Aktis Oncology, Inc. (AKTS) Business

Item 1. Business.

Overview

We are a clinical-stage oncology company focused on expanding the breakthrough potential of targeted radiopharmaceuticals to large patient populations, including those not addressed by existing platform technologies. The field of targeted radiopharmaceuticals is currently led by two marketed products that illustrated transformative survival outcomes and quality of life benefits can be conferred by delivering radioisotopes to solid tumors. These leading products, which target prostate specific membrane antigen or somatostatin-2 receptor, are each currently approved in only one tumor type, yet have seen considerable commercial uptake and have become fundamental pillars of cancer treatment. Despite these advances, we believe that the field of radiopharmaceuticals is still in its infancy, with many emerging companies still primarily focused on these same two targets. In contrast, we see a significant opportunity to broaden the cancer patient populations benefiting from targeted radiopharmaceuticals by developing next-generation technologies that expand the scope of tumor targets for which it is possible to safely deliver a powerful payload of an alpha-emitting radioisotope. To ensure patient demand is reliably met, we are also establishing efficient end-to-end supply, with a combination of critical internal capabilities paired with established external vendors. Through these efforts, we seek to maximize clinical utility across multiple indications in multiple tumor types, and to expand the commercial uptake of radiopharmaceuticals beyond the traditional nuclear medicine setting and into the more expansive clinical oncology setting.

We have built a proprietary miniprotein radioconjugate platform that aims to safely confer breakthrough efficacy to a broad range of patient populations. Our miniprotein radioconjugates are designed to selectively deliver the tumor-killing properties of radioisotopes to targeted tumors with high tumor penetration and prolonged tumor retention, while being rapidly cleared from normal organs and tissues to minimize systemic radiation exposure. Our miniproteins have demonstrated the ability to potently bind to tumor targets outside the scope of current delivery technologies such as peptide-based radioconjugates. We are leveraging the capabilities of our platform technology, together with our expertise and know-how in radiopharmaceutical development, supply chain and manufacturing, to address these challenges with the aim of advancing a deep pipeline of programs against a broad range of tumor targets that have not been successfully targeted with radiopharmaceuticals.

Our platform capabilities have generated a pipeline of several novel product candidates. Our most advanced program is a radiopharmaceutical targeting Nectin-4. It is a miniprotein radioconjugate with multi-indication potential across multiple tumor types, in clinical development for the treatment of locally advanced or metastatic urothelial cancer, or UC, and multiple other Nectin-4 expressing solid tumor types. The learnings from the optimization of our Nectin-4 program, the first miniprotein radioconjugate ever advanced into human investigational studies, are being applied to benefit the development of our robust pipeline of several other unpartnered miniprotein radioconjugate programs, which are designed to address other clinically-validated targets.

Our lead product candidate, [225Ac]Ac-AKY-1189, contains a miniprotein, AKY-1189, that specifically binds to Nectin-4, and is conjugated via chelation to actinium-225, 225Ac. 225Ac, is an alpha-emitting radioisotope that when conjugated to a prostate specific membrane antigen, or PSMA, binding peptide has been shown to confer increased anticancer activity in the post-chemotherapy setting of metastatic castration-resistant prostate cancer compared to an identical PSMA binding peptide with beta-emitting Lutetium-177, or 177Lu. Nectin-4 is a surface protein found on a wide variety of tumors and has very limited expression in normal adult tissues. Nectin-4 is also the target of Padcev, an antibody-drug conjugate, or ADC, approved worldwide for the treatment of locally advanced or metastatic UC. Padcev has an annualized treatment cost of approximately $500,000 and had worldwide sales of $1.9 billion in 2024, with estimated peak sales of up to $7.0 billion.

Despite the commercial success of Padcev, its impact beyond UC has been limited likely due to the need to develop a companion diagnostic for tissue testing when utilizing an ADC. In contrast, we intend to use imaging radioisotopes conjugated to AKY-1189 to select patients most likely to benefit from therapeutic treatment with [225Ac]Ac-AKY-1189. We believe the commercial impact of Padcev validates Nectin-4 as an anticancer target in UC and that significant unmet medical need exists for our lead product candidate in post-Padcev UC. Additionally, we see potential to treat several non-UC Nectin-4-expressing tumor types such as breast cancers and lung cancers. We believe that the therapeutic potential of [225Ac]Ac-AKY-1189 across multiple tumor types is supported by our preclinical studies and data collected by a third-party physician in South Africa pursuant to Section 21 of the Medicines and Related Substances Act, or MRSA, which demonstrated the ability of radiolabeled AKY-1189 to specifically localize to Nectin-4 expressing tumors and rapidly clear from normal organs and tissues. In April 2025, the U.S. Food and Drug Administration, or the FDA, cleared our investigational new drug, or IND, application for [225Ac]Ac-AKY-1189 for the treatment of locally advanced or metastatic UC and other Nectin-4 expressing tumors. We have commenced a multi-site Phase 1b clinical trial in the United States and anticipate preliminary results from the Part-1 dose escalation portion of this trial in the first quarter of 2027.

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To overcome the manufacturing challenges and supply chain reliability issues that have historically hindered the development and commercialization of radiopharmaceuticals, we are focused on investing in manufacturing and ensuring supply chain continuity and reliability. We have built significant internal capabilities, including subject matter expertise for our product manufacturing processes and a state-of-the-art radiopharmaceutical development suite. Additionally, we have partnered with multiple domestic and international isotope suppliers that provides us priority access to 225Ac, and with multiple contract manufacturers for the production of our drug product, which collectively are designed to create redundancies across all components of our supply chain. We are also establishing our own current good manufacturing practice, or cGMP, facility to enhance flexibility, increase control, and establish a hybrid internal and external clinical supply chain. We believe our team’s expertise and experience in the development of radiopharmaceuticals will allow us to address the challenges presented by the half-life of radioactive isotopes and establish an efficient supply chain from production to patient administration.

We believe that radiopharmaceuticals represent one of the most promising modalities for the treatment of solid tumors. Approved radiopharmaceuticals have demonstrated the ability to overcome the challenges of conventional cancer treatments and provide patients with targeted therapies that have superior efficacy and better tolerability. We believe our approach is validated by, and builds upon, the clinical and commercial success of current radiopharmaceuticals and that our approach has the potential to further transform the cancer treatment paradigm for large patient populations.

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Clinical validation of targeted radiopharmaceuticals. Approved beta-emitting radiopharmaceuticals, Pluvicto and Lutathera, have demonstrated statistically significant and clinically meaningful overall survival, progression-free survival and quality of life benefits in global registrational clinical trials. Early-stage clinical trials have also demonstrated that the use of alpha-emitting 225Ac radioconjugates can deliver more profound anticancer activity than beta-emitting 177Lu conjugates in similar patient populations, and in patients whose disease has progressed on prior beta-emitting targeted therapies. These promising early clinical data have led to the advancement of 225Ac-based radioconjugates to pivotal clinical trials, though none yet have filed for approval by the FDA.

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Commercial validation of approved radiopharmaceuticals. Pluvicto achieved a first full year of sales of approximately $1 billion, with an annualized treatment cost of approximately $300,000, representing the strongest oncology commercial launch since Ibrance in 2015, which demonstrates the patient impact potential and rapid adoption of radiopharmaceuticals into clinical practice. The estimated global peak sales for Pluvicto are approximately $5.4 billion in prostate cancer alone. The global radiopharmaceuticals market is one of the fastest growing categories among anticancer medicines, and is projected to grow to over $26 billion in sales by 2032. The therapeutic segment of this market is estimated to achieve a total addressable market of $25 billion to $60 billion post-2030.

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Strategic validation of radiopharmaceuticals. The commercial success of radiopharmaceuticals, paired with significant increases in investment in innovative approaches, has led to significant value creation through partnering and acquisitions. Aggregate transaction values over the last 10 years are approximately $33 billion. Several large multinational biopharmaceutical oncology leaders have also been significantly investing in radiopharmaceutical operations globally. We believe that the continued capital investment and expansion of operations and the advancement of supply chain capabilities represent recognition of the significant medical and commercial opportunity for radiopharmaceuticals.

Our proprietary miniprotein radioconjugate platform

We created our proprietary miniprotein radioconjugate platform to build on the successes of currently available radiopharmaceuticals and enable the discovery of next-generation precision radiopharmaceuticals. We are leveraging our platform to discover and develop radiopharmaceutical therapies that selectively deliver the tumor-killing properties of radioisotopes to targeted tumors with high tumor penetration and prolonged retention, with the goal of enhancing the safety and tolerability profile by rapidly clearing from normal organs and tissues to minimize systemic radiation exposure. Our miniprotein radioconjugates are designed for use with either imaging isotopes to select patients expressing the target, or therapeutic isotopes to treat tumors. The radioconjugates are formed by a chelation reaction to bind the isotopes to DOTA, which is covalently linked to the tumor-targeting miniprotein. This approach will enable clinicians to first visualize and verify target tumor engagement using an imaging radioisotope, thereby identifying the patients who are most likely to benefit from our therapy.

Our platform has enabled us to engineer potent, precision miniprotein-based radioconjugates that bind to the surface targets on tumor cells to localize radioisotope payloads. Miniproteins are polypeptides of less than one hundred amino acids that are amenable to biologic and medicinal chemistry optimization methods. We are prioritizing miniprotein binders of 40 to 70 amino acids in length, which are classified as biologics from a regulatory perspective providing a twelve-year exclusivity period for approved products. Miniproteins have differentiated and highly attractive properties as radioconjugates based on their antibody-like ability to potently and selectively bind to a highly diverse set of tumor targets, while having the pharmacologic profile of small peptides to enable high tumor penetration and rapid clearance from the body. We believe that miniproteins have many of the advantages of larger biologics like antibodies, as well as advantages of the smallest binders like peptides, without the limitations specific to either

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class. In particular, based on our preclinical studies, we believe miniproteins have the following beneficial characteristics for use in radiopharmaceuticals:

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Enhanced anticancer activity. Tumor killing is achieved through delivery of absorbed radiation dose, which is enhanced by high tumor penetration, high binding affinity for tumor targets, and prolonged retention of drug in the tumor.

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Improved tumor penetration as compared to larger biologics. Due to their small diameters, miniproteins can achieve high tumor penetration. In contrast, antibodies are unable to rapidly penetrate tumors to the same extent due to their much larger size.

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High affinity for tumor targets. Increased affinity is associated with higher tumor uptake. We have reproducibly generated sub-nanomolar affinity miniprotein binders to specific tumor targets.

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Internalization into tumor cells and prolonged tumor retention. Our miniprotein radioconjugates are internalized into cancer cells, which we believe drives prolonged retention time in tumors. In a clinical imaging assessment, AKY-1189 was measured for two days following administration and robust tumor retention was observed through the duration of the assessment. In preclinical studies in animals with significantly faster plasma clearance than humans, we measured out to three days following administration and observed robust retention of AKY-1189 in the tumor for the duration of the study.

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Enhanced clearance, selectivity and kidney exposure.

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Rapid clearance from the body to minimize toxicities. The most common dose-limiting toxicity for targeted radiopharmaceuticals is hematologic and bone marrow toxicity. To lower the risk of radiation exposure to bone marrow, we have designed our product candidates to have a short plasma half-life in order to be rapidly cleared through the kidney. Rapid clearance of the radioisotope payload from the body minimizes the exposure to radiation of normal organs and tissues, such as the blood, bone marrow and skin. Unlike antibodies or other large biologic radioconjugates that take days to weeks to be eliminated from circulation, miniproteins are typically eliminated from circulation within hours, thereby minimizing systemic exposure and potentially increasing the therapeutic index of our miniproteins relative to other radiopharmaceutical constructs.

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High selectivity. Miniproteins, like antibodies, can target specific isoforms or variants of closely related protein targets and differentiate among them, resulting in higher selectivity as compared to peptides. Our product candidates have demonstrated high selectivity for their tumor targets using a well-established cell-surface array assay. We believe this selectivity will reduce the risk of off-target binding and radioactive exposure to normal organs and tissues.

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Reduced kidney exposure through molecular engineering. The kidney is not only the organ that clears miniproteins from the body but it also plays the physiologic role in reabsorbing renally-cleared peptides and proteins to reclaim nutrients. We have developed proprietary capabilities and expertise to engineer our product candidates to minimize their renal reabsorption. Based on data to date, we do not expect either of [225Ac]Ac-AKY-1189 or [225Ac]Ac-AKY-2519 to require renal protection strategies, such as pre-treatment with amino acids that are required for peptide-based radiopharmaceuticals targeting somatostatin-2 receptor, or SSTR2, such as Lutathera.

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Broader number of addressable targets as compared to peptides. Miniproteins, like antibodies, bind to targets with high affinity, which enables highly selective and potent binding to targets through protein-protein intermolecular contacts. This allows miniproteins to bind to many, diverse protein targets, whether or not the protein target has a cleft or other structural feature commonly required for peptide binders.

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Enables rapid advancement to development candidates. We utilize proprietary yeast surface display techniques that enable us to efficiently screen greater than five billion miniprotein variants and select the most promising candidates for advancement. Furthermore, unlike larger biologics, we couple biological in vitro evolution with medicinal chemistry. Medicinal chemistry utilizes solid phase peptide synthesis, which enables the rapid synthesis of miniproteins with site-specific modifications, including the incorporation of unnatural amino acids, to efficiently optimize our drug candidates to have beneficial characteristics likely to confer a strong clinical profile.

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Enables rapid advancement into first-in-human evaluation. Unlike larger biologics, which require time-consuming and expensive recombinant manufacture by cells in culture, miniproteins allow for efficient chemical synthesis using solid phase peptide synthesis and rapid and cost-effective scale-up.

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Lack of manufacturing constraints. For each clinically-administered dose, only microgram quantities of our miniprotein are anticipated to be required. The microdose quantities allow for small gram-scale batches of our miniprotein to be efficiently produced at contract manufacturers to enable development through first-in-human studies in contrast to other approved peptide drugs that require kilogram-scale batches.

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We strengthen our miniprotein discovery workflow by incorporating artificial intelligence, or AI, technologies. We use various AI tools to help us select the best radiopharmaceutical biological targets, generate miniprotein libraries based on naturally evolved protein domains, design new miniprotein structures de novo using generative AI, and support our optimization efforts using machine learning models that are trained on our proprietary data. We can uniquely couple these state-of-the-art AI approaches with our wet-lab capabilities and our acquired expertise in discovery and optimization of miniprotein binders.

Manufacturing and supply

Manufacturing challenges and ensuring supply chain continuity and reliability have historically hindered the development and commercialization of radiopharmaceuticals. To overcome these challenges, we have established manufacturing and supply chain capabilities that are designed to be reliable and capital efficient with the ability to scale to meet global commercial demand for large cancer patient populations. Our end-to-end supply chain capabilities are orchestrated by our seasoned radiopharmaceutical development and manufacturing team that has experience advancing radiopharmaceutical programs from preclinical to commercialization. We have a state-of-the-art radiopharmaceutical development suite to apply our proprietary insights into process, formulation, and product development for preclinical, first-in-human, clinical trial, and commercial manufacturing and supply.

In addition, we have multiple domestic and international isotope supply agreements spanning therapeutic and diagnostic uses, including agreements with NorthStar Medical Technologies, LLC, TerraPower Isotopes, LLC and Niowave, Inc., among others, with priority access to 225Ac.

We have partnered with leading contract manufacturing organizations to facilitate reliable and efficient supply, including co-located drug product manufacturing with 225Ac and 64Cu production to reduce costs, improve product turnaround time, and ease supply logistics, for our proprietary targeted miniprotein radiopharmaceutical precursors and products. Leveraging this network of partners, we are currently manufacturing drug product for our clinical trial. Additionally, we are building an internal cGMP radiopharmaceutical facility to enhance flexibility, increase control, and establish a hybrid internal and external clinical supply chain of our product candidates. We expect our manufacturing facility to be fully operational in the second half of 2026. As we grow our organization, we are continuing to evaluate options for internal commercial manufacturing to complement our network of commercial contract manufacturers.

Our pipeline

We are leveraging our proprietary miniprotein radioconjugate platform to discover and develop a deep pipeline of targeted radiopharmaceutical programs to address unmet needs in prevalent solid tumors. Our most advanced program, [225Ac]Ac-AKY-1189, is targeting Nectin-4 expressing solid tumors, including locally advanced or metastatic UC, breast cancer, NSCLC, colorectal cancer and cervical cancer. Our second most advanced program, [225Ac]Ac-AKY-2519, is targeting B7-H3 expressing solid tumors, such as prostate, lung and breast cancers.

Beyond [225Ac]Ac-AKY-1189 and [225Ac]Ac-AKY-2519, we have a robust discovery pipeline of several unpartnered miniprotein radioconjugate programs in the discovery phase that focus on clinically-validated targets. Our learnings from the optimization of [225Ac]Ac-AKY-1189 are being applied to benefit the development of [225Ac]Ac-AKY-2519 and these subsequent programs. We retain exclusive, worldwide development and commercialization rights to all our current product candidates and discovery programs. We also have a discovery collaboration with Eli Lilly and Company, or Eli Lilly, to generate novel anticancer radiopharmaceuticals against targets beyond the scope of our unpartnered pipeline programs.

