple action mechanism. First, it blocks dietary sodium absorption, leading to increased intestinal transit time and softer stool to address constipation. Second, it decreases intestinal permeability to reduce abdominal pain, and, third, it decreases visceral hypersensitivity to reduce abdominal pain. The triple action mechanism of IBSRELA is differentiated from existing therapies and has been shown to provide significant improvement in abdominal pain, bloating, and constipation – with a quick onset of action and sustained efficacy. Treatment with IBSRELA has been demonstrated to result in improved quality of life versus placebo and patient treatment satisfaction.

We plan to launch IBSRELA in the U.S. in April 2022.

IBS-C is a gastrointestinal disorder characterized by both abdominal pain and altered bowel movements, estimated to affect 11 million people in the U.S. IBS-C is associated with significantly impaired quality of life, reduced productivity, and substantial economic burden. The introduction of new agents over the last decade has led to an established prescription ("RX") treated market with 9,000 writers accounting for 50% of the RXs. Despite the active use of GCC agonist therapies, 83% of Health Care Providers ("HCPs") report a significant unmet need for new therapies, and report that approximately 35% of the patients currently under their care do not adequately respond to the available treatments. When presented with the IBSRELA product profile, 75% of HCPs respond favorably, with the efficacy profile and novel method of action rated as the most compelling aspects of the product profile.

In preparation for our commercial launch of IBSRELA, we have built a commercial organization highly experienced in launching novel therapies into specialty areas. The established nature of the market, limited number of players, concentration of prescribers, recognized unmet need, and favorable response to the novel mechanism IBSRELA product profile enable a targeted promotional effort centered on the 9,000 health care providers that account for 50% of IBS-C prescriptions. Central to the go to market strategy is a highly experienced specialty sales force, many with existing relationships across their GI target base, full company engagement, and innovative peer-to-peer and digital initiatives leveraging the rapidly evolving market dynamics in how HCPs receive information and interact with industry.

With a concentrated promotional focus on patients currently being managed for IBS-C by high writing HCPs - in contrast to the DTC centered, market building approach taken by the existing GCC agonists - competition for IBSRELA will come largely from the four prescription products indicated for IBS-C: Linzess (linaclotide); Amitiza (lubiprostone); Trulance (plecanatide) and Zelnorm (tegaserod). Additionally, over the counter products are commonly used to treat the constipation component of IBS-C, both alone, and in combination with the IBS-C indicated RX therapies.

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We have established commercial agreements with Shanghai Fosun Pharmaceutical Industrial Development Co. Ltd. (“Fosun Pharma”) in China and Knight Therapuetics, Inc. (“Knight”) in Canada for IBSRELA for IBS-C. Knight is currently marketing IBSRELA in Canada.

Development Candidate XPHOZAH: A New Approach for The Control of Serum Phosphorus in Adult Patients with CKD on Dialysis

XPHOZAH is a first-in-class medicine being developed for the control of serum phosphorus in adult patients with CKD on dialysis. XPHOZAH has a unique mechanism of action and acts locally in the gut to inhibit NHE3. This results in the tightening of the epithelial cell junctions, thereby significantly reducing paracellular uptake of phosphate, the primary pathway of phosphate absorption. If approved, XPHOZAH would be the first therapy for phosphate management that blocks phosphorus absorption at the primary site of uptake. It is not a phosphate binder.

In June 2020, we submitted a new drug application ("NDA") to the U.S. Food and Drug Administration (“FDA”) for tenapanor the control of serum phosphorus in adult patients with CKD on dialysis. The NDA was supported by three Phase 3 trials involving over 1,000 adult patients that evaluated the use of tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis, with two trials evaluating tenapanor as monotherapy and one trial evaluating tenapanor as part of a dual mechanism approach with phosphate binders. All three Phase 3 trials met their primary and key secondary endpoints.

