Scholar Rock Holding Corp

1. Nature of the Business and Basis of Presentation

Organization

Scholar Rock Holding Corporation and its subsidiaries (collectively, the “Company”) is a global biopharmaceutical company dedicated to dramatically improving the lives of children and adults with spinal muscular atrophy (“SMA”) and additional rare, severe and debilitating neuromuscular diseases. As a leader in the biology of the transforming growth factor beta (“TGFβ”) superfamily, the Company’s novel understanding of the molecular mechanisms of growth factor activation enabled the development of a proprietary platform for the discovery and development of monoclonal antibodies that locally and selectively target the precursor, or latent, forms of growth factors. Based on the Company’s innovative, proprietary, and scalable technology platform, the Company is building a world-leading anti-myostatin pipeline.

The Company’s lead pipeline product candidates include apitegromab, a subcutaneous formulation of apitegromab, and SRK-439.

Apitegromab is a novel, investigational, fully human monoclonal antibody that inhibits myostatin activation by selectively binding the pro- and latent forms of myostatin in skeletal muscle. Myostatin is a catabolic agent that functions as a negative regulator of muscle mass, therefore inhibition of myostatin results in increased muscle mass and strength. Apitegromab is in development for the treatment of people with SMA and for the treatment of people with facioscapulohumeral muscular dystrophy (“FSHD”).

Positive data from the successful Phase 3 SAPPHIRE study evaluating apitegromab in children and adults with SMA was reported in October 2024. The Company submitted a U.S. Biologics License Application (“BLA”) to the U.S. Food and Drug Administration (“FDA”) in January 2025 and the BLA was granted priority review designation. In September 2025, the Company received a Complete Response Letter (“CRL”) from the FDA related to observations identified during an FDA inspection of a third-party fill-finish facility. The facility was issued a Form 483 by the FDA in July 2025 and the inspection classification of this facility is official action indicated (“OAI”). The observations were related to the facility and were not specific to apitegromab. The CRL did not cite any other approvability concerns, including apitegromab’s efficacy and safety data or the third-party drug substance manufacturer. In November 2025, the Company completed an in-person Type A meeting with the FDA that included participation of representatives from the third-party fill-finish facility. Also in November 2025, the third-party fill-finish facility received a Warning Letter from the FDA and continues to work with the FDA to resolve the outstanding issues cited in the warning letter. The Company plans to resubmit the apitegromab BLA at such time after the facility resolves the cGMP deficiencies identified in the CRL. In March 2025, the Company submitted to the European Medicines Agency (“EMA”) and received validation of its marketing authorisation application (“MAA”) for apitegromab for the treatment of SMA. If apitegromab is approved by the FDA or EMA, the Company expects to initiate a commercial product launch in the applicable jurisdictions upon approval.

The Company continues to develop apitegromab in SMA with its ongoing long-term extension ONYX trial and its Phase 2 OPAL trial in SMA patients under two years of age, which was initiated in the third quarter of 2025. Additionally, a Phase 2 study evaluating apitegromab in patients with FSHD is expected to initiate in mid-2026.

In addition to the current intravenous (“IV”) formulation, the Company is developing a subcutaneous (“SC”) formulation of apitegromab. A Phase 1 study in healthy volunteers has been completed, demonstrating that SC apitegromab has favorable bioavailability and a comparable pharmacodynamic profile relative to IV administered apitegromab. Further development activities are ongoing, including planned FDA and EMA regulatory engagements.

The Company’s clinical-stage pipeline also includes SRK-439, a novel, investigational, subcutaneously administered fully human anti-pro/latent myostatin antibody that has high inhibitory potency while maintaining selectivity towards myostatin. SRK-439 is being developed for the treatment of patients with rare, severe, and debilitating neuromuscular

diseases. A Phase 1 study of SRK-439 in healthy volunteers is currently underway, with topline data anticipated in the second half of 2026.

As the Company focuses its strategy on rare neuromuscular diseases, the Company is currently seeking partnerships for its additional programs. These programs include: SRK-181, a Phase 2-ready investigational inhibitor of latent TGFβ1 in development for the treatment of patients with solid tumors that are resistant to anti-PD-(L)1 antibody therapies; SRK-373, an investigational, highly selective inhibitor of the latent TGFβ1 isoform with selective activity in the fibrotic extracellular matrix, in preclinical development for the treatment of fibrotic diseases; and SRK-256, an investigational inhibitor of RGMc, or hemojuvelin, in preclinical development for the treatment of iron-restricted anemias. We are also seeking partners to further evaluate the potential for myostatin inhibition in combination with GLP-1 weight loss approaches following our positive Phase 2 EMBRAZE study, demonstrating proof-of-concept in the ability of apitegromab to drive statistically significant preservation of lean mass during tirzepatide-induced weight loss.

Beyond the clinical-stage product candidates, the company’s early-stage pipeline includes additional programs for the treatment of patients with rare, severe, and debilitating neuromuscular diseases. The Company was originally formed in May 2012. Its principal offices are in Cambridge, Massachusetts.

