PRME US Equity☆

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

You should read the following discussion and analysis of our financial condition and results of operations together with our consolidated financial statements and the related notes and other financial information included elsewhere in this Annual Report on Form 10-K. Some of the information contained in this discussion and analysis or set forth elsewhere in this Annual Report on Form 10-K, including information with respect to our plans and strategy for our business, includes forward-looking statements that involve risks and uncertainties. You should review "Item 1A, Risk Factors" of this Annual Report on Form 10-K for a discussion of important factors that could cause actual results to differ materially from the results described in or implied by the forward-looking statements contained in the following discussion and analysis.

Overview

We are a biotechnology company focused on developing a new class of genetic medicines designed to provide durable, and potentially curative, treatment options for patients with diseases driven by defined genetic alterations, acquired cellular dysfunction, or dysregulated gene expression.

We are focused on advancing our in vivo liver franchise, where we are advancing programs to cure two of the largest genetic liver diseases, Wilson Disease and AATD. Both programs are currently in late stages of pre-clinical development and are on track for IND and/or CTA filings in the first half of 2026 for Wilson Disease and the middle of 2026 for AATD. We intend to leverage the modularity of our platform to expeditiously and efficiently develop these programs supported by our universal liver lipid nanoparticle along with potential regulatory, clinical and other synergies from our modular technology.

We also continue to advance our in vivo Cystic Fibrosis program with support from CFF, and our efforts to develop Prime Edited CAR-T products for hematology, immunology and oncology in partnership with BMS. In addition, we will continue to pursue additional business development opportunities to accelerate innovation, ensure the broadest application of Prime Editing, and further bolster our financial resources.

In August 2025, we announced additional data from the first patient dosed and initial data from the second patient dosed in our Phase 1/2 trial in CGD. Discussions are underway with the FDA to explore a potential accelerated path to approval in the United States.

Components of Our Results of Operations

Revenues

To date, we have not generated any revenue from product sales and do not expect to generate any revenue from the sale of products for the foreseeable future. Our revenues to date have been generated through research collaboration and license agreements. We recognize revenue over the expected performance period under each agreement. We expect that our revenue for the next several years will be derived primarily from our current collaboration agreements and any additional collaborations that we may enter into in the future. To date, we have not received any royalties under any of our existing collaboration agreements.

Research and Development Expenses

Research and development expenses consist primarily of costs incurred in connection with the development and research of our immediate target indications and our differentiation target indications. These expenses include:

•personnel-related expenses, including salaries, bonuses, benefits and stock-based compensation for employees engaged in manufacturing, and research and development functions;

•expenses incurred in connection with continuing our current research programs and preclinical and clinical development of any product candidates we may identify, including under agreements with third parties, such as consultants and contractors;

•the cost of developing and validating our manufacturing process for use in our preclinical and clinical studies;

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•laboratory supplies and research materials;

•facilities, depreciation and other expenses related to research and development activities, which include direct or allocated expenses for rent and maintenance of facilities, and utilities;

•the cost allocated to acquire in-process research and development, with no alternative future use associated with asset acquisitions or transactions to license intellectual property, such as our Broad License Agreement; and

•expenses incurred in connection with our Pledge to Broad Institute.

We expense all research and development costs in the periods in which they are incurred. Most of our research and development expenses have been related to early stage development activities. In the future, external research and development costs for any individual product candidate will be tracked commencing upon product candidate nomination. We do not allocate employee costs, costs associated with our discovery efforts, laboratory supplies, and facilities expenses, including depreciation or other indirect costs, to specific product development programs because these costs are deployed across multiple programs and our platform and, as such, are not separately classified.

Upfront and milestone payments made are accrued for and expensed when the achievement of the milestone is probable up to the point of regulatory approval. Milestone payments made upon regulatory approval will be capitalized and amortized over the remaining useful life of the related product.

We expect our research and development expenses may continue to increase in the future with our planned research and development activities related to developing any future product candidates, including investments in manufacturing, as we advance any product candidates we may identify and begin to conduct clinical trials, and with our obligations under the BMS Collaboration Agreement.

General and Administrative Expenses

General and administrative expenses consist of salaries and personnel-related costs, including stock-based compensation, for our personnel in executive, legal, finance and accounting, human resources and other administrative functions. General and administrative expenses also include legal fees relating to patents and corporate matters; professional fees paid for accounting, auditing, consulting and tax service; insurance costs; office and information technology costs; and facilities, depreciation and other general and administrative expenses, which include direct or allocated expenses for rent and maintenance of facilities and utilities.

We anticipate that our general and administrative expenses will increase in the future if we increase our headcount to support research and development activities; increased accounting, legal, insurance, and investor and public relations costs as we continue to operate as a public company; and additional intellectual property-related expenses as we file patent applications to protect innovations arising from our research and development activities.

Other Income (Expense)

Other income (expense), net consists of:

•interest and amortization related to our short-term investments; and

•the change in the fair value of our short-term investment in Beam, a related party, in connection with the Beam Collaboration Agreement, which is discussed in greater detail in Item 1. Business, of this Annual Report on Form 10-K.