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[225Ac]Ac-AKY-1189 targeting Nectin-4 expressing tumors

Our lead product candidate, [225Ac]Ac-AKY-1189, was generated using our miniprotein radioconjugate platform and is designed to deliver 225Ac, a highly potent alpha-emitting radioisotope, to Nectin-4 expressing tumors. Nectin-4 is a cell-surface protein found on a wide variety of tumors and has very limited expression in normal adult tissues. Nectin-4 is also the target of enfortumab vedotin, or Padcev, an approved ADC for the treatment of locally advanced and metastatic UC. Although Padcev has validated Nectin-4 as an oncology target, there has been limited clinical development activity to design other therapeutics targeting other Nectin-4 expressing tumors, which may be due to the need to develop a companion diagnostic for tissue testing when utilizing an ADC. In contrast, we intend to use imaging radioisotopes conjugated to AKY-1189 to readily select patients most likely to benefit from therapeutic treatment with [225Ac]Ac-AKY-1189.

We believe AKY-1189, when conjugated to a radioisotope, has the potential to treat UC as well as other Nectin-4 expressing tumors by selectively delivering cytotoxic radioisotopes such as 225Ac to Nectin-4 expressing tumors to kill the tumor. AKY-1189’s short plasma half-life is designed to limit its radiation exposure to sensitive organs like bone marrow. We have also specifically designed AKY-1189 to minimize reabsorption by the kidneys to avoid potential toxicity concerns associated with renally-cleared radiopharmaceuticals.

In our preclinical studies, [225Ac]Ac-AKY-1189 has demonstrated antitumor activity and increased overall survival in animals inoculated with Nectin-4 expressing cancer cell xenografts. It also demonstrated a compelling biodistribution profile, with low absorbed doses observed outside of the tumor, which supports [225Ac]Ac-AKY-1189’s potential to widen the therapeutic window. Furthermore, the Section 21 data included clinical imaging and dosimetry data from radioactive imaging radioisotope conjugates of AKY-1189, [68Ga]Ga-AKY-1189 and [177Lu]Lu-AKY-1189, which enabled assessment of tumor uptake and retention in 15 patients with solid tumors known to have high Nectin-4 expression, including UC, breast cancer, NSCLC, colorectal cancer and cervical cancer. In this assessment, AKY-1189 was observed to specifically localize and be retained in all tumor types examined, while being rapidly cleared from normal organs and tissues, including the kidney, with no adverse events observed. In this assessment, we also observed tumor uptake and retention at levels we expect to be sufficient to drive efficacious responses, based on similar measurements to those of leading marketed radiopharmaceuticals.

We have commenced a multi-site Phase 1b trial in the United States for the treatment of locally advanced or metastatic UC and other Nectin-4 expressing tumors and anticipate preliminary results from the Part-1 dose escalation portion of this trial in the first quarter of 2027. An imaging radioisotope is being used to directly assess tumor binding by AKY-1189 and identify patients most likely to respond to [225Ac]Ac-AKY-1189 with the aim of delivering early clinical therapeutic signals across multiple Nectin-4 expressing tumor types. Patients determined to be Nectin-4 positive will move to the [225Ac]Ac-AKY-1189 dose-escalation portion of the trial. That phase of the study will investigate increasing doses of [225Ac]Ac-AKY-1189. Following completion of each dose level, safety of the drug will be assessed by a safety review committee and, if deemed safe, enrollment of the next higher dose level will commence. In December 2025, we disclosed that we had completed the first dose level of the Part 1 dose escalation of the Phase 1b clinical trial and had commenced enrollment of the next dose level. Enrollment in the trial remains on track, and we expect to present data from the Part 1 dose escalation in the first quarter of 2027. Upon completion of the dose escalation portion, a dose expansion portion will be conducted in patients with locally advanced or metastatic UC and other Nectin-4 expressing tumors. [225Ac]Ac-AKY-1189 was granted Fast Track Designation by the FDA in February 2026 for the treatment of locally advanced or metastatic UC in patients who had progressed on or after prior systemic therapies.

[225Ac]Ac-AKY-2519 targeting B7-H3 expressing tumors

Our second product candidate, [225Ac]Ac-AKY-2519, is designed to deliver 225Ac to B7-H3 (CD276) expressing tumors, including prostate, lung and other solid tumors. B7-H3 is a cell-surface protein that is highly expressed in many types of solid tumors, while having limited expression in normal tissues. We estimate that approximately 90% of all metastatic castration-resistant prostate cancers, 80% of NSCLCs and 70% of small cell lung cancers, express B7-H3, while also being expressed on other solid tumors like breast cancers. High expression of B7-H3 has been associated with poor overall survival outcomes and a lack of responsiveness to anti-PD-1 therapeutics in several tumor types. B7-H3 has attracted substantial clinical development efforts across different modalities, including ADCs, with several late-stage ADCs demonstrating preliminary efficacy signals and acceptable safety profiles. Regarding the potential for B7-H3 as a target in prostate cancer, we believe B7-H3 to be differentiated from PSMA for imaging and treatment due to its high tumor expression and limited expression in normal organs and tissues, such as kidneys and salivary glands.

In our preclinical studies, [225Ac]Ac-AKY-2519 has demonstrated robust antitumor activity and increased overall survival in mice inoculated with B7-H3 expressing cancer cell xenografts. It also demonstrated a compelling biodistribution profile, with low absorbed doses observed outside of the tumor.

[68Ga]Ga-AKY-2519 and [177Lu]Lu-AKY-2519 uptake in tumors and normal tissue biodistribution is currently being assessed in patients with various B7-H3 expressing solid tumors. To date, each of [68Ga]Ga-AKY-2519 and [177Lu]Lu-AKY-2519 has demonstrated robust tumor uptake with low uptake in normal tissues and a differentiated biodistribution profile, showcasing rapid clearance from normal organ and tissues, including kidneys. We expect the results of the imaging and dosimetry assessment in patients with various tumor types to be reported in mid-2026. In March 2026, our INDs for [225Ac]Ac-AKY-2519 and for [64

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Cu]Cu-AKY-2519 were cleared by the FDA to proceed to a Phase 1b clinical trial. We expect to initiate the multi-site Phase 1b clinical trial mid-2026.

Eli Lilly collaboration

In May 2024, we entered into a discovery collaboration with Eli Lilly to leverage our proprietary miniprotein radioconjugate platform to generate novel anticancer radiopharmaceuticals against targets beyond the scope of our unpartnered pipeline programs. We received a $60.0 million upfront cash payment in addition to an equity investment and are eligible to receive up to an additional $1.2 billion upon achievement of preclinical, clinical, regulatory, and commercial milestones, as well as tiered royalties. We are responsible for program discovery of a defined set of targets selected by Eli Lilly through initial human imaging studies and Eli Lilly is responsible for worldwide clinical development and commercialization from Phase 1 clinical trials onward. We retain worldwide rights to our proprietary pipeline programs, including our lead Nectin-4 targeting program.

Our team

We have assembled an experienced management team with deep expertise in drug development, approval, and commercialization, with members of our management being involved in the approval and commercialization of 14 currently marketed FDA-approved products. Our team is led by executives who have significant experience in company-building in the biopharmaceutical industry and a shared vision to build a leading radiopharmaceutical company. The experience of our President and Chief Executive Officer, Matthew Roden, PhD, in the biopharmaceutical industry includes leadership positions in corporate strategy and business development at Bristol Myers Squibb, and senior equity research coverage of the biotechnology sector at J.P. Morgan and UBS. He also serves as an Entrepreneur Partner at MPM BioImpact and on the Boards of Directors of other biotechnology companies. Our Chief Financial Officer, Kyle D. Kuvalanka, brings over 20 years of experience as a senior leader in the biopharmaceutical industry, having served in executive leadership roles at ROME Therapeutics, Syros Pharmaceuticals, Blueprint Medicines and Goldfinch Bio. Paul L. Feldman, PhD, our Chief Scientific Officer, was Co-founder and Chief Executive Officer of Phoundry Pharmaceuticals and, upon its acquisition by Intarcia Therapeutics, served as Head of Discovery and Translational Medicine at Intarcia. In his previous roles at GlaxoSmithKline, he was directly involved in the discovery of five approved drugs. Shulamit Ron-Bigger, PhD, our Chief Operating Officer, previously served as Head of Strategy and Operations for the Research and Early Development organization at Bristol Myers Squibb. Akos Czibere, MD, PhD, our Chief Medical Officer, has extensive experience in clinical development, most recently serving as Therapeutic Area Development Head of Hematology-Oncology at Pfizer. Dr. Czibere has been directly involved in the approval of six oncology drugs, including Elrexfio and Talzenna. Tyler Benedum, PhD, our Chief Technical Officer, previously served as Vice President of Chemistry, Manufacturing, and Controls Development at Avid Radiopharmaceuticals, a wholly-owned subsidiary of Eli Lilly, where he oversaw global commercial and clinical trial radiopharmaceutical manufacturing and played a key role in developing and advancing Amyvid and Tauvid through marketing authorization approval and commercialization.

Our company was co-founded by Todd Foley, a Managing Director at MPM BioImpact, who is currently Chair of our Board of Directors; Patrick Baeuerle, PhD, an MPM BioImpact Advisor, and currently a member of our Scientific Advisory Board; and Brian Goodman, PhD, a Partner at Vida Ventures.

Expanding the potential of radiopharmaceuticals

We believe that the field of radiopharmaceuticals is still in its infancy and is poised to become a fundamental pillar of cancer care and deliver transformative survival and quality of life outcomes for patients. External beam radiation therapy, or EBRT, has proven to be an effective option for cancer treatment but has limitations including lack of sufficient precision to avoid collateral damage to normal organs and tissues. Radiopharmaceuticals have the ability to deliver high levels of radiation directly and precisely to diseased tissue by combining the proven tumor-killing ability of radiation therapy with the high degree of molecular precision provided by their targeting components, offering cancer patients better outcomes than other anticancer modalities.

Several radiopharmaceutical drugs have been developed and commercialized in an expanding field, demonstrating the significant market potential of radiopharmaceuticals. Commercial adoption of Pluvicto and Lutathera, along with expanding operational and commercial infrastructure, positions radiopharmaceuticals as the next emerging modality. To date, the development of radiopharmaceutical candidates has been primarily focused on two biological targets: PSMA, the target of Pluvicto; and SSTR2, the target of Lutathera. Our company was founded with the aim of maximizing the impact of radiopharmaceuticals by bringing excellence to all aspects of radiopharmaceutical drug development, by discovering therapeutic candidates that broaden the set of targets and tumors that are addressed by radiopharmaceuticals. As a result, none of our programs target PSMA or SSTR2. We instead focus on leveraging our miniprotein radioconjugate platform to a broader set of addressable targets such as Nectin-4 and B7-H3, which are expressed in tumor types such as lung, breast, bladder, prostate and gastrointestinal tumors, and collectively account for an estimated 193,000 and 215,000 incident cases per year, respectively.

Radioisotopes used in radiopharmaceuticals fall into two classes: alpha-emitting and beta-emitting radioisotopes. Alpha particles are much larger and heavier than beta particles, with higher energy and shorter travel distances. Although both alpha-emitting and beta-emitting radioisotopes cause damage to the DNA of tumor cells resulting in tumor cell death, there are distinct differences. Beta-emitting radioisotopes create single-strand DNA breaks and can travel to more distant cells not in direct contact with the delivery point of the radiopharmaceutical. In contrast, alpha-emitting radioisotopes create catastrophic double-stranded

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DNA breaks and are 1,000 times more potent in cell killing than beta-emitters but can only travel two to three cell lengths. Radiopharmaceuticals using alpha-emitting radioisotopes also offer advantages with administration as they result in less radiation exposure to the clinic staff during administration, as well as convenience to patients with no post-treatment restrictions on having contact with other people.

In third-party studies, alpha-emitting radioconjugates have also demonstrated increased anticancer activity in patients with tumors that did not respond to beta-emitting radioconjugates. As seen in the graphic below, a patient with widespread metastatic disease was observed to have progressive disease following treatment with two cycles of 177Lu-PSMA-617. Subsequent treatment with 225Ac-PSMA-617 resulted in profound regression of disease. Objective response rates of over 30% have been observed in academic trials of 225Ac-PSMA-617, and a recent company-sponsored trial of 225Ac-containing PSMA-617 radioligand showed a 43% response rate in patients previously treated with 177Lu-containing PSMA-617 radioligand therapies. These results illustrate the powerful efficacy potential for 225Ac-containing targeted radioconjugates.

Anticancer activity of alpha-emitting radioconjugates in patients with tumors that did not respond to beta-emitting radioconjugates

We believe alpha radioconjugates represent a significant opportunity for improved clinical outcomes for patients with cancer. Due to the inherent advantages and breakthrough efficacy potential, we are initially focused on alpha-emitting radioisotopes. However, our miniprotein radioconjugates have the ability to deliver both alpha-emitting and beta-emitting radioisotopes, which we believe expands the potential impact and tumor treatment options available for our radiopharmaceuticals.

Our proprietary miniprotein radioconjugate platform

We were founded to improve outcomes for cancer patients by pioneering a new class of targeted radiopharmaceuticals to unlock the benefit of the modality for prevalent tumor types that have historically been beyond the reach of radiopharmaceuticals. Our ability to leverage the killing power of a radioconjugate provides significant opportunity for discovering targeted radiopharmaceuticals with the potential to transform the cancer treatment paradigm for patients with a broad set of tumor types. Our aim is to discover targeting molecules that can bind with high affinity and prolonged duration on cancer cells to maximize efficacy, while having high selectivity and short residence time in the rest of the body to avoid toxicity to normal organs and tissues.

Our founders created our company with a focus on a category of polypeptides, referred to as miniproteins. Miniproteins consist of manifold scaffolds of less than one hundred amino acids in length that fold into a stable tertiary structure, making them larger than small peptides but smaller than large biologics. Similar to larger biologics, such as antibodies, miniproteins possess the ability to recognize and bind with high selectivity to a highly diverse set of tumor targets, but lack some of the known radiopharmaceutical property limitations of antibodies, including long circulating half-life and poor tumor uptake. Miniproteins also share some of the pharmacological profile advantages of small peptides such as high tumor penetration and short plasma half-life. However, miniproteins are able to bind to, and exhibit high selectivity for, tumor targets that are less tractable with smaller peptides. We believe miniproteins possess pharmacological properties that make them ideal targeting molecules for radiopharmaceutical product development, since they retain the advantages of large biologics and smaller peptides without the limitations specific to either class. We are focused on the discovery of novel miniproteins that are 40 to 70 amino acids in length, which categorizes them as biologics from a regulatory perspective, providing a twelve-year exclusivity period for approved products.

Our miniprotein radioconjugates offer both the potential for both potent antitumor activity and an enhanced safety and tolerability profile. The small size of miniproteins allows them to rapidly penetrate tumors. Furthermore, our miniprotein radioconjugates are able to internalize into cancer cells, which we believe drives prolonged retention. We have reproducibly

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generated high affinity miniprotein binders to specific tumor targets. Tumor killing is achieved through delivery of absorbed radiation dose, which is enhanced by high tumor penetration, high binding affinity for tumor targets, and prolonged retention of drug in the tumor.

Two of the major concerns for toxicity with radiopharmaceuticals are renal damage due to radiation exposure in the kidney and hematological toxicity due to bone marrow exposure. The short plasma half-lives of miniproteins results in rapid clearance through the kidneys, limiting the overall radiation exposure of normal organs and tissues, such as the blood, bone marrow and skin, while the high target selectivity of our miniproteins further reduces off-target binding and exposure risk. We have built on this beneficial profile and engineered our product candidates to minimize their renal reabsorption using primary sequence modifications. Our lead optimization efforts have resulted in decreases in renal retention and increases in tumor uptake, which attributes are predicted to widen the therapeutic index of our product candidates relative to other radiopharmaceutical constructs.

Our miniprotein platform is designed to broaden the number of tumor targets addressable by radiopharmaceuticals. Our miniproteins bind to targets with high affinity, which enables highly selective and potent binding to targets through protein-protein intermolecular contacts and allows them to potentially bind to many protein targets, whether or not it has a cleft or other structural feature commonly required for peptide binders.

Our platform enables rapid advancement to product candidate and first-in-human evaluation. Miniproteins can be synthesized using solid phase peptide synthesis. This allows the evaluation of a large number of variants and enables the establishment of rich structure-activity relationships and site-specific modifications, including the incorporation of unnatural amino acids, to optimize for the desired drug-like properties.

Our proprietary miniprotein radioconjugate platform uniquely combines the following non-exhaustive list of technologies we use during our discovery process:

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novel, proprietary libraries of greater than 100 miniprotein scaffolds that enable yeast surface display selections of approximately five billion variants;

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machine-learning based design and optimization of miniprotein variants;

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unique biological assays to rapidly assess our miniprotein radioconjugate candidates; and

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medicinal chemistry enabling site-specific incorporation of proprietary unnatural amino acids into our miniprotein radioconjugates to optimize pharmacological properties.

We routinely apply our platform to rapidly generate and optimize miniprotein binders to tumor cell targets, not only selecting for product candidates that bind to their targets with high selectivity and affinity, but also optimizing for other properties that we believe will increase their potential as high-value therapeutics. As illustrated below, this iterative process to optimize miniproteins utilizes computational design with biological evolution and medicinal chemistry.

Iterative process optimizing miniprotein discovery combines computational design, biological evolution and medicinal chemistry.