Since its inception, the Company’s operations have focused on research and development of monoclonal antibodies that selectively inhibit activation of growth factors for therapeutic effect, as well as establishing the Company’s intellectual property portfolio and performing research and development activities. The Company has primarily financed its operations through various equity financings, the exercise of stock options and warrants, as well as research and development collaboration agreements and the Company’s debt facility (Note 14).

Revenue generation activities have been limited totwo collaborations, both containing research services and the issuance of a license. No revenues have been recorded from the sale of any commercial product.

The Company is subject to a number of risks similar to other life science companies, including, but not limited to, successful discovery and development of its drug candidates, raising additional capital, development by its competitors of new technological innovations, protection of proprietary technology and regulatory approval and market acceptance of the Company’s product candidates. The Company anticipates that it will continue to incur significant operating losses for the next several years as it continues to develop and seek regulatory approval for its product candidates.

The Company believes that its existing cash, cash equivalents and marketable securities as of December 31, 2025, along with cash available to the Company (see Note 18), will be sufficient to allow the Company to fund its current operations through at least a period of one year after the date these financial statements are issued.

Basis of Presentation

The consolidated financial statements include the accounts of Scholar Rock Holding Corporation and its wholly owned subsidiaries. All intercompany balances have been eliminated in consolidation.

These consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the U.S. (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).

2. Summary of Significant Accounting Policies

Use of Estimates

The preparation of financial statements in accordance with GAAP requires management to make estimates and judgments that may affect the reported amounts of assets and liabilities and related disclosures of contingent assets and liabilities at the date of the financial statements and the related reporting of revenues and expenses during the reporting

period. Management bases its estimates on historical experience and on various assumptions that are believed to be reasonable under the circumstances. Actual results could differ from those estimates.

Concentration of Credit Risk and Off-Balance Sheet Risk

The Company has no off-balance sheet risk, such as foreign exchange contracts, option contracts or other foreign-hedging arrangements. The Company follows an investment policy approved by the Board of Directors. Its primary objectives are the preservation of capital and maintenance of liquidity. The Company invests only in fixed income instruments denominated and payable in U.S. dollars including obligations of the U.S. government and its agencies and money market funds registered according to SEC Rule 2a-7 of the Investment Company Act of 1940. All securities must have a readily ascertainable market value, must be readily marketable and be U.S. dollar denominated.

Cash, Cash Equivalents and Restricted Cash

The Company considers highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Cash equivalents are stated at cost, which approximates market value. At December 31, 2025 and 2024, cash equivalents include money market funds that invest primarily in U.S. government-backed securities and treasuries.

At December 31, 2025 and 2024, restricted cash consists of letters of credit related to its leased facility and a collateral account associated with the Company’s corporate credit card program. The following table reconciles cash, cash equivalents and restricted cash per the balance sheet to the statement of cash flows (in thousands):

Foreign Currency Translation

The financial statements of our subsidiaries with functional currencies other than the U.S. dollar are translated into U.S. dollars using period-end exchange rates for assets and liabilities, historical exchange rates for stockholders’ equity and weighted average exchange rates for operating results. Translation gains and losses are included in accumulated other comprehensive income (loss) in stockholders’ equity. Foreign currency transaction gains and losses are included in the results of operations in other income and expense.

Marketable Securities

The Company classifies its marketable securities as available-for-sale. Marketable securities with a remaining maturity date greater than one year are classified as non-current if the Company does not intend to utilize the marketable securities to fund current operations. Marketable securities are maintained by an investment manager and consist of U.S. treasury obligations and government agency securities. Marketable securities are carried at fair value with the unrealized gains and losses included in accumulated other comprehensive income (loss) as a component of stockholders’ equity until realized. Any premium or discount arising at purchase is amortized and/or accreted to interest income and/or expense over the life of the underlying marketable security.

Although available to be sold to meet operating needs or otherwise, securities are generally held through maturity. The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense) within the statement of operations and comprehensive loss.

The Company reviews its portfolio of available-for-sale debt securities, using both quantitative and qualitative factors, to determine if declines in fair value below cost have resulted from a credit loss or other factors. If the decline in fair value

is due to credit loss factors, a loss is recognized in net income. To date, the Company has not experienced any credit losses and does not believe it is exposed to any significant credit risk on these investments.

Property and Equipment

Property and equipment are recorded at cost. Expenditures for major renewals or betterments that extend the useful lives of property and equipment are capitalized; expenditures for maintenance and repairs are charged to expense as incurred. Depreciation is calculated on a straight-line basis over the estimated useful lives of the related asset. Property and equipment are depreciated as follows:

Impairment of Long-Lived Assets

Long-lived assets consist of property and equipment and right-of-use assets. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset group over its fair value, determined based on discounted cash flows. The Company didnot record any impairment losses on long-lived assets during the years ended December 31, 2025 or 2024.

Leases

The Company accounts for leases using ASC Topic 842, Leases (“ASC 842”). At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances present. Leases with a term greater than one year are recognized on the balance sheet as right-of-use assets, lease liabilities and, if applicable, long-term lease liabilities. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the right-of-use asset may be required for items such as incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its estimated incremental borrowing rates, which are the rates incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment.

