howl-20241231

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

______________________________________________________________________________________

FORM 10-K

______________________________________________________________________________________

(Mark One)

For the fiscal year ended December 31, 2024

For the transition period from ____________to_____________.

Commission File Number: 001-40366

______________________________________________________________________________________

WEREWOLF THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

______________________________________________________________________________________

Registrant’s telephone number, including area code: (617) 952‐0555

(Former name, former address and former fiscal year, if changed since last report)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class Trading Symbol(s) Name of each exchange on which registered

Common Stock, $0.0001 par value per share HOWL The Nasdaq Global Select Market

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☐ No ☒

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐ No ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S‐T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non‐accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b‐2 of the Exchange Act.

Large accelerated filer ☐ Accelerated filer ☐

Non‐accelerated filer ☒ Smaller reporting company ☒

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☒

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☐

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. ☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to § 240.10D-1(b). ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b‐2 of the Exchange Act). Yes ☐ No ☒

As of June 28, 2024, the last business day of the registrant’s most recently completed second fiscal quarter, the aggregate market value of the registrant’s Common Stock held by non-affiliates of the registrant was approximately $69,689,962, based upon the closing price of the registrant’s Common Stock on June 28, 2024.

As of March 5, 2025, there were 44,827,159 shares of common stock, $0.0001 par value per share, outstanding.

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Documents Incorporated by Reference

Portions of the registrant’s Definitive Proxy Statement on Schedule 14A relating to its 2025 Annual Meeting of Stockholders to be filed within 120 days of the registrant’s fiscal year ended December 31, 2024 are incorporated by reference into Part III of this Annual Report on Form 10-K to the extent stated herein.

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Page

PART I

Item 1. Business 3

Item 1A. Risk Factors 35

Item 1B. Unresolved Staff Comments 90

Item 1C. Cybersecurity 90

Item 2. Properties 91

Item 3. Legal Proceedings 91

Item 4. Mine Safety Disclosures 91

PART II

Item 6. Reserved 91

Item 7A. Quantitative and Qualitative Disclosures about Market Risk 103

Item 8. Financial Statements and Supplementary Data 103

Item 9A. Controls and Procedures 103

Item 9B. Other Information 104

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections 104

PART III

Item 10. Directors, Executive Officers and Corporate Governance 104

Item 11. Executive Compensation 105

Item 14. Principal Accountant Fees and Services 106

PART IV

Item 15. Exhibit and Financial Statement Schedules 107

SIGNATURES

EXHIBIT INDEX

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References to Werewolf

Throughout this Annual Report on Form 10-K, or Annual Report, the “Company,” “Werewolf,” “Werewolf Therapeutics,” “we,” “us,” “our,” and similar references, except where the context requires otherwise, refer to Werewolf Therapeutics, Inc. and its consolidated subsidiary, and “board of directors” refers to the board of directors of Werewolf Therapeutics, Inc.

Cautionary Note Regarding Forward-Looking Statements and Industry Data

This Annual Report contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, or the Exchange Act, that involve substantial risks and uncertainties. All statements other than statements of historical facts contained in this Annual Report, including statements regarding our strategy, future operations, future financial position, future revenue, projected costs, prospects, plans, objectives of management and expected market growth, are forward-looking statements.

The words “aim,” “anticipate,” “believe,” “contemplate,” “continue,” “could,” “design,” “designed to,” “engineered,” “estimate,” “expect,” “goal,” “intend,” “may,” “might,” “objective,” “ongoing,” “plan,” “potential,” “predict,” “promise,” “project,” “should,” “target,” “will,” “would,” or the negative of these words or other similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These forward-looking statements include, among other things, statements about:

•the initiation, timing, progress and results of our research and development programs, preclinical studies and ongoing and planned clinical trials, including the anticipated timing of data announcements;

•our estimates regarding expenses, capital requirements, need for additional financing and the period over which we believe our existing cash and cash equivalents will be sufficient to fund our operating expenses and capital expenditure requirements;

•our plans to develop and, if approved, subsequently commercialize product candidates;

•the timing of and our ability to submit applications and obtain and maintain regulatory approvals for product candidates;

•the potential advantages of our PREDATOR platform and our ability to use our platform to identify and develop future product candidates;

•our estimates regarding the potential market opportunities for our product candidates;

•our commercialization, marketing and manufacturing capabilities and strategy;

•our intellectual property position and our expectations regarding our ability to obtain and maintain intellectual property protection;

•our ability to identify additional products, product candidates or technologies with significant commercial potential that are consistent with our commercial objectives;

•the impact of government laws and regulations;

•our competitive position and expectations regarding developments and projections relating to our competitors and any competing therapies that are or become available; and

•developments and expectations regarding developments and projections relating to our competitors and our industry.

There are a number of important risks and uncertainties that could cause our actual results to differ materially from those indicated by forward-looking statements. We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. We have included important factors in the cautionary statements included in this Annual Report, particularly in Part I, Item 1A. “Risk Factors”, that we believe could cause actual results or events to differ materially from the forward-looking statements that we make. New risk factors and uncertainties may emerge from time to time, and it is not possible for management to predict all risk factors and uncertainties, nor can we assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements we make. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, collaborations, joint ventures or investments that we may make or enter into.

You should read this Annual Report and the documents that we have filed or incorporated by reference as exhibits to this Annual Report completely and with the understanding that our actual future results may be materially different from what we expect. The forward-looking statements contained in this Annual Report are made as of the date of this Annual Report, and we

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do not assume any obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by applicable law.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this Annual Report, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete. Our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain, and you are cautioned not to unduly rely on these statements.

Trademarks and Trade names

We own or have rights to trademarks, service marks and trade names that we use in connection with the operation of our business, including our corporate name, logos and website names. The service marks and trademarks that we own include the marks PREDATOR® and INDUKINETM. Other trademarks, service marks and trade names appearing in this Annual Report are the property of their respective owners. Solely for convenience, some of the trademarks, service marks and trade names referred to in this Annual Report are listed without the ® and TM symbols, but we will assert, to the fullest extent under applicable law, our rights to our trademarks, service marks and trade names.

Risk Factor Summary

Our business is subject to numerous risks that, if realized, could materially and adversely affect our business, financial condition, results of operations and future growth prospects. These risks are discussed more fully in Part I, Item 1A. Risk Factors in this Annual Report. These risks include, but are not limited to, the following:

•We have a limited operating history, have incurred significant operating losses since our inception and expect to incur significant losses for the foreseeable future.

•We have no products approved for commercial sale and have not generated any revenue from product sales. We may never generate any revenue from product sales or become profitable or, if we achieve profitability, we may not be able to sustain it.

•We will need to obtain substantial additional funding to finance our operations and complete the development and any commercialization of WTX-124, WTX-330 and any future product candidates.

•We are early in our development efforts and our current product candidates will require successful completion of preclinical and clinical development before we can seek regulatory approval for any product candidates.

•Our business is highly dependent on the success of our initial INDUKINE molecules, which are in the early stages of development and will require significant additional preclinical and clinical development before we can seek regulatory approval for and launch a product commercially.

•Our approach to the discovery and development of product candidates based on our PREDATOR platform is unproven, and we do not know whether we will be able to develop any products of commercial value.

•Manufacturing INDUKINE molecules is subject to risk since they are a novel class of multi-domain biologics that include protease cleavable linkers, and they have never been produced on a commercial scale. We may be unable to manufacture INDUKINE molecules at the scale needed for clinical development and commercial production on a timely basis or at all.

•Preclinical studies and clinical trials are expensive, time-consuming and difficult to design and implement, and involve uncertain outcomes.

•We may encounter substantial delays in the commencement or completion, or termination or suspension, of our clinical trials, which could result in increased costs to us, delay or limit our ability to generate revenue and adversely affect our commercial prospects.

•If we experience delays or difficulties in the enrollment of patients in clinical trials, our clinical development activities could be delayed or otherwise adversely affected.

•We are developing WTX-124, and could potentially develop WTX-330 and future product candidates, in combination with third-party drugs, some of which may still be in development, and we will have limited or no control over the safety, supply, regulatory status or regulatory approval of such drugs.

•We face substantial competition, which may result in others discovering, developing or commercializing products before or more successfully than we do.

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•We rely, and expect to continue to rely, on third parties to conduct our preclinical studies and clinical trials. If these third parties do not successfully carry out their contractual duties or meet expected deadlines or comply with regulatory requirements, we may not be able to obtain regulatory approval of or commercialize any product candidates.

•The manufacturing of biologics is complex, and we do not have our own clinical manufacturing capabilities. We will rely on third parties to produce preclinical, clinical and commercial supplies of all current and any future product candidates.

•We rely on our license agreement with Harpoon Therapeutics, Inc. for patent rights with respect to our product candidates and may in the future acquire additional third-party intellectual property rights on which we may similarly rely. We face risks with respect to such reliance, including the risk that we could lose these rights that are important to our business if we fail to comply with our obligations under these licenses.

•Our proprietary position in part depends upon patents that are manufacturing, formulation or method-of-use patents, which may not prevent a competitor or other third party from using the same product candidate for another use.

•In the past, we have identified material weaknesses in our internal control over financial reporting, and if we are unable to implement and maintain effective internal control over financial reporting in the future, investors may lose confidence in the accuracy and completeness of our financial reports, and the market price of our common stock may be materially adversely affected.

PART I

Item 1. Business

Company Overview

We are an innovative biopharmaceutical company pioneering the development of therapeutics engineered to stimulate the body’s immune system for the treatment of cancer and other immune-mediated conditions. We are leveraging our proprietary PREDATOR platform to design conditionally activated molecules that stimulate both adaptive and innate immunity with the goal of addressing the limitations of conventional proinflammatory immune therapies. Our molecules, which we refer to as INDUKINE molecules, are intended to activate selectively in the tumor microenvironment, or TME. Our most advanced product candidates, WTX-124 and WTX-330, are systemically delivered, conditionally activated Interleukin-2 (IL-2) and Interleukin-12 (IL-12), respectively, INDUKINE molecules for the treatment of multiple tumor types.

We are currently evaluating WTX-124 in a Phase 1/1b clinical trial as a monotherapy and in combination with Merck & Co., Inc.’s anti-PD-1 therapy KEYTRUDA (pembrolizumab) in patients with immunotherapy sensitive advanced or metastatic solid tumors who have failed standard of care treatment, including checkpoint inhibitor therapy. In November 2023, we announced preliminary first-in-human clinical data from the initial monotherapy dose-escalation cohorts in the Phase 1/1b clinical trial establishing proof of mechanism for WTX-124 and proof of concept for our INDUKINE design, and included assessments of safety and tolerability, pharmacokinetics, relevant biomarkers and preliminary antitumor activity. In June 2024, we reported updated interim data from the monotherapy dose-escalation arms of the Phase 1/1b clinical trial, selected a recommended dose for expansion and initiated monotherapy dose expansion arms, and reported initial data from the combination dose escalation cohorts of the Phase 1/1b clinical trial. We completed the dose-escalation phase of our Phase 1/1b clinical trial and continue to enroll patients in the monotherapy and combination expansion arms of the Phase 1/1b clinical trial. We have targeted full enrollment in the monotherapy dose expansion arm in the first half of 2025 and in the combination arm in the second half of 2025. We plan to meet with regulatory authorities to discuss potential registrational pathways in the second half of 2025 and to release a monotherapy and combination therapy clinical data update in the fourth quarter of 2025.

We have evaluated WTX-330 in a Phase 1 clinical trial for the treatment of immunotherapy resistant advanced or metastatic solid tumors or lymphoma. We reported initial data from the Phase 1 clinical trial in June 2024 and presented updated interim safety and efficacy data from the Phase 1 clinical trial at the Society for Immunotherapy of Cancer Annual Meeting held in November 2024, highlighting the tolerability profile and monotherapy efficacy signals of WTX-330. Guided by these data, we expect to initiate a Phase 1/2 dose and regimen-finding clinical trial of WTX-330 in the first quarter of 2025 in patients with selected advanced or metastatic solid tumors.

We have licensed the worldwide right to develop and commercialize JZP898, formerly WTX-613, a differentiated, conditionally activated interferon alpha, or IFNα, INDUKINE molecule, to Jazz Pharmaceuticals Ireland Limited, or Jazz.

We continue to further the development of our preclinical product candidates, WTX-712, WTX-518, and WTX-921. WTX-712 is a systemically delivered, conditionally activated Interleukin-21 (IL-21) INDUKINE molecule that is being developed to minimize the severe toxicities that have been observed with recombinant IL-21 therapy and maximize clinical benefit when administered as monotherapy or in combination with checkpoint inhibitors in refractory and/or immunologically unresponsive

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tumors. In April 2024, we presented preclinical data for WTX-712 at the American Association for Cancer Research, or AACR, annual meeting demonstrating that WTX-712 acts through a unique mechanism that robustly activates tumor-specific T lymphocytes with an expanded therapeutic window through its selective release of wild-type IL-21 in the TME. WTX-518 is a systemically delivered, conditionally activated Interleukin-18 (IL-18) INDUKINE molecule in development for the treatment of cancer and is designed to promote activation of immune cells in the TME, resulting in antitumor immunity. In April 2024, we also presented preclinical data for WTX-518 at the AACR Annual Meeting demonstrating that WTX-518 exhibits remarkable tumor-selective activation, resistance to IL-18BP and robust immune activation. WTX-921 is a systemically delivered, conditionally activated Interleukin-10 (IL-10) INDUKINE molecule in development for the treatment of inflammatory bowel disease, or IBD, and potentially other inflammatory diseases.