Learnings from our Nectin-4 program and discovery programs have enabled additional technological advancements to be incorporated into subsequent programs, including our B7H3 program, to enhance our miniprotein radioconjugate platform and efficiently advance novel radiopharmaceutical programs.

Enhancing our discovery efforts by utilizing AI

AI, and its sub-categories of machine learning, deep learning, generative AI, and expert systems, are making a significant impact in the pharmaceutical industry and spawning many new companies and technologies. We have been utilizing AI to advance our miniprotein discovery and development over the past several years. Our reliance on AI has increased with advancement of AI tools, especially with accumulation of experimental data that informs AI models. Within discovery, we use AI tools to help us select radiopharmaceutical biological targets, generate miniprotein libraries based on naturally evolved protein domains, and design new

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miniprotein structures de novo using generative AI. In addition, we apply machine learning to critical experimental datasets and use structure-based modeling to support optimization of our miniprotein binders.

Recent advances in de novo design software have been used to design small-molecule, peptide, macrocycle, and antibody binders to proteins. More recently, this software has been adapted and modified by us and others to design miniprotein binders to biological targets. We can uniquely couple these state-of-the-art AI approaches with our wet-lab capabilities and our acquired expertise in discovery and optimization of miniprotein binders.

We utilize AI tools throughout the entire process of advancing our radiopharmaceutical pipeline. In particular, we apply AI technology and yeast surface display to discover miniprotein binders to targets of interest in two ways: (1) to re-engineer naturally evolved protein-domain folds into libraries with hundreds of millions of variants each, from which target-binding miniproteins are captured by yeast surface display, and (2) to design novel miniproteins specifically for binding to biological targets of interest, and to use yeast surface display to identify the most successful designs.

In addition to our internal work using and advancing AI tools, we continue to assess potential third-party partners who are using AI tools, in order to further advance our specific discovery capabilities.

[225Ac]Ac-AKY-1189: Our lead product candidate targeting Nectin-4 expressing tumors

Our lead product candidate, [225Ac]Ac-AKY-1189, was discovered using our miniprotein platform and is designed to deliver 225Ac, a highly potent alpha-emitting radioisotope, to Nectin-4 expressing tumors. The therapeutic potential of [225Ac]Ac-AKY-1189 is supported by our preclinical studies and an investigator-initiated clinical imaging and dosimetry assessment demonstrating the ability of AKY-1189 radioconjugates to specifically localize to Nectin-4-expressing tumors and rapidly clear from normal organs and tissues. In April 2025, the FDA cleared our IND for [225Ac]Ac-AKY-1189 for the treatment of locally advanced or metastatic UC and other Nectin-4 expressing tumors. We have commenced a multi-site Phase 1b clinical trial in the United States and anticipate preliminary results from the Part-1 dose escalation portion of this trial in the first quarter of 2027. [225Ac]Ac-AKY-1189 was granted Fast Track Designation by the FDA in February 2026 for the treatment of locally advanced or metastatic UC in patients who had progressed on or after prior systemic therapies.

Nectin-4: a clinically validated oncology target

Nectin-4 is the target of Padcev which is approved worldwide for the treatment of locally advanced or metastatic UC. Nectin-4 is a surface protein that is expressed in a wide variety of solid tumor types and has very limited expression in normal adult tissues. Robust expression of Nectin-4 has been reported in various solid tumor indications, including UC, breast, NSCLC, colorectal, pancreatic, ovarian, cervical, head and neck, gastric, and esophageal cancers, with Nectin-4 expression levels of approximately 50%-95% observed in multiple tumor types. Up to an estimated 193,000 cancer patients are diagnosed annually in the United States with solid tumors that may express Nectin-4. The expression of Nectin-4 is associated with poor patient prognosis and unfavorable tumor progression. We believe that elevated Nectin-4 expression in these solid tumors supports our ongoing evaluation of [225Ac]Ac-AKY-1189 in UC and beyond.

Elevated Nectin-4 mRNA expression expressed in multiple tumor types

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Background on UC and other Nectin-4 expressing solid tumors

UC is a cancer that begins in the cells that line the urethra, bladder, ureters, renal pelvis and other organs. Over 90% of bladder cancers in the United States are UCs. The National Cancer Institute estimated that there would be greater than 83,000 new cases of bladder cancer and approximately 16,800 bladder cancer related deaths in the United States in 2024. Bladder cancer represents 4% of all cancers in the United States and is the fourth most common cancer in men, though less common in women. In 2024, the total number of patients with locally advanced or metastatic UC in the United States was estimated to be approximately 18,000. Annually, an estimated 4,200 patients are diagnosed with metastatic UC.

Until recently, the most common treatment for patients diagnosed with locally advanced or metastatic UC was chemotherapy with platinum-based drugs, such as carboplatin or cisplatin in combination with gemcitabine. Patients with metastatic disease that progressed during or after platinum-based chemotherapy were increasingly being treated with checkpoint immunotherapy. A number of PD-1 and PD-L1 checkpoint inhibitors have been approved by the FDA for use in refractory bladder cancer with objective response rates observed in clinical trials between 15% to 21%.

Due to the ubiquitous and robust expression of Nectin-4 in UC, no companion diagnostic or tissue testing for Nectin-4 is required. To date, there is only one approved Nectin-4 targeted therapy for UC, the ADC enfortumab vedotin, marketed as Padcev by Pfizer and Astellas. Padcev in combination with pembrolizumab is the standard of care for first-line treatment of patients with locally advanced or metastatic UC with no clear standard of care for subsequent lines of therapy. In locally advanced or metastatic UC patients previously treated with a PD-1 or PD-L1 inhibitor and/or platinum-based chemotherapy, treatment with Padcev monotherapy led to a 40.6% overall response rate and improved overall survival to 12.9 months compared to 9.0 months for patients treated with chemotherapy. In treatment-naïve patients with locally advanced or metastatic disease, Padcev in combination with pembrolizumab led to a 67.7% overall response rate and an overall survival of 31.5 months compared to 16.1 months for patients treated with chemotherapy. These data from Padcev in combination with pembrolizumab led to its recommendation as a first-line treatment for patients with locally advanced or metastatic bladder cancer. Sales of Padcev in 2024 were approximately $1.9 billion with estimated peak sales of up to $7.0 billion.

Although Padcev received initial regulatory approval from the FDA in 2019 for the treatment of locally advanced or metastatic UC, it has not been approved for the treatment of other Nectin-4-expressing tumors and there has been limited clinical development activity to design therapeutics targeting other Nectin-4 expressing tumors, which may be due to the need to develop a companion diagnostic for tissue testing when utilizing an ADC. In clinical trials leading to the initial approval of Padcev, Nectin-4 expression was observed in all 120 UC patients with available tumor biopsies, and the FDA agreed that the use of an in vitro diagnostic for Nectin-4 expression was not essential to the safe and effective use of Padcev.

Other cancers, including breast, NSCLC, colorectal and cervical have been shown to express Nectin-4, though overexpression may not be as ubiquitous as in UC. Breast cancer is the second most common type of cancer in women in the United States with more than an estimated 360,000 patients diagnosed in 2024. Lung cancer is the third most common cancer in the United States with 235,000 patients diagnosed annually and more people in the United States dying from lung cancer than any other type of cancer. NSCLC is the most common type of lung cancer, accounting for about 80% to 85% of all lung cancer cases. Colorectal cancer develops in the colon or rectum with 150,000 new cases in the United States estimated in 2024. Cervical cancer starts in the cells lining the cervix, the lower part of the uterus, and it is estimated that approximately 13,800 new cases of invasive cervical cancer were diagnosed in the United States in 2024.

We believe there is a significant opportunity to develop novel therapies with improved therapeutic profiles in these large patient populations with significant unmet medical needs.

Our solution: [225Ac]Ac-AKY-1189

Our lead product candidate, [225Ac]Ac-AKY-1189, contains a miniprotein, AKY-1189, that specifically binds to Nectin-4, which is conjugated via chelation to 225Ac. AKY-1189 is a 45-amino-acid miniprotein covalently attached to an established radioisotope chelator, DOTA, through a short, chemically stable linker. In our preclinical mouse models, AKY-1189 was observed to specifically localize to Nectin-4 expressing tumors while minimizing exposure to the kidneys and other normal organs and tissues. Clinical imaging and dosimetry assessments using [68Ga]Ga-AKY-1189 and [177Lu]Lu-AKY-1189 in patients demonstrated high tumor uptake of AKY-1189 in UC and four other tumor types known to express Nectin-4, while being rapidly cleared from the body and avoiding normal organs and tissues.

Discovery and development of AKY-1189 utilizing our miniprotein radioconjugate platform

We have leveraged our proprietary miniprotein radioconjugate platform to discover and develop AKY-1189 following an evaluation of millions of potential candidates through a combination of computational modeling, directed evolution, functional screening, in vivo profiling and medicinal chemistry. Our approach enabled us to optimize the physicochemical, potency, and pharmacological properties of miniprotein binders that led to the discovery of AKY-1189.

AKY-1189 is engineered to be thermally stable to at least 75°C to enable the manufacture of [225Ac]Ac-AKY-1189. The conjugated radiopharmaceutical is designed to maintain radiochemical stability for at least four days to support central manufacturing and enable flexible distribution and clinical administration.

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The binding affinity, referred to as KD, of AKY-1189 to Nectin-4 was determined to be 0.22 nanomolar, or nM, by surface plasmon resonance. The Ki, or inhibitory constant, which also measures binding affinity, of this miniprotein to Nectin-4 expressing tumor cells was determined to be 0.82 nM, and within the range of 0.1 nM to 1 nM targeted by therapeutic antibodies designed to deliver cytotoxins to tumors, such as ADCs. No off-target binding of AKY-1189 was detected when tested at a concentration of 450 times higher than its KD for Nectin-4. This selectivity testing was conducted for more than 6,200 surface expressed or secreted proteins, including Nectin-1, -2, and -3. Furthermore, no binding was observed in a tumor cell line in which the gene for Nectin-4 had been removed by CRISPR knockout. We believe the binding affinity and selectivity of AKY-1189 supports a favorable risk-benefit profile.

In addition to high Nectin-4 binding affinity, we designed AKY-1189 to be minimally retained in the kidney. Our optimization process is exemplified by examining the progression of the properties from our earlier Nectin-4 targeted miniproteins, AKY-807 and AKY-1162, to AKY-1189. In vitro binding assays demonstrated that AKY-807 was a potent and selective binder to Nectin-4 expressing tumor cells but in vivo imaging studies with an imaging radioisotope, [111In]In-AKY-807, demonstrated that the AKY-807 also localized to the kidneys. However, while some localization in the kidneys was expected given renally-cleared molecules are subject to reabsorption in the kidney, we observed that high levels remained in the kidneys for 22 hours after dosing. Through a series of sequence modifications to the miniprotein, we generated a series of molecules, including AKY-1162 and AKY-1189, that improved the Nectin-4 binding affinity and tumor binding, while simultaneously reducing kidney retention. As seen in the images below, there was considerable improvement in the lack of kidney retention, coupled with improvement in tumor uptake from AKY-807 to AKY-1162 to AKY-1189.

AKY-1189’s rapid tumor uptake and kidney washout 22 hours after administration compared with previous miniproteins

Brightly colored areas depict presence of imaging radioisotope in mice implanted with xenograft tumors on right forelimb

Figure left shows low kidney uptake and more rapid washout of AKY-1189 over 22 hours compared to other miniproteins. Figure right depicts more rapid and retained tumor uptake of AKY-1189 over 22 hours compared to other miniproteins.

In vivo preclinical studies

Tumor and normal tissue uptake

To assess the potential of AKY-1189 in tumor xenograft models we used two versions of the HT-1376 human UC cell line, which is epithelial-like cell isolated from the urinary bladder of a patient with cancer. The expression levels were determined by

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histochemical staining and scored using the Histochemical Scoring Assessment, or H-score, which has a range of 0-300, with higher scores representing higher expression. In one cell line, noted as low expression in the image below, Nectin-4 expression was limited to the endogenous levels of the cell line, with an H score of 175. In the other cell line, noted as representative expression in the image below, we used genetic engineering to increase the level of Nectin-4 expression to more closely match that observed in representative metastatic UC patient biopsies, with an H-score of 291. Between 55% to 90% of metastatic UC patients are initially diagnosed with a H-score similar to the representative expression cell line.

Nectin-4 expression in the modified HT-1376 cell line matched that observed in a representative biopsy from a metastatic UC patient that has high levels of Nectin-4 expression

We assessed the ability of AKY-1189 to localize to tumors in a mouse xenograft model using the representative Nectin-4 expressing HT-1376 cell line. Dosing with the imaging radioisotope [111In]In-AKY-1189 allowed quantitative measurement of [111In]In-AKY-1189 biodistribution using single-photon emission computed tomography, or SPECT, imaging. Within minutes of dosing, the highest levels of [111In]In-AKY-1189 were found in the tumor. These levels in the tumor were maintained for approximately two hours, after which the levels slowly declined over the 24-hour observation period, with retention observed for up to three days after dosing. In contrast, the levels of [111In]In-AKY-1189 observed in the kidneys rose within minutes after dosing and then rapidly declined as [111In]In-AKY-1189 was eliminated from the body. This desired preclinical biodistribution profile, high tumor uptake and reduced exposure to organs and normal tissues, supported the advancement of [225Ac]Ac-AKY-1189. We believe this biodistribution profile enables a wide therapeutic window for [225Ac]Ac-AKY-1189 in treating patients with Nectin-4 expressing tumors.

AKY-1189 was localized and retained in tumors, while being rapidly washed out from the kidneys

Brightly colored areas depict presence of imaging radioisotope four hours after dosing (left) and 24 hours after dosing (right), in mice implanted with xenograft tumors on right forelimb

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Figure left shows low kidney uptake and rapid washout of AKY-1189 over 24 hours. Figure right depicts high, rapid and retained tumor uptake of AKY-1189 over 24 hours.

Based on our modeling of the pharmacokinetics of AKY-1189 and scaling to projected human doses, we estimate that a dose of 7.4 MBq of [225Ac]Ac-AKY-1189, a standard dose of 225Ac-based radiopharmaceuticals that has demonstrated anticancer effects, will result in a low systemic and kidney exposure to radiation. The ability to deliver a radiopharmaceutical at a dose that is both safe and efficacious is critical and these preclinical predictions lie well within what we believe is a viable range for eventual clinical development and, if approved, commercialization. We believe that the therapeutic window of [225Ac]Ac-AKY-1189 can improve tolerability and patient quality of life and provide the opportunity to potentially explore higher doses that could improve efficacy.

The profile of [225Ac]Ac-AKY-1189 provides the potential for flexibility in both the schedule and administered dose before approaching the EBRT benchmark limit of 23 RBE5Gy for kidneys. This is a level at which EBRT has been associated with a risk of chronic kidney disease in five percent of patients five years after dosing.

Dosimetry scaling suggests that the radiation exposure to the kidney in humans will be well within the range generally considered to be acceptable in the field and below thresholds associated with kidney toxicity

Antitumor activity of [225Ac]Ac-AKY-1189

As shown below, [225Ac]Ac-AKY-1189 also had increased antitumor activity in both high and low Nectin-4 expressing tumors in xenograft models. In our preclinical study, we observed that mice bearing HT-1376 tumors expressing low or representative levels of Nectin-4 were administered with either a single intravenous dose of 1 µCi, or microcuries, of [225Ac]Ac-AKY-1189 or vehicle (n=8 mice per group). Treatment with [225Ac]Ac-AKY-1189 resulted in a mean tumor regression of 53% in the representative Nectin-4 expressing tumors by day 25 (n=8 remaining animals) and an overall survival rate of 75% at the end of an eight-week observation period where median survival was not reached during the observation period. Treatment with vehicle in the representative Nectin-4 expressing tumors had no surviving animals at the end of the observation period and had a median overall survival of 28.5 days (n=5 remaining animals at day 25). In low Nectin-4 expressing tumors, [225Ac]Ac-AKY-1189 treatment led to an average tumor growth inhibition of 62% at day 25 (n=8 remaining animals at day 25) and led to a median survival of 49 days. In low Nectin-4 expressing tumors, treatment with vehicle led to a median survival of 26.5 days (n=6 remaining animals at day 25). Body weight was monitored as a surrogate of overall animal health. Animal weights remained constant throughout the treatment period, indicating that [225Ac]Ac-AKY-1189 treatment was well tolerated.

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[225Ac]Ac-AKY-1189 had increased antitumor activity in both high and low Nectin-4 expressing tumors in xenograft models

Furthermore, treatment of mice harboring HT-1376 tumors with a single dose of [225Ac]Ac-AKY-1189 resulted in improved tumor growth inhibition compared to multiple doses of Padcev, assessed in the same study. The mice expressing low levels of Nectin-4 were treated with a single intravenous dose of 2 µCi of [225Ac]Ac-AKY-1189 on day zero. As depicted below, this resulted in a mean tumor growth inhibition of 75% at day 38 compared to 53% inhibition after three administrations of Padcev on day zero, 7 and 14 (depicted in figure A below). Animal weights remained constant during the treatment period, indicating that both regimens were well-tolerated (depicted in figure B below). To compare the antitumor activity and tolerability of Padcev, we calculated the dose to be used in mice based off the approved clinical dose and regimen. The dosing regimen used for Padcev of 3mg/kg once a week for three weeks in mice, demonstrated plasma exposures with an area under the curve, or AUC, of 88 µg*day/mL (depicted in figure C below), similar to those observed in patients treated with the clinical regimen of 1.25mg/m2 (AUC = 111+38 µg*day/mL). AUC is a measure of drug exposure over time. When comparing this clinically relevant dose of Padcev to [225Ac]Ac-AKY-1189, we observed a favorable response for [225Ac]Ac-AKY-1189 in Padcev responsive tumors.