In accordance with the guidance in ASC 842, components of a lease should be split into three categories: lease components (e.g., land, building, etc.), non-lease components (e.g., common area maintenance, consumables, etc.), and non-components (e.g., property taxes, insurance, etc.). Then the fixed and in-substance fixed contract consideration (including any related to non-components) must be allocated based on the respective relative fair values to the lease components and non-lease components. For operating leases, lease expense relating to fixed payments is recognized on a straight-line basis over the term. The Company has elected to not separate lease expense relating to variable payments and therefore expenses costs as incurred.

Fair Value Measurements

ASC Topic 820, Fair Value Measurement ("ASC 820"), establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. ASC 820 identifies fair value as the exchange price, or exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tier fair value hierarchy that distinguishes between the following:

Level 1 — Quoted market prices in active markets for identical assets or liabilities.

Level 2 — Inputs other than Level 1 inputs that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves.

Level 3 — Unobservable inputs developed using estimates of assumptions developed by the Company, which reflect those that a market participant would use.

To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized as Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

Segment Information

Operating segments are defined as components of an entity about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business inone operating segment (Note 17).

Research and Development Expenses and Related Accruals/Prepaids

Research and development expenses are expensed as incurred and consist of costs incurred in performing research and development activities, including compensation related expenses for research and development personnel, preclinical and clinical activities including cost of clinical drug supply, commercial drug supply prior to FDA approval, overhead expenses including facilities expenses, materials and supplies, amounts paid to consultants and outside service providers, and depreciation of equipment. Upfront license payments related to acquired technologies which have not yet reached technological feasibility and have no alternative future use are also included in research and development expense.

The Company has entered into various research and development service arrangements under which vendors perform various services. The Company records accrued expenses for estimated costs incurred under the arrangements in excess of vendor invoices received while cash payments to vendors, including those that are nonrefundable, in excess of estimated costs incurred are recorded as prepaid expenses. Prepaid expenses are expensed as the related services are performed or goods are received. When evaluating the adequacy and accuracy of the accrued and prepaid expenses, the Company reviews open contracts and purchase orders, the level of service performed, invoices received, contracted costs, and progress of studies, clinical trials or other activities based on communication with internal and/or external personnel. Significant judgments and estimates are made in determining the accrued and prepaid expense balances at the end of each reporting period, and payments for these activities are due based on the terms of individual arrangements, which may differ from the pattern of costs incurred.

Equity-Based Compensation

The Company accounts for equity awards, including restricted stock units, performance stock units, equity classified warrants and common stock options, granted as equity-based compensation in accordance with ASC Topic 718, Compensation — Stock Compensation ("ASC 718"). ASC 718 requires all stock-based payments to employees, which includes grants of employee equity awards, to be recognized as expense in the statements of operations based on their grant date fair values.

The fair value of each restricted stock unit is based on the fair value of the Company’s common stock less any purchase price, if applicable. The fair value of each performance stock unit is estimated using a Monte-Carlo simulation, which uses as inputs the fair value of the Company’s common stock and certain subjective assumptions, including the historical stock price volatility, the risk-free rate and expected dividends. The fair value of each stock option award and equity classified warrant is estimated using the Black-Scholes option-pricing model, which uses as inputs the fair value of the Company’s common stock and certain subjective assumptions, including the historical stock price volatility, the expected term of the award, the risk-free rate and expected dividends. Through the second quarter of 2024, expected volatility was calculated based on a blend of the Company’s reported volatility data for the length of time that market data was available for the Company’s stock and the historical data for a representative group of publicly traded companies, for which historical information was available. As of the third quarter of 2024, the Company’s own volatility data covered a period of time that was sufficient to meet the expected term of the granted awards and the blended approach was no longer needed. The historical volatility is generally calculated based on a period of time commensurate with the expected term assumptions. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant commensurate with the expected term assumption. The Company uses the simplified method, under which the expected term is presumed to be the midpoint between the vesting date and the end of the contractual term. The Company utilizes this method due to lack of historical exercise data and the plain nature of its stock-based awards. The expected dividend yield is assumed to bezero as the Company has never paid dividends and has no current plans to pay any dividends on common stock.

Compensation expense related to equity awards to employees that are subject to service-based vesting is recognized on a straight-line basis, based on the grant date fair value, over the requisite service period of the award, which is generally the vesting term. For awards subject to performance conditions, the Company recognizes equity-based compensation expense using an accelerated recognition method over the remaining service period when management determines that achievement of the performance condition is probable. Management evaluates whether the achievement of the performance condition is probable at each reporting date. Compensation expense related to equity awards to non-employees for services is recognized based on the grant date fair value, over the period during which services are rendered by such non-employees.

The Company classifies equity-based compensation expense in its consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s salary and related costs are classified or based on the nature of the services being provided in the case of non-employees.

The Company accounts for forfeitures when they occur.

Comprehensive Loss

Comprehensive loss is the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Comprehensive loss includes net loss and the change in accumulated other comprehensive income (loss) for the period. Accumulated other comprehensive loss consisted of unrealized losses on available-for-sale marketable securities and foreign currency translation adjustments during the period ending December 31,2025. Accumulated other comprehensive income consisted entirely of unrealized gains on available-for-sale marketable securities during the period ending December 31, 2024.