We continue to build our PREDATOR platform to generate a pipeline of innovative therapeutics that cover a diversity of immune stimulating mechanisms with the potential to address significant unmet medical need in therapeutic areas including new immuno-oncology, autoimmune, and inflammatory diseases. Our PREDATOR platform consists of our protein engineering technologies and our know-how, which we use to generate INDUKINE molecules with multiple functional domains rationally engineered into a single protein to achieve the desired pharmaceutical profile. Each of our lead INDUKINE molecules consists of four components: a cytokine, an inactivation domain, a half-life extension domain and a proprietary protease-cleavable linker. Our INDUKINE molecules for oncology contain cytokines that mediate pro-inflammatory, anti-cancer mechanisms within the TME, with full potency and functionality observed in preclinical studies. The inactivation domain physically blocks the cytokine portion of the INDUKINE molecule in non-tumor tissue throughout the body, or the periphery, preventing it from binding to its receptor until it is cleaved and thereby activated in the TME. The half-life extension domain enables high systemic and tumor tissue exposure for the INDUKINE molecule prior to its cleavage in the tumor. After cleavage in the tumor, the half-life extension domain is removed, and the cytokine is released to activate immune cells. We select the proprietary protease-cleavable linker to enable conditional release of the cytokine portion of the INDUKINE molecule within tumor tissue. This selection is based on our extensive screening in preclinical studies to identify protease-cleavable linkers that are efficiently cleaved by a broad array of human tumor tissues with minimal cleavage in non-tumor tissues.

Our Pipeline

We are leveraging our novel PREDATOR platform to engineer conditionally activated proinflammatory immunomodulators, or INDUKINE molecules, which are delivered systemically but activated only in the TME, with the goal of generating potent antitumor response while minimizing toxicities. Except for JZP898, which we have licensed to Jazz, we have worldwide rights to our PREDATOR platform and our portfolio of INDUKINE product candidates, all of which we have developed internally. We believe our approach has the potential to overcome current limitations of systemic proinflammatory immunomodulatory

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therapies, such as cytokines, for the treatment of cancer and other immune-mediated conditions. Our current pipeline is summarized below:

Using our PREDATOR platform, we have identified and are continuing to develop five initial product candidates: WTX-124, WTX-330, WTX-712, WTX-518, and WTX-921. In addition to these product candidates, we are pursuing additional immuno-oncology discovery programs in which we are applying our novel engineering approach to other targets. We are also expanding our technology to other disease areas, such as inflammatory diseases.

Our Strategy

Our goal is to utilize our proprietary PREDATOR platform to redefine the cancer treatment landscape with therapies to transform the lives of cancer patients, as well as to continue to develop our preclinical portfolio for the treatment of inflammatory bowel disease and potentially other inflammatory diseases. Key elements of our strategy include:

•Advancing our lead product candidate, WTX-124, through clinical development in selected solid tumor indications.

•Advancing WTX-330 through clinical development in selected solid tumors and lymphoma.

•Advancing WTX-712, WTX-518, and WTX-921 through preclinical development.

•Establishing a leading position in protein engineering and developing optimized conditionally activated molecules.

•Selectively entering into strategic partnerships while retaining key rights to our programs and platform in major pharmaceutical markets.

Traditional Cancer Therapy, Immunotherapy and the Need for New Treatment Options

The treatment of certain cancers has improved markedly over the past decade. Whereas many cancer treatments were historically limited to surgical removal, chemotherapy and radiation, recent advances target specific genetic changes in individual tumors or redirect the patient’s immune system to eliminate tumors and improve patient outcomes.

The latter approach, referred to as immunotherapy, represents one of the fastest growing segments in cancer treatment. The goal of immunotherapy is to harness an individual’s immune system to better enable it to identify, attack and kill tumor cells and to form long-term immunologic memory against tumors. The immune system is generally divided into the innate and adaptive arms, which are responsible for driving immediate and lasting antitumor responses, respectively. The innate immune system involves a diverse set of cells, including natural killer, or NK, cells, mast cells, eosinophils, basophils, neutrophils, macrophages and dendritic cells, or DCs, all of which generate a rapid local response to a foreign body, pathogen or tumor cell and release signals to activate and recruit cells, specifically lymphocytes, from the adaptive immune system. The adaptive immune system is the line of defense that is specific to a pathogen or tumor antigen and is composed of T cells and B cells, which work in concert to kill cells directly, produce antibodies and form immunologic memory. The latter is critical for the

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body’s immune response upon re-exposure to the initial antigen or pathogen. Many of the recent advances in immuno-oncology, such as immune checkpoint inhibitors, have focused on improving the function of T cells.

The development of immune checkpoint inhibitors, in particular programmed cell death protein 1, or PD-1, and programmed death-ligand 1, or PD-L1, inhibitors, revolutionized the treatment of many cancers. The efficacy of these T cell targeted immunomodulators, both as single agents or in combination with standard of care therapies, including chemotherapy, has resulted in many of these regimens moving up the treatment paradigm to become first- or second-line treatment options in numerous cancer types, and the landscape for immunotherapy continues to rapidly evolve. However, features of the tumor cells or the TME play a role in the efficacy of immune checkpoint inhibitors, leaving many patients with advanced or metastatic disease either ineligible for or unresponsive to treatment with immune checkpoint inhibitors. The majority of patients who do respond to these therapies ultimately develop resistance and experience disease progression. As a result, many patients are still underserved and could benefit from novel approaches to immunotherapy that complement and/or enhance checkpoint inhibition, whether as monotherapy or in combination. We believe that the best way to improve outcomes for cancer patients is to stimulate additional or de novo immune cell responses within the innate and adaptive arms of the immune system to complement immune checkpoint inhibitor therapy.

Leveraging our PREDATOR platform and drug development capabilities, we are creating a portfolio of conditionally activated proinflammatory immunomodulators, including cytokines, designed to be optimized for the treatment of cancer, and suppressive immunomodulators for the treatment of immune mediated diseases. Cytokines are small biologically active proteins that play an essential role in immune cell function of both the innate and adaptive arms of the immune system. These proteins regulate immune responses by acting as chemical messengers for the body’s immune cells through receptor site binding. Interleukins, such as IL-2 and IL-12, IFNα, IL-21, IL-18, and IL-10 are specific types of cytokines, produced primarily by cells of the immune system to signal and organize the immune response. In cancer, cytokines facilitate the ability of the immune system to recognize tumor cells as abnormal and harmful to the host. Cytokines further increase the proliferation of, enhance the survival of and direct a variety of immune cell types to infiltrate the TME and promote potent antitumor immune responses resulting in tumor cell killing and tumor clearance. Three cytokine therapies have received U.S. Food and Drug Administration, or FDA, approval for cancer treatment: (1) aldesleukin for the treatment of metastatic renal cell carcinoma, or RCC, and metastatic melanoma; (2) interferon alfa-2b for the treatment of several malignancies, including advanced melanoma; and most recently (3) nogapendekin alfa inbakicept (IL-15 receptor agonist) for non-muscle invasive bladder cancer.

However, despite promising antitumor activity, the clinical utility of approved cytokine therapies is limited due to toxicity and poor pharmaceutical properties, such as short half-life, reduced exposure of active drug in the tumor and the requirement for frequent administration. The efficacy observed is often accompanied by side effects that can be severe and can make treatment difficult for many patients to tolerate, which limits the ability of patients to remain on therapy long-term. The need to improve the pharmaceutical properties of cytokines to achieve increased therapeutic indexes provides an opportunity to address a large unmet need for safer, and potentially more efficacious, cytokine therapeutics for the treatment of cancer. Our PREDATOR platform allows us to engineer cytokines that can be delivered systemically and have activity selectively upon reaching the TME, thus potentially limiting systemic toxicity. We believe this unique profile will help overcome the limitations seen with other cytokine approaches.

Our Solution

Our PREDATOR Platform

We designed our PREDATOR platform to overcome the current limitations of systemic proinflammatory therapies. We use our PREDATOR platform to design molecules with superior tolerability and optimal pharmaceutical properties when administered systemically as inactive prodrugs. They then undergo transformation to an active state upon reaching the TME, thereby delivering the full biological potency of antitumor immune modulation for maximum therapeutic potential.

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Our PREDATOR platform is based on protein engineering to combine four critical components into a single INDUKINE molecule, as shown in the figure below.

•Cytokine Domain: An immunostimulatory molecule. Upon tumor specific conditional activation, the released cytokine works as a fully potent agonist, displaying the expected pro-inflammatory mechanism and pharmacology.

•Inactivation Domain: A domain that blocks the activity of the immunostimulatory molecule outside of the tumor, for which we have identified and optimized multiple formats with high affinity blockade to achieve minimal off-tumor toxicity and low peripheral target receptor-mediated clearance.

•Half-Life Extension Domain: A domain that imparts a longer half-life to the INDUKINE molecule thereby increasing systemic and tumor tissue exposure. Following cleavage within the tumor, half-life extension domain is removed and the immunostimulatory cytokine is released. We have selected multiple domain formats to enable our INDUKINE product candidates to maintain high systemic and tumor tissue exposure.

•Protease-Cleavable Linker: A novel, proprietary protease-cleavable linker substrate with optimal tumor selectivity that is used to impart conditional activation of the INDUKINE molecule through its cleavage, which releases the active cytokine. We have observed high stability of these proprietary protease-cleavable linker substrates in rodents and non-human primates, or NHPs, with minimal non-tumor tissue cleavage.

Linker Selection

A key challenge in the design of tumor-selective conditionally activated immunomodulators is the heterogeneity of tumor protease profiles. There is no single protease that is uniquely dysregulated in human tumors. Therefore, the identification of a linker substrate with the optimal profile cannot be achieved by biasing the linker sequence towards any single protease or protease family.

To ensure INDUKINE molecules are broadly activated across multiple tumor types, the linker substrate must be efficiently cleaved in the TME of many different tumors while remaining stable in circulation and in normal non-tumor tissues. We achieve this by utilizing a differentiated approach for linker identification and let the tumors select the substrate, rather than screening for linkers sensitive to cleavage by a single protease. Our process begins with a novel proprietary library of peptide sequences designed to target the universe of protease families known to be dysregulated in tumors. We initially screen these libraries for a high efficiency of cleavage and, based on the result, generate additional libraries to optimize the sequence motifs. We then screen the prioritized linker sequences that we have identified from the initial novel proprietary library of peptide sequences for cleavage by a panel of primary human tumor specimens and for stability when incubated with human serum or normal tissues. Leveraging this screening process, we initially screened several thousand linker sequences for optimal biochemical properties, and then screened the lead sequences for cleavage by a panel of primary human tumor specimens and normal non-tumor tissues. Linker sequences that were not efficiently cleaved by human tumor samples (for example, the linker shown as Linker 1 in the diagram below) were eliminated in the screening and those that were efficiently cleaved by human tumors but not cleaved by normal serum or tissues (for example, the linker shown as Linker 3 in the diagram below) were selected for incorporation into our INDUKINE molecules to confirm their activity in vitro and in vivo. We have selected linkers for our INDUKINE molecules with characteristics similar to those of Linker 3 in the table below.

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Human Tissue Screening for Selection of Optimized Linker Candidates

We seek to protect aspects of our PREDATOR platform technology by obtaining patent protection in the United States and internationally. Currently, our patent portfolio for our PREDATOR platform technology includes two families of pending patent applications, which disclose and claim protease cleavable linkers and libraries of protease cleavable linkers, as well as polypeptides that contain such linkers, methods of making libraries and methods of screening libraries to identify linkers with desired properties. These patent families were recently filed, and no patents have been granted. For more information see “Intellectual Property” described in this Part I, Item 1.

INDUKINE Molecules

We have rationally engineered INDUKINE molecules to have four key characteristics that we believe provide our product candidates with a unique profile and potential advantages in clinical settings when compared to other cytokines currently approved or in development:

•Optimized Antitumor Activity: The active portion of our INDUKINE molecules consists of a fully potent and functional cytokine molecule delivered directly into the tumor. We believe that delivery of a cytokine molecule into the TME will enable our product candidates to capture the full proinflammatory and immunomodulatory potential of cytokines and potentially result in optimal antitumor activity.

•Enhanced Tolerability: To improve tolerability, our INDUKINE molecules are designed to be administered as inactive prodrugs that employ a tailored, high affinity blockade to minimize off-target toxicity. We aim to prevent peripheral pathway activation, as well as target-mediated disposition in normal tissues, with the goal of minimizing potential toxicity.

•Optimized Pharmaceutical Properties: We design INDUKINE molecules to be stable in the bloodstream and periphery and to have a long serum half-life to achieve efficacy without requiring the frequent dosing that is a limiting requirement of approved recombinant cytokines, such as aldesleukin, a recombinant human IL-2, or rhIL-2, therapy. Our design allows us to achieve high, biologically relevant tumor tissue exposure with our INDUKINE molecules. Once our molecules are cleaved within the tumor, the cytokine is released for either intratumoral target binding or rapid systemic clearance.

•Conditional Activation: Upon reaching the TME, INDUKINE molecules are activated via cleavage of our proprietary linkers by tumor-specific proteases which results in release of the cytokines in the tumor. We select our linkers to be

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specifically cleaved in the tumor and be stable in circulation and normal non-tumor tissues, with the goal enhancing the tolerability profile of our INDUKINE molecules.