On July 28, 2021, we received a Complete Response Letter ("CRL") from the FDA regarding our NDA for tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis. According to the CRL, while the FDA agrees “that the submitted data provide substantial evidence that tenapanor is effective in reducing serum phosphorus in adult patients with CKD on dialysis,” the FDA characterizes the magnitude of the treatment effect as “small and of unclear clinical significance.” Following an End-of-Review Type A meeting (“End of Review Meeting”) in October 2021, with the FDA’s Division of Cardiology and Nephrology (the “Division”), we submitted a Formal Dispute Resolution Request (“FDRR”) in December 2021. The FDRR was focused on demonstrating that the data submitted in the NDA supported the clinical significance of the treatment effect of tenapanor.

On February 4, 2022, we received an Appeal Denied Letter (“ADL”) from the FDA’s Office of Cardiology, Hematology, Endocrinology and Nephrology (“OCHEN”). On February 18, 2022, we submitted an appeal of the ADL to the FDA’s Center for Drug Evaluation and Research, Office of New Drugs (“OND”). If accepted, we expect a decision on the appeal to the OND in April 2022. While the CRL noted that in order for the NDA to be approved, we need to conduct an additional adequate and well-controlled trial demonstrating a clinically relevant treatment effect on serum phosphorus or an effect on the clinical outcome thought to be caused by hyperphosphatemia in adult patients with CKD on dialysis, the ADL provided a potential additional path forward involving the resubmission of the NDA (without conducting an additional trial) with a number of new analyses of each of our Phase 3 clinical trials; an assessment of tenapanor’s benefits and risks; and a proposal of how to label tenapanor for prescribers. There can be no assurances that the Formal Dispute Resolution (“FDR”) process will result in approval of our NDA, or in a clear path to resubmission of our NDA that is achievable in terms of clinical endpoints, time and cost.

RDX013 Program: Small Molecule for Treating Hyperkalemia

We are also advancing a small molecule potassium secretagogue program, RDX013, for the potential treatment of hyperkalemia. Hyperkalemia is a common problem in patients with heart and kidney disease, particularly in patients taking customary blood pressure medications known as renin-angiotensin-aldosterone system (“RAAS”) inhibitors. RDX013 is a novel mechanism agent designed to target the underlying biological mechanisms of potassium secretion to lower elevated potassium. While currently available therapies are all ion exchange agents, RDX013 is a first in class secretagogue with demonstrated proof of concept in a Phase 2 dose ranging study evaluating the safety and pharmacodynamics of RDX013 in adult patients with hyperkalemia. The next steps for RDX013 will be determined based on final analyses of the Phase 2 results, continued formulation development, and sufficient financial resources.

RDX020 Program: Small molecule for Treating Metabolic Acidosis

We have an ongoing discovery program targeting the inhibition of bicarbonate exchange inhibitor for the treatment of metabolic acidosis, a highly prevalent comorbidity in CKD patients that is strongly correlated with disease progression and adverse outcomes. We have identified lead compounds that are potent, selective and proprietary inhibitors of bicarbonate secretion. Our research organization was eliminated as part of our October 2021 restructuring, and therefore, we currently expect to continue to advance this discovery program utilizing third-party resources managed by internal non-clinical expertise.

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FINANCIAL OPERATIONS OVERVIEW

Revenue

Our revenue to date has been generated primarily through license, research and development collaborative agreements with various collaboration partners. We have not generated any revenue from commercial product sales. We currently expect to commence commercialization of IBSRELA in April 2022. In the future, we may generate revenue from a combination of our own product sales and payments in connection with our current or future collaborative partnerships, including license fees, other upfront payments, milestone payments, royalties and payments for drug product and/or drug substance. We expect that any revenue we generate will fluctuate in future periods as a result of, among other factors: the extent to which we are successful in our efforts to commercialize IBSRELA; whether we receive regulatory approval for tenapanor for the control of serum phosphorous in adult patients with CKD on dialysis (the “Hyperphosphatemia Indication”), and if such approval is received, the timing of such approval and the extent to which we are successful in our efforts to commercialize XPHOZAH for such indication; the timing and progress of goods and services provided pursuant to our current or future collaborative partnerships; our or our collaborators’ achievement of preclinical, clinical, regulatory or commercialization milestones, to the extent achieved; the timing and amount of any payments to us relating to the aforementioned milestones; and the extent to which any of our product candidates are approved and successfully commercialized by a collaboration partner. If we are not able to obtain market acceptance for IBSRELA; if we are not successful in our efforts to obtain and sustain an adequate level of coverage and reimbursement for IBSRELA by third-party payors; if we fail to obtain regulatory approval for tenapanor for the Hyperphosphatemia indication and/or our current collaboration partners or any future collaboration partners fail to obtain regulatory approval for tenapanor in their respective territories, our ability to generate future revenue from our product sales or from our collaborative arrangements, and our results of operations and financial position, would be materially and adversely affected. Our past revenue performance is not necessarily indicative of results to be expected in future periods. See Note 2, Summary of Significant Accounting Policies, in the notes to our financial statements, included in Part II, Item 8, of this Annual Report on Form 10-K, for further details.