A single administration of [225Ac]Ac-AKY-1189 resulted in greater inhibition of tumor growth than Padcev in low Nectin-4 expressing tumors in xenograft models

Cmax denotes maximum drug concentration; T1/2 denotes time required to decrease drug concentration by half

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Named patient use pursuant to Section 21 of South Africa’s Medicines and Related Substances Act

Mike Sathekge, MD, Head of Nuclear Medicine Department, University of Pretoria and Steve Biko, Academic Hospital, and President and Chief Executive Officer, Nuclear Medicine Research Infrastructure, or NuMeRI, administered radioconjugated AKY-1189 provided by us to a limited number of their patients in South Africa pursuant to Section 21 of the MRSA, which allows healthcare providers to administer unregistered medicines to patients, as authorized by SAPHRA.

AKY-1189 conjugated to an imaging radioisotope, [68Ga]Ga-AKY-1189, was dosed in 20 patients with UC, breast cancer, NSCLC, colorectal cancer and cervical cancer. Of these 20 patients, all 20 were available for safety and normal tissue distribution assessment, and 15 were evaluable for tumor uptake. A subset of nine patients underwent kidney dosimetry with [177Lu]Lu-AKY-1189 and eight patients were evaluable for quantitative assessment of the absorbed dose of radiation to the kidney and bone marrow. One patient also received

AKY-807 conjugated to the same imaging isotopes allowing for intra-patient comparison of tumor uptake and absorbed dose to the kidney. In line with the preclinical predictions, AKY-1189 showed superior tumor uptake with less radiation exposure to the kidneys compared to AKY-807, with no adverse events observed.

The figure below depicts normal tissue distribution of [68Ga]Ga-AKY-1189, and robust tumor uptake, including in brain metastasis. Dark areas in the image below depict uptake of [68Ga]Ga-AKY-1189.

Representative PET/CT image of a patient dosed with [68Ga]Ga-AKY-1189 after 1 hour

Tumor uptake was evaluated with [68Ga]Ga-AKY-1189 in 15 patients via PET/CT one hour post-injection. Standard uptake values, or SUVs, were calculated using standard methodology also utilized in standard diagnostic PET/CT images. As depicted in the chart below, SUVs were consistently at or above the levels expected to be required for efficacy and in line with SUVs reported for approved radiopharmaceuticals. This was observed across all tumor types assessed including UC, breast cancer, NSCLC, colorectal cancer and cervical cancer, as depicted in the image below on the left. For context, in an editorial published in 2023, Michael Hofman depicted the observed SUVmax for various approved radiopharmaceuticals, including Pluvicto, Lutathera and

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purported next alpha generation therapies. His study set forth the observed SUVmax for PSMA and SSTR in the range from 10-100, as depicted in the image below on the right.

Increasing tumor uptake with [177Lu]Lu-AKY-1189 with no accumulation observed in normal tissues observed at 48 hours

1 ~5.55 GBq (150mCi) administered activity

The figures above depict normal tissue deposition and tumor uptake of [177Lu]Lu-AKY-1189 during a 48-hour period. Dark areas in image depict tissue and tumor uptake of [177Lu]Lu-AKY-1189. At 24 hours post administration, [177Lu]Lu-AKY-1189 exposure increased in the tumors without accumulation of exposure to normal tissues.

The [177Lu]Lu-AKY-1189 data suggests the predicted absorbed dose to the kidney (median absorbed dose of 0.30 gray/gigabecquerel, or Gy/GBq) and bone marrow (median absorbed dose: 0.01 Gy/GBq) allows for six or more therapeutic doses to be safely administered. These data are consistent with other approved radiopharmaceuticals, including Pluvicto, where the kidneys and bone marrow are not considered dose-limiting organs, when conjugated to either 177Lu or 225Ac. We plan to evaluate these findings in future clinical trials.

Our clinical development strategy

In April 2025, the FDA cleared our IND for [225Ac]Ac-AKY-1189 for the treatment of locally advanced or metastatic UC and other Nectin-4 expressing tumors. We have commenced a multi-site Phase 1b clinical trial in the United States and anticipate preliminary results from the Part-1 dose escalation portion of this trial in the first quarter of 2027. The Phase 1b trial in the United States will enroll approximately 150 patients and follow a dose escalation strategy utilizing the Bayesian Optimal Interval, or BOIN,

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design, which is a method used for early phase dose-finding based on model-assisted design elements and is used to determine a suitable dose for consideration in later-stage oncology trials. The Phase 1b trial will only enroll patients with locally advanced or metastatic UC in the dose escalation portion. Imaging and dosimetry in the United States trial will be done with [64Cu]Cu-AKY-1189 allowing for multiple timepoint assessments through PET/CT. No imaging selection criteria are employed through dose escalation. Patients will receive up to six cycles of [225Ac]Ac-AKY-1189 at increasing dose levels. Following completion of dose escalation, dose expansions will be conducted in locally advanced or metastatic UC (n=30), triple-negative breast cancer (n=30) and a basket cohort of other tumors known to have high Nectin-4 expression, including NSCLC, colorectal cancer and cervical cancer (n=40). The primary endpoint of the trial will be to assess safety and tolerability of [225Ac]Ac-AKY-1189. Secondary endpoints include objective response rate (as measured by RECIST v1.1, a standard way to measure the response of a tumor to treatment), duration of response, progression-free survival, overall survival, changes in quality of life, and to characterize pharmacokinetic and pharmacodynamic profiles.

In December 2025, we disclosed that we had completed the first dose level of the Part 1 dose escalation of the Phase 1b clinical trial and had commenced enrollment of the next dose level. Enrollment in the trial remains on track, and we expect to present data from the Part 1 dose escalation in the first quarter of 2027. Upon completion of the dose escalation portion, a dose expansion portion will be conducted in patients with locally advanced or metastatic UC and other Nectin-4 expressing tumors. Based on the results of our trial, we plan to seek alignment with the FDA to conduct a pivotal Phase 2 trial for accelerated approval of [225Ac]Ac-AKY-1189 for locally advanced or metastatic UC and other Nectin-4 expressing tumors. [225Ac]Ac-AKY-1189 was granted Fast Track Designation by the FDA in February 2026 for the treatment of locally advanced or metastatic UC in patients who had progressed on or after prior systemic therapies.

[225Ac]Ac-AKY-2519 targeting B7-H3 expressing tumors

Our second product candidate, [225Ac]Ac-AKY-2519, is designed to deliver 225Ac to B7-H3 (CD276) expressing tumors, including prostate, lung and other solid tumors. B7-H3 is a cell-surface protein that is highly expressed in many types of solid tumors, while having limited expression in normal tissues. In the United States, an estimated 146,000 patients are diagnosed with metastatic NSCLC, small cell lung cancer or prostate cancer annually. We estimate that approximately 90% of all metastatic castration-resistant prostate cancers, 80% of NSCLCs and 70% of small cell lung cancers, express B7-H3, while also being expressed on other solid tumors like breast cancers. High expression of B7-H3 has been correlated with poor overall survival and a lack of responsiveness to anti-PD-1 therapeutics in several tumor types. B7-H3 has attracted substantial clinical development efforts across different modalities, including antibody-drug conjugates, with several late-stage antibody-drug conjugates demonstrating preliminary efficacy signals and acceptable safety profiles. Regarding the potential for B7-H3 as a target in prostate cancer, we believe B7-H3 may be superior to PSMA for imaging and treatment of patients with prostate cancer due to higher sensitivity and tumor specificity with a clean normal tissue expression profile.

We discovered AKY-2519, a highly potent and specific binder of B7-H3, characterized it, and advanced it to a development candidate in the fourth quarter of 2024. AKY-2519, a proprietary 49-amino acid rationally designed miniprotein, met all of our pre-specified development candidate criteria including those for potency, selectivity, thermal stability, radiochemical stability, and solubility. AKY-2519 also met or exceeded our desired pharmacokinetic and biodistribution benchmarks while demonstrating robust preclinical efficacy.

Preclinical studies of [225Ac]Ac-AKY-2519

As shown below, [225Ac]Ac-AKY-2519 demonstrated dose-dependent antitumor activity after a single administration in mice harboring a non-small cell lung cancer cell, or NSCLC, line-derived xenograft tumor. Mice treated with a [225Ac]Ac-AKY-2519 showed marked tumor growth inhibition of 92% for the 1.0 µCi dose and 80% for the 0.5 µCi dose, compared to vehicle (n=8 mice per group), and a best response of 48% regression at the 1.0 µCi group. The observed tumor growth inhibition led to prolonged survival for mice treated at each dose level compared to vehicle-treated mice. Body weight remained constant throughout the treatment period, suggesting that both dose levels of [225Ac]Ac-AKY-2519 were well tolerated.

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[225Ac]Ac-AKY-2519 demonstrated antitumor activity and increased survival in xenograft models

An analysis of B7-H3 expression across human tumor microarrays demonstrated that B7-H3 is highly expressed in multiple solid tumor indications, specifically squamous NSCLC, squamous esophageal, prostate and triple-negative breast cancers, or TNBC. Levels of B7-H3 expression across these indications are comparable to the level of expression of the mouse model utilized in our preclinical studies, supporting the translational relevance of this model and suggesting that a majority of patients in these indications express equivalent or higher levels of B7-H3 compared to the mouse model that responded robustly to [225Ac]Ac-AKY-2519 treatment.

B7-H3 expression across multiple tumor types

Our development strategy for [225Ac]Ac-AKY-2519

[68Ga]Ga-AKY-2519 and [177Lu]Lu-AKY-2519 uptake in tumors and normal tissue biodistribution is currently being assessed in patients with various B7-H3 expressing solid tumors. To date, each of [68Ga]Ga-AKY-2519 and [177Lu]Lu-AKY-2519 has demonstrated compelling tumor uptake across different tumor types with low uptake in normal tissues and a differentiated biodistribution profile, showcasing rapid clearance from normal organ and tissues, including the kidney. We expect the results of the imaging and dosimetry assessment in patients with various tumor types to be reported in mid-2026. In March 2026, our INDs for [225Ac]Ac-AKY-2519 and for [64Cu]Cu-AKY-2519 were cleared by the FDA to proceed to a Phase 1b clinical trial. We expect

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to initiate the multi-site Phase 1b clinical trial mid-2026. We currently anticipate that the Phase 1b program will follow a dose escalation strategy utilizing the BOIN design. The Phase 1b program is planned to enroll patients with mCRPC, NSCLC or small cell lung cancer, using [64Cu]Cu-AKY-2519 for dosimetry and imaging and [225Ac]Ac-AKY-2519 for therapy. Following completion of dose escalation, dose expansions are planned for mCRPC and lung cancers. The primary endpoint will be to assess safety and tolerability of [225Ac]Ac-AKY-2519. Secondary endpoints will include objective response rate (as measured by RECIST v1.1), duration of response, progression-free survival, overall survival, changes in quality of life, and to characterize pharmacokinetic and pharmacodynamic profiles.

Competition

The development and commercialization of new radiopharmaceutical products is highly competitive. We face and will continue to face competition from third parties that use radiopharmaceuticals and from companies focused on more traditional therapeutic modalities. Potential competitors also include academic institutions, government agencies and other public and private research organizations that conduct research, seek patent protection, and establish collaborative arrangements for research, development, manufacturing, and commercialization of new products.

We consider our most direct competitors to be companies developing targeted alpha-based radiopharmaceuticals for the treatment of cancer. There are several companies developing targeted alpha-based radiopharmaceuticals for the treatment of cancer, including Abdera Therapeutics, Actinium Pharmaceuticals, Inc., Alpha9 Oncology, Inc., Artbio AS, Bayer AG, Convergent Therapeutics, Fusion Pharmaceuticals Inc. (acquired by AstraZeneca), Johnson & Johnson, Mariana Oncology, Inc. (acquired by Novartis AG), Perspective Therapeutics, POINT Biopharma Global Inc. (acquired by Eli Lilly), RadioMedix, Inc., Radionetics Oncology, RayzeBio, Inc. (acquired by Bristol Myers Squibb) and Telix Pharmaceuticals Limited. These companies are targeting a wide range of solid and hematologic malignancies using various alpha emitting isotopes, including radium-223, lead-212, and 225Ac. The first and only approved alpha particle-based therapy is Bayer’s Xofigo (radium-223) which is a salt of radium that cannot easily and robustly be attached to a targeting molecule, but naturally localizes to regions where cancer cells infiltrate bone. Xofigo was approved in 2013 for the treatment of prostate cancer with symptomatic bone metastases.

There are several companies with approved beta-emitting radiopharmaceuticals, including Lantheus Holdings, Novartis, Bayer, Sirtex, Boston Scientific and Q BioMed Inc. and other companies developing beta-emitting radiopharmaceuticals, including POINT Biopharma Global (acquired by Eli Lilly), ITM Isotope Technologies Munich SE, Y-Mabs and Telix Pharmaceuticals Limited. The beta emitting isotopes used by these companies include iodine-131, 177Lu, strontium-89 and yttrium-90. A recently approved beta particle-based radiopharmaceutical is Novartis’ Pluvicto, which was approved by the FDA in 2022 for the treatment of patients with metastatic prostate cancer.

Our competitors will also include companies that are or will be developing other treatment methods, including those utilizing other radioisotopes, as well as therapies for the same indications in oncology that we are targeting. In addition to the competitors we face in developing radiopharmaceuticals, we will also face competition in the indications we expect to pursue. To compete effectively with these existing therapies, we will need to demonstrate that our therapies are favorable to existing therapeutics and obtain comparable coverage and reimbursement for our product candidates.

Many of our current or future competitors have significantly greater financial resources and expertise in research and development, isotope supply chain logistics, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals, obtaining reimbursement for and marketing of approved products than we do. Mergers and acquisitions in the biotechnology, pharmaceutical and diagnostic industries may result in even more resources being concentrated among a smaller number of our competitors. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These competitors also compete with us in recruiting and retaining qualified personnel and establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs.

Our commercial opportunity could be reduced or eliminated if our competitors develop and commercialize products that are safer, more effective, have fewer or less severe side effects, are more convenient or are less expensive than any products that we or our collaborators may develop. Our competitors also may obtain FDA or other foreign regulatory approval for their products more rapidly than we may obtain approval for ours, which could result in our competitors establishing a strong market position before we or our collaborators are able to enter the market. Even if the product candidates we may develop in the future achieve regulatory approval, they may be priced at a significant premium over competitive products if any have been approved by then, resulting in reduced competitiveness. Moreover, technological advances or products developed by our competitors may render our technologies or product candidates we may develop in the future obsolete, less competitive, or not economical. The key competitive factors affecting the success of [225Ac]Ac-AKY-1189 and our other current and future product candidates, if approved, are likely to be their efficacy, safety, convenience, price, the level of generic competition and the availability of reimbursement from government and other third-party payors.

Intellectual property

Our success depends in part on our ability to obtain, maintain, protect, defend and enforce proprietary protection for our product candidates and other discoveries, inventions, trade secrets and know-how that are critical to our business operations. Our success

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also depends in part on our ability to operate without infringing, misappropriating or otherwise violating the intellectual property or proprietary rights of others, and in part on our ability to prevent others from infringing, misappropriating or violating our intellectual property or proprietary rights. A discussion of risks relating to intellectual property is provided under the section titled “Risk factors—Risks related to intellectual property.”

With respect to our [225Ac]Ac-AKY-1189 program, as of March 1, 2026, we own one pending international patent application filed under the Patent Cooperation Treaty, or a PCT Application, one issued U.S. patent, one pending U.S. non-provisional utility application and two pending foreign non-provisional patent applications in each of Taiwan and Argentina, which are directed to, among other things, composition of matter and uses of [225Ac]Ac-AKY-1189. We do not own or license, and do not expect to own or license, any patents or patent applications that cover the radioactive payload in [225Ac]Ac-AKY-1189, which is 225Ac. The issued U.S. patent and any patents issuing from the patent applications we own or future patent applications that we may file based on these applications are expected to expire in 2044, excluding any patent term adjustments or extensions that may be available and assuming timely payment of all appropriate maintenance, renewal, annuity or other governmental fees.

With respect to our [225Ac]Ac-AKY-2519 program, as of March 1, 2026, we own one pending PCT Application, one pending U.S. non-provisional utility application, and two pending foreign non-provisional patent applications in each of Taiwan and Argentina, which are directed to, among other things, composition of matter and uses of [225Ac]Ac-AKY-2519. We do not own or license any issued patents related to our [225Ac]Ac-AKY-2519 program. In addition, we do not expect to own or license any patents or patent applications that cover the radioactive payload in [225Ac]Ac-AKY-2519, which is 225Ac. Any patents issuing from the patent applications we own or future patent applications that we may file based on these applications are expected to expire in 2044, excluding any patent term adjustments or extensions that may be available and assuming timely payment of all appropriate maintenance, renewal, annuity or other governmental fees.