Our Programs

WTX-124: Our IL-2 INDUKINE Molecule

Overview

Our lead product candidate, WTX-124, is a systemically delivered, conditionally activated IL-2 INDUKINE molecule that we are developing to minimize the severe toxicities observed with rhIL-2 therapy and maximize clinical benefit when administered as monotherapy or in combination with immune checkpoint inhibitors in patients with immunotherapy sensitive advanced or metastatic solid tumors. We believe that these properties will also allow WTX-124 to have potential applicability in indications beyond those for which rhIL-2 therapy is currently approved. Key features of WTX-124 include preservation of full IL-2 potency and function as observed in preclinical studies, high affinity blockade of IL2—IL2R interaction in systemic circulation and non-tumor tissues, half-life extension for optimal tumor exposure and conditional protease activation within the TME due to our proprietary linker.

We designed WTX-124 to address the limitations of next generation IL-2 therapies in development by blocking the binding of IL-2 to the IL-2R in the periphery, thereby inhibiting IL-2 signaling and potentially minimizing toxicities, while maintaining binding to the high affinity IL-2Ra/ß/g in tumors to ensure the full pharmacology of IL-2.

WTX-124 consists of wild-type human IL-2, an IL-2Rß blockade element that eliminates binding to both high and medium affinity IL-2Rs expressed in normal tissues to neutralize IL-2 activity in the periphery, an antibody fragment that extends the circulation half-life and a proprietary linker for cleavage in the TME. As a prodrug, WTX-124 is conditionally activated in the TME to release an IL-2 cytokine to stimulate an antitumor immune response but with reduced peripheral toxicities. In preclinical studies, WTX-124 exhibited favorable pharmacokinetic and tolerability profile with robust antitumor activity driven by the differentiation, activation and expansion of T effector and memory lymphocyte immune responses.

Market Opportunity

We are initially developing WTX-124 in tumor types known to be responsive to IL-2 and/or PD-1 targeting therapies including melanoma, RCC and non-small cell lung cancer. These are aggressive tumor types and many patients will eventually progress following treatment with standard of care. As a result, we believe there is a need for new therapies to improve response and durability. If successfully developed and approved, we believe WTX-124 represents a promising therapeutic option for patients with life-threatening diseases with high unmet medical need, either as monotherapy or in combination with immune checkpoint inhibitors or current or potential future standard of care agents. We have the opportunity to potentially expand upon the patient populations and indications beyond those for which Proleukin (aldesleukin) is approved. We intend to develop WTX-124 as monotherapy and in combination with pembrolizumab, and eventually in combination with other standard of care therapeutics across different lines of therapy.

According to the Checkpoint Inhibitors Global Market Report 2024, the global checkpoint inhibitors market is expected to grow to $55.64 billion in 2028 at a CAGR of 10.1%.

WTX-124 Clinical Development Plan and Interim Results

We are currently evaluating WTX-124 in a Phase 1/1b clinical trial as a monotherapy and in combination with Merck & Co., Inc.’s anti-PD-1 therapy KEYTRUDA (pembrolizumab) in patients with immunotherapy sensitive advanced or metastatic solid tumors who have failed standard of care treatment, including checkpoint inhibitor therapy. In November 2023, we announced preliminary first-in-human clinical data from the initial monotherapy dose-escalation cohorts in the Phase 1/1b clinical trial. The preliminary data established proof of mechanism for WTX-124 and proof of concept for our INDUKINE design, and included assessments of safety and tolerability, pharmacokinetics, relevant biomarkers and preliminary antitumor activity. In June 2024, at the American Society of Clinical Oncology, or ASCO, Annual Meeting, we presented updated interim data from dose escalation, both monotherapy and combination therapy with pembrolizumab, in the Phase 1/1b clinical trial, and announced our recommended dose for expansion, or RDE, of 18 mg for monotherapy, and opening of monotherapy expansion arms. As of May 1, 2024, 47 patients had been treated with at least one dose of WTX-124, 35 in monotherapy and 12 in combination dose escalation. The data continued to demonstrate that WTX-124 was generally well-tolerated in the outpatient setting at monotherapy doses up to 28 mg and combination doses up to 12 mg, with no new safety signals in combination with pembrolizumab. WTX-124 as a monotherapy produced objective clinical responses, including a durable confirmed complete response, or CR, and two partial responses, or PRs, at the active dose levels of 12 and 18 mg. Both PRs were confirmed subsequent to the data cutoff, and one remained progression-free as of November 7, 2024. Increased T cell activation signature for the combination suggested a potential for improved efficacy by combining WTX-124 with pembrolizumab. Of the two previously disclosed PRs in combination therapy, one PR improved to a CR, and both combination responses remain ongoing at greater than eight months.

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We have targeted full enrollment in the monotherapy dose expansion arm in the first half of 2025 and in the combination arm in the second half of 2025. We plan to meet with regulatory authorities to discuss potential registrational pathways in the second half of 2025 and to release a monotherapy and combination therapy clinical data update in the fourth quarter of 2025.

The rationale for our clinical development strategy is as follows:

•IL-2 has been shown to have single agent activity in some cancers. Aldesleukin is approved for the treatment of metastatic RCC and metastatic melanoma. However, due to the toxicity associated with aldesleukin, which is noted in a black box warning, the drug is used infrequently. We believe, based on the mechanism of action of WTX-124, that it may be able to achieve higher intratumoral exposures of IL-2 than aldesleukin with minimal systemic toxicity, leading to monotherapy antitumor immune responses in patients with historically immunotherapy-sensitive tumor types who have progressed on, or subsequent to, immune checkpoint inhibitor therapy. Our preclinical data with WTX-124 show that WTX-124 has single agent antitumor activity in mouse tumor models and was well-tolerated. WTX-124 was also tolerated in NHPs at doses greater than predicted to be required for antitumor activity based on modeling the mouse tumor data. The data in our Phase 1/1b clinical trial has demonstrated monotherapy antitumor activity at doses safely delivered in the outpatient setting. Single agent activity with competitor IL-2 compounds has been limited, potentially affording an opportunity for us to pursue an expedited clinical development and regulatory strategy for WTX-124 if we can continue to show positive single arm efficacy data in a relapsed or refractory tumor type with high unmet medical need.

•IL-2 agonists and immune checkpoint inhibitors may act synergistically to enhance antitumor immune response. Clinical results have shown that aldesleukin induces responses as a single agent in patients who have progressed on immune checkpoint inhibitors. Our preclinical data with WTX-124 highlight the potential benefit of WTX-124 when combined with an anti-PD-1 antibody. These results suggest that combining novel IL-2 therapies with checkpoint inhibitors merits further evaluation as a regimen for treating cancer.

WTX-330: Our IL-12 INDUKINE Molecule

Overview

Our second product candidate, WTX-330, is a systemically delivered, conditionally activated IL-12 INDUKINE molecule that we are developing to minimize the severe toxicities observed with recombinant human IL-12, or rhIL-12, therapy and maximize clinical benefit when administered as monotherapy or in combination with standard of care therapies including checkpoint inhibitors in relapsed or refractory advanced or metastatic solid tumors or lymphoma.

IL-12 is a potent, pleiotropic cytokine for immune-mediated killing of cancer cells, whose mechanism of action includes stimulation of both innate and adaptive immune responses. IL-12 is a heterodimeric cytokine (p70) containing two subunits (p35 and p40). A subset of antigen-presenting cells, such as DCs, produce IL-12 upon activation, during the antigen presentation process. Binding of IL-12 to the IL-12R expressed on multiple immune cell populations activates the JAK/STAT signaling pathway resulting in helper T cell differentiation, activation of cytotoxic NK and T cells, and inhibition or reprogramming of immunosuppressive cells such as tumor-associated macrophages or myeloid-derived suppressor cells. IL-12 also increases the expression of antigen-presentation machinery, which is necessary to initiate an immune response in tumors that have not naturally stimulated an antitumor immune response, also referred to as “cold” tumors. IL-12 induces the production of interferon gamma, or IFNγ, a potent proinflammatory mediator of the downstream activities of IL-12 signaling. IFNγ, in turn, increases the production of IL-12 by mature DCs aiding in their antigen presentation capacity and driving activation of effector T cells. Numerous studies conducted by others have demonstrated that IL-12 treatment has significant antitumor activity in a range of preclinical models, with the induction of a long-lasting antitumor immune memory.

Due to the robust antitumor activity seen in preclinical studies, there has been significant interest in developing rhIL-12 therapy for advanced solid tumors. In early clinical trials conducted by a third party, the use of systemically administered rhIL-12 produced evidence of clinical activity in several tumor types, including RCC, melanoma and non-Hodgkin’s lymphoma. However, the systemic administration of rhIL-12 was shown to be toxic, resulting in the death of two patients in one Phase 2 trial and multiple hospitalizations. Additional trials at tolerated doses yielded modest clinical activity, potentially due to a lack of sufficient and durable exposure of rhIL-12 in the TME at lower doses.

WTX-330 is designed to improve the pharmacological properties of IL-12 and require less frequent systemic administration. The prodrug is designed to remain inactive while circulating in the periphery and is activated preferentially in the TME to release an IL-12 cytokine. We believe activation of WTX-330 in the TME has the potential to stimulate a robust antitumor immune response while minimizing the peripheral toxicities that have been associated with systemic administration of rhIL-12 therapy. Key features of WTX-330 include high affinity blockade of IL-12 – IL-12R interaction in systemic circulation and non-tumor tissues, half-life extension for optimal tumor exposure and conditional protease activation due to our proprietary linker. In preclinical studies, we have observed high antitumor activity of an IL-12 INDUKINE surrogate molecule across a broad range of preclinical tumor models and that it has a favorable pharmacokinetic and tolerability profile.

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WTX-330 Clinical Development Plan

We have evaluated WTX-330 in a Phase 1 clinical trial for the treatment of immunotherapy resistant advanced or metastatic solid tumors or lymphoma, followed by expansion arms in relapsed/refractory tumors following treatment with checkpoint inhibitors or tumors for which checkpoint inhibitors are not approved. In November 2024, at the 39th Annual Meeting of the Society for Immunotherapy Cancer, or SITC, we presented preliminary first-in-human clinical data from the Phase 1 clinical trial of WTX-330. The preliminary data established proof of mechanism for WTX-330 and proof of concept for our second INDUKINE molecule, and included assessments of safety and tolerability, pharmacokinetics, relevant biomarkers and preliminary antitumor activity. The preliminary data, collected as of October 7, 2024, was generated from 25 heavily pretreated patients from three dose escalation cohorts (0.016, 0.024, and 0.032 mg/kg) and two expansion arms at 0.024 mg/kg in patients resistant to checkpoint inhibitors or for whom checkpoint inhibitors were not indicated. WTX-330 was generally well-tolerated, with the most common adverse events expected for IL-12 therapy, including cytokine release syndrome, pyrexia, and liver function test elevations. WTX-330 delivered 22-fold more IL-12 than rhIL-12 therapy at its maximal tolerated dose. Anti-tumor activity was noted, including one confirmed PR in metastatic melanoma and stable disease in patients with less immunosensitive tumors. Biomarker data, including NanoString, showed pleiotropic immune activation in the TME, consistent with the mechanism of action of IL-12.

We expect to initiate a Phase 1/2 dose and regimen-finding clinical trial of WTX-330 in the first quarter of 2025 in patients with selected advanced or metastatic solid tumors.

WTX-712: Our IL-21 INDUKINE Molecule

WTX-712 is a systemically delivered, conditionally activated IL-21 INDUKINE molecule. IL-21 is a pluripotent cytokine that activates antitumor T cell responses, induces B cell activation, and promotes generation and maintenance of germinal centers and tertiary lymphoid structures. A member of the common g-chain family of cytokines, IL-21 acts on a broader range of cells than IL-2 and does not induce vascular leak syndrome. Despite being a potent inducer of immune activation, IL-21 development has been hampered by poor PK properties and adverse events at dose levels associated with antitumor activity. WTX-712 is being developed to minimize the severe toxicities that have been observed with recombinant IL-21 therapy and maximize clinical benefit. In April 2024, we presented preclinical data for WTX-712 at the AACR annual meeting demonstrating that WTX-712 acts through a unique mechanism that robustly activates tumor-specific T lymphocytes with an expanded therapeutic window through its selective release of wild-type IL-21 in the TME.

WTX-518: Our IL-18 INDUKINE Molecule

WTX-518 is a systemically delivered, conditionally activated IL-18 INDUKINE molecule in development for the treatment of cancer and is designed to promote activation of immune cells in the TME, resulting in antitumor immunity. In April 2024, we presented preclinical data for WTX-518 at the AACR annual meeting demonstrating that WTX-518 exhibits remarkable tumor-selective activation, resistance to IL-18BP and robust immune activation.

WTX-921: Our IL-10 INDUKINE Molecule

WTX-921 is a systemically delivered, conditionally activated IL-10 INDUKINE molecule for the treatment of inflammatory bowel disease and potentially other inflammatory diseases. We have generated an IND-enabling data package, and WTX-921 is available for partnering opportunities.

Our Early Stage Programs

In addition to IL-2, IL-12, IFNα, IL-21, IL-18, and IL-10 INDUKINE molecules, we are also applying our novel engineering approach to other modalities with a focus on conditionally activated immune cell engagers. We believe that our PREDATOR platform protein engineering principles can be extended to conditionally activated immune cell engagers, optimizing how immune cell engagers leverage the immune system to fight cancer.

Our goal is to better understand how the localized tumor delivery of immunomodulatory molecules might contribute to disease control while reducing the toxicity that in many cases accompany the systemic delivery of molecules such as cytokines or immune cell engagers.