Cost of Revenue

Cost of revenue represents payments due to AstraZeneca AB (“AstraZeneca”), which under the terms of a termination agreement entered into in 2015 (the “AZ Termination Agreement”) is entitled to (i) future royalties at a rate of 10% of net sales of tenapanor or other NHE3 products by us or our licensees, and (ii) 20% of non-royalty revenue received from our collaboration partners as a result of the development and commercialization of tenapanor or certain other NHE3 inhibitors. We have agreed to pay AstraZeneca up to a maximum of $75.0 million in the aggregate for (i) and (ii). We recognize these expenses as cost of revenue when we recognize the corresponding revenue that gives rise to payments due to AstraZeneca. To date, we recognized an aggregate of $11.6 million as cost of revenue under the AZ Termination Agreement since 2017. See details in Note 5, Collaboration and Licensing Agreements, under AstraZeneca, in the notes to our financial statements, included in Part II, Item 8, of this Annual Report on Form 10-K.

Research and Development

Pursuant to the October 2021 restructuring plan, we have eliminated our internal research organization and expect to continue our discovery efforts with respect to RDX020 through the use of third-parties managed internally by non-clinical expertise. We recognized all research and development expenses as they were incurred to support the discovery, research, development and manufacturing of our product candidates. Research and development expenses include, but are not limited to, the following:

•external research and development expenses incurred under agreements with consultants, third-party contract research organizations (“CROs”) and investigative sites where a substantial portion of our clinical studies are conducted, and with contract manufacturing organizations where our clinical supplies are produced;

•expenses associated with supplies and materials consumed in connection with our research operations;

•expenses associated with producing tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis prior to FDA approval;

•other costs associated with research, clinical development and regulatory activities;

•employee-related expenses, which include salaries, bonuses, benefits, travel and stock-based compensation; and

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•facilities and other allocated expenses, which include direct and allocated expenses for rent and maintenance of facilities, depreciation and amortization expense, information technology expense and other supplies.

General and Administrative

General and administrative expenses consist primarily of salaries and related benefits, including stock-based compensation, for certain of our executives, our board members, and our finance, legal, business development, market development, commercial and support staff. Other general and administrative expenses include facility related costs and professional fees for legal, accounting and audit, investor relations, other consulting services and allocated facility related costs not otherwise included in research and development expenses.

Interest Expense

Interest expense represents the interest paid on our loan payable.

Other Income, net

Other income, net consists of interest income earned on our cash and cash equivalents and held-to-maturity investments, the periodic revaluation of the exit fee related to our loan and currency exchange gains and losses.

Provision for Income Taxes

Our provision for income taxes includes current and deferred tax, including foreign withholding taxes paid on payments received from certain collaboration partners. Deferred income taxes reflect the tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Our deferred tax assets continue to be fully offset by a valuation allowance, including deferred tax assets related to our net operating loss carryforwards, which may be subject to annual limitations as a result of ownership changes that may have occurred or could occur in the future.

CRITICAL ACCOUNTING POLICES AND ESTIMATES

A detailed discussion of our significant accounting policies can be found in Note 2, Summary of Significant Accounting Policies, in the notes to our financial statements, included in Part II, Item 8, of this Annual Report on Form 10-K. Critical accounting policies are those that require significant judgment and/or estimates by management at the time that financial statements are prepared such that materially different results might have been reported if other assumptions had been made. These estimates form the basis for making judgments about the carrying values of assets and liabilities. We base our estimates and judgments on historical experience and on various other assumptions that we believe to be reasonable under the circumstances. Actual results could differ materially from these estimates.