With respect to our platform program, as of March 1, 2026, we own one pending PCT Application, 22 pending non-provisional patent applications in each of Australia, Brazil, Canada, Chile, China, Colombia, Eurasia, Europe, Israel, India, Japan, Morocco, Mexico, Peru, Philippines, Saudi Arabia, South Africa, South Korea, Taiwan, Tunisia, United Arab Emirates, and the United States, and one pending U.S. provisional patent application. We do not own or license any issued patents related to our platform program. Any patents that issue from the patent applications we own or future patent applications that we may file based on these applications are expected to expire in 2043, 2045 and 2046, excluding any patent term adjustments or extensions that may be available and assuming timely payment of all appropriate maintenance, renewal, annuity or other governmental fees.

With respect to our discovery programs, as of March 1, 2026, we own one pending PCT Application, one pending U.S. provisional patent application, and four non-provisional patent applications (one each in China, Europe, the United States and South Africa), each of which is directed to compositions of matter and uses for miniproteins against our targets of interest. We do not own or license any issued patents related to our discovery programs. Any patents issuing from the patent applications we own or future patent applications that we may file based on these applications are expected to expire in 2043, 2044 and 2046, excluding any patent term adjustments or extensions that may be available and assuming payment of all appropriate maintenance, renewal, annuity or other governmental fees.

U.S. provisional patent applications are not eligible to become issued patents unless and until, among other things, we file one or more non-provisional U.S., foreign, and/or PCT Applications within 12 months of the first-filed provisional application to which these non-provisional applications claim priority. With regard to such U.S. provisional patent applications, if we do not timely file any non-provisional patent applications, we will lose our priority date with respect to subject matter and inventions disclosed in these provisional patent applications. Provided no statutory bars to patentability have occurred during the 12-month pendency of the provisional patent application, the option to refile and obtain a later filing date remains open. While we intend to timely file non-provisional patent applications related to our provisional patent applications, we cannot predict whether any such patent applications will result in the issuance of patents that provide us with any competitive advantage. Further, our PCT Applications are not eligible to become patents until, among other things, we timely file national stage patent applications in jurisdictions that are party to the Patent Cooperation Treaty, and in which we seek patent protection. If we do not timely file any national stage patent applications, we may lose our priority date with respect to our PCT Applications and any patent protection on inventions disclosed in such PCT Applications.

The proprietary nature of, and protection for, our product candidates and their methods of use are an important part of our strategy to develop and commercialize novel medicines. We have filed for or licensed patents rights relating to certain of our product candidates and are pursuing additional patent protection for them and for our other product candidates and technologies. In addition to patent protection, we also rely on trade secrets, know-how, trademarks, confidential information, other proprietary information and continuing technological innovation to develop, strengthen and maintain our competitive position. We seek to protect and maintain the confidentiality of proprietary information to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection. Although we take steps to protect our proprietary information and trade secrets, including through contractual means with our employees, consultants, contractors and collaborators, third parties may independently develop substantially equivalent proprietary information and techniques or otherwise gain access to our trade secrets or disclose our technology. Thus, we may not be able to meaningfully protect our trade secrets. It is our policy to require our employees, consultants, outside scientific collaborators, sponsored researchers and other advisors to execute confidentiality and invention assignment agreements upon the commencement of employment or consulting relationships with us. However, such

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confidentiality agreements can be breached, and we may not have adequate remedies for any such breach. For more information regarding the risks related to our intellectual property, see the section titled “Risk factors—Risks related to intellectual property.”

License and collaboration agreements

Institute for Protein Innovation License Agreement

On November 1, 2021, we and the Institute for Protein Innovation, Inc., or IPI, entered into an Exclusive License Agreement, as amended on July 26, 2022, the IPI Agreement, pursuant to which IPI granted us an exclusive, worldwide license, with the right to sublicense (subject to certain conditions), under certain of IPI’s patents and know-how related to certain binder proteins, targeting up to 14 target proteins, including Nectin-4, to research, develop, make, have made, and commercialize certain products. Pursuant to the IPI Agreement, IPI also granted us a non-exclusive license to certain intellectual property rights required to research, develop, make, have made, and commercialize certain products.

Upon execution of the IPI Agreement, we paid an upfront license fee of $0.2 million and are required to pay an annual license fee of less than $0.1 million until the first commercial sale of the first licensed product, pursuant to which we have paid an aggregate of $0.2 million through December 31, 2025. The IPI Agreement requires us to pay up to an aggregate of $24.0 million upon achievement of certain regulatory and development milestones. In addition, if we successfully commercialize a licensed product under the IPI Agreement, we are required to pay low single-digit royalties on net sales, on a product-by-product and country-by-country basis, subject to specified reductions, until the later of (a) the expiration of the last to expire valid claim covering the manufacture, use or sale of such licensed product in such country or (b) ten years after the first licensed product sale in such country. The royalties are subject to specified and capped reductions for payments owed to third parties for additional rights necessary to commercialize licensed products.

The IPI Agreement requires us to use diligent and commercially reasonable efforts to develop and commercialize a licensed product.

At any time after the fifth year anniversary of the IPI Agreement, if IPI receives a third-party request to license certain rights granted to us pursuant to the IPI Agreement for which we are not actively developing or commercializing a licensed product, we must either (i) submit a commercially reasonable development plan for such undeveloped field to IPI that we will put into effect within a certain number of days, (ii) substantiate why granting a license to such rights in such undeveloped field to the third party is not in our best business interest or (iii) enter into good faith negotiations with such third party for such rights in such undeveloped field.

Unless earlier terminated, the IPI Agreement will expire at the end of the last to expire royalty term. IPI may, at its election, either terminate the IPI Agreement, convert any of our exclusive license rights into non-exclusive rights, or choose to reduce the field or territory, if (a) the first commercial sale of a licensed product does not occur by January 1, 2035 or the payment of earned royalties, once begun, ceases for more than eight consecutive calendar quarters; (b) we default in the timely payment of any amount due or are otherwise in breach of the IPI Agreement and fail to remedy such default or breach within 30 days after written notice thereof; (c) we are found, on more than one examination, to have underreported or underpaid any royalty payment by more than five percent in any three calendar quarters in the period under examination; (d) we cease to carry on our business related to the subject matter of the licensed patents or (e) we become insolvent or file a petition regarding bankruptcy or insolvency or other certain insolvency or bankruptcy-related events occur. We may terminate the IPI Agreement in its entirety, with or without cause, upon 60 days’ written notice.

TRIUMF License Agreement

On July 21, 2022, we and TRIUMF Inc., a Canadian non-profit, or TRIUMF, TRIUMF Innovations, Inc., a Canadian non-profit, the University of British Columbia, and BC Cancer, a provincial health services authority, entered into a License Agreement, the TRIUMF License. Pursuant to the TRIUMF License, TRIUMF, the University of British Columbia and BC Cancer, or the Licensors, granted us a non-exclusive, worldwide license, with right to sublicense (subject to certain conditions), under certain patents and know-how related to the Licensors’ chelator technology to make, use, sell, offer for sale, import, and export certain radiopharmaceutical products for the diagnosis, treatment, amelioration, and prevention of human diseases and conditions. None of our product candidates currently incorporate, or rely on, the licensed patents and know-how from the TRIUMF License.

We paid an initial license fee of $0.1 million upon execution of the TRIUMF License. The TRIUMF License requires us to pay up to an aggregate of $2.0 million upon achievement of certain regulatory and development milestones. We are also obligated to pay low single digit royalties on net sales of licensed products, on a product-by-product basis.

For licensed products not covered by a valid claim of a licensed patent, our royalty obligation terminates on the tenth anniversary of the first commercial use of such licensed product in each country.

Unless earlier terminated, the TRIUMF License will expire on the later of the twelfth-year anniversary of the TRIUMF License or the expiry of the last patent subject to the TRIUMF License. We may terminate the TRIUMF License for convenience upon 60 days’ written notice. The Licensor may, at its option, terminate the TRIUMF License if (i) we become insolvent, cease to carry on business or other certain insolvency or bankruptcy-related events occur, (ii) we breach certain provisions (including those related to sublicenses, confidentiality, and insurance), (iii) the licensed patents and know-how become subject to any security interest, lien,

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charge or encumbrance in favor of a third party through our action or (iv) there is an uncured breach by our sublicensee and we do not terminate the respective sublicense agreement. Either party may terminate the TRIUMF License for uncured breach, subject to specified cure periods.

University of Minnesota License Agreement

On March 3, 2023, we and the Regents of the University of Minnesota, or the University of Minnesota, entered into an Exclusive License Agreement, the Minnesota License, pursuant to which the University of Minnesota and the Stanford University, or Stanford, granted us, solely for human and veterinary uses, an exclusive license under the University of Minnesota’s and Stanford’s rights in certain patents related to certain binding proteins to make, use, sell, offer for sale, and import certain therapeutic and diagnostic products in the countries where there are licensed patents and a non-exclusive license to use licensed technical information. None of our product candidates incorporate, or rely on, the patents and know-how from the Minnesota License.

We paid an upfront fee of $0.1 million upon entering into the Minnesota License and paid an annual license fee of less than $0.1 million throughout the term of the Minnesota License, pursuant to which we have paid an aggregate of $0.4 million through September 30, 2025. No milestones were achieved under the Minnesota License prior to the termination of this agreement.

In July 2025, we provided notice to the University of Minnesota to terminate the Minnesota License and paid the $10,000 early termination fee, with an effective termination date of September 9, 2025.

Eli Lilly and Company License, Research and Collaboration Agreement

On May 16, 2024, we and Eli Lilly entered into a License, Research and Collaboration Agreement, the Collaboration Agreement. Pursuant to the Collaboration Agreement, we granted Eli Lilly an exclusive (even as to us and our affiliates), royalty-bearing, worldwide license, with the right to sublicense, to certain of our patents and other intellectual property rights to exploit certain compounds and therapeutic or diagnostic products that contain such compounds solely as products that contain a radioactive isotope. We also granted Eli Lilly a non-exclusive, royalty-bearing, worldwide license, with the right to sublicense, to the intellectual property necessary or useful to exploit the licensed compounds and licensed products solely as products that contain a radioactive isotope and a non-exclusive, fully paid-up license, with the right to sublicense, to exploit certain other intellectual property developed under the Collaboration Agreement for any and all purposes (subject to certain limitations). In addition, we and Eli Lilly agreed to negotiate in good faith to enter into a separate agreement in the event the parties agree that the clinical development of a licensed compound requires, or would be benefited by, a license to one of our other compounds.

Under the Collaboration Agreement, Eli Lilly may designate a specified number of initial collaboration targets, with the right to substitute other targets. We will be responsible for research activities through initial human imaging studies for a lead candidate for each selected target, and Eli Lilly will thereafter be responsible for regulatory filings, clinical development and commercialization activities worldwide. There is a separate research plan for each collaboration target, and our development costs are capped, on a research plan-by-research plan basis. Eli Lilly will reimburse our reasonable out-of-pocket costs and full-time equivalent costs incurred in excess of the cap.

Eli Lilly paid us an upfront license fee of $60.0 million upon execution of the Collaboration Agreement. The Collaboration Agreement requires Eli Lilly to pay up to an aggregate of $525.0 million upon achievement of certain research, development, regulatory and commercial launch milestones and up to an aggregate of $630 million upon achievement of certain sales milestones. In addition, if Eli Lilly successfully commercializes a therapeutic or diagnostic product under the Collaboration Agreement, Eli Lilly is required to pay us tiered royalties of up to 10% based on annual net sales, on a product-by-product and country-by-country basis, subject to specified reductions, until the later of the expiration of licensed patent rights in a country, expiration of regulatory exclusivity, or ten years after the first product sale in such country. The Collaboration Agreement requires Eli Lilly to use commercially reasonable efforts to develop and commercialize a licensed product from a research program in certain markets and through satisfaction of certain criteria.

Unless earlier terminated, the Collaboration Agreement will continue on a licensed product-by-licensed product and country-by-country basis until the expiration of the applicable royalty term for such licensed product. Either party may terminate the Collaboration Agreement for uncured material breach, subject to specified cure periods. In certain instances, if Eli Lilly has the right to terminate the Collaboration Agreement for our uncured material breach, Eli Lilly may, at its option, continue the Collaboration Agreement where all payments due from Eli Lilly to us, on a prospective basis, will be reduced by a specified percentage and Eli Lilly diligence and reporting obligations will end. Eli Lilly may, at any time and without cause, terminate the Collaboration Agreement in its entirety or on a collaboration target-by-collaboration target or region-by-region basis upon sixty days’ notice.

In connection with the Collaboration Agreement, we and Eli Lilly entered into a Series A-1 redeemable convertible preferred stock purchase agreement pursuant to which we issued and sold an aggregate of 2,500,000 shares of our Series A-1 redeemable convertible preferred stock at a purchase price of $4.00 per share for aggregate net proceeds of $10.0 million.

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Government regulation

Government authorities in the U.S., including federal, state, and local authorities, and in other countries, extensively regulate, among other things, the manufacturing, research and clinical development, marketing, labeling and packaging, storage, distribution, post-approval monitoring and reporting, advertising and promotion, and export and import of biological products, such as those we are developing. In addition, some government authorities regulate the pricing of such products. The process of obtaining regulatory approvals and the subsequent compliance with appropriate federal, state, local, and foreign statutes and regulations require the expenditure of substantial time and financial resources.

Review and approval for licensing biologics in the U.S.

In the U.S., the FDA regulates biological products under the Federal Food, Drug, and Cosmetic Act, or the FDCA, the Public Health Service Act, or the PHSA, and their implementing regulations. FDA approval is required before any biological product can be marketed in the U.S. Biological products are also subject to other federal, state, and local statutes and regulations. If we fail to comply with applicable FDA or other requirements at any time during the product development process, clinical testing, the approval process or after approval, we may become subject to administrative or judicial sanctions or other consequences, including the FDA’s refusal to allow us to proceed with clinical testing, issuance of clinical holds for planned or ongoing studies, refusal to approve pending applications, license suspension or revocation, withdrawal of an approval, issuance of untitled or warning letters, product recalls, product seizures, import detentions or refusals, total or partial suspension of manufacturing or distribution, injunctions, fines, civil penalties or criminal prosecution. Any such action could have a material adverse effect on us.

The process required by the FDA before product candidates may be marketed in the U.S. generally involves the following:

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completion of extensive nonclinical laboratory tests and nonclinical animal studies in compliance with applicable good laboratory practices, or GLP, requirements;

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submission to the FDA of an IND application, which must become effective before human clinical trials may begin in the U.S. and must be updated annually;

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approval by an independent institutional review board, IRB, or ethics committee representing each clinical site before each clinical trial may be initiated;

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performance of adequate and well-controlled human clinical trials in accordance with good clinical practices, or GCPs, to establish the safety and efficacy of the product candidate for each proposed indication;

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manufacture of the drug substance and drug product in accordance with the FDA’s cGMP requirements, along with required analytical and stability testing;

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preparation of and submission to the FDA of a biologics license application, or BLA, requesting marketing approval for one or more proposed indications, that includes sufficient evidence of establishing the safety, purity and potency of the proposed biological product for its intended indication, including from results of nonclinical testing and clinical trials;

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review of the product application by an FDA Advisory Committee, where appropriate and if applicable;

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a determination by the FDA within 60 days of its receipt of a BLA to file the application for review;

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satisfactory completion of one or more FDA pre-approval inspections of the manufacturing facility or facilities where the proposed product is produced to assess compliance with cGMPs and to assure that the facilities, methods, and controls are adequate to preserve the product’s identity, quality, and strength;

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satisfactory completion of any FDA audits of the nonclinical studies and clinical trial sites to assure compliance with GLPs and GCPs, as applicable, and the integrity of data in support of the BLA;

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payment of user fees under the Prescription Drug User Fee Act, or the PDUFA, unless exempted; and

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the FDA’s review and approval of the BLA.

The nonclinical and clinical testing and approval process requires substantial time, effort, and financial resources, and we cannot be certain that any approvals for our product candidates will be granted on a timely basis, if at all.

Nonclinical studies and investigational New Drug Application

Before testing any biological product in humans, a product candidate must undergo rigorous preclinical testing. Preclinical studies include laboratory evaluations of product chemistry, formulation, and stability, as well as in vitro and animal studies to assess safety and in some cases to establish the rationale for therapeutic use. The conduct of preclinical studies is subject to federal and state regulation and requirements, including GLP requirements for safety/toxicology studies. The results of the preclinical studies, together with manufacturing information and analytical data, must be submitted to the FDA as part of an IND.

An IND is a request for authorization from the FDA to administer an investigational biological product to humans in clinical trials in the U.S. The central focus of an IND submission is on the general investigational plan, the protocol(s) for human trials and the safety of trial participants. The IND also includes results of animal and in vitro studies assessing the toxicology, pharmacokinetics, pharmacology, and pharmacodynamic characteristics of the product; chemistry, manufacturing and controls

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information; and any available human data or literature to support the use of the investigational product. An IND must become effective before human clinical trials may begin. An IND will automatically become effective 30 days after receipt by the FDA, unless before that time the FDA raises concerns or questions related to the proposed clinical trials. In such a case, the IND may be placed on clinical hold and the IND sponsor and the FDA must resolve any outstanding concerns or questions before clinical trials can begin. Accordingly, submission of an IND may or may not result in the FDA allowing clinical trials to commence.