Our Partnered Programs

JZP898: IFNα INDUKINE Molecule Licensed Globally to Jazz Pharmaceuticals

JZP898 (formerly WTX-613) is a systemically delivered, conditionally activated IFNα INDUKINE molecule that we are collaborating with Jazz to develop to minimize the severe toxicities that have been observed with recombinant human IFNα, or rhIFNα, therapy and maximize clinical benefit when administered as monotherapy or in combination with checkpoint inhibitors or other standard of care therapy.

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IFNα is a member of the type-I IFN family and a proinflammatory cytokine that exerts dual mechanisms of inhibiting tumor cell growth through both cytotoxic effects directly on tumor cells as well as driving antitumor immune responses. While IFNα can inhibit proliferation and induce direct cell apoptosis of some cancer cell types, this mechanism by itself is unlikely to be sufficient to fully control tumor growth. The additional ability of IFNα to activate and engage different cells of the immune system makes IFNα a potentially effective antitumor agent. IFNα activation of the immune response can occur directly by engagement of IFNARs on immune cells or indirectly by the induction of chemokines that attract immune cells to the tumor site. IFNα can activate NK cells, enhance their ability to kill and increase their production of IFNγ. Furthermore, it can increase macrophage activation and support differentiation and activation of DCs. Lastly, IFNα can have a direct effect on B lymphocytes as well as T lymphocytes where IFNα favors the differentiation of naïve CD4+ T cells into helper T cells and directly activates CD8+ T cells, augmenting their IFNγ production and survival.

IFNα was one of the first cytokines clinically tested as a therapy for patients with cancer. Encouraging clinical benefit, although limited, resulted in regulatory approvals for the treatment of several hematological malignancies and solid tumors, such as chronic myelogenous leukemia, lymphoma and malignant melanoma. Widespread use of IFNα for hematologic and oncologic indications has unfortunately been hampered by adverse events linked to the on-target, off-tumor activity and its use in clinical practice has been supplanted by other therapies. In our preclinical studies, we observed the potential benefit of IFNα treatment in syngeneic mouse tumor models using colon, melanoma and breast tumor cell lines and the superior response obtained by the INDUKINE molecule format when compared to the dosing of recombinant cytokine.

In April 2022, we entered into a global collaboration and license agreement, or the Collaboration Agreement, with Jazz under which Jazz acquired exclusive global development and commercialization rights to WTX-613, which has subsequently been designated JZP898, as well as products containing certain isolated recombinant polypeptides comprising IFNα that meet specified criteria (each such product, a Licensed Product). Pursuant to the terms of the Collaboration Agreement, we are responsible for certain preclinical development activities with respect to JZP898 and other development activities specified in mutually agreed upon development plans. Jazz will generally reimburse us for the cost of such activities. Jazz will be responsible for all other development and commercialization activities conducted to exploit the Licensed Products. In June 2024, we executed a transfer agreement, or the Transfer Agreement, to assign our rights in a development agreement with a contract manufacturer of our interferon alpha INDUKINE molecule JZP898 to Jazz. The execution of this Transfer Agreement was the last material performance obligation required of us under the Collaboration Agreement. As of the execution of the Transfer Agreement, we no longer have any material performance obligations under the Collaboration Agreement.

Competition

The pharmaceutical industry is characterized by rapidly advancing technologies, intense competition and a strong emphasis on proprietary drugs. While we believe that our technology, knowledge, experience and scientific resources provide us with certain competitive advantages, we face potential competition from many different sources, including major pharmaceutical, specialty pharmaceutical and biotechnology companies; academic institutions; governmental agencies; and public and private research institutions. Any product candidates that we successfully develop and commercialize will compete with existing treatments and new treatments that may become available in the future.

We compete with other companies working to develop immunotherapies for the treatment of cancer including divisions of large pharmaceutical and biotechnology companies of various sizes. These companies are developing cytokines as immunotherapies using different modalities, including monoclonal antibodies, cell therapies, oncolytic viruses and vaccines.

Our lead product candidate, WTX-124, if approved, may face competition from other IL-2 based cancer therapies. Proleukin (aldesleukin) has been approved and is marketed for the treatment of both metastatic RCC and metastatic melanoma. In addition, we are aware of numerous clinical and preclinical IL-2 molecules using different platforms being developed for oncology indications, including programs from Anaveon AG, Anwita Biosciences, Inc., Ascendis Pharma A/S, Asher Biotherapeutics, Inc., Aulos Bioscience, Inc., BioNTech SE, Cue Biopharma, Inc., DEKA Biosciences, Inc., Merck & Co., Inc., Medicenna Therapeutics Corp., Mural Oncology PLC, F. Hoffmann-La Roche AG, Synthekine, Inc., and Xilio Therapeutics, Inc.

There are no approved IL-12 therapies currently on the market for the treatment of cancer. However, if approved, WTX-330 may face competition from other IL-12 cytokine programs in clinical and preclinical development for oncology indications, including programs from Sanofi S.A. (Amunix), DEKA Biosciences, Inc., DragonFly Therapeutics, Inc., Juno Therapeutics, Inc. (Bristol-Myers Squibb Company), Mural Oncology, OncoSec Medical Incorporated, Philogen S.p.A., Sonnet BioTherapeutics, Inc., Turnstone Biologics Corp. (partnered with Takeda Pharmaceutical Company Limited), Xilio Therapeutics, Inc., and Zymeworks Inc.

We are developing WTX-124 and WTX-330 as potential monotherapies in relapsed or refractory tumor types or in combination with checkpoint inhibitors or other standard of care therapies in advanced or metastatic malignancies with high unmet medical need. Standard of care therapies include chemotherapy, targeted therapy, and more recently, immunotherapies, including

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monoclonal antibodies and bispecific formats, antibody drug conjugates, adoptive cellular therapies, and cytokines. In addition, there are numerous investigational agents in clinical development. Combining agents to improve patient outcomes and prevent emergence of resistance has become the paradigm for treatment of cancer.

Many of our competitors, either alone or with their collaboration partners, have significantly greater financial resources and expertise in research and development, preclinical testing, clinical trials, manufacturing and marketing than we do. Future collaborations and mergers and acquisitions may result in further resource concentration among a smaller number of competitors. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These competitors will also compete with us in recruiting and retaining qualified scientific and management personnel and establishing clinical trial sites and subject registration for clinical trials, as well as in acquiring technologies complementary to, or that may be necessary for, our programs.

Our commercial potential 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 products that we may develop. Our competitors also may obtain FDA or other 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 are able to enter the market or make our development more complicated. The key competitive factors affecting the success of all of our programs are likely to be efficacy, safety and convenience.

Manufacturing

To date, we have produced limited quantities of our product candidates at our own facilities for preclinical evaluation. We do not own manufacturing facilities capable of producing drug product for clinical trials or at clinical scale. We must manufacture drug product for clinical trial use in compliance with current Good Manufacturing Practices, or cGMPs, or similar foreign standards. The cGMP regulations include requirements relating to organization of personnel, buildings and facilities, equipment, control of components and drug product containers and closures, production and process controls, packaging and labeling controls, holding and distribution, laboratory controls, records and reports, and returned or salvaged products. We do not have and we do not currently plan to acquire or develop the facilities or capabilities to manufacture cGMP drug substance or filled drug product for use in human clinical trials. As a result, we rely on third-party contract manufacturers to manufacture some of our preclinical product candidate supplies and rely on third-party contract manufacturers to manufacture all of our clinical trial product supplies. We will also contract with additional third parties for the filling, labeling, packaging, storage and distribution of our product candidates investigational drug products.

The manufacturing facilities for our product candidates must meet cGMP requirements and FDA certification before any product is approved and we can manufacture commercial products. Our third-party manufacturers will also be subject to periodic inspections of facilities by the FDA and other authorities, including procedures and operations used in the testing and manufacture of our products to assess our compliance with applicable regulations. In March 2024, we received alignment from the U.S. Food and Drug Administration, or the FDA, on the comparability path for WTX-330 for an improved manufacturing process.

Commercialization Plan

We intend to retain significant development and commercial rights to our product candidates and, if marketing approval is obtained, to commercialize our product candidates on our own, or potentially with a partner, in the United States and other major pharmaceutical markets. We currently have no sales, marketing or commercial product distribution capabilities and have no experience as a company commercializing products. We intend to build the necessary infrastructure and capabilities over time for the United States, and potentially other regions, following further advancement of our product candidates. Clinical data, the size of the addressable patient population, the size of the commercial infrastructure and manufacturing needs may all influence or alter our commercialization plans.

Intellectual Property

Our intellectual property is critical to our business, and we strive to protect it, including by seeking to obtain and maintaining patent protection in the United States and internationally to cover our product candidates, their methods of use and processes for their manufacture and any other inventions that are commercially important to the development of our business. We also rely on trade secrets and proprietary know-how to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection.

Our patent portfolio includes patents and patent applications with composition of matter and method of use claims with respect to our product candidates, WTX-124, WTX-330, JZP898, WTX-712, WTX-518, and WTX-921, and claims directed to our PREDATOR platform technology. For our product candidates, we will, in general, initially pursue patent protection covering compositions of matter and methods of use. Throughout the development of our product candidates, we will seek to identify

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additional opportunities for obtaining patent protection that would potentially enhance commercial success, including through additional methods of use, processes for manufacture, formulation and dosing regimen-related claims.

Our commercial success depends in part on our ability to obtain and maintain proprietary protection for our current and future product candidates, platform technologies, novel discoveries, product development technologies and know-how, to operate without infringing on the proprietary rights of others and to prevent others from infringing our proprietary rights. We seek to protect our proprietary position by, among other methods, filing or in-licensing U.S. and foreign patents and patent applications related to technology, inventions and improvements that are important to the development and implementation of our business. We also rely on or may rely in the future on trademarks, trade secrets, copyright protection, know-how, continuing technological innovation and confidential information to develop and maintain our proprietary position. For the product candidates we develop and plan to commercialize, as a normal course of business, we have been granted and intend to continue to pursue composition and method of manufacture and use, including therapeutic use, patents, as well as novel indications for our product candidates. We also have obtained and will continue to seek patent protection with respect to novel discoveries. We have sought and plan to continue to seek patent protection, either alone or jointly with our collaborators, as our agreements may dictate.

In some instances, we submit patent applications directly with the United States Patent and Trademark Office, or USPTO, as provisional patent applications. Provisional applications for patents were designed to provide a lower-cost first patent filing in the United States. Corresponding non-provisional patent applications must be filed not later than 12 months after the provisional application filing date. The corresponding non-provisional application benefits in that the priority date(s) of the patent application is/are the earlier provisional application filing date(s), and the patent term of the finally issued patent is calculated from the later non-provisional application filing date. This system allows us to obtain an early priority date, add material to the patent application(s) during the priority year, obtain a later start to the patent term and to delay prosecution costs, which may be useful in the event that we decide not to pursue examination in an application. While we intend to timely file non-provisional patent applications relating 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.

We file U.S. non-provisional applications and Patent Cooperation Treaty, or PCT, applications that claim the benefit of the priority date of earlier filed provisional applications, when applicable. The PCT system allows a single application to be filed within 12 months of the original priority date of the patent application, and to designate all of the PCT member states in which national patent applications can later be pursued based on the international patent application filed under the PCT. The PCT searching authority performs a patentability search and issues a non-binding patentability opinion, which can be used to evaluate the chances of success for the national applications in foreign countries prior to having to incur the filing fees. Although a PCT application does not issue as a patent, it allows the applicant to seek protection in any of the member states through national-phase applications.

At the end of the period of two and a half years from the first priority date of the patent application, separate patent applications can be pursued in any of the PCT member states either by direct national filing or, in some cases by filing through a regional patent organization, such as the European Patent Organization. The PCT system delays expenses, allows a limited evaluation of the chances of success for national/regional patent applications and enables substantial savings where applications are abandoned within the first two and a half years of filing.

For all patent applications, we determine claiming strategy on a case-by-case basis. Advice of counsel and our business model and needs are always considered. We file patent applications containing claims for protection of all useful applications of our proprietary technologies and any products, as well as all new applications and/or uses we discover for existing technologies and products, assuming these are strategically valuable. We continuously reassess the number and type of patent applications, as well as the existing patent claims to ensure that maximum coverage and value are obtained for our processes and compositions, given existing patent office rules and regulations. Further, claims may be modified during patent prosecution to meet our intellectual property and business needs.

We recognize that the ability to obtain patent protection and the degree of such protection depends on a number of factors, including the extent of the prior art, the novelty and non-obviousness of the invention and the ability to satisfy the enablement requirement of the patent laws. The patent positions of therapeutic polypeptide companies like ours are generally uncertain and involve complex legal, scientific and factual questions. In addition, the coverage claimed in a patent application can be significantly reduced before the patent is issued, and its scope can be reinterpreted or further altered even after patent issuance. Consequently, we may not obtain or maintain adequate patent protection for any of our future product candidates or for our platform technology. We cannot predict whether the patent applications we are currently pursuing will issue as patents in any particular jurisdiction or whether the claims of any issued patents will provide sufficient proprietary protection from competitors. Any patents that we hold may be challenged, circumvented or invalidated by third parties.