Net Loss per Share

The Company applies the two-class method to compute basic and diluted net loss per share. The two-class method determines net income (loss) per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income (losses) available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to share in the earnings as if all income (losses) for the period had been distributed. During periods of loss, there is no allocation required under the two-class method since the participating securities do not have a contractual obligation to fund the losses of the Company.

The Company calculates basic net loss per share by dividing net loss by the weighted average number of common shares outstanding, including pre-funded warrants. The Company calculates diluted net loss per share by dividing net loss by the weighted average number of common shares outstanding, as applicable, after giving consideration to the dilutive effect of restricted stock units, performance stock units, warrants and stock options that are outstanding during the period.

Income Taxes

Income taxes are recorded in accordance with ASC Topic 740, Income Taxes ("ASC 740"), which provides for deferred taxes using an asset and liability approach. Under this method, deferred income tax assets and liabilities are recognized based on future income tax consequences attributable to differences between the financial statement carrying amount of existing assets and liabilities, and their respective income tax basis. Deferred income tax assets and liabilities are measured using enacted income tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled.

The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions, as necessary. The tax benefits recorded are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is "more likely than not" to be realized following resolution of any uncertainty related to the tax benefit, assuming that the matter in question will be raised by the tax authorities. The Company has not recorded any interest or penalties on any unrecognized tax benefits since its inception.

The Company is open to examination by the Internal Revenue Service for the tax years ended December 31, 2013 to December 31, 2025. Since the Company is in a U.S. loss carryforward position, carryforward tax attributes generated in prior years may still be adjusted upon future examination if they have or will be used in a future period. The Company is currently not under examination by the Internal Revenue Service or any other jurisdictions for any tax years.

Recently Adopted Accounting Pronouncements

In December 2023, the FASB issued ASU 2023-09,Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”), which enhances the transparency of income tax disclosures to provide information to investors to better assess how a company’s operations and related tax risks, tax planning and operational opportunities affect its tax rate and prospects for future cash flows. This requires public entities to disclose additional categories in the rate reconciliation regarding federal and state income taxes and provide more details surrounding reconciling items if a quantitative threshold is met. The Company adopted ASU 2023-09 on January 1, 2025, which did not have a material impact on the financial statements and related disclosures (see Note 11).

Recently Issued Accounting Pronouncements

In November 2024, the FASB issued ASU No. 2024-03,Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40):Disaggregation of Income Statement Expenses (“ASU 2024-03”), and in January 2025, the FASB issued ASU No. 2025-01,Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Clarifying the Effective Date. ASU 2024-03 requires additional disclosure of the nature of expenses included in the income statement as well as disclosures about specific types of expenses included in the expense captions presented in the income statement. ASU 2024-03, as clarified by ASU 2025-

01, is effective for public companies for annual periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is still evaluating the impact on its disclosures in future years as a result of the adoption of ASU 2024-03.

3. Fair Value of Financial Assets and Liabilities

The following tables summarize the assets and liabilities measured at fair value on a recurring basis at December 31, 2025 and 2024 (in thousands):

Level 1 assets include investments in money market funds, U.S. treasury obligations and government agency securities that are valued using quoted market prices in active markets. There wereno transfers of assets between fair value measurement levels during the years ended December 31, 2025 and 2024.

The carrying amounts reflected in the balance sheets for prepaid expenses and other current assets, accounts payable, and accrued expenses approximate their fair values at December 31, 2025 and 2024, due to their short-term nature.

The Company believes the terms of its debt reflect current market conditions for an instrument with similar terms and maturity, therefore the carrying value of the Company's debt approximates its fair value based on Level 2 of the fair value hierarchy.

4. Marketable Securities

The following table summarizes the Company’s investments as of December 31, 2025 (in thousands):

The following table summarizes the Company’s investments as of December 31, 2024 (in thousands):

The Company believes that U.S. treasury obligations and government agency securities are subject to minimal credit risk. As a result, the Company did not record any charges for credit-related impairments for its available-for-sale securities for the year ended December 31, 2025 and 2024.

5. Prepaid Expenses and Other Current Assets

At December 31, 2025 and 2024, prepaid expenses and other current assets consist of the following (in thousands):

At December 31, 2025 and 2024, other long-term assets consist of the following (in thousands):

6. Property and Equipment, Net

At December 31, 2025 and 2024, property and equipment consists of the following (in thousands):

Depreciation and amortization expense was $1.7 million and $1.9 million for the years ended December 31, 2025 and 2024, respectively.

7. Accrued Expenses

At December 31, 2025 and 2024, accrued expenses consist of the following (in thousands):

8. Preferred Stock

The Board of Directors or any authorized committee thereof is expressly authorized, to the fullest extent permitted by law, to provide by resolution or resolutions for, out of the unissued shares of Preferred Stock, the issuance of the shares of Preferred Stock in one or more series of such stock, and by filing a certificate of designations pursuant to applicable law of the State of Delaware, to establish or change from time to time the number of shares of each such series, and to fix the designations, powers, including voting powers, full or limited, or no voting powers, preferences and the relative, participating, optional or other special rights of the shares of each series and any qualifications, limitations and restrictions thereof.