We consider certain accounting policies related to revenue recognition, accrued research and development expenses and stock-based compensation to be critical policies to understanding the judgments and estimates applied in our reported financial results.

Revenue Recognition

We generate revenue primarily from research and collaboration and license agreements with customers. Goods and services in the agreements may include the grant of licenses for the use of our technology, the provision of services associated with the research and development of product candidates, manufacturing services, and participation in joint steering committees. The terms of these arrangements typically include payment to us of one or more of the following: non-refundable, up-front license fees; research, development, regulatory and commercial milestone payments; reimbursement of research and development services; option payments; reimbursement of certain costs; payments for manufacturing supply services; and future royalties on net sales of licensed products.

When two or more contracts are entered into with the same customer at or near the same time, we evaluate the contracts to determine whether the contracts should be accounted for as a single arrangement. Contracts are combined and accounted for as a single arrangement if one or more of the following criteria are met: (i) the contracts are negotiated as a package with a single commercial objective; (ii) the amount of consideration to be paid in one contract depends on the price or performance of the other contract; or (iii) the goods or services promised in the contracts (or some goods or services promised in each of the contracts) are a single performance obligation.

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In determining the appropriate amount of revenue to be recognized as we fulfill our obligations under each of our agreements, management performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including any constraints on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) we satisfy each performance obligation. As part of the accounting for contracts with customers, we develop assumptions that require judgment to determine whether promised goods and services represent distinct performance obligations and the standalone selling price for each performance obligation identified in the contract. This evaluation is subjective and requires us to make judgments about the promised goods and services and whether those goods and services are separable from other aspects of the contract. Further, determining the standalone selling price for performance obligations requires significant judgment, and when an observable price of a promised good or service is not readily available, we consider relevant assumptions to estimate the standalone selling price, including, as applicable, market conditions, development timelines, probabilities of technical and regulatory success, reimbursement rates for personnel costs, forecasted revenues, potential limitations to the selling price of the product and discount rates.

We apply judgment in determining whether a combined performance obligation is satisfied at a point in time or over time, and, if over time, concluding upon the appropriate method of measuring progress to be applied for purposes of recognizing revenue. We evaluate the measure of progress each reporting period and, as estimates related to the measure of progress change, related revenue recognition is adjusted accordingly. Changes in our estimated measure of progress are accounted for prospectively as a change in accounting estimate. We recognize collaboration revenue by measuring the progress toward complete satisfaction of the performance obligation using an input measure. In order to recognize revenue over the research and development period, we measure actual costs incurred to date compared to the overall total expected costs to satisfy the performance obligation. Revenues are recognized as the program costs are incurred. We will re-evaluate the estimate of expected costs to satisfy the performance obligation each reporting period and make adjustments for any significant changes. Amounts received prior to satisfying the revenue recognition criteria are recorded as contract liabilities in our balance sheets. If the related performance obligation is expected to be satisfied within the next twelve months, this will be classified in current liabilities. Amounts recognized as revenue prior to receipt are recorded as contract assets in our balance sheets. If we expect to have an unconditional right to receive the consideration in the next twelve months, this will be classified in current assets. A net contract asset or liability is presented for each contract with a customer.

Milestone Payments: At the inception of each arrangement that includes research and development milestone payments, we evaluate whether the milestones are considered probable of being reached and estimate the amount to be included in the transaction price using the most likely amount method. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. Milestone payments that are not within the control of us or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative standalone selling price basis, for which 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 of achievement of such development milestones and any related constraints, and if necessary, adjust our estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect earnings in the period of adjustment.

Manufacturing supply services: Arrangements that include a promise for the future supply of drug substance or drug product for either clinical development or commercial supply at the customer’s discretion are generally considered as options. We assess if these options provide a material right to the licensee and if so, they are accounted for as separate performance obligations. If we are entitled to additional payments when the customer exercises these options, any payments are recorded in product supply revenues when the customer obtains control of the goods, which is upon delivery.

Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and 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). To date, we have not recognized any royalty revenue resulting from any of our licensing arrangements.

Licenses of intellectual property: If a license granted to a customer to use our intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, we recognize revenue from consideration allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, we apply 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

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time, to conclude upon the appropriate method of measuring progress for purposes of recognizing revenue related to consideration allocated to the performance obligation.

Options: Customer options, such as options granted to allow a licensee to choose to research, develop and commercialize licensed compounds are evaluated at contract inception in order to determine whether those options provide a material right (i. e., an optional good or service offered for free or at a discount) to the customer. If the customer options represent a material right, the material right is treated as a separate performance obligation at the outset of the arrangement. We allocate the transaction price to material rights based on the standalone selling price, and revenue is recognized when or as the future goods or services are transferred or when the option expires. Customer options that are not material rights do not give rise to a separate performance obligation, and as such, the additional consideration that would result from a customer exercising an option in the future is not included in the transaction price for the current contract. Instead, the option is deemed a marketing offer, and additional option fee payments are recognized or being recognized as revenue when the licensee exercises the option. The exercise of an option that does not represent a material right is treated as a separate contract for accounting purposes.

Contract modifications: Contract modifications, defined as changes in the scope or price (or both) of a contract that are approved by the parties to the contract, such as a contract amendment, exist when the parties to a contract approve a modification that either creates new or changes existing enforceable rights and obligations of the parties to the contract. Depending on facts and circumstances, we account for a contract modification as one of the following: (i) a separate contract; (ii) a termination of the existing contract and a creation of a new contract; or (iii) a combination of the preceding treatments. A contract modification is accounted for as a separate contract if the scope of the contract increases because of the addition of promised goods or services that are distinct and the price of the contract increases by an amount of consideration that reflects our standalone selling prices of the additional promised goods or services. When a contract modification is not considered a separate contract and 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 the contract modification as a termination of the existing contract and a creation of a new contract. When a contract modification is not considered a separate contract and the remaining goods or services are not distinct, we account for the contract modification as an add-on to the existing contract and as an adjustment to revenue on a cumulative catch-up basis.

We receive payments from our licensees as established in each contract. 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. Where applicable, amounts are recorded as unbilled revenue when our right to consideration is unconditional. We do not assess whether a contract with a customer has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less.

Accrued Research and Development Expenses

As part of the process of preparing our financial statements, we are required to estimate our accrued expenses. This process involves reviewing open contracts and purchase orders, communicating with our personnel to identify services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of the actual cost. The majority of our service providers invoice us monthly in arrears for services performed or when contractual milestones are met. We make estimates of our accrued expenses as of each balance sheet date in our financial statements based on facts and circumstances known to us at that time. We periodically confirm the accuracy of our estimates with the service providers and make adjustments if necessary. Examples of estimated accrued research and development expenses include fees paid to:

•CROs in connection with clinical studies;

•investigative sites in connection with clinical studies;

•vendors related to contract manufacturing, development and distribution of clinical supplies;

•collaborator entities in connection with our collaboration agreements; and

•vendors in connection with preclinical development activities.

We record expenses related to clinical studies and manufacturing development activities based on our estimates of the services received and efforts expended pursuant to contracts with our CROs and manufacturing vendors that conduct and manage these activities on our behalf. The financial terms of these agreements are subject to negotiation, vary from contract to

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contract, and may result in uneven payment flows. There may be instances in which payments made to our vendors will exceed the level of services provided and result in a prepayment of the expense. Payments under some of these contracts depend on factors such as the successful enrollment of subjects and the completion of clinical trial milestones. In accruing service fees, we estimate the time period over which each component of a service will be performed, and estimate, with vendor input if appropriate, the resulting level of completion of each component of the service, with such estimates often involving drivers that provide a surrogate measurement of completion such as number of enrolled subjects and/or number of sites activated in the calculation of clinical trial fee accruals. If the actual timing of the performance of services or the level of effort varies from our estimate, we adjust the accrued or prepaid expense balance accordingly. Although we do not expect our estimates to be materially different from amounts actually incurred, if our estimates of the status and timing of services performed differ from the actual status and timing of services performed, we may report amounts that are too high or too low in any particular period.