Regardless of the coverage we seek under our existing patent applications, there is always a risk that an alteration to the product or process may provide sufficient basis for a competitor to avoid infringement claims. In addition, the coverage claimed in a

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patent application can be significantly reduced before a patent is issued, and courts can reinterpret patent scope after issuance. Moreover, many jurisdictions, including the United States, permit third parties to challenge allowed or issued patents in administrative proceedings, which may result in further narrowing or even cancellation of patent claims. Moreover, we cannot provide any assurance that any patents will be issued from our pending or any future applications or that any current or future issued patents will adequately protect our products.

Our patent portfolio, including patents and patent applications that we own and comprises about 23 patent families that are in various stages of the patent application filing and examination process in various jurisdictions worldwide, and include claims to our product candidates and claims directed to our PREDATOR platform technology for potential products and developments. The status of our patent portfolio changes frequently in the ordinary course of patent prosecution. As of February 5, 2025, our patent portfolio included approximately eight (8) issued patents in the United States, approximately forty (40) pending U.S. provisional or non-provisional patent applications, eight (8) pending international patent applications filed under the PCT and approximately one hundred nine (109) pending foreign patent applications, including pending applications in Australia, Brazil, Canada, China, European Patent Office, Hong Kong, India, Israel, Japan, Republic of Korea, Mexico, Russian Federation, Singapore, South Africa and Taiwan. These patent applications, if issued, are expected to expire on various dates from 2039 through about 2045, in each case without taking into account any possible patent term extension that may be available.

Our patent portfolio on our PREDATOR platform technology includes three patent families directed to protease cleavable linkers and libraries of protease cleavable linkers, as well as polypeptides that contain such linkers and methods of making libraries and screening libraries to identify linkers with desired properties. One of the patent families includes one issued U.S. patent with claims directed to protease cleavable linkers, and pending applications in the United States, Australia, Brazil, Canada, China, European Patent Office, Hong Kong, Israel, India, Japan, Republic of Korea, Mexico and Singapore. The 20-year term for patents in this family runs through 2040, excluding any extension of patent term that may be available. The second patent family currently consists of a pending U.S. non-provisional application. The 20-year term for patents in this family runs through 2044. The third patent family currently consists of a pending U.S. provisional application. We plan to file an international patent application under the PCT based on this provisional application before the applicable deadlines.

Our platform technology patent portfolio also includes a patent family directed to conditionally activated immune cell engagers. The patent family currently consists of a pending U.S. provisional application. We plan to file an international patent application under the PCT based on this provisional application before the applicable deadlines.

Our patent portfolio also includes patent and patent applications that we license from Harpoon Therapeutics, Inc., or Harpoon.

Our patent portfolio for each of the product candidates is summarized below.

WTX-124

We own seven patent families directed to IL-2 INDUKINE molecules and our WTX-124 product candidate. One of the families includes patents issued in the U.S. (four patents), Australia, Europe, Hong Kong, Japan, and Russian Federation with certain composition of matter claims with respect to IL-2 INDUKINE molecules and WTX-124. We have also filed pending U.S. applications and pending foreign patent applications in Australia, Brazil, Canada, China, European Patent Office, Hong Kong, India, Israel, Japan, Republic of Korea, Mexico, Russian Federation, Singapore and South Africa that claim certain compositions of matter and methods of use with respect to IL-2 INDUKINE molecules and WTX-124. The 20-year term for patents in this family runs through 2039, excluding any extension of patent term that may be available. A second patent family currently includes patents issued in the U.S. (two patents), and pending applications in U.S., Australia, Brazil, Canada, China, European Patent Office, India, Israel, Japan, Republic of Korea, Mexico, Russian Federation, Singapore and South Africa with claims direct to certain compositions of matter and methods of use with respect to IL-2 INDUKINE molecules and WTX-124. These applications also claim certain compositions of matter and method of use with respect to INF-a INDUKINE molecules and WTX-613. The 20-year term for patents in this family runs through to 2040, excluding any extension of patent term that may be available. A third patent family that we co-own currently includes pending applications in the U.S., Australia, Canada, China, Europe, Japan, and Republic of Korea that claim certain pharmaceutical compositions and methods of use of IL-2 INDUKINE molecules and our WTX-124 product candidate. The 20-year term for patents in this family will run through to 2042, excluding any extension of patent term that may be available. A fourth patent family currently includes pending applications in the U.S., Canada, Europe, Japan, and Republic of Korea that claims certain methods of use of IL-2 INDUKINE molecules and our WTX-124 product candidate. The 20-year term for patents in this family will run through to 2042, excluding any extension of patent term that may be available. Our fifth patent family also includes pending applications in the U.S., Australia, Canada, Europe, Japan, Taiwan, and the U.S. that claim certain methods of use with respect our IL-2 INDUKINE molecules and our WTX-124 product candidate. This family also claims certain methods of use with respect to IL-12 INDUKINE molecules and our WTX-330 product candidate, and INF-a INDUKINE molecules and WTX-613.The 20-year term for patents in this family will run through to 2042, excluding any extension of patent term that may be available. A fifth patent family includes a pending U.S. provisional application that claims certain compositions of matter and method of use with respect to IL-2 INDUKINE molecules and our WTX-124 product candidate. The 20-year term for patents in this family will run

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through 2045, excluding any extension of patent term that may be available. We plan to file an international patent application under the PCT based on this provisional application before the applicable deadlines. A sixth patent family includes a pending U.S. provisional application that claims certain compositions of matter and methods of use with respect to IL-2 INDUKINE molecules and our WTX-124 product candidate. This family also claims certain compositions of matter and methods of use with respect to IL-12 INDUKINE molecules and our WTX-330 product candidate, and INF-a INDUKINE molecules and WTX-613. The 20-year term for patents in this family will run through 2045, excluding any extension of patent term that may be available. We plan to file an international patent application under the PCT based on this provisional application before the applicable deadlines. Our seventh patent family includes a pending U.S. provisional application that claims certain methods of use with respect to our IL-2 INDUKINE molecules and our WTX-124 product candidate. The 20-year term for patents in this family will run through 2045, excluding any extension of patent term that may be available. We plan to file an international patent application under the PCT based on this provisional application before the applicable deadlines.

WTX-330

We own seven families directed to IL-12 INDUKINE molecules and our WTX-330 product candidate. One of the families includes patents issued in the U.S. (two patents), Australia, Japan, and Russian Federation with certain composition of matter claims with respect to IL-12 INDUKINE molecules. We have also filed a pending U.S. application and pending foreign applications in Australia, Brazil, Canada, China, European Patent Office, Hong Kong, India, Israel, Japan, Republic of Korea, Mexico, Russian Federation, Singapore and South Africa that claim certain compositions of matter and methods of use with respect to IL-12 INDUKINE molecules and WTX-330. The 20-year term for patents in this family runs through 2039, excluding any extension of patent term that may be available. A second patent family currently includes pending patent applications in the U.S., Australia, Brazil, Canada, China, European Patent Office, Hong Kong, India, Israel, Japan, Republic of Korea, Mexico, Russian Federation, Singapore and South Africa with claims directed to certain compositions of matter and methods of use with respect to IL-12 INDUKINE molecules and WTX-330. The 20-year term for patents in this family runs through to 2041, excluding any extension of patent term that may be available. Our third patent family includes pending applications in the U.S., Australia, Canada, European Patent Office, Japan, and Republic of Korea that claim certain methods of use with respect to IL-12 INDUKINE molecules and our WTX-330 product candidate. The 20-year term for patents based on this international application will run through 2043, excluding any extension of patent term that may be available. Our fourth patent family currently includes a pending PCT application and pending applications in the U.S., Australia, Canada, European Patent Office, Japan, and Taiwan, that claim certain methods of use of IL-12 INDUKINE molecules and our WTX-330 product candidate. This family also claims certain methods of use with respect to INF-a INDUKINE molecules and WTX-613, and IL-2 INDUKINE molecules and our WTX-124 product candidate. The 20-year term for patents in this family will run through to 2042, excluding any extension of patent term that may be available. A fifth patent family includes a pending PCT application that claims certain methods of use of our IL-12 INDUKINE molecules and WTX-330 product candidate. We intend to file national applications in other jurisdictions based on the PCT application before the applicable deadlines. The 20-year term for patents in this family will run through 2044, excluding any extension of patent term that may be available. A sixth patent family includes a pending U.S. provisional application that claims certain methods of use of our IL-12 INDUKINE molecules and WTX-330 product candidate. We plan to file an international patent application under the PCT based on this provisional application before the applicable deadlines. The 20-year term for patents in this family will run through 2045, excluding any extension of patent term that may be available. A seventh patent family includes a pending U.S. provisional application that claims certain compositions of matter and methods of use with respect to IL-12 INDUKINE molecules and our WTX-330 product candidate. This family also claims certain compositions of matter and methods of use with respect to IL-2 INDUKINE molecules and our WTX-124 product candidate, and INF-a INDUKINE molecules and WTX-613. The 20-year term for patents in this family will run through 2045, excluding any extension of patent term that may be available. We plan to file an international patent application under the PCT based on this provisional application before the applicable deadlines.

WTX-613

We own five patent families directed to our INF-a INDUKINE molecules and our WTX-613 product candidate. We own a first patent family that includes pending foreign applications in the United States, Australia, Brazil, Canada, China, European Patent Office, Hong Kong, India, Israel, Japan, Republic of Korea, Mexico, Russian Federation, Singapore and South Africa that claim certain compositions of matter and methods of use with respect to INF-a INDUKINE molecules and WTX-613. The 20-year term for patents in this family runs through 2039, excluding any extension of patent term that may be available. A second patent family currently includes patents issued in the U.S. (two patents), and pending patent applications in the U.S., Australia, Brazil, Canada, China, European Patent Office, Hong-Kong, India, Israel, Japan, Republic of Korea, Mexico, Russian Federation, Singapore and South Africa with claims directed to certain compositions of matter and methods of use with respect to WTX-613. These applications also claim certain compositions of matter and method of use with respect to IL-2 INDUKINE molecules and our WTX-124 product candidate. The 20-year term for patents in this family runs through 2040, excluding any extension of patent term that may be available. We filed a pending application in the United States that combined the disclosures of the first and second families and claims compositions of matter and certain methods of use with respect to

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WTX-613. The 20-year term for patents based on the pending U.S. application will run through to 2039 or 2040, depending on the particular claims, excluding any extension of patent term that may be available. Our third patent family includes pending applications in the U.S., Canada, China, European Patent Office, Japan, and Taiwan. that claim certain compositions of matter and methods of use with respect our INF-a INDUKINE molecules. The 20-year term for patents in this family will run through to 2042, excluding any extension of patent term that may be available. Our fourth patent family also includes pending applications in the U.S., Australia, Canada, European Patent Office, Japan, and Taiwan that claim certain methods of use with respect to INF-a INDUKINE molecules and WTX-613. This family also claims certain methods of use of with respect to IL-12 INDUKINE molecules and our WTX-330 product candidate, and IL-2 INDUKINE molecules and our WTX-124 product candidate. The 20-year term for patents in this family will run through to 2042, excluding any extension of patent term that may be available. Our fifth patent family currently consists of a pending PCT application directed to certain methods of use with respect to WTX-613. The 20-year term for patents in this family will run through 2045, excluding any extension of patent term that may be available. We plan to file an international patent application under the PCT based on this provisional application before the applicable deadlines.

WTX-712

We own a patent family directed to our IL-21 INDUKINE molecules and our WTX-712 product candidate. This patent family includes a pending PCT application that claims certain compositions of matter and method of use with respect to WTX-712. We intend to file national applications in other jurisdictions based on the pending PCT application before the applicable deadline. The 20-year term for patents in this family runs through 2044, excluding any extension of patent term that may be available.

WTX-518

We have an exclusive option under our November 2022 collaboration agreement with Adimab LLC to acquire ownership of a patent family directed to our IL-18 INDUKINE molecules and our WTX-518 product candidate. This patent family includes a pending PCT application that claims certain compositions of matter and method of use with respect to IL-18 INDUKINE molecules and WTX-518. We intend to exercise the option and acquire ownership of this patent family before applicable deadlines and to file national applications in other jurisdictions based in the pending PCT application before applicable deadlines. The 20-year term for patents in this family runs through 2044.

WTX-921

We own two patent families directed to our IL-10 INDUKINE molecules and our WTX-921 product candidate. We own a first patent family that includes a pending PCT application that claims certain compositions of matter and method of use with respect to IL-10 INDUKINE molecules and WTX-921. We intend to file national applications in other jurisdictions based in the pending PCT application before applicable deadlines. The 20-year term for patents in this family runs through 2044. Our second patent family includes a pending U.S. provisional application directed to certain compositions of matter and method of use with respect to IL-10 INDUKINE molecules and WTX-921. The 20-year term for patents in this family will run through 2045, excluding any extension of patent term that may be available. We plan to file an international patent application under the PCT based on this provisional application before the applicable deadlines.

In-Licensed Patents

We have licensed from Harpoon certain patents that are directed to single immunoglobulin variable domains that bind human serum albumin. We use the licensed technology in our current product candidates and may use the technology in additional development candidates we discover in the future. The licensed patent family includes granted U.S. patents and pending applications, and pending applications in Brazil, India, Canada, Japan, Mexico, Singapore, Australia, Eurasian Patent Organization, Republic of Korea, European Patent Office, China, and Israel. The 20-year term for the licensed patents runs through 2037, excluding any extension of patent term that may be available. See the discussion under “License Agreement with Harpoon Therapeutics, Inc.” for more information regarding our license agreement with Harpoon.