9. Common Stock

In June 2024, the stockholders approved an amendment to the Company’s amended and restated certificate of incorporation to increase the number of authorized shares of common stock from 150,000,000 to 300,000,000.

In October 2024, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with J.P. Morgan Securities LLC, Jefferies LLC and Piper Sandler & Co., as representatives of the several underwriters named therein (the “Underwriters”), relating to the issuance and sale of an aggregate of 10,265,488 shares of the Company’s common stock at$28.25 per share and pre-funded warrants to purchase 353,983 shares of its common stock. The offering price per pre-funded warrant was$28.2499, which equals the per share public offering price for the common stock less the$0.0001 exercise price for each such pre-funded warrant. The pre-funded warrants are exercisable at any time and only expire when exercised in full. The offering closed on October 10, 2024. Pursuant to the Underwriting Agreement, the Underwriters were granted a 30-day option to purchase up to 1,592,920 additional shares (the “Option

Shares”) of common stock, which was exercised in full on October 16, 2024. Total proceeds of the transaction, including the Option Shares were approximately$324.4 million, net of underwriting discounts and estimated offering expenses.

The Company has had a sales agreement in place during various time periods with Jefferies LLC (“Jefferies”) with respect to an at-the-market (“ATM”) offering program. Under this program, the Company is able to offer and sell, from time to time at its sole discretion, shares of its common stock through Jefferies as its sales agent. In an ATM offering, exchange-listed companies incrementally sell newly issued shares into the secondary trading market through a designated broker-dealer at prevailing market prices. The current ATM agreement with Jefferies, established in November 2022, allows for the sale of shares of common stock from time to time in “at the market” offerings through Jefferies as the Company’s sales agent. As of December 31, 2025, the Company has sold 3,386,290 shares, generating net proceeds of$96.9 million, under the ATM program. Of this amount, the Company sold 2,767,000 shares of its common stock under the ATM program during the year ended December 31, 2025, generating net proceeds of$91.7 million.

The Company has issued pre-funded warrants to purchase common stock, as well as warrants to purchase common stock as part of its financing activities. Both the pre-funded warrants and warrants meet the conditions for equity classification and are recorded as a component of stockholders’ equity within additional paid-in capital. In October 2024, June 2022 and November 2020, the Company issued 353,983,25,510,205 and 2,179,487 pre-funded warrants, respectively. During the years ended December 31, 2025 and 2024,0 and 2,526,833, respectivelyof the Company’s pre-funded warrants were exercised. As of December 31, 2025, the Company has 17,362,147 pre-funded warrants outstanding. In June 2022, the Company also issued 10,459,181 warrants with an exercise price of$7.35. During the years ended December 31, 2025 and 2024,8,678,664 and 1,309,492, respectively of the Company’s warrants were exercised. As of December 31, 2025, all of the common warrants outstanding associated with the June 2022 financing have been exercised.

In October 2025, the Company issued 250,000 warrants with an exercise price of$28.59 for non-employee services. Warrants issued to non-employees in connection with providing services meet the conditions for equity classification and are recorded as a component of stockholders’ equity within additional paid in capital. There wereno exercises of the warrants issued for non-employee services during the year ended December 31, 2025.

Shares Reserved For Future Issuance

As of December 31, 2025, the Company had common shares reserved for issuance as follows:

10. Equity-Based Compensation

Equity Plans

As of December 31, 2025, the Company has four active equity plans, the 2018 Stock Option and Incentive Plan (the “2018 Plan”), the 2017 Stock Option and Incentive Plan (the “2017 Plan”), the 2018 Employee Stock Purchase Plan (the “2018 ESPP”) and the 2022 Inducement Equity Plan (the “2022 Inducement Plan”).

2018 Stock Option and Incentive Plan

The 2018 Plan has replaced the 2017 Plan asno additional awards will be granted under that plan following the consummation of the Initial Public Offering (“IPO”).

The 2018 Plan provides for the grant of equity-based incentive awards, including incentive stock options, non-qualified stock options, restricted stock awards, unrestricted stock awards and restricted stock units to the Company’s officers, employees, directors and other key persons (including consultants). Stock options and restricted stock units granted under the 2018 Plan to employees generally vest over four years. The shares of common stock underlying any awards that are forfeited, cancelled, repurchased or are otherwise terminated by the Company under the 2018 Plan will be added back to the shares of common stock available for issuance under the 2018 Plan.

The 2018 Plan provides that the number of shares reserved and available for issuance under the plan will automatically increase each January 1, beginning on January 1, 2019, by 4% of the outstanding number of shares of common stock on the immediately preceding December 31 or such lesser number of shares as determined by the Board of Directors or compensation committee (the “Annual Increase”). These limits are subject to adjustment in the event of a stock split, stock dividend or other change in the Company’s capitalization.

2017 Stock Option and Incentive Plan

The 2017 Plan provides for the grant of incentive stock options, non-qualified stock options, restricted stock awards, unrestricted stock awards and restricted stock units. Stock options granted under the 2017 Plan to employees generally vest over four years. The Company no longer issues grants from the 2017 Plan. The shares of common stock underlying any awards that are forfeited, cancelled, repurchased or are otherwise terminated by the Company under the 2017 Plan will be added back to the shares of common stock available for issuance under the 2018 Plan.