At any time during the initial 30 day IND review period or while clinical trials are ongoing under the IND, the FDA may impose a partial or complete clinical hold. Clinical holds may be imposed by the FDA when there is concern for patient safety, and may be a result of new data, findings, or developments in clinical, nonclinical, and/or chemistry, manufacturing and controls or where there is non-compliance with regulatory requirements. A clinical hold would delay either a proposed clinical trial or cause suspension of an ongoing trial, until all outstanding concerns have been adequately addressed and the FDA has notified the company that investigations may proceed. A separate submission to an existing IND must also be made for each successive clinical trial to be conducted, and the FDA must grant permission, either explicitly or implicitly by not objecting, before each clinical trial can begin.

Clinical trials

Clinical trials involve the administration of the investigational product to human subjects under the supervision of qualified investigators in accordance with GCPs, which include the requirement that all research subjects provide their informed consent for their participation in any clinical trial. Clinical trials are conducted under protocols detailing, among other things, the objectives of the trial, the inclusion and exclusion criteria, the parameters to be used in monitoring safety, and the efficacy criteria to be evaluated. A protocol for each clinical trial and any subsequent protocol amendments must be submitted to the FDA as part of the IND.

Additionally, approval must also be obtained from each clinical trial site’s IRB, before the trials may be initiated and the IRB must monitor the trial until completed. The IRB will consider, among other things, clinical trial design, patient informed consent, ethical factors, the safety of human subjects and the possible liability of the institution. There are also requirements governing the reporting of ongoing clinical trials and clinical trial results to public registries, including on clinicaltrials.gov.

The clinical investigation of a biological product is generally divided into three or four phases. Although the phases are usually conducted sequentially, they may overlap or be combined.

Phase 1. The investigational product is initially introduced into healthy human subjects or, in the case of some products designed to address severe or life-threatening diseases, patients with the target disease or condition. These trials are designed to evaluate the safety, dosage tolerance, metabolism and pharmacologic actions of the investigational product in humans, the side effects associated with increasing doses, and if possible, to gain early evidence on effectiveness.

Phase 2. The investigational product is administered to a limited patient population to evaluate dosage tolerance and optimal dosage, identify possible adverse side effects and safety risks, and preliminarily evaluate efficacy.

Phase 3. The investigational product is administered to an expanded patient population, generally at geographically dispersed clinical trial sites to generate enough data to statistically evaluate safety, purity and potency, to evaluate the overall benefit-risk profile of the investigational product, and to provide an adequate basis for physician labeling.

Phase 4. In some cases, the FDA may condition approval of a BLA for a product candidate on the sponsor’s agreement to conduct additional clinical trials after approval or a sponsor may voluntarily conduct additional clinical trials after approval to gain more information about the biological product. Such post-approval trials are typically referred to as Phase 4 clinical trials.

Sponsors must also report to the FDA, within certain timeframes, serious and unexpected adverse reactions, any clinically important increase in the rate of a serious suspected adverse reaction over that listed in the protocol or investigator’s brochure, or any findings from other studies or animal or in vitro testing that suggest a significant risk in humans exposed to the product candidate. The FDA, the IRB, or the clinical trial sponsor may suspend or terminate a clinical trial at any time on various grounds, including a finding that the research subjects are being exposed to an unacceptable health risk. Additionally, some clinical trials are overseen by an independent group of qualified experts organized by the clinical trial sponsor, known as a data and safety monitoring board or committee. This group provides authorization for whether or not a trial may move forward at designated check points based on access to certain data from the trial. We may also suspend or terminate a clinical trial based on evolving business objectives or competitive climate.

A sponsor of an investigational biological product for a serious disease or condition is required to make available, such as by posting on its website, its policy on evaluating and responding to requests for individual patient access to such investigational biological product. This requirement applies on the earlier of the first initiation of a Phase 2 or Phase 3 trial of the investigational biological product or, as applicable, 15 days after the biological product receives a designation as a breakthrough therapy or fast track product.

Concurrent with clinical trials, sponsors usually complete additional animal studies and must also develop additional information about the chemistry and physical characteristics of the product candidate and finalize a process for manufacturing the drug product in commercial quantities in accordance with cGMP requirements. The manufacturing process must be capable of consistently producing quality batches of the product candidate and manufacturers must develop, among other things, methods for testing the identity, strength, quality, and purity of the final drug product. Additionally, appropriate packaging must be selected and tested, and stability studies must be conducted to demonstrate that the product candidate does not undergo unacceptable deterioration over its shelf life.

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During the development of a new biologic, sponsors are given opportunities to meet with the FDA at certain points. These points may be prior to submission of an IND, at the end of Phase 1, at the end of Phase 2, and before a BLA is submitted. Meetings at other times may be requested. These meetings can provide an opportunity for the sponsor to share information about the data gathered to date, for the FDA to provide advice, and for the sponsor and the FDA to reach agreement on the next phase of development.

Submission of a BLA to the FDA

Assuming successful completion of all required testing in accordance with all applicable regulatory requirements, detailed investigational product information is submitted to the FDA in the form of a BLA requesting approval to market the product for one or more indications. Under federal law, the submission of most BLAs is subject to an application user fee, and the sponsor of an approved BLA is also subject to an annual program fee for each approved biological product on the market. Applications for orphan drug products are exempted from the BLA application fee and may be exempted from program fees, unless the application includes an indication for other than a rare disease or condition.

A BLA must include all relevant data available from pertinent nonclinical studies and clinical trials, including negative or ambiguous results as well as positive findings, together with detailed information relating to the product’s chemistry, manufacturing, controls, and proposed labeling, among other things. Data can come from company-sponsored clinical trials intended to test the safety and effectiveness of a use of a product, or from a number of alternative sources, including trials initiated by investigators. To support marketing approval, the data submitted must be sufficient in quality and quantity to establish the safety and effectiveness of the investigational product to the satisfaction of the FDA.

The FDA conducts a preliminary review of all BLAs within the first 60 days after submission before accepting them for filing to determine whether they are sufficiently complete to permit substantive review. The FDA may request additional information rather than accept an application for filing. Under the performance goals and policies implemented by the FDA under PDUFA, once a BLA has been submitted, the FDA’s goal for novel biological products generally is to review the application within ten months after it accepts the application for filing, or, if the application is granted priority review, six months after the FDA accepts the application for filing. The FDA does not always meet its PDUFA goal dates, and the review process may be extended. For example, the review process and the PDUFA goal date may be extended by three months if the FDA requests or if the applicant otherwise provides additional data, analysis or information that FDA deems a major amendment.

Before approving a BLA, the FDA typically will inspect the facility or facilities where the product is manufactured. The FDA will not approve an application unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and adequate to assure consistent production of the product within required specifications. Additionally, before approving a BLA, the FDA will typically inspect the sponsor and one or more clinical sites to assure compliance with GCPs. Material changes in manufacturing equipment, location, or process post-approval, may result in additional regulatory review and approval.

The FDA is required to refer an application for a novel biological product to an advisory committee or explain why such referral was not made. An advisory committee is a panel of independent experts, including clinicians and other scientific experts, that reviews, evaluates and provides a recommendation as to whether the application should be approved and under what conditions. The FDA is not bound by the recommendations of an advisory committee, but it considers such recommendations carefully when making decisions.

The FDA’s decision on a BLA

On the basis of the FDA’s evaluation of the application and accompanying information, including the results of the inspection of the manufacturing facilities and any FDA inspections of nonclinical and clinical trial sites to assure compliance with GLPs or GCPs, the FDA may approve the BLA or issue a complete response letter. Under the PHSA, the FDA may approve a BLA if it determines the product is safe, pure, and potent, and that the facility in which the product will be manufactured, processed, packaged or held meets standards designed to assure the product’s continued safety, purity and potency. If the FDA determines the product meets those standards, it may issue an approval letter authorizing commercial marketing of the biological product with specific prescribing information for specific indications. If the application is not approved, FDA will issue a complete response letter, which indicates that the review cycle of the application is complete and the application is not ready for approval. A complete response letter will identify the deficiencies that prevent the FDA from approving the application and may require additional clinical data or an additional Phase 3 clinical trial(s), or other significant, expensive and time-consuming requirements related to clinical trials, nonclinical studies or manufacturing. Even if such additional information is submitted, the FDA may ultimately decide that the BLA does not satisfy the criteria for approval and issue a denial.

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The FDA could also approve the BLA with a Risk Evaluation and Mitigation Strategy, or REMS, program to mitigate risks, which could include medication guides, physician communication plans, or elements to assure safe use, such as restricted distribution methods, patient registries and other risk minimization tools. The FDA also may condition approval on, among other things, changes to proposed labeling, development of adequate controls and specifications, or a commitment to conduct one or more post-market studies or clinical trials. Such post-market testing may include Phase 4 clinical trials and surveillance to further assess and monitor the product’s safety and effectiveness after commercialization.

Orphan drug designation

Under the Orphan Drug Act, the FDA may grant orphan designation to a drug or biological product intended to treat a rare disease or condition, which is generally a disease or condition that affects fewer than 200,000 individuals in the U.S., or more than 200,000 individuals in the U.S. and for which there is no reasonable expectation that the cost of developing and making a drug or biological product available in the U.S. for this type of disease or condition will be recovered from sales of the product. Orphan product designation must be requested before submitting a BLA. After the FDA grants orphan product designation, the identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA. Orphan product designation does not convey any advantage in or shorten the duration of the regulatory review and approval process.

Orphan drug designation entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages and user-fee waivers. Additionally, if a product that has orphan designation subsequently receives the first FDA approval for the disease or condition for which it has such designation, the product is entitled to orphan product exclusivity, which means that the FDA may not approve any other applications to market the same drug or biological product for the same indication for seven years, except in limited circumstances, such as a showing of clinical superiority to the product with orphan exclusivity.

The period of exclusivity begins on the date that the marketing application is approved by the FDA and applies only to the indication for which the product has been designated. The FDA may approve a second application for the same product for a different use or a second application for a clinically superior version of the product for the same use. The FDA cannot, however, approve the same product made by another manufacturer for the same indication during the market exclusivity period unless it has the consent of the sponsor, or the sponsor is unable to provide sufficient quantities. If a drug or biological product designated as an orphan product receives marketing approval for an indication broader than what is designated, it may not be entitled to orphan product exclusivity. Orphan drug status in the European Union has similar, but not identical, benefits.

The FDA has historically taken the position that the scope of orphan exclusivity aligns with the approved indication or use of a product, rather than the disease or condition for which the product received orphan designation. However, in Catalyst Pharms., Inc. v. Becerra, 14 F.4th 1299 (11th Cir. 2021), the court disagreed with this position, holding that orphan-drug exclusivity blocked the FDA’s approval of the same drug for all uses or indications within the same orphan-designated disease. On January 24, 2023, the FDA published a notice in the Federal Register to clarify that the FDA intends to continue to apply its longstanding interpretation of the regulations to all matters outside of the scope of the Catalyst order and will continue tying the scope of orphan-drug exclusivity to the uses or indications for which a drug is approved. It is unclear how future litigation, legislation, agency decisions, and administrative actions will impact the scope of orphan drug exclusivity.

Expedited review programs

The FDA offers a number of expedited development and review programs for qualifying product candidates. New biological products are eligible for fast track designation if they are intended to treat a serious or life-threatening disease or condition and demonstrate the potential to address unmet medical needs for the disease or condition. Fast track designation applies to the combination of the product and the specific indication for which it is being studied. The sponsor of a new biologic may request that the FDA designate the biologic as a fast track product at any time during the clinical development of the product. The sponsor of a fast track product has opportunities for more frequent interactions with the applicable FDA review team during product development and, once a BLA is submitted, the product candidate may be eligible for priority review. A fast track product may also be eligible for rolling review, where the FDA may consider for review sections of the BLA on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the submission of the sections of the BLA, the FDA agrees to accept sections of the BLA and determines that the schedule is acceptable, and the sponsor pays any required user fees upon submission of the first section of the BLA.

A product candidate intended to treat a serious or life-threatening disease or condition may also be eligible for breakthrough therapy designation to expedite its development and review. A product candidate can receive breakthrough therapy designation if preliminary clinical evidence indicates that the product candidate, alone or in combination with one or more other drugs or biologics, may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. The designation includes all of the fast track program features, as well as more intensive FDA interaction and guidance beginning as early as Phase 1 and an organizational commitment to expedite the development and review of the product candidate, including involvement of senior managers.

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Any marketing application for a biologic submitted to the FDA for approval, including a product candidate with a fast track designation and/or breakthrough therapy designation, may be eligible for other types of FDA programs intended to expedite development and review, such as priority review. An application for a biological product will receive priority review designation if it is for a biological product that treats a serious condition and, if approved, would provide a significant improvement in safety or effectiveness. The FDA will attempt to direct additional resources to the evaluation of an application for a new biological product designated for priority review in an effort to facilitate the review. For original BLAs, priority review designation means the FDA’s goal is to take action on the marketing application within six months of the 60-day filing date (as compared to ten months under standard review).

Fast track designation, breakthrough therapy designation, and priority review do not change the standards for approval but may expedite the development or approval process. Even if a product candidate qualifies for one or more of these programs, the FDA may later decide that the product no longer meets the conditions for qualification or decide that the time period for FDA review or approval will not be shortened.

Accelerated approval

Product candidates studied for their safety and effectiveness in treating serious conditions may receive accelerated approval upon a determination that the product has an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit, or on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality, that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit, taking into account the severity, rarity or prevalence of the condition and the availability or lack of alternative treatments. As a condition of accelerated approval, the FDA will generally require the sponsor to perform adequate and well-controlled post-marketing clinical studies to verify and describe the anticipated effect on irreversible morbidity or mortality or other clinical benefit. Under the Food and Drug Omnibus Reform Act of 2022, or FDORA, the FDA may require, as appropriate, that such trials be underway prior to approval or within a specific time period after the date of approval for a product granted accelerated approval. Under FDORA, the FDA has increased authority for expedited procedures to withdraw approval of a biologic or indication approved under accelerated approval if, for example, the sponsor fails to conduct the required post-marketing studies or if such studies fail to verify the predicted clinical benefit. In addition, for products being considered for accelerated approval, the FDA generally requires, unless otherwise informed by the FDA, that all advertising and promotional materials intended for dissemination or publication within 120 days of marketing approval be submitted to FDA for review during the pre-approval period. After 120 days following marketing approval, unless otherwise informed by the FDA, advertising and promotional materials must be submitted at least 30 days prior to the intended time of initial dissemination or publication.

Project Optimus

In 2021, the FDA’s Oncology Center of Excellence launched Project Optimus, an initiative to reform the dose optimization and dose selection paradigm in oncology drug development to emphasize selection of an optimal dose, which is a dose that maximizes not only the efficacy of a drug but also its safety and tolerability.

Project Optimus was driven by the FDA’s concerns that the historical approach to dose selection, which generally determined the maximum tolerated dose, may have resulted in doses and schedules of molecularly targeted therapies that were inadequately characterized before the initiation of pivotal trials.

Project Optimus requires the implementation of strategies for dose finding and dose optimization that leverage nonclinical and clinical data in dose selection, including randomized evaluations of a range of doses in trials. This initiative emphasizes the performance of dose finding and dose optimization studies as early and efficiently as possible in development programs. In support of this initiative, the FDA may request sponsors of oncology product candidates to conduct dose optimization studies.

Post-approval requirements

Biological products manufactured or distributed pursuant to FDA approvals are subject to pervasive and continuing regulation by the FDA, including, among other things, requirements relating to recordkeeping, periodic reporting, product sampling and distribution, advertising and promotion and reporting of adverse experiences with the product. After approval, most changes to the approved product, such as adding new dosage forms, indications or other labeling claims, are subject to prior FDA review and approval.

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Biological product manufacturers are required to register their establishments with the FDA and certain state agencies and are subject to periodic unannounced inspections for compliance with cGMPs. Changes to the manufacturing process are strictly regulated, and, depending on the significance of the change, may require prior FDA approval before being implemented. FDA regulations also require investigation and correction of any deviations from cGMP and impose reporting and documentation requirements upon us and any third-party manufacturers that we may decide to use. Manufacturers and manufacturers’ facilities are also required to comply with applicable product tracking and tracing requirements and notify the FDA of counterfeit, diverted, stolen and intentionally adulterated products or products that are otherwise unfit for distribution in the U.S. Accordingly, manufacturers must continue to expend time, money and effort in the area of production and quality control to maintain compliance with cGMP and other aspects of regulatory compliance.

A biological product may also be subject to official lot release, meaning that the manufacturer is required to perform certain tests on each lot of the product before it is released for distribution. If the product is subject to official lot release, the manufacturer must submit samples of each lot, together with a release protocol showing a summary of the history of manufacture of the lot and the results of all of the manufacturer’s tests performed on the lot, to the FDA. The FDA may perform certain confirmatory tests on lots of some products before releasing the lots for distribution.

Until we are able to establish our own cGMP manufacturing facility, we expect to continue to rely on third parties for the production of clinical quantities of our product candidates, and expect to rely in the future on third parties for the production of commercial quantities. Future FDA and state inspections may identify compliance issues at our facilities or at the facilities of our contract manufacturers that may disrupt production, or distribution, or may require substantial resources to correct. In addition, discovery of previously unknown problems with a product or the failure to comply with applicable requirements may result in restrictions on a product, manufacturer or holder of an approved BLA, including withdrawal or recall of the product from the market or other voluntary, FDA-initiated or judicial action that could delay or prohibit further marketing.