Patent Term and Patent Term Extensions

The term of individual patents depends upon the legal term for patents in the countries in which they are obtained. In most countries, including the United States, the patent term is 20 years from the earliest filing date of a non-provisional patent application. In addition, in certain instances, the term of a U.S. patent can be extended to compensate a patentee for administrative delays by the USPTO in examining and granting a patent. The term of a patent that covers a drug, biological product or medical device approved pursuant to a pre-market approval may also be eligible for patent term extension when FDA approval is granted, provided statutory and regulatory requirements are met. The length of the patent term extension is related to the length of time the drug is under regulatory review while the patent is in force. The Drug Price Competition and Patent Term Restoration Act of 1984, or the Hatch-Waxman Amendments, permits a patent term extension of up to five years beyond the expiration date set for the patent. Patent extension cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval, only one patent applicable to each regulatory review period may be granted an

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extension and only those claims reading on the approved drug are extended. Similar provisions are available in Europe and other foreign jurisdictions to extend the term of a patent that covers an approved drug. We will, in general, pursue available patent term extensions in the United States and in foreign jurisdictions that provide for patent term extensions, however, there is no guarantee that the applicable authorities, including the FDA in the United States, will agree with our assessment of whether such extensions should be granted, and if granted, the length of such extensions.

Trademarks, Trade Secrets and Know-How

In connection with the ongoing development and advancement of our product candidates in the United States and various international jurisdictions, we seek to create protection for our marks and enhance their value by pursuing trademarks where available and when appropriate. In addition to patent and trademark protection, we rely upon trade secrets and know-how and continuing technological innovation to develop and maintain our competitive position. We seek to protect our proprietary information, in part, using confidentiality agreements with our commercial partners, collaborators, employees and consultants and invention assignment agreements with our employees and selected consultants. We also seek to preserve the integrity and confidentiality of our data and trade secrets by maintaining physical security of our premises and physical and electronic security of our information technology systems. While we have confidence in these individuals, organizations and systems, agreements or security measures may be breached and our trade secrets and other proprietary information may be disclosed. We may not have adequate remedies for any breach and could lose our trade secrets and other proprietary information through such a breach. In addition, our trade secrets may otherwise become known or be independently discovered by competitors. To the extent that our consultants, contractors or collaborators use intellectual property owned by others in their work for us, disputes may arise as to the rights in related or resulting trade secrets, know-how and inventions.

Our commercial success will also depend in part on not infringing the proprietary rights of third parties. In addition, we have licensed rights under proprietary technologies of third parties to develop, manufacture and commercialize specific aspects of our future products and services. It is uncertain whether the issuance of any third-party patent would require us to alter our development or commercial strategies, alter our processes, obtain licenses or cease certain activities. The expiration of patents or patent applications licensed from third parties or our breach of any license agreements or failure to obtain a license to proprietary rights that we may require to develop or commercialize our future technology may have a material adverse impact on us. If third parties prepare and file patent applications in the United States that also claim technology to which we have rights, we may have to participate in interference proceedings in the USPTO to determine priority of invention.

For more information regarding the risks related to our intellectual property, please see “Risks Related to Our Intellectual Property” under Part I, Item 1A. Risk Factors in this Annual Report.

License and Royalty Agreements

License Agreement with Harpoon Therapeutics, Inc.

In March 2018, we entered into an assignment and license agreement, or the Harpoon Agreement, with Harpoon, pursuant to which we assigned to Harpoon certain patents related to adoptive cell therapies and binding moieties for conditional activation of immunoglobulin and non-immunoglobulin molecules, and Harpoon assigned to us certain patents related to certain inducible polypeptides and a binding moiety for conditional activation of certain polypeptides. Harpoon also granted to us a worldwide, non-exclusive, royalty-bearing, sublicensable license under certain other patents owned by Harpoon and related to certain proteins to make, have made, use, sell, offer for sale and import products that are covered by such patents in the field of molecules comprising a certain polypeptide. Under the Harpoon Agreement, we agreed to pay to Harpoon an upfront fee of $0.5 million and, if we commercialize any products covered by these licensed patents, a low single digit percentage royalty on net sales of such products by us or any of our affiliates or licensees, subject to an obligation to make a minimum annual royalty payment at an amount in the low hundreds of thousands of dollars beginning with the first commercial sale of any such product by us.

In October 2018, we and Harpoon amended the Harpoon Agreement by entering into a First Amended and Restated Assignment and License Agreement, which amended certain terms of the original agreement, but did not change the terms of the license to us, patent assignments between the parties or payments due to Harpoon.

In December 2019, we and Harpoon amended the Harpoon Agreement by entering into a Second Amended and Restated Assignment and License Agreement, or the Second Amended Harpoon Agreement, which granted to us an additional worldwide, exclusive, irrevocable, royalty-bearing, transferable, assignable, sublicensable license under certain patents owned by Harpoon and related to certain proteins, to make, have made, use, sell, offer for sale and import products that are covered by such patents in the field of molecules comprising a certain protein. Under the Second Amended Harpoon Agreement, we agreed to pay to Harpoon a low single digit percentage royalty on net sales by us or any of our affiliates or licensees of any products that we commercialize covered by these additional licensed patents. In addition, we also agreed to grant to Harpoon, and Harpoon agreed to grant to us, a perpetual, non-exclusive, irrevocable, royalty-free license under certain other patents directed

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to a certain binding domain of a certain protein, to make, have made, use, sell, offer for sale and import products that are covered by such patents in a field defined by a certain type of molecule with respect to each party.

Unless earlier terminated, our obligations to pay any royalties under the Second Amended Harpoon Agreement will expire on a country-by-country basis upon expiration of the last to expire valid claim of the relevant patents covering the manufacture, use or sale of such covered products in the applicable country. Harpoon may terminate the Second Amended Harpoon Agreement in the event of a material breach by us and our failure to cure such breach within a specified period and may terminate certain licenses if we become insolvent or bankrupt. We may terminate the Second Amended Harpoon Agreement voluntarily with prior written notice to Harpoon.

Amended and Restated Royalty Transfer Agreement

In December 2017, in connection with our sale of convertible promissory notes, we entered into a royalty transfer agreement with MPM Oncology Impact Fund Charitable Foundation, Inc., or MPM Charitable Foundation, and UBS Optimus Foundation, or the Royalty Transfer Agreement. Under the Royalty Transfer Agreement, we agreed to pay a royalty of 0.5% of net sales of our products to each of MPM Charitable Foundation and UBS Optimus Foundation. In August 2019, we amended the Royalty Transfer Agreement by entering into an amended and restated royalty transfer agreement, or the Amended Royalty Transfer Agreement, which provided that only products in our product pipeline at the time of our initial public offering or a change in control would be subject to the royalty on net sales. Under the Amended Royalty Transfer Agreement, our obligation to pay a royalty expires on a product-by-product and country-by-country basis upon the later of the 12th anniversary of the first commercial sale of such product in such country and expiration of the last valid claim in such country covering such product. The royalty rate is subject to a specified reduction for lack of any valid claim covering such product in a country. The obligation to pay royalties under the Amended Royalty Transfer Agreement shall not apply to any product that would only infringe our intellectual property rights that are discovered or developed after our initial public offering or to any product of an acquirer, assignee of the agreement or merger partner of us so long as such product does not incorporate any of our pre-acquisition intellectual property.

Government Regulation and Product Approval

Government authorities in the United States, at the federal, state and local level, and in other countries and jurisdictions, including the European Union, or EU, extensively regulate, among other things, the research, development, testing, manufacture, quality control, approval, packaging, storage, recordkeeping, labeling, advertising, promotion, distribution, marketing, sales, pricing, reimbursement, post-approval monitoring and reporting, and import and export of pharmaceutical products. The processes for obtaining regulatory approvals in the United States and in foreign countries and jurisdictions, along with subsequent compliance with applicable statutes and regulations and other regulatory authorities, require the expenditure of substantial time and financial resources. The regulatory requirements applicable to product development, approval and marketing are subject to change, and regulations and administrative guidance often are revised or reinterpreted by the agencies in ways that may have a significant impact on our business.

Review and Approval of Drugs and Biologics in the United States

In the United States, the FDA approves and regulates drugs under the Federal Food, Drug, and Cosmetic Act, or FDCA, and related regulations. Biological products, or biologics, are licensed for marketing under the Public Health Service Act, or PHSA, and subject to regulation under the FDCA and related regulations. A company, institution, or organization which takes responsibility for the initiation and management of a clinical development program for such products, and for their regulatory approval, is typically referred to as a sponsor. A sponsor seeking approval to market and distribute a new drug or biological product in the United States must typically secure the following:

•completion of preclinical laboratory tests in compliance with the FDA’s good laboratory practice, or GLP, standards and applicable regulations;

•design of a clinical protocol and submission to the FDA of an IND, which must take effect before human clinical trials may begin;

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

•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 proposed drug product for each proposed indication and the safety, potency and purity of the proposed biological product for each proposed indication;

•submission to the FDA of a new drug application, or NDA, for a drug candidate product and a biological license application, or BLA, for a biological product requesting marketing for one or more proposed indications;

•review of the request for approval by an FDA advisory committee, where appropriate or if applicable;

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•completion of one or more FDA inspections of the manufacturing facility or facilities at which the product, or components thereof, are produced to assess compliance with current good manufacturing practice, or cGMP, requirements to assure the product’s identity, strength, quality and purity;

•completion of FDA audits of clinical trial sites to assure compliance with GCPs and the integrity of the clinical data;

•payment of user application and program fees pursuant to the Prescription Drug User Fee Act, or PDUFA;

•securing FDA approval of the NDA or BLA authorizing marketing of the product in the United States or particular indications; and

•compliance with any post-approval requirements, including the potential requirement to implement a Risk Evaluation and Mitigation Strategy, or REMS, and the potential requirement to conduct post-approval studies.

Preclinical Studies

Before a sponsor begins testing a compound with potential therapeutic value in humans, the product candidate enters the preclinical testing stage. Preclinical studies include laboratory evaluation of the purity and stability of the manufactured substance or active pharmaceutical ingredient and the formulated product, as well as in vitro and animal studies to assess the safety and activity of the product candidate for initial testing in humans and to establish a rationale for therapeutic use. These studies are generally referred to as IND-enabling studies. The conduct of preclinical studies is subject to federal regulations and requirements, including GLP standards and regulations and the United States Department of Agriculture’s Animal Welfare Act, if applicable. Some long-term preclinical testing, such as animal tests of reproductive adverse events and carcinogenicity, and long-term toxicity studies, may continue after the IND is submitted.

The IND and IRB Processes

An IND is a request for FDA authorization to administer an investigational product candidate to humans. Such authorization must be secured prior to interstate shipment and administration of any new drug or biologic that is not the subject of an approved NDA or BLA. In support of a request for an IND, sponsors must submit a protocol for each clinical trial and any subsequent protocol amendments must be submitted to the FDA as part of the IND. In addition, the results of the preclinical tests, together with manufacturing information, analytical data, any available clinical data or literature and plans for clinical trials, among other things, are submitted to the FDA as part of an IND. The FDA requires a 30-day waiting period after the filing of each IND before clinical trials may begin. This waiting period is designed to allow the FDA to review the IND to determine whether human research subjects and patients will be exposed to unreasonable health risks and to address any other issues, including chemistry, manufacturing and controls, or CMC, for the proposed product. At any time during this 30-day period, the FDA may raise concerns or questions about the conduct of the trials as outlined in the IND and impose a clinical hold or partial clinical hold. In this case, the IND sponsor and the FDA must resolve any outstanding concerns before clinical trials can begin. The FDA’s primary objectives in reviewing an IND are to assure the safety and rights of patients and to help assure that the quality of the investigation will be adequate to permit an evaluation of the drug’s effectiveness and safety and of the biological product’s safety, purity and potency.

Following commencement of a clinical trial under an IND, the FDA may also place a clinical hold or partial clinical hold on that trial. Clinical holds imposed by the FDA may be a result of new data, findings, or developments in clinical, nonclinical, and CMC. A clinical hold is an order issued by the FDA to the sponsor to delay a proposed clinical investigation or to suspend an ongoing investigation. A partial clinical hold is a delay or suspension of only part of the clinical work requested under the IND. For example, a specific protocol or part of a protocol is not allowed to proceed, while other protocols may do so. No more than 30 days after imposition of a clinical hold or partial clinical hold, the FDA will provide the sponsor a written explanation of the basis for the hold. Following issuance of a clinical hold or partial clinical hold, an investigation may only resume after the FDA has notified the sponsor that the investigation may proceed. The FDA will base that determination on information provided by the sponsor correcting the deficiencies previously cited or otherwise satisfying the FDA that the investigation can proceed.

In addition to the foregoing IND requirements, an IRB representing each institution participating in the clinical trial must review and approve the plan for any clinical trial before it commences at that institution, and the IRB must conduct continuing review and reapprove the trial at least annually. The IRB must review and approve, among other things, the trial protocol and informed consent information to be provided to trial subjects. An IRB must operate in compliance with FDA regulations. An IRB can suspend or terminate approval of a clinical trial at its institution, or an institution it represents, if the clinical trial is not being conducted in accordance with the IRB’s requirements or if the product candidate has been associated with unexpected serious harm to patients.

Additionally, some trials are overseen by an independent group of qualified experts organized by the trial sponsor, known as a data monitoring committee, or DMC. This group provides authorization for whether a trial may move forward at designated check points based on access that only the group maintains to available data from the trial. Suspension or termination of

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development during any phase of clinical trials can occur if it is determined that the participants or patients are being exposed to an unacceptable health risk or for other reasons.