2018 Employee Stock Purchase Plan

At December 31, 2025 there were 2,550,305 shares available to grant under the 2018 ESPP andno shares had been issued. The ESPP provides that the number of shares reserved and available for issuance will automatically increase each January 1, beginning on January 1, 2019 through January 1, 2028, by the lesser of (i)353,614 shares of common stock, (ii)1% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31 or (iii) such lesser number of shares as determined by the 2018 ESPP administrator. The number of shares reserved under the 2018 ESPP is subject to adjustment in the event of a stock split, stock dividend or other change in the Company’s capitalization.

2022 Inducement Equity Plan

The 2022 Inducement Plan provides for thegrant of non-qualified stock options, stock appreciation rights, restricted stock awards, restricted stock units, unrestricted stock awards and dividend equivalent rights to individuals that were not previously an employee or director of the Company or individuals returning to employment after a bona fide period of non-employment with the Company. Stock options and restricted stock units granted under the 2022 Inducement Plan to employees generally vest over four years. The shares of common stock underlying any awards that are forfeited, cancelled, repurchased or are otherwise terminated by the Company under the 2022 Inducement Plan will be added back to the shares of common stock available for issuance under the 2022 Inducement Plan. The 2022 Inducement Plan was approved for 1,000,000 shares of common stock in June 2022. Since its inception and through December 31, 2025, an additional 6,000,000 shares of common stock have been authorized for issuance under the 2022 Inducement Plan.

Total Equity-Based Compensation Expense

The Company recorded equity-based compensation expense related to all equity-based awards, which was allocated as follows in the consolidated statements of operations and comprehensive loss for the years ended December 31, 2025 and 2024 (in thousands):

During the year ended December 31, 2025, the Company entered into separation agreements with five employees. Per the separation terms, certain stock option awards and RSUs were amended and may provide for continued vesting, accelerated vesting, and extended time to exercise vested options. As a result, equity-based compensation expense during the year ended December 31, 2025 includes $13.5 million related to the modification of certain equity awards. No equity modifications occurred during the year ended December 31, 2024.

The following table summarizes the Company’s unrecognized equity-based compensation expense as of December 31, 2025:

Restricted Stock Units

The following table summarizes the Company’s RSU activity for the current year:

The total fair value of RSUs vested during the years ended December 31, 2025 and 2024 was $49.5 million and $9.7 million, respectively.

Performance Stock Units

The following table summarizes the Company’s PSU activity for the current year:

In April 2025, the Company granted PSUs to certain employees. The fair value of the PSUs are estimated using a Monte Carlo simulation model. The Monte Carlo simulation model requires key inputs for risk-free interest rate, dividend yield and volatility. The number of PSUs granted represents the target number of units that are eligible to vest based on the Company’s common stock achieving certain price targets and time-based vesting over four years. The Company concluded that issued PSUs are equity-based awards and include market and service-based vesting conditions. Participants may ultimately earn up to 250% of the target number of units granted based on the degree of actual performance metric achievement.

No PSUs vested during the year ended December 31, 2025.

Stock Options

The following table summarizes the Company’s stock option activity for the current year:

Using the Black-Scholes option pricing model, the weighted average grant date fair value of options granted during the years ended December 31, 2025 and 2024 was $28.72 and $11.79, respectively.

The following weighted average assumptions were used in determining the fair value of options granted in the years ended December 31, 2025 and 2024:

11. Income Taxes

For the years ended December 31, 2025 and 2024, the loss before income taxes consisted of the following (in thousands):

The Company has not recorded a current tax provision for the years ended December 31, 2025 and 2024.

The effective income tax rate differed from the amount computed by applying the federal statutory rate to the Company’s loss before income taxes as follows (in thousands):

The amount of cash income taxes paid (net of refunds) during the year are as follows (in thousands):

Deferred tax assets (liabilities) consist of the following at December 31, 2025 and 2024 (in thousands):

Total Net Deferred Tax Assets

Deferred tax assets are reduced by a valuation allowance if, based on the weight of available positive and negative evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. Accordingly, a full valuation allowance has been established against the net deferred tax assets as of December 31, 2025 and 2024. The valuation allowance for deferred tax assets increased by $120.0 million and $76.5 million in 2025 and 2024, respectively. This increase mainly relates to the establishment of a valuation allowance against the Company’s net deferred tax assets in connection with net operating losses generated in each year and additional tax credit carryforwards generated. As of December 31, 2025, the Company had approximately $921.9 million and $861.4 million of Federal and State operating loss carryforwards respectively, which begin to expire in 2032, except for $871.4 million of the Company’s federal net operating loss carryforwards, and $3.2 million of state net operating losses that do not expire. These loss carryforwards may be available to reduce future taxable income, if any. These loss carryforwards are subject to review and possible adjustment by the appropriate taxing authorities. As of December 31, 2025, the Company also had federal and state credit carryforwards of $74.1 million and $10.4 million, respectively, which begin to expire in 2034 and 2032, respectively. The amount of loss and credit carryforwards that may be utilized in any future period may be limited based upon changes in the ownership of the Company. Additionally, the deductibility of federal net operating

losses generated after December 31, 2017 and the indefinite state net operating losses is limited to 80% of the Company’s taxable income in any future taxable year.