The FDA may suspend or revoke product license approvals if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or with manufacturing processes, or failure to comply with regulatory requirements, may result in revisions to the approved labeling to add new safety information; imposition of post-market studies or clinical trials to assess new safety risks; or imposition of distribution restrictions or other restrictions under a REMS program.

FDA has authority to require post-market studies, in certain circumstances, on reduced effectiveness of a biological product and FDA may require labeling changes related to new reduced effectiveness information. Other potential consequences of a failure to maintain regulatory compliance include, among other things:

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restrictions on the marketing or manufacturing of the product, complete withdrawal of the product from the market or product recalls;

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issuance of safety alerts, Dear Healthcare Provider letters, press releases or other communications containing warnings or other safety information about the product;

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untitled letters or warning letters;

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imposition of clinical holds on ongoing clinical trials;

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refusal of the FDA to approve pending BLAs or supplements to approved BLAs, or suspension or revocation of approved BLAs;

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product seizure or detention, or refusal to permit the import or export of products;

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mandated modification of promotional materials and labeling, and the issuance of corrective information;

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consent decrees, corporate integrity agreements, debarment or exclusion from federal healthcare programs; or

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fines, injunctions or the imposition of civil or criminal penalties.

The FDA strictly regulates marketing, labeling, advertising, and promotion of prescription drug products, including biological products. These regulations include, among other things, standards and regulations for direct-to- consumer advertising, communications regarding unapproved uses, industry-sponsored scientific and educational activities and promotional activities involving the internet and social media. Promotional claims about a drug’s safety or effectiveness are prohibited before the BLA is approved. Once a BLA is approved, the sponsor can only make those claims relating to safety, efficacy, purity and potency that are consistent with the biological product’s approved label. Additionally, promotional materials for prescription drug products must be submitted to the FDA in conjunction with their first use.

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In the U.S., healthcare professionals are generally permitted to prescribe legally available drugs for uses that are not described in the product’s labeling and that differ from those approved by the FDA. The FDA does not regulate the practice of medicine or healthcare providers’ choice of treatments; however, FDA restricts manufacturers’ communications of off-label uses. If a company, including any agent of the company or anyone speaking on behalf of the company, is found to have promoted off-label uses, the company may become subject to adverse public relations and administrative and judicial enforcement by the FDA, the DOJ, or the Office of the Inspector General of HHS, as well as state authorities. This could subject a company to a range of penalties that could have a significant commercial impact, including civil and criminal fines and agreements that materially restrict the manner in which a company promotes or distributes drug products. The federal government has levied large civil and criminal fines against companies for alleged improper promotion and has also requested that companies enter into consent decrees or permanent injunctions under which specified promotional conduct is changed or curtailed.

Pediatric trials and exclusivity

Under the Pediatric Research Equity Act of 2003, a BLA (or BLA supplement thereto) must contain data that are adequate to assess the safety and effectiveness of the product for the claimed indications in all relevant pediatric subpopulations and to support dosing and administration for each pediatric subpopulation for which the product is safe and effective. A sponsor who is planning to submit a marketing application for a biological product that includes a new active ingredient, new indication, new dosage form, new dosing regimen or new route of administration must submit an initial Pediatric Study Plan, or PSP, within sixty days of an end of Phase 2 meeting or as may be agreed between the sponsor and FDA. The initial PSP must include an outline of the pediatric study or studies that the sponsor plans to conduct, including study objectives and design, age groups, relevant endpoints and statistical approach, or a justification for not including such detailed information, and any request for a deferral of pediatric assessments or a full or partial waiver of the requirement to provide data from pediatric studies along with supporting information. Generally, development program candidates designated as orphan drugs are exempt from the above requirements. FDA and the sponsor must reach agreement on the PSP. A sponsor can submit amendments to an agreed upon initial PSP at any time if changes to the pediatric plan need to be considered based on data collected from nonclinical studies, early phase clinical trials, and/or other clinical development programs.

The FDA may, on its own initiative or at the request of the applicant, grant deferrals for submission of some or all pediatric data until after approval of the product for use in adults, or full or partial waivers from the pediatric data requirements. The FDA may send a non-compliance letter to any sponsor that fails to submit the required assessment, keep a deferral current or fails to submit a request for approval of a pediatric formulation. Unless otherwise required by regulation, the pediatric data requirements do not apply to products with orphan designation.

Pediatric exclusivity is another type of non-patent exclusivity in the U.S. and, if granted for a biologic, provides for the attachment of an additional six months of marketing protection to the term of any existing regulatory exclusivity for all formulations, dosage forms, and indications of the biologic, including the five-year and three-year non-patent and orphan exclusivity. This six-month exclusivity may be granted if a BLA sponsor submits pediatric data that fairly respond to a written request from the FDA for such data, provided that at the time pediatric exclusivity is granted there is not less than nine months of term remaining. The data do not need to show the product to be effective in the pediatric population studied; rather, if the clinical trial is deemed to fairly respond to the FDA’s request, the additional protection is granted. If reports of FDA-requested pediatric trials are submitted to and accepted by the FDA within the statutory time limits, whatever statutory or regulatory periods of exclusivity or patent protection covering the product are extended by six months. This is not a patent term extension, but it effectively extends the regulatory period during which the FDA cannot accept or approve another application relying on the BLA sponsor’s data.

Patent term restoration

Depending upon the timing, duration, and specifics of the FDA approval of the use of our product candidates, some of our U.S. patents may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, commonly referred to as the Hatch-Waxman Amendments. The Hatch-Waxman Amendments permit a patent restoration term of up to five years as compensation for patent term lost during product development and the FDA regulatory review process. However, patent term restoration cannot extend the remaining term of a patent beyond a total of 14 years from the product’s approval date. The patent term restoration period is generally one-half the time between the effective date of an IND and the submission date of a BLA, plus the time between the submission date and the approval of that application. Only one patent applicable to an approved product is eligible for the extension and the application for the extension must be submitted prior to the expiration of the patent and within 60 days of the product’s approval. The U.S. Patent and Trademark Office, in consultation with the FDA, reviews and approves the application for any patent term extension or restoration. In the future, we may apply for restoration of patent term for one of our currently owned or licensed patents to add patent life beyond its current expiration date, depending on the expected length of the clinical trials and other factors involved in the filing of the relevant BLA.

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Regulation of diagnostic patient selection tool

We believe that the success of certain of our product candidates may depend, in part, on the development and commercialization of an imaging agent that will serve, where needed, as a patient selection tool. This diagnostic imaging agent is subject to FDA regulation, review, and approval in the same manner as the therapeutic biological products we are seeking to develop and commercialize and are subject to the same risks.

Other regulatory matters

Manufacturing, sales, promotion and other activities of product candidates following product approval, where applicable, or commercialization are also subject to regulation by numerous regulatory authorities in the U.S. in addition to the FDA, which may include the Centers for Medicare & Medicaid Services, or CMS, other divisions of the Department of Health and Human Services, or HHS, the Department of Justice, the Drug Enforcement Administration, the Consumer Product Safety Commission, the Federal Trade Commission, the Occupational Safety & Health Administration, the Environmental Protection Agency and state and local governments and governmental agencies.

European Union/rest of world government regulation

In addition to regulations in the U.S., we will be subject to a variety of regulations in other jurisdictions governing, among other things, clinical trials and any commercial sales and distribution of our products. The cost of establishing a regulatory compliance system for numerous varying jurisdictions can be very significant. Although many of the issues discussed above with respect to the United States apply similarly in the context of the European Union and in other jurisdictions, the approval process varies between countries and jurisdictions and can involve additional product testing and additional administrative review periods. The time required to obtain approval in other countries and jurisdictions might differ from and be longer than that required to obtain FDA approval. Regulatory approval in one country or jurisdiction does not ensure regulatory approval in another, but a failure or delay in obtaining regulatory approval in one country or jurisdiction may negatively impact the regulatory process in others.

Whether or not we obtain FDA approval for a product, we must obtain the requisite approvals from regulatory authorities in foreign countries prior to the commencement of clinical trials or marketing of the product in those countries. Certain countries outside of the United States have a similar process that requires the submission of a clinical trial application much like the IND prior to the commencement of human clinical trials. In the European Union, for example, a clinical trial authorization application must be submitted for each clinical protocol to each country’s national health authority and an independent ethics committee, much like the FDA and IRB, respectively. Under the EU Clinical Trials Regulation, this is now done through a single application submitted through the Clinical Trials Information System, or CTIS, as described in more detail below.

The requirements and process governing the conduct of clinical trials vary from country to country. In all cases, the clinical trials are conducted in accordance with GCP, the applicable regulatory requirements, and the ethical principles that have their origin in the Declaration of Helsinki.

To obtain regulatory approval of a medicinal product under European Union regulatory systems, we must submit a marketing authorization application. The content of the BLA filed in the U.S. is similar to that required in the European Union, with the exception of, among other things, country-specific document requirements.

For other countries outside of the European Union, such as countries in Eastern Europe, Latin America or Asia, the requirements governing product licensing, pricing, and reimbursement vary from country to country.

Countries that are part of the European Union, as well as countries outside of the European Union, have their own governing bodies, requirements, and processes with respect to the approval of biological products. If we fail to comply with applicable foreign regulatory requirements, we may be subject to, among other things, fines, suspension or withdrawal of regulatory approvals, product recalls, seizure of products, operating restrictions and criminal prosecution.

Clinical trial approval in the European Union

In April 2014, the European Union adopted the Clinical Trials Regulation (EU) No 536/2014, which replaced the Clinical Trials Directive 2001/20/EC on January 31, 2022. The Clinical Trials Regulation is directly applicable in all European Union Member States meaning no national implementing legislation in each European Union Member State is required. The Clinical Trials Regulation aims to simplify and streamline the approval of clinical trials in the European Union. The main characteristics of the regulation include: a streamlined application procedure via a single-entry point, through the CTIS; a single set of documents to be prepared and submitted for the application as well as simplified reporting procedures for clinical trial sponsors; and a harmonized procedure for the assessment of applications for clinical trials, which is divided in two parts (Part I contains scientific and medicinal product documentation and Part II contains the national and patient-level documentation). Part I is assessed by a coordinated review by the competent authorities of all European Union Member States in which an application for authorization of a clinical trial has

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been submitted (Member States concerned) of a draft report prepared by a reference Member State. Part II is assessed separately by each Member State concerned. Strict deadlines have also been established for the assessment of clinical trial applications.

Marketing authorization procedures in the European Union

Medicines can be authorized in the European Union by using either the centralized authorization procedure or national authorization procedures.

The European Commission implemented the centralized procedure for the approval of human medicines to facilitate marketing authorizations that are valid throughout the European Economic Area, or the EEA, which is comprised of the Member States of the European Union plus Norway, Iceland, and Lichtenstein. The centralized procedure is administered by the European Medicines Agency, or EMA, and is compulsory for human medicines that are: derived from certain biotechnology processes, such as genetic engineering, contain a new active substance indicated for the treatment of certain diseases, such as HIV, AIDS, cancer, diabetes, neurodegenerative disorders or autoimmune diseases and other immune dysfunctions, advanced therapy medicines (gene therapy, somatic cell therapy or tissue-engineered medicines), and officially designated orphan medicines.

For medicines that do not fall within these categories, an applicant has the option of submitting an application for a centralized marketing authorization to the EMA, as long as the medicine concerned contains a new active substance not yet authorized in the European Union, is a significant therapeutic, scientific or technical innovation, or if its authorization would be in the interest of public health in the European Union.

Under the centralized procedure, the EMA’s Committee for Medicinal Products for Human Use, or the CHMP, is responsible for conducting the initial assessment of a product and for several post-authorization and maintenance activities, such as the assessment of modifications or extensions to an existing marketing authorization. Under the centralized procedure in the European Union, the maximum timeframe for the evaluation of a marketing authorization application is 210 days (excluding clock stops, when additional written or oral information is to be provided by the applicant in response to questions asked by the CHMP). Clock stops may extend the timeframe of evaluation of a marketing authorization application considerably beyond 210 days. Where the CHMP gives a positive opinion, it provides the opinion together with supporting documentation to the European Commission, who makes the final decision to grant a marketing authorization, which is issued within 67 days of receipt of the EMA’s recommendation. Accelerated evaluation might be granted by the CHMP in exceptional cases, when a medicinal product is expected to be of a major public health interest, particularly from the point of view of therapeutic innovation. In this circumstance, the EMA ensures that the opinion of the CHMP is given within 150 days, excluding clock stops, but it is possible that the CHMP can revert to the standard time limit for the centralized procedure if it considers that it is no longer appropriate to conduct an accelerated assessment.

Prior to obtaining a marketing authorization in the European Union, applicants must demonstrate compliance with all measures included in an EMA-approved pediatric investigation plan, or PIP, covering all subsets of the pediatric population, unless the EMA has granted a product-specific waiver, a class waiver, or a deferral for one or more of the measures included in the PIP. The Pediatric Committee of the EMA, or the PDCO, may grant deferrals for some medicines, allowing a company to delay development of the medicine for children until there is enough information to demonstrate its effectiveness and safety in adults. The PDCO may also grant waivers when development of a medicine for children is not needed or is not appropriate, such as for diseases that only affect the elderly population.

Data and market exclusivity in the European Union

In the European Union, innovative medicinal products approved on the basis of a complete and independent data package qualify for eight years of data exclusivity upon marketing authorization and an additional two years of market exclusivity. This data exclusivity, if granted, prevents regulatory authorities in the European Union from referencing the innovator’s pre-clinical and clinical trial data contained in the dossier of the reference product when applying for a generic or biosimilar marketing authorization in the European Union, during a period of eight years from the date on which the reference product was first authorized in the European Union.

Reform of the regulatory framework in the European Union

The European Commission introduced legislative proposals in April 2023 that, if implemented, will replace the current regulatory framework in the European Union for all medicines (including those for rare diseases and for children). The European Commission has provided the legislative proposals to the European Parliament and the European Council for their review and approval and, in April 2024, the European Parliament proposed amendments to the legislative proposals. Once the European Commission’s legislative proposals are approved (with or without amendment), they will be adopted into European Union law.

The aforementioned European Union rules are generally applicable in the EEA.

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Brexit and the Regulatory Framework in the United Kingdom

The United Kingdom, or UK, formally left the European Union on January 31, 2020, and the European Union and the UK have concluded a trade and cooperation agreement, or TCA, which was provisionally applicable since January 1, 2021 and has been formally applicable since May 1, 2021. The TCA includes specific provisions concerning pharmaceuticals, which include the mutual recognition of cGMP, inspections of manufacturing facilities for medicinal products and cGMP documents issued, but does not provide for wholesale mutual recognition of UK and EU pharmaceutical regulations. At present, Great Britain has implemented European Union legislation on the marketing, promotion and sale of medicinal products through the Human Medicines Regulations 2012 (as amended) (under the Northern Ireland Protocol, the European Union regulatory framework currently continues to apply in Northern Ireland). The regulatory regime in Great Britain therefore aligns in many ways with current European Union regulations, however it is likely that these regimes will diverge significantly in the future now that Great Britain’s regulatory system is independent from the European Union and the TCA does not provide for mutual recognition of UK and European Union pharmaceutical legislation. However, notwithstanding that there is no wholesale recognition of European Union pharmaceutical legislation under the TCA, under a new international recognition procedure which was put in place by the Medicines and Healthcare products Regulatory Agency, or the MHRA, on January 1, 2024, the MHRA may take into account decisions on the approval of a marketing authorization from the EMA (and certain other regulators) when considering an application for a Great Britain marketing authorization.

On February 27, 2023, the UK government and the European Commission announced a political agreement in principle to replace the Northern Ireland Protocol with a new set of arrangements, known as the “Windsor Framework”. This new framework fundamentally changes the existing system under the Northern Ireland Protocol, including with respect to the regulation of medicinal products in the UK. In particular, the MHRA will be responsible for approving all medicinal products destined for the UK market (i.e., Great Britain and Northern Ireland), and the EMA will no longer have any role in approving medicinal products destined for Northern Ireland. A single UK-wide marketing authorization will be granted by the MHRA for all medicinal products to be sold in the UK, enabling products to be sold in a single pack and under a single authorization throughout the UK. The Windsor Framework was approved by the EU-UK Joint Committee on March 24, 2023, so the UK government and the European Union will enact legislative measures to bring it into law. On June 9, 2023, the MHRA announced that the medicines aspects of the Windsor Framework will apply from January 1, 2025.

Pharmaceutical coverage, pricing and reimbursement

In the U.S. and foreign markets, sales of any products for which we may receive regulatory approval for commercial sale will depend in part on the availability of coverage and reimbursement for our products from third-party payors, such as government healthcare programs (e.g., Medicare, Medicaid), managed care organizations, private health insurers, health maintenance organizations, and other organizations. These third-party payors decide which medications they will pay for and will establish reimbursement levels. The availability of coverage and extent of reimbursement by governmental and other third-party payors is essential for patients depending on government or commercial insurance to pay for the costs of prescription medications and other medical products.

In the U.S., the principal decisions about reimbursement for new medicines are typically made by the CMS, an agency within the HHS. CMS decides whether and to what extent products will be covered and reimbursed under Medicare and private payors tend to follow CMS to a substantial degree. Third-party payors may also limit coverage to specific products on an approved list, or formulary, which might not include all of the FDA-approved products for a particular indication.