Human Clinical Studies in Support of an NDA or BLA

Clinical trials involve the administration of the investigational product to human subjects under the supervision of qualified investigators in accordance with GCP requirements, which include, among other things, the requirement that all research subjects provide their informed consent in writing before their participation in any clinical trial. Clinical trials are conducted under written trial protocols detailing, among other things, the inclusion and exclusion criteria, the objectives of the trial, the parameters to be used in monitoring safety and the effectiveness criteria to be evaluated.

The clinical investigation of an investigational drug or biological product is generally divided into four phases. Although the phases are usually conducted sequentially, they may overlap or be combined. The four phases of an investigation are as follows:

•Phase 1. Phase 1 studies include the initial introduction of an investigational new drug or biological product into humans. These studies are designed to evaluate the safety, dosage tolerance, metabolism and pharmacologic actions of the investigational drug or biological product in humans, the side effects associated with increasing doses, and if possible, to gain early evidence on effectiveness.

•Phase 2. Phase 2 includes the controlled clinical trials conducted to preliminarily or further evaluate the effectiveness of the investigational drug or biological product for a particular indication(s) in patients with the disease or condition under trial, to determine dosage tolerance and optimal dosage, and to identify possible adverse side effects and safety risks associated with the drug or biological product. Phase 2 clinical trials are typically well-controlled, closely monitored, and conducted in a limited patient population.

•Phase 3. Phase 3 clinical trials are generally controlled clinical trials conducted in an expanded patient population generally at geographically dispersed clinical trial sites. They are performed after preliminary evidence suggesting effectiveness of the drug or biological product has been obtained, and are intended to further evaluate dosage, clinical effectiveness and safety, to establish the overall benefit-risk relationship of the investigational drug or biological product, and to provide an adequate basis for product approval.

•Phase 4. Post-approval studies may be conducted after initial marketing approval. These studies are used to gain additional experience from the treatment of patients in the intended therapeutic indication.

A clinical trial may combine the elements of more than one phase and the FDA often requires more than one Phase 3 trial to support marketing approval of a product candidate. A company’s designation of a clinical trial as being of a particular phase is not necessarily indicative that the study will be sufficient to satisfy the FDA requirements of that phase because this determination cannot be made until the protocol and data have been submitted to and reviewed by the FDA. Generally, pivotal trials are Phase 3 trials, but they may be Phase 2 trials if the design provides a well-controlled and reliable assessment of clinical benefit, particularly in an area of unmet medical need.

In March 2022, the FDA released final guidance entitled “Expansion Cohorts: Use in First-In-Human Clinical Trials to Expedite Development of Oncology Drugs and Biologics,” which outlines how developers can utilize an adaptive trial design commonly referred to as a seamless trial design in early stages of oncology biological product development (i.e., the first-in-human clinical trial) to compress the traditional three phases of trials into one continuous trial called an expansion cohort trial. Information to support the design of individual expansion cohorts are included in IND applications and assessed by the FDA. Expansion cohort trials can potentially bring efficiency to biological product development and reduce developmental costs and time.

In December 2022, with the passage of Food and Drug Omnibus Reform Act, or FDORA, Congress required sponsors to develop and submit a diversity action plan, or DAP, for each Phase 3 clinical trial or any other “pivotal study” of a new drug or biological product. These plans are meant to encourage the enrollment of more diverse patient populations in late-stage clinical trials of FDA-regulated products. Specifically, action plans must include the sponsor’s goals for enrollment, the underlying rationale for those goals, and an explanation of how the sponsor intends to meet them. In addition to these requirements, the legislation directs the FDA to issue new guidance on diversity action plans. In June 2024, as mandated by FDORA, the FDA issued draft guidance outlining the general requirements for DAPs. Unlike most guidance documents issued by the FDA, the DAP guidance when finalized will have the force of law because FDORA specifically dictates that the form and manner for submission of DAPs are specified in FDA guidance.

In June 2023, the FDA issued draft guidance with updated recommendations for GCPs aimed at modernizing the design and conduct of clinical trials. The updates are intended to help pave the way for more efficient clinical trials to facilitate the development of medical products. The draft guidance is adopted from the International Council for Harmonisation’s recently updated E6(R3) draft guideline that was developed to enable the incorporation of rapidly developing technological and methodological innovations into the clinical trial enterprise. In addition, the FDA issued draft guidance outlining recommendations for the implementation of decentralized clinical trials.

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Finally, sponsors of clinical trials are required to register and disclose certain clinical trial information on a public registry (clinicaltrials.gov) maintained by the U.S. National Institutes of Health, or NIH. In particular, information related to the product, patient population, phase of investigation, study sites and investigators and other aspects of the clinical trial is made public as part of the registration of the clinical trial. Although the FDA has historically not enforced these reporting requirements due to the long delay by the Department of Health and Human Services, or HHS, in issuing final implementing regulations, those regulations have now been issued. As of December 19, 2024, the FDA has issued six notices of non-compliance, thereby signaling the government’s willingness to begin enforcing these requirements against non-compliant clinical trial sponsors. While these notices of non-compliance did not result in civil monetary penalties, the failure to submit clinical trial information to clinicaltrials.gov is a prohibited act under the FDCA with violations subject to potential civil monetary penalties of up to $10,000 for each day the violation continues. Violations may also result in injunctions and/or criminal prosecution or disqualification from federal grants.

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

Interactions with FDA During the Clinical Development Program

Following the clearance of an IND and the commencement of clinical trials, the sponsor will continue to have interactions with the FDA. Progress reports detailing the results of clinical trials must be submitted annually within 60 days of the anniversary dates that the IND went into effect and more frequently if serious adverse events occur. These reports must include a development safety update report, or DSUR, which is submitted on an annual basis to the FDA. In addition, IND safety reports must be submitted to the FDA for any of the following: serious and unexpected suspected adverse reactions; findings from other trials or animal or in vitro testing that suggest a significant risk in humans exposed to the product; and any clinically important increase in the occurrence of a serious suspected adverse reaction over that listed in the protocol or investigator brochure. Phase 1, Phase 2 and Phase 3 clinical trials may not be completed successfully within any specified period, or at all. The FDA will typically inspect one or more clinical sites to assure compliance with GCP and the integrity of the clinical data submitted.

In addition, sponsors are given opportunities to meet with the FDA at certain points in the clinical development program. Specifically, sponsors may meet with the FDA prior to the submission of an IND (pre-IND meeting), at the end of Phase 2 clinical trial (EOP2 meeting) and before a BLA is submitted (pre-BLA meeting). Meetings at other times may also be requested. There are five types of meetings that occur between sponsors and the FDA. Type A meetings are those that are necessary for an otherwise stalled product development program to proceed or to address an important safety issue. Type B meetings include pre-IND and pre-BLA meetings, as well as end of phase meetings such as EOP2 meetings. A Type C meeting is any meeting other than a Type A or Type B meeting regarding the development and review of a product, including for example meetings to facilitate early consultations on the use of a biomarker as a new surrogate endpoint that has never been previously used as the primary basis for product approval in the proposed context of use. A Type D meeting is focused on a narrow set of issues, which should be limited to no more than two focused topics, and should not require input from more than three disciplines or divisions. Finally, INTERACT meetings are intended for novel products and development programs that present unique challenges in the early development of an investigational product.

The FDA has indicated that its responses, as conveyed in meeting minutes and advice letters, only constitute mere recommendations and/or advice made to a sponsor and, as such, sponsors are not bound by such recommendations and/or advice. Nonetheless, from a practical perspective, a sponsor’s failure to follow the FDA’s recommendations for design of a clinical program may put the program at significant risk of failure.

Clinical Studies Outside the United States in Support of FDA Approval

In connection with our clinical development program, we may conduct trials at sites outside the United States. When a foreign clinical study is conducted under an IND, all IND requirements must be met unless waived. When a foreign clinical study is not conducted under an IND, the sponsor must ensure that the study complies with certain regulatory requirements of the FDA in order to use the study as support for an IND or application for marketing approval. Specifically, the studies must be conducted in accordance with GCP, including undergoing review and receiving approval by an independent ethics committee, or IEC, and seeking and receiving informed consent from subjects. GCP requirements encompass both ethical and data integrity standards for clinical studies. The FDA’s regulations are intended to help ensure the protection of human subjects enrolled in non-IND foreign clinical studies, as well as the quality and integrity of the resulting data. They further help ensure that non-IND foreign studies are conducted in a manner comparable to that required for IND studies.

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The acceptance by the FDA of study data from clinical trials conducted outside the United States in support of U.S. approval may be subject to certain conditions or may not be accepted at all. In cases where data from foreign clinical trials are intended to serve as the sole basis for marketing approval in the U.S., the FDA will generally not approve the application on the basis of foreign data alone unless (i) the data are applicable to the U.S. population and U.S. medical practice; (ii) the trials were performed by clinical investigators of recognized competence and pursuant to GCP regulations; and (iii) the data may be considered valid without the need for an on-site inspection by the FDA, or if the FDA considers such inspection to be necessary, the FDA is able to validate the data through an on-site inspection or other appropriate means.

In addition, even where the foreign study data are not intended to serve as the sole basis for approval, the FDA will not accept the data as support for an application for marketing approval unless the study is well-designed and well-conducted in accordance with GCP requirements and the FDA is able to validate the data from the study through an onsite inspection if deemed necessary. Many foreign regulatory authorities have similar approval requirements. In addition, such foreign trials are subject to the applicable local laws of the foreign jurisdictions where the trials are conducted.

Manufacturing and cGMP requirements

Concurrent with clinical trials, sponsors usually complete additional animal safety studies, develop additional information about the chemistry and physical characteristics of the product candidate and finalize a process for manufacturing commercial quantities of the product candidate in accordance with cGMP requirements. The manufacturing process must be capable of consistently producing quality batches of the product candidate and, among other criteria, the sponsor must develop methods for testing the identity, strength, quality, and purity of the finished 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.

The FDA’s regulations require that pharmaceutical products be manufactured in specific approved facilities and in accordance with cGMPs. The cGMP regulations include requirements relating to organization of personnel, buildings and facilities, equipment, control of components and product containers and closures, production and process controls, packaging and labeling controls, holding and distribution, laboratory controls, records and reports and returned or salvaged products. Manufacturers and other entities involved in the manufacture and distribution of approved pharmaceuticals are required to register their establishments with the FDA and some state agencies and they are subject to periodic unannounced inspections by the FDA for compliance with cGMPs and other requirements.

Inspections must follow a “risk-based schedule” that may result in certain establishments being inspected more frequently. Manufacturers may also have to provide, on request, electronic or physical records regarding their establishments. Delaying, denying, limiting, or refusing inspection by the FDA may lead to a product being deemed to be adulterated. Changes to the manufacturing process, specifications or container closure system for an approved product are strictly regulated and often require prior FDA approval before being implemented. The FDA’s regulations also require, among other things, the investigation and correction of any deviations from cGMP and the imposition of reporting and documentation requirements upon the sponsor and any third-party manufacturers involved in producing the approved product. The PREVENT Pandemics Act, which was enacted in December 2022, clarifies that foreign drug manufacturing establishments are subject to registration and listing requirements even if a drug or biologic undergoes further manufacture, preparation, propagation, compounding, or processing at a separate establishment outside the United States prior to being imported or offered for import into the United States.

Pediatric Studies

Under the Pediatric Research Equity Act of 2003, or PREA, an application or 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. Sponsors must also submit an initial Pediatric Study Plan, or PSP, prior to the assessment data. The PSP must contain an outline of the proposed pediatric study or studies the sponsor plans to conduct, including study objectives and design, any deferral or waiver requests and other information required by regulation. The sponsor, the FDA, and the FDA’s internal review committee must then review the information submitted, consult with each other and agree upon a final plan. The FDA or the sponsor may request an amendment to the plan at any time. In May 2023, the FDA issued new draft guidance that further describes the pediatric study requirements under PREA.

For investigational products intended to treat a serious or life-threatening disease or condition, the FDA must, upon the request of a sponsor, meet to discuss preparation of the initial pediatric study plan or to discuss deferral or waiver of pediatric assessments. In addition, the FDA will meet early in the development process to discuss pediatric study plans with sponsors, and the FDA must meet with sponsors by no later than the end-of-phase 1 meeting for serious or life-threatening diseases and by no later than ninety days after the FDA’s receipt of the study plan.

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The FDA may, on its own initiative or at the request of the sponsor, 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. A deferral may be granted for several reasons, including a finding that the product or therapeutic candidate is ready for approval for use in adults before pediatric trials are complete or that additional safety or effectiveness data needs to be collected before the pediatric trials begin. The FDA is required to send a PREA Non-Compliance letter to sponsors who have failed to submit their pediatric assessments required under PREA, have failed to seek or obtain a deferral or deferral extension or have failed to request approval for a required pediatric formulation. Unless otherwise required by regulation, the pediatric data requirements do not apply to products with orphan designation, although the FDA has taken steps to limit what it considers abuse of this statutory exemption. Further, Section 505B of the FDCA, as amended by the FDA Reauthorization Act of 2017, or FDARA, requires that any original NDA or BLA submitted on or after August 18, 2020, for a new active ingredient, must contain reports on the molecularly targeted pediatric cancer investigation, unless the requirement is waived or deferred, if the drug that is the subject of the application is: (1) intended for the treatment of an adult cancer, and (2) directed at a molecular target that the Secretary determines to be substantially relevant to the growth or progression of a pediatric cancer in accordance with FDA guidance. The FDA also maintains a list of diseases that are exempt from PREA requirements due to low prevalence of disease in the pediatric population.