The Company follows the provisions of ASC 740-10, “Accounting for Uncertainty in Income Taxes,” which specifies how tax benefits for uncertain tax positions are to be recognized, measured, and recorded in financial statements; requires certain disclosures of uncertain tax matters; specifies how reserves for uncertain tax positions should be classified on the balance sheet; and provides transition and interim period guidance, among other provisions. As of December 31, 2025 and 2024, the Company hasnot recorded any amounts for uncertain tax positions. The Company’s policy is to recognize interest and penalties accrued on any uncertain tax positions as a component of income tax expense, if any, in its statements of income.

The Company’s net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50 percent as defined under Section 382 and 383 of the U.S. Internal Revenue Code of 1986, respectively, as well as similar state provisions. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. The Company conducted a Section 382 study covering the period of November 26, 2013 through December 31, 2023. The study concluded that ownership changes occurred during that period which limit the amount of the Company’s net operating losses and tax credit carryforwards that can be utilized before expiring. The carryforwards disclosed represent the amount of attributes that can be utilized based on the results of the study.

All of the Company’s tax years will remain open for examination by the federal and state tax authorities to the extent that the Company's tax attributes are utilized in future years to offset income or income taxes.

12. Leases

Operating Lease

In November 2019, the Company entered into a lease of office and laboratory space at 301 Binney Street in Cambridge, Massachusetts to be used as its new corporate headquarters (“the Lease”). The expiration date of the Lease was originally in August 2025 and included anoption to extend the term bytwo years. The base rent under the original Lease was $6.9 million per year, subject to an annual increase of 3.5%. Variable lease payments include the Company’s allocated share of costs incurred and expenditures made by the landlord in the operation and management of the building. The Lease included incentives of $14.1 million in the form of an allowance for tenant improvements related to the design and build out of the space. In connection with the Lease, the Company has secured a letter of credit for $2.3 million which renews automatically each year.

In May 2024, the Company entered into the First Amendment (the “Lease Amendment”) to the Lease to extend the term for approximatelytwo years, commencing on August 19, 2025 (the “First Extension Term”) with the base rent to start at approximately $6.2 million per year, followed by a 3% annual increase. Pursuant to the Lease Amendment, the Company also has anoption to extend the term of the Lease byfive years, upon the expiration of the First Extension Term.

In October 2025, the Company entered into a lease of office space in Zug, Switzerland (the “Switzerland Lease”). The Switzerland Lease commencement date is January 1, 2026, which is when the Company gained access to the space under the terms of the lease, and an expiration date of December 31, 2029, with a minimum lease term oftwelve months. The base rent under the Switzerland lease is CHF 276,000 per year.

Other information related to the Lease is as follows (in thousands, except lease term and discount rate):

The following is a maturity analysis of the annual undiscounted cash flows reconciled to the carrying value of the operating lease liabilities as of December 31, 2025 (in thousands):

13. Commitments and Contingencies

Legal Proceedings

The Company, from time to time, may be party to litigation arising in the ordinary course of its business. The Company was not subject to any material legal proceedings during the years ended December 31, 2025 and 2024.

14. Debt

On October 16, 2020 (the “Closing Date”) the Company entered into a Loan and Security Agreement with Oxford Finance LLC (“Oxford”) and Silicon Valley Bank (“SVB”) for $50.0 million (the “Loan and Security Agreement”), which was to increase the Company’s borrowing capacity. Pursuant to the Loan and Security Agreement, the Company was required to maintain cash equal to the lesser of 100% of the Company’s consolidated cash or 105% of the dollar amount of the outstanding debt.

On February 10, 2025, the Company entered into an Amended and Restated Loan and Security Agreement (the “Amended and Restated Loan and Security Agreement”) with Oxford. The Amended and Restated Loan and Security Agreement amends and restates in its entirety that certain Loan and Security Agreement, as amended.

The Amended and Restated Loan and Security Agreement provides for term loans in an aggregate principal amount of up to $200.0 million (each, a “Term Loan” and together, the “Term Loans”) subject to funding infour tranches. The

Amended and Restated Loan and Security Agreement consolidates the existing outstanding loan tranches solely with Oxford and also extends the interest-only payment period through March 2029, with principal payments to commence in April 2029. The maturity date of the loan was extended to February 1, 2030. If certain business and development milestones are achieved, the interest-only payment period may be extended by an additional twelve months, and the maturity date will be extended to February 1, 2031. In conjunction with the Amended and Restated Loan and Security Agreement, the Company was required to pay $0.9 million, which included $0.5 million to SVB for the final payment on the outstanding tranche.

The outstanding principal of each Term Loan has an annual interest rate of (a) the greater of (i) the 1-Month CME Term SOFR on the last business day of the month that immediately precedes the month in which the interest will accrue and (ii)3%, plus (b)5.5%. Interest is payable on a monthly basis based on the principal amount outstanding during the preceding month. In addition, the Company is required to pay Oxford a final payment fee equal to 2.00% of the original principal amount of each Term Loan advanced to the Company.