Stock-Based Compensation

We estimate the fair value of stock options and Employee Stock Purchase Plan (“the ESPP”) shares using the Black-Scholes valuation model. The Black-Scholes model requires the input of highly subjective assumptions which determine the fair value of stock-based awards. These assumptions include:

Expected Term—We have limited historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for our stock-option grants. As such, the expected term is estimated using the simplified method whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the option. Beginning in 2021, we estimate the expected term of our options based upon historical exercises and post-vesting termination behavior, which has not resulted in a material difference as compared to using the simplified method.

Expected Volatility— We use the historic volatility of our own stock over the retrospective period corresponding to the expected remaining term of the options, or the period since our shares were first quoted on The Nasdaq Global Market, if that is shorter, to compute our expected stock price volatility.

Risk-Free Interest Rate—The risk-free interest rate assumption is based on zero-coupon U.S. Treasury instruments on the date of grant with a maturity date consistent with the expected term of our stock option grants.

Expected Dividend— To date, we have not declared or paid any cash dividends and do not have any plans to do so in the future. Therefore, we use an expected dividend yield of zero.

As required, we review our valuation assumptions at each grant date and, as a result, we are likely to change our valuation assumptions used to value employee stock-based awards granted in future periods. Employee and director stock-based compensation costs are to be recognized over the vesting period of the award, and we have elected to use the straight-line attribution method. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. We estimate forfeitures based on historical experience.

Restricted stock units ("RSUs") are measured at the fair value of our common stock on the date of grant and expensed over the period of vesting using the straight-line attribution approach.

Performance-based RSUs ("PRSUs") are valued at grant-date fair market value. The vesting of the PRSUs is based on performance conditions. Performance conditions include: (i) a specific performance criteria and (ii) the employee’s continuous employment by the company for a stated period of time in order to earn the right to the related PRSUs to vest. The Company recognizes compensation cost with respect to the vesting of the PRSUs on a ratable basis over the requisite service period, upon the performance conditions being deemed probable of achievement.

Restructuring

We recognize restructuring charges related to reorganization plans that have been committed to by management and when liabilities have been incurred. In connection with these activities, we record restructuring charges at fair value for, (a) contractual employee termination benefits when obligations are associated to services already rendered, rights to such benefits have vested, and payment of benefits is probable and can be reasonably estimated, (b) one-time employee termination benefits when management has committed to a plan of termination, the plan identifies the employees and their expected termination dates, the details of termination benefits are complete, it is unlikely changes to the plan will be made or the plan will be withdrawn and communication to such employees has occurred, and (c) contract termination costs when a contract is terminated before the end of its term.

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One-time employee termination benefits are recognized in their entirety when communication has occurred and future services are not required. If future services are required, the costs are recorded ratably over the remaining period of service. Contract termination costs to be incurred over the remaining contract term without economic benefit are recorded in their entirety when the contract is canceled.

RESULTS OF OPERATIONS

Comparison of the Years Ended December 31, 2021, 2020 and 2019

Revenue

Below is a summary of our total revenue (dollars in thousands):

Fiscal 2021 compared to 2020: The increase to total revenues is primarily attributable to a $5.0 million development milestone which we earned and recognized as licensing revenue during the current year upon the initiation by KKC of phase 3 clinical studies in Japan to evaluate tenapanor for hyperphosphatemia. The increase was partially offset by lower collaborative development revenue and product supply revenue from KKC during the current year.

Fiscal 2020 compared to 2019: The increase in our revenue was primarily attributable to $4.9 million higher collaborative development revenue recognized in connection with the KKC Agreement, which was entered into in November 2019, a $0.7 million licensing revenue recognized upon Knight’s achievement of a development milestone pursuant to the Knight Agreement and a $1.4 million increase in manufacturing supply of tenapanor and other materials sold to KKC in accordance with the 2017 KKC Agreement, partially offset by $3.0 million revenue related to achievement of a milestone pursuant to the Fosun agreement during the year ended December 31, 2019.

Operating Expenses

Below is a summary of our operating expenses (dollars in thousands):