Submission and Review of an NDA or BLA by the FDA

In order to obtain approval to market a drug or biological product in the United States, a marketing application must be submitted to the FDA that provides data establishing the safety and effectiveness of the proposed drug product for the proposed indication, and the safety, purity and potency of the biological product for its intended indication. The application includes all relevant data available from pertinent preclinical 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 studies initiated by investigators.

The application is the vehicle through which sponsors formally propose that the FDA approve a new product for marketing and sale in the United States for one or more indications. Every new product candidate must be the subject of an approved NDA or BLA before it may be commercialized in the United States. Under federal law, the fee required for the submission and review of an application under the Prescription Drug User Fee Act, or the PDUFA, is substantial (for example, for federal fiscal year 2025 this application fee is approximately $4.3 million), and the sponsor of an approved application is also subject to an annual program fee, currently more than $403,889 per eligible prescription product for federal fiscal year 2025. Certain exceptions and waivers are available for some of these fees, such as an exception from the application fee for products with orphan designation and a waiver for certain small businesses. If an application is withdrawn prior to the FDA acceptance for filing, 75% of these fees may be refunded to the sponsor. If an application is withdrawn after filing, a lower portion of these fees may be refunded in certain circumstances.

Following submission of an NDA or BLA, the FDA conducts a preliminary review of the application within 60 calendar days of its receipt and must inform the sponsor by that time or before whether the application is sufficiently complete to permit substantive review. In the event that the FDA determines that an application does not satisfy this standard, it will issue a Refuse to File, or RTF, determination to the sponsor. The FDA may request additional information and studies and the application must be resubmitted with the additional information. The resubmitted application is also subject to review before the FDA accepts it for filing.

Once the submission is accepted for filing, the FDA begins an in-depth substantive review. The FDA has agreed to specified performance goals in the review process of NDAs and BLAs. Under that agreement, 90% of applications seeking approval of New Molecular Entities, or NMEs, are meant to be reviewed within ten months from the date on which the FDA accepts the NDA for filing, and 90% of applications for NMEs that have been designated for “priority review” are meant to be reviewed within six months of the filing date. The review process and the PDUFA goal date may be extended by the FDA for three additional months to consider new information or clarification provided by the sponsor to address an outstanding deficiency identified by the FDA following the original submission.

The FDA seeks to meet these timelines for review of an application but its ability to do so may be affected by a variety of factors, including government budget and funding levels, the ability to hire and retain key personnel and statutory, regulatory and policy changes. Average review times at the agency have fluctuated in recent years as a result. For example, during the past decade, the U.S. government has shut down several times and certain regulatory agencies, including the FDA, have had to furlough critical employees and stop critical activities, including the review of both NDAs and BLAs.

In connection with its review of an application, the FDA typically will inspect the facility or facilities where the product is or will be manufactured. These pre-approval inspections may cover all facilities associated with an NDA or BLA submission, including drug component manufacturing (e.g., active pharmaceutical ingredients), finished drug product manufacturing, and control testing laboratories. The FDA will not approve an application unless it determines that the manufacturing processes and

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facilities are in compliance with cGMP requirements and adequate to assure consistent production of the product within required specifications.

Moreover, the FDA will review a sponsor’s financial relationship with the principal investigators who conducted the clinical trials in support of the BLA or NDA. Depending on the level of that compensation and any other financial interest a principal investigator may have in a sponsor, the sponsor may be required to report these relationships to the FDA. The FDA will then evaluate that financial relationship and determine whether it creates a conflict of interest or otherwise affects the interpretation of the trial or the integrity of the data generated at the principal investigator’s clinical trial site. If so, the FDA may exclude data from the clinical trial site in connection with its determination of the approvability of the application for the investigational product.

Additionally, before approving an NDA or BLA, the FDA will typically inspect one or more clinical sites to assure compliance with GCP standards and the integrity of the clinical data supporting the application. With the passage of FDORA, Congress clarified the FDA’s authority to conduct inspections by expressly permitting inspection of facilities involved in the preparation, conduct, or analysis of clinical and non-clinical studies submitted to the FDA as well as other persons holding study records or involved in the study process.

The FDA may also refer an application for a novel product to an advisory committee or explain why such referral was not made. Typically, 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 an NDA or BLA

After evaluating the application and all related information, including the advisory committee recommendations, if any, and inspection reports of manufacturing facilities and clinical trial sites, the FDA will issue either a Complete Response Letter, or CRL, or an approval letter. To reach this determination, the FDA must determine that the expected benefits of the proposed product outweigh its potential risks to patients. This “benefit-risk” assessment is informed by the extensive body of evidence about the product in the NDA or BLA.

If the FDA decides not to license or approve the application, it will issue a CRL. A CRL will describe all of the deficiencies that the FDA has identified in the application, except that where the FDA determines that the data supporting the application are inadequate to support approval, the FDA may issue the CRL without first conducting required inspections, testing submitted product lots, and/or reviewing proposed labeling. In issuing the CRL, the FDA may recommend actions that the applicant might take to place the application in condition for approval, including requests for additional information or clarification. The FDA may delay or refuse approval of an application if applicable regulatory criteria are not satisfied, require additional testing or information and/or require post-marketing testing and surveillance to monitor safety or efficacy of a product. If a CRL is issued, the applicant will have one year to respond to the deficiencies identified by the FDA, at which time the FDA can deem the application withdrawn or, in its discretion, grant the applicant an additional six month extension to respond. For those seeking to challenge the FDA’s CRL decision, the FDA has indicated that sponsors may request a formal hearing on the CRL or they may file a request for reconsideration or a request for a formal dispute resolution.

An approval letter, on the other hand, authorizes commercial marketing of the product with specific prescribing information for specific indications. If the FDA approves a product, it may limit the approved indications for use for the product, require that contraindications, warnings or precautions be included in the product labeling, require that post-approval studies, including phase 4 clinical trials, be conducted to further assess the drug’s safety after approval, require testing and surveillance programs to monitor the product after commercialization, or impose other conditions, including distribution restrictions or other risk management mechanisms, including REMS, which can materially affect the potential market and profitability of the product. The FDA may prevent or limit further marketing of a product based on the results of post-market studies or surveillance programs. After approval, many types of changes to the approved product, such as adding new indications, manufacturing changes and additional labeling claims, are subject to further testing requirements and FDA review and approval.

Fast Track, Breakthrough Therapy and Priority Review Designations

The FDA is authorized to designate certain products for expedited review if they are intended to address an unmet medical need in the treatment of a serious or life-threatening disease or condition. These programs include fast track designation, breakthrough therapy designation and priority review designation. None of these expedited programs changes the standards for approval but each may help expedite the development or approval process governing product candidates.

Specifically, the FDA may designate a product for Fast Track review if it is intended, whether alone or in combination with one or more other products, for the treatment of a serious or life-threatening disease or condition, and it demonstrates the potential to address unmet medical needs for such a disease or condition. For Fast Track products, sponsors may have greater interactions

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with the FDA and the FDA may initiate review of sections of a Fast Track product’s application before the application is complete. This rolling review may be available if the FDA determines, after preliminary evaluation of clinical data submitted by the sponsor, that a Fast Track product may be effective. The sponsor must also provide, and the FDA must approve, a schedule for the submission of the remaining information and the sponsor must pay applicable user fees. However, the FDA’s time period goal for reviewing a Fast Track application does not begin until the last section of the application is submitted. In addition, the Fast Track designation may be withdrawn by the FDA if the FDA believes that the designation is no longer supported by data emerging in the clinical trial process.

Second, a product may be designated as a Breakthrough Therapy if it is intended, either alone or in combination with one or more other products, to treat a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the product 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 FDA may take certain actions with respect to Breakthrough Therapies, including holding meetings with the sponsor throughout the development process; providing timely advice to the product sponsor regarding development and approval; involving more senior staff in the review process; assigning a cross-disciplinary project lead for the review team; and taking other steps to help the sponsor design the clinical trials in an efficient manner.

Third, the FDA may designate a product for priority review if it is a product that treats a serious condition and, if approved, would provide a significant improvement in safety or effectiveness. The FDA determines, on a case-by-case basis, whether the proposed product represents a significant improvement when compared with other available therapies. Significant improvement may be illustrated by evidence of increased effectiveness in the treatment of a condition, elimination or substantial reduction of a treatment-limiting product reaction, documented enhancement of patient compliance that may lead to improvement in serious outcomes, and evidence of safety and effectiveness in a new subpopulation. A priority designation is intended to direct overall attention and resources to the evaluation of such applications, and to shorten the FDA’s goal for taking action on a marketing application from ten months to six months.

Accelerated Approval Pathway

The FDA may grant accelerated approval to a product for a serious or life-threatening condition that provides meaningful therapeutic advantage to patients over existing treatments based upon a determination that the product has an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit. The FDA may also grant accelerated approval for such a condition when the product has an effect on an intermediate clinical endpoint that can be measured earlier than an effect on irreversible morbidity or mortality, or IMM, and 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. Products granted accelerated approval must meet the same statutory standards for safety and effectiveness as those granted traditional approval.

For the purposes of accelerated approval, a surrogate endpoint is a marker, such as a laboratory measurement, radiographic image, physical sign or other measure that is thought to predict clinical benefit, but is not itself a measure of clinical benefit. Surrogate endpoints can often be measured more easily or more rapidly than clinical endpoints. An intermediate clinical endpoint is a measurement of a therapeutic effect that is considered reasonably likely to predict the clinical benefit of a drug, such as an effect on IMM. The FDA has limited experience with accelerated approvals based on intermediate clinical endpoints, but has indicated that such endpoints generally may support accelerated approval where the therapeutic effect measured by the endpoint is not itself a clinical benefit and basis for traditional approval, if there is a basis for concluding that the therapeutic effect is reasonably likely to predict the ultimate clinical benefit of a product.

The accelerated approval pathway is most often used in settings in which the course of a disease is long and an extended period of time is required to measure the intended clinical benefit of a product, even if the effect on the surrogate or intermediate clinical endpoint occurs rapidly. Thus, accelerated approval has been used extensively in the development and approval of products for treatment of a variety of cancers in which the goal of therapy is generally to improve survival or decrease morbidity and the duration of the typical disease course requires lengthy and sometimes large trials to demonstrate a clinical or survival benefit. Thus, the benefit of accelerated approval derives from the potential to receive approval based on surrogate endpoints sooner than possible for trials with clinical or survival endpoints, rather than deriving from any explicit shortening of the FDA approval timeline, as is the case with priority review.

The accelerated approval pathway is usually contingent on a sponsor’s agreement to conduct, in a diligent manner, additional post-approval confirmatory studies to verify and describe the product’s clinical benefit. As a result, a product candidate approved on this basis is subject to rigorous post-marketing compliance requirements, including the completion of Phase 4 or post-approval clinical trials to confirm the effect on the clinical endpoint. Failure to conduct required post-approval studies, or confirm a clinical benefit during post-marketing studies, would allow the FDA to initiate expedited proceedings to withdraw approval of the product. All promotional materials for product candidates approved under accelerated regulations are subject to prior review by the FDA.

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With the passage of FDORA, Congress modified certain provisions governing accelerated approval of drug and biologic products. Specifically, the new legislation authorized the FDA to require a sponsor to have its confirmatory clinical trial underway before accelerated approval is awarded and to submit progress reports on its post-approval studies to the FDA every six months until the study is completed. Moreover, FDORA established expedited procedures authorizing the FDA to withdraw an accelerated approval if certain conditions are met, including where a required confirmatory study fails to verify and describe the predicted clinical benefit or where evidence demonstrates the product is not shown to be safe or effective under the conditions of use. The FDA may also use such procedures to withdraw an accelerated approval if a sponsor fails to conduct any required post-approval study of the product with due diligence, including with respect to “conditions specified by the Secretary.” The new procedures include the provision of due notice and an explanation for a proposed withdrawal, and opportunities for a meeting with the Commissioner or the Commissioner’s designee and a written appeal, among other things.

In March 2023, the FDA issued draft guidance that outlines its current thinking and approach to accelerated approval. The agency indicated that the accelerated approval pathway is commonly used for approval of oncology drugs due to the serious and life-threatening nature of cancer. Although single-arm trials have been commonly used to support accelerated approval, a randomized controlled trial is the preferred approach as it provides a more robust efficacy and safety assessment and allows for direct comparisons to an available therapy. To that end, the FDA outlined considerations for designing, conducting, and analyzing data for trials intended to support accelerated approvals of oncology therapeutics. Subsequently, in December 2024 and January 2025, the FDA issued additional draft guidances relating to accelerated approval. These guidances describe FDA’s views on what it means to conduct a confirmatory trial with due diligence and how the agency plans to interpret whether such a study needs to be underway at the time of approval. While these guidances are currently only in draft form and will ultimately not be legally binding even when finalized, sponsors typically observe the FDA’s guidance closely to ensure that their investigational products qualify for accelerated approval.

Post-Approval Regulation

Drugs and biologics 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 indications or other labeling claims, are subject to prior FDA review and approval. There also are continuing, annual user fee requirements for any marketed products and the establishments at which such products are manufactured, as well as new application fees for supplemental applications with clinical data.

In addition, changes to the manufacturing process are strictly regulated and often 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 the sponsor and any third-party manufacturers that the sponsor may decide to use. Accordingly, manufacturers must continue to expend time, money, and effort in the area of production and quality control to maintain cGMP compliance.

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HOWL · 10-K · period ended 2024-12-31

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