On September 19, 2025, the Company entered into a Third Amendment to the Amended and Restated Loan and Security Agreement (the “Third Amendment”) with Oxford. Pursuant to the Third Amendment, the Company was required to maintain cash equal to the lesser of 100% of the Company’s consolidated cash or 115% of the dollar amount of the outstanding debt in a U.S. controlled bank account.

On September 29, 2025, the Company received $50.0 million from the next available tranche under the Amended and Restated Loan and Security Agreement. To date, the Company has received $100.0 million of Term Loans. The remainingtwo tranches, each in an amount of $50.0 million, are available to be borrowed (a) in the case of the third tranche, after the achievement of certain development and business performance milestones until September 30, 2026 and (b) in the case of the fourth tranche, after the achievement of certain development and business performance milestones until December 31, 2027.

The following table shows required principal payments (excluding interest fees), during the next five years on debt outstanding at December 31, 2025 (in thousands):

The Company incurred costs on behalf of the lender recorded as a debt discount of $0.5 million and incurred debt issuance costs of $0.1 million, both of which are recorded as a deduction from the carrying amount of the debt and are being amortized as interest expense over the term of the loan. The final payment fee will be treated as an additional debt discount and accreted to the debt balance over the term.

For the years ended December 31, 2025 and 2024, the Company recorded total interest expense for the debt of $6.3 million and $6.6 million, respectively.

15. Net Loss per Share

The Company calculates basic net loss per share by dividing net loss by the weighted average number of common shares outstanding. The weighted average number of common shares used in the basic and diluted net loss per share calculation includes the pre-funded warrants issued in connection with the Company’s November 2020, June 2022 and October 2024 follow-on offerings as the pre-funded warrants are exercisable at any time for nominal cash consideration. The Company has generated a net loss in all periods presented, so the basic and diluted net loss per share are the same, as the inclusion of the potentially dilutive securities would be anti-dilutive.

Basic and diluted net loss per share is calculated as follows (in thousands, except share and per share data):

The following table sets forth the outstanding common stock equivalents, presented based on amounts outstanding at each period end, that have been excluded from the calculation of diluted net loss per share for the periods indicated because their inclusion would have been anti-dilutive:

16. Retirement Plans

The Company sponsors a 401(k) retirement plan, in which substantially all U.S. employees are eligible to participate upon employment. Participants may contribute a percentage of their annual compensation to this plan, subject to statutory limitations. Effective January 1, 2020, the Company adopted a policy to match 50% of the employee contributions to the 401(k) plan up to a maximum of 6% of the participating employee’s eligible earnings, resulting in a maximum company match of 3% of the participating employee’s eligible earnings subject to statutory limitations. The Company recognized $1.9 million and $1.1 million in expense related to the match during the years ended December 31, 2025 and 2024, respectively.

Beginning in 2025, the Company sponsors a defined contribution pension plan for its employees in Ireland. Participants contribute a percentage of their annual compensation to this plan, subject to statutory requirements. The Company contributes 10% of the participating employee’s eligible earnings. The Company recognized an immaterial amount of expense during the year ended December 31, 2025.

17. Segment Reporting

The Company operates and manages its business on a consolidated basis as asingle reportable andsingle operating segment for the purposes of assessing performance and making operating decisions. The Company’s chief executive officer, who is the chief operating decision maker (“CODM”), reviews the Company’s financial information on a consolidated basis for purposes of evaluating financial performance and allocating resources. When evaluating the Company’s financial performance, the CODM regularly reviews net loss. The CODM considers net loss in making decisions on how to allocate resources. Net loss is used to monitor budget versus actual results in an effort to refine forecasts and control costs. The measure of segment assets is reported on the balance sheet as total consolidated assets. All of the Company's long-lived assets are held in the United States.

The following table presents significant expense information about the Company’s operating segment:

(1) Excludes equity-based compensation expense.

(2)Consists of other segment expenses related to supplies, corporate and facilities expenses.

(3) Certain prior period amounts have been recast to conform with current period presentation.

18. Subsequent Events

In February 2026, the Company entered into the 2026 Loan Agreement with Blue Owl for up to $350.0 million, of which $100.0 million of the initial term loan (the “Initial Term Loan”) was received in February 2026. The Company used the proceeds of the Initial Term Loan upon the closing under the 2026 Loan Agreement to repay all outstanding obligations, totaling $103.7 million, under the Existing Loan Agreement with Oxford and upon such repayment, terminated the Existing Loan Agreement. The amount repaid by the Company included $100.0 million of outstanding indebtedness plus accrued and unpaid interest as of February 27, 2026 (the “Closing Date”) and fees. As a result of the termination, all credit commitments under the Existing Loan Agreement were terminated and all security interests and guarantees executed in connection with the Existing Loan Agreement were released.

An initial delayed draw term loan commitment in an aggregate principal amount not to exceed $100.0 million will be available after the Closing Date until the earliest of the full usage thereof, termination thereof and March 31, 2026 (the “DDTL-1 Commitments”, and any term loans made with respect thereto, the “DDTL-1 Term Loans”), which the Company may borrow at our sole option upon satisfying certain customary conditions, including satisfaction of the minimum cash covenant.