Factors payors consider in determining reimbursement are based on whether the product is:

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a covered benefit under its health plan;

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safe, effective and medically necessary;

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appropriate for the specific patient;

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cost-effective; and

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neither experimental nor investigational.

Our ability to successfully commercialize our product candidates will depend in part on the extent to which coverage and adequate reimbursement for these products and related treatments will be available from third-party payors, including government healthcare programs (e.g., Medicare, Medicaid), managed care organizations, private health insurers, health maintenance organizations, and other organizations. Moreover, a payor’s decision to provide coverage for a drug product does not imply that an adequate reimbursement rate will be approved.

In the U.S., no uniform policy of coverage and reimbursement for drug products exists among third-party payors. Therefore, coverage and reimbursement for drug products can differ significantly from payor to payor. One payor’s determination to provide coverage for a product does not assure that other payors will also provide coverage and reimbursement for the product, and the level of coverage and reimbursement can differ significantly from payor to payor. Third-party payors are increasingly challenging pharmaceutical prices and examining the medical necessity and cost- effectiveness of medical products and services, in addition to their safety and efficacy. In order to secure coverage and reimbursement for any product that might be approved for sale, we may need to conduct expensive pharmacoeconomic studies in order to demonstrate the medical necessity and cost-effectiveness of our

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products, in addition to the costs required to obtain FDA or comparable regulatory approvals. Additionally, we may also need to provide discounts to purchasers, private health plans or government healthcare programs. Our product candidates may nonetheless not be considered medically necessary or cost-effective. If third-party payors do not consider a product to be cost-effective compared to other available therapies, they may not cover the product after approval as a benefit under their plans or, if they do, the level of payment may not be sufficient to allow a company to sell its products at a profit. A decision by a third-party payor not to cover a product could reduce utilization once the product is approved and have a material adverse effect on sales, our operations and financial condition.

Further, the process for determining whether a payor will provide coverage for a product may be separate from the process for setting the reimbursement rate that the payor will pay for the product. A payor’s decision to provide coverage for a drug product does not imply that an adequate reimbursement rate will be approved. Even if we obtain coverage for a given product, the resulting reimbursement payment rates might not be adequate for us to achieve or sustain profitability or may require co-payments that patients find unacceptably high. There is significant uncertainty related to insurance coverage and reimbursement of newly approved products. It is difficult to predict at this time what third-party payors will decide with respect to the coverage and reimbursement for our product candidates.

Net prices for drugs may be reduced by mandatory discounts or rebates required by government healthcare programs or private payors and impacted by any future relaxation of laws that presently restrict imports of drugs from countries where they may be sold at lower prices than in the U.S. In addition, many pharmaceutical manufacturers must calculate and report certain price reporting metrics to the government, such as average sales price and best price. Penalties may apply in some cases when such metrics are not submitted accurately and timely.

The marketability of any product candidates for which we receive regulatory approval for commercial sale may suffer if third-party payors fail to provide adequate coverage and reimbursement. In addition, emphasis on managed care in the U.S. has increased and could increase the pressure on pharmaceutical pricing. Coverage policies and third-party reimbursement rates may change at any time. Even if favorable coverage and reimbursement status is attained for one or more products for which we receive regulatory approval, less favorable coverage policies and reimbursement rates may be implemented in the future.

Other U.S. Healthcare Laws

Healthcare providers, physicians, and third-party payors will play a primary role in the recommendation and prescription of drug products for which we obtain marketing approval. Arrangements with third-party payors, healthcare providers and physicians, as well as patients and other third parties, in connection with the clinical research, sales, marketing and promotion of products, once approved, and related activities, may expose a pharmaceutical manufacturer to broadly applicable fraud and abuse and other healthcare laws and regulations. In the U.S., these laws include, without limitation, state and federal anti-kickback, false claims, transparency, consumer protection, and patient data privacy and cybersecurity laws and regulations, including but not limited to those described below:

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The Anti-Kickback Statute, or AKS, makes it illegal for any person or entity, including a prescription drug manufacturer (or a party acting on its behalf) to knowingly and willfully solicit, receive, offer or pay any remuneration (including any kickback, bribe, or rebate), directly or indirectly, overtly or covertly, in cash or in kind, that is intended to induce or reward, referrals including the purchase, recommendation, order or prescription of a particular drug for which payment may be made, in whole or in part, under a federal healthcare program, such as the Medicare and Medicaid programs. The term “remuneration” has been broadly interpreted to include anything of value. The AKS has been interpreted to apply to arrangements between pharmaceutical manufacturers on one hand and prescribers, purchasers, patients, and formulary managers on the other. A person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation. Further, courts have found that if “one purpose” of remuneration is to induce referrals, the AKS is violated. In addition, the government may assert that a claim including items or services resulting from a violation of the AKS constitutes a false or fraudulent claim for purposes of the federal False Claims Act, or FCA.

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The federal civil and criminal false claims laws, including the FCA, impose criminal and civil penalties against individuals or entities for, among other things, knowingly presenting, or causing to be presented, claims for payment or approval from Medicare, Medicaid, or other federal or state health care programs that are false or fraudulent; knowingly making or causing a false statement material to a false or fraudulent claim or an obligation to pay or transmit money or property to the federal government; or knowingly concealing or knowingly and improperly avoiding or decreasing such an obligation. The FCA also permits a private individual acting as a whistleblower to bring actions on behalf of the federal government alleging violations of the FCA and to share in any monetary recovery. Manufacturers can be held liable under the federal False Claims Act even when they do not submit claims directly to government payors if they are deemed to “cause” the submission of false or fraudulent claims. Pharmaceutical and other healthcare companies have been, and continue to be, prosecuted under these laws, among other things, for allegedly providing kickbacks to providers or patients or causing false claims to be submitted because of the companies’ marketing of the product for unapproved, off-label, and thus

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generally non-reimbursable, uses. Similar to the AKS, a person or entity does not need to have actual knowledge of these statutes or specific intent to violate them in order to have committed a violation.

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The Civil Monetary Penalties Law, which covers a variety of conduct, often violations under other laws, and includes penalties for violating the AKS, causing the submission of false claims, and offering or transfer of remuneration to a Medicare or state healthcare program beneficiary if the person knows or should know it is likely to influence the beneficiary’s selection of a particular provider, practitioner, or supplier of services reimbursable by Medicare or a state healthcare program.

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The federal Health Insurance Portability and Accountability Act of 1996, or HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act of 2009, or HITECH, and their respective implementing regulations, imposes criminal and civil liability for knowingly and willfully executing, or attempting to execute, a scheme to defraud any healthcare benefit program (e.g., public or private) or making any false, fictitious or fraudulent statements in connection with the delivery of, or payment for, healthcare benefits, items or services relating to healthcare matters. Like the AKS, the Patient Protection and Affordable Care Act, or the ACA, amended the intent standard for certain healthcare fraud statutes under HIPAA such that a person or entity no longer needs to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation.

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HIPAA, also imposes requirements related to the privacy, security and transmission of individually identifiable health information that may apply to many healthcare providers, physicians, and third-party payors with whom we interact.

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The federal Physician Payments Sunshine Act and its implementing regulations, which require manufacturers of drugs, devices, biologics and medical supplies for which payment is available under Medicare, Medicaid or the Children’s Health Insurance Program, with specific exceptions, to report annually to CMS, under the Open Payments Program, information related to payments or other transfers of value made to physicians (which has the same meaning as under Section 1861(r) of the Social Security Act, which generally includes doctors of medicine, osteopathy, dentists, optometrists, podiatrists and chiropractors who are legally authorized to practice by a state), to certain non-physician providers such as physician assistants and nurse practitioners, and to teaching hospitals, as well as ownership and investment interests held by physicians and their immediate family members.

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Federal government price reporting laws, which require manufacturers to calculate and report certain calculated product prices to the government or provide certain discounts or rebates to government authorities or private entities, often as a condition of reimbursement under governmental healthcare programs.

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Federal consumer protection and unfair competition laws broadly regulate marketplace activities and activities that potentially harm consumers.

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Analogous state laws and regulations, such as state anti-kickback, false claims, consumer protection and unfair competition laws which may apply to pharmaceutical business practices, including but not limited to, research, distribution, sales and marketing arrangements as well as submitting claims involving healthcare items or services reimbursed by any third-party payor, including commercial insurers; state laws that require pharmaceutical companies to comply with the pharmaceutical industry’s voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government that otherwise restricts payments that may be made to healthcare providers and other potential referral sources; state laws that require drug manufacturers to file reports with states regarding pricing and marketing information, such as the tracking and reporting of gifts, compensation and other remuneration and items of value provided to healthcare professionals and entities; state and local laws requiring the registration of pharmaceutical sales representatives; and state laws governing the privacy and security of health information in certain circumstances, many of which differ from each other in significant ways and may not have the same effect, thus complicating compliance efforts. The scope and enforcement of each of these laws is uncertain and subject to rapid change in the current environment of healthcare reform. In addition, commercialization of any drug product outside the U.S. will also likely be subject to foreign equivalents of the healthcare laws mentioned above, among other foreign laws.

Because of the breadth of these laws and the narrowness of the statutory exceptions and safe harbors available, it is possible that some of our business activities could be subject to challenge under one or more of such laws in the future. If our operations are found to be in violation of any of such laws or any other governmental regulations that apply to us, we may be subject to, on a corporate or individual basis, penalties, including civil and criminal penalties, damages, fines, the curtailment or restructuring of our operations, the exclusion from participation in federal and state healthcare programs and even imprisonment, any of which could materially adversely affect our ability to operate our business and our financial results. In addition, the cost of implementing sufficient systems, controls, and processes to ensure compliance with all of the aforementioned laws could be significant. Any action for violation of these laws, even if successfully defended, could cause us to incur significant legal expenses and divert management’s attention from the operation of the company’s business. If any of the physicians or other healthcare providers or entities with whom we expect to do business is found noncompliant with applicable laws, that person or entity may be subject to criminal, civil or administrative sanctions, including exclusions from government funded healthcare programs.

It is not always possible to identify and deter employee misconduct, and the precautions we take to detect and prevent inappropriate conduct may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to be in compliance with such laws or regulations. Efforts to ensure that our business arrangements will comply with applicable healthcare laws may involve substantial costs. It is

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possible that governmental and enforcement authorities will conclude that our business practices may not comply with current or future statutes, regulations or case law interpreting applicable fraud and abuse or other healthcare laws and regulations. If any such actions are instituted against us and we are not successful in defending ourselves or asserting our rights those actions, our business may be impaired.

In the ordinary course of our business, we and the third parties upon which we rely collect, receive, store, or otherwise process personal data, including information we may collect about participants in our clinical trials. Our data processing activities subject us to numerous, evolving data privacy and cybersecurity obligations, such as various laws, regulations, guidance, industry standards, external and internal privacy and security policies, contractual requirements, and other obligations relating to data privacy and cybersecurity.

The legislative and regulatory framework for the processing of personal data worldwide is rapidly evolving in a manner that is increasingly stringent and, globally, this legal and regulatory framework is likely to remain uncertain for the foreseeable future. In the U.S., numerous federal, state and local laws and regulations, including federal health information privacy laws, state information security and data breach notification laws, federal consumer protection laws (e.g., Section 5 of the Federal Trade Commission Act), state consumer protection and privacy laws, and other similar laws (e.g., wiretapping and communications interception laws) govern the processing of health-related and other personal data.

At the state level, numerous U.S. states have enacted comprehensive privacy laws that impose certain obligations on covered businesses, including providing specific disclosures in privacy notices and affording individuals certain rights concerning their personal data. Similar laws are being considered in several other states, as well as at the federal and local levels, and we expect more states to pass similar laws in the future. While existing state comprehensive privacy laws exempt some data processed in the context of clinical trials, these developments may further complicate compliance efforts, and increase legal risk and compliance costs for us and the third parties upon whom we rely.

Additionally, a smaller number of states have passed or are considering laws governing the privacy of consumer health data. For example, Washington’s My Health My Data Act broadly defines consumer health data, creates a private right of action to allow individuals to sue for violations of the law, imposes stringent consent requirements, and grants consumers certain rights with respect to their health data, including to request deletion of their information. Connecticut and Nevada have also passed similar laws regulating consumer health data. These various data privacy and cybersecurity laws may impact our business activities, including our identification of research subjects, relationships with business partners and ultimately the marketing and distribution of our products.

Additionally, to the extent we collect personal information from individuals outside of the United States, through clinical trials or otherwise, we are, or may become, subject to foreign data privacy and security laws, such as the European Union’s General Data Protection Regulation 2016/679 (or EU GDPR) and other national data protection legislation in force in relevant EEA Member States, and the EU GDPR as it forms part UK law by virtue of section 3 of the European Union (Withdrawal) Act 2018 (or UK GDPR). Foreign data privacy and cybersecurity laws impose significant and complex compliance obligations on entities that are subject to those laws, as more fully discussed in the section titled “Risk Factors—Risks related to government regulation”.

Current and Future U.S. Healthcare Reform Legislation

Payors, whether domestic or foreign, or governmental or private, are developing increasingly sophisticated methods of controlling healthcare costs and those methods are not always specifically adapted for new and innovative technologies, such as pharmaceutical products like [225Ac]Ac-AKY-1189. In both the U.S. and certain foreign jurisdictions, there have been a number of legislative and regulatory changes to the health care system that could impact our ability to sell products profitably.

By way of example, the U.S. and state governments continue to propose and pass legislation designed to reduce the cost of healthcare. In March 2010, the ACA, was enacted, which, among other things, increased the minimum Medicaid rebates owed by most manufacturers under the Medicaid Drug Rebate Program; extended the Medicaid Drug Rebate program to utilization of prescriptions of individuals enrolled in Medicaid managed care organizations; subjected manufacturers to new annual fees and taxes for certain branded prescription drugs; created the Medicare Part D coverage gap discount program, in which manufacturers agree to provide 70% point-of-sale discounts off negotiated prices of applicable brand drugs to eligible beneficiaries during their coverage gap period, as a condition for the manufacturer’s outpatient drugs to be covered under Medicare Part D; and provided incentives to programs that increase the federal government’s comparative effectiveness research. Current laws, as well as other healthcare reform measures that may be adopted in the future, may result in more rigorous coverage criteria and in additional downward pressure on the price for any approved products.

Since its enactment, there have been, and continue to be, numerous judicial, administrative, executive, and legislative challenges to certain aspects of the ACA, and there could be additional amendments to the ACA in the future. It is unclear whether the ACA will be overturned, repealed, replaced, or further amended. We cannot predict what effect further changes to the ACA would have on our business.

Additionally, there have been several U.S. congressional inquiries and proposed federal and proposed and enacted state legislation designed to, among other things, bring more transparency to drug pricing, review the relationship between pricing and manufacturer patient support programs, reduce the costs of drugs under Medicare and reform government program reimbursement

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methodologies for drug products. For example, on August 16, 2022, the Inflation Reduction Act of 2022, or IRA, was signed into law by President Biden. The IRA includes several provisions that may impact pharmaceutical companies to varying degrees, including provisions that create a $2,000 out-of-pocket cap for Medicare Part D beneficiaries; impose new manufacturer financial liability on all drugs in Medicare Part D; allow the U.S. government to negotiate Medicare Part B and Part D pricing caps for certain high-cost drugs and biologics without generic or biosimilar competition; require companies to pay rebates to Medicare for drug prices that increase faster than inflation; and delay the rebate rule that would require pass through of pharmacy benefit manager rebates to beneficiaries. Generally, these government prices can apply as soon as nine years (for small-molecule drugs) or 13 years (for biological products) from their FDA approval and will be capped at a statutory ceiling price that is likely to represent a significant discount from average prices to wholesalers and direct purchasers. The implementation of the IRA is currently subject to ongoing litigation that challenges the constitutionality of the IRA’s Medicare drug price negotiation program. The full impact of the IRA on our business and the pharmaceutical and healthcare industry in general is not yet known.

At the state level, legislatures have increasingly passed legislation and implemented regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing.

Employees and Human Capital Resources

As of December 31, 2025, we had 79 full-time employees. Of these employees, 67 are engaged in research and development and 12 are engaged in business development, finance, legal, and general management and administration. Our human capital resources objectives include identifying, recruiting, retaining, incentivizing and integrating our existing and new employees, advisors and consultants. None of our employees are represented by labor unions or covered by collective bargaining agreements. We consider our relationship with our employees to be good.

Corporate Information

We were originally incorporated under the laws of the State of Delaware in August 2020 under the name HotKnot Therapeutics, Inc. We changed our name to Aktis Oncology, Inc. in April 2021. Our principal executive offices are located at 17 Drydock Avenue, Suite 17-401, Boston, Massachusetts 02210 and our telephone number is (617) 461-4023.

Available Information

We file electronically with the Securities and Exchange Commission, the SEC, our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, proxy statements and other information. Our SEC filings are available to the public over the Internet at the SEC’s website at http://www.sec.gov. Our website address is https://www.aktisoncology.com. We make available on our website, under “Investors,” free of charge, copies of these reports as soon as reasonably practicable after filing or furnishing these reports with the SEC. The information contained in, or accessible through, our website does not constitute a part of this Annual Report. All statements made in any of our securities filings, including all forward-looking statements or information, are made as of the date of the document in which the statement is included, and we do not assume or undertake any obligation to update any of those statements or documents unless we are required to do so by law.