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Results of Operations — Comparison of the Years Ended December 31, 2025 and 2024

Operating Expenses

Research and Development Expenses

Year ended December 31,

Research and development expenses:

The $5.3 million increase in research and development expense for the year ended December 31, 2025 as compared to the year ended December 31, 2024 is primarily driven by:

•$11.0 million increase in facility-related expense primarily due to the expansion and build out of our laboratory space at 60 First Street and 500 Arsenal Street and due to a higher amount of facility costs being allocated to our research and development function;

•$6.9 million increase in license and IP costs, primarily due to the issuance of restricted stock units;

•$1.8 million increase in professional and consultant fees, primarily related to our in-house vivarium; and

•$1.2 million increase in clinical expense as we advance our Wilson Disease and AATD programs, both of which are on track for IND and/or CTA filings in 2026.

These were offset by:

•$9.3 million decrease in personnel expenses resulting from the workforce reduction announced in May 2025; and

•$6.2 million decrease in research costs, primarily due to the deprioritization of our CGD programs as we strategically focus our internal efforts on advancing our in vivo liver franchise.

General and Administrative Expenses

Year ended December 31,

General and administrative expenses:

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The $2.2 million increase in general and administrative expense for the year ended December 31, 2025 as compared to the year ended December 31, 2024 is primarily driven by a $7.0 million increase in professional and consultant fees due to an increase in corporate legal expenses. This is offset by:

•$3.5 million decrease in personnel expense, due to a decrease in non-cash stock-based compensation expense of $3.5 million; and

•$1.3 million decrease in facility related and other primarily due to a higher proportion of our facility space being utilized in research and development activities.

Other Income (Expense)

Year ended December 31,

Other income:

Accretion (amortization) of investments $ 2,479 $ 3,507 $ (1,028)

Change in fair value of short-term investment — related party 432 (485) 917

Accretion (amortization) of investments

Accretion (amortization) of investments for each of the periods presented is a result of increase (decrease) in the value of the our marketable securities purchased at a discount (premium) to their face value.

Liquidity and Capital Resources

Since our inception, we have incurred significant operating losses. We expect to incur significant expenses and operating losses for the foreseeable future as we commence the clinical development of our programs and continue our platform development and early-stage research activities. We have not yet commercialized any products and we do not expect to generate revenue from sales of products for several years, if at all. To date, we have funded our operations primarily with proceeds from sales of preferred stock, public offerings of our common stock, and through payments from our collaboration partners. As of December 31, 2025, we had cash and cash equivalents, and short-term investments of $177.7 million, excluding our restricted cash, or $191.4 million, including restricted cash.

In November 2023, we filed a shelf registration statement on Form S-3 (File No. 333-275321), including a base prospectus and sales agreement prospectus, or the Prior Registration Statement, for the issuance and sale of up to $500.0 million of our common stock, preferred stock, debt securities, warrants and/or units, as declared effective by the SEC on November 13, 2023.

In November 2025, we filed an automatic shelf registration statement on Form S-3ASR (File No. 333-291348), including a base prospectus and sales agreement prospectus, or the New Registration Statement, to replace the Prior Registration Statement that was set to expire on November 13, 2026, for the registration of an unspecified amount of our common stock, preferred stock, debt securities, warrants and/or units or any combination thereof. The New Registration Statement became automatically effective upon filing, and in accordance with Rule 415(a)(6) under the Securities Act, the offering of securities under the Prior Registration Statement is deemed terminated as of the date of effectiveness of the New Registration Statement. Concurrently with the filing of this Annual Report on Form 10-K, we plan to convert the New Registration Statement on Form S-3ASR to Form S-3 by post-effective amendments.

In November 2023, we entered into an Open Market Sale AgreementSM, or the Sales Agreement, with Jefferies LLC, or Jefferies, under which we may, from time to time, issue and sell shares of our common stock having an aggregate sales proceeds of up to $300.0 million, in a series of one or more at-the-market equity offerings, or the 2023 ATM Program. Any shares will be sold pursuant to the New Registration Statement and the sales agreement prospectus filed therewith, which covers the offer and sale of shares of our common stock under the 2023 ATM Program having an aggregate offering price of up to $200.0 million of the $300.0 million authorized under the Sales Agreement. If

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we wish to offer and sell additional shares of our common stock under the Sales Agreement in excess of the $200.0 million registered under the New Registration Statement, for up to an additional $100.0 million, we must file with the SEC one or more additional prospectus supplements to register under the Securities Act, the offer and sale of any such additional shares of our common stock we wish to offer and sell from time to time under the Sales Agreement. Jefferies is not required to sell any specific share amounts but acts as our sales agent, using commercially reasonable efforts consistent with its normal trading and sales practices. We will pay Jefferies a commission equal to 3.0% of the aggregate gross proceeds we receive from each sale of our shares of common stock. Our common stock will be sold at prevailing market prices at the time of the sale, and as a result, prices may vary. As of December 31, 2025, we have not sold any shares of common stock under the 2023 ATM Program.

In August 2025, we issued and sold 43,700,000 shares of our common stock, including 5,700,000 shares pursuant to the exercise of the underwriters’ option to purchase additional shares, at a price to the public of $3.30 per share. As a result of the offering, we received approximately $138.4 million in net proceeds, after deducting underwriting discounts, commissions and offering costs of approximately $5.8 million.

Going Concern

Since our inception, we have incurred substantial losses. As of December 31, 2025, we had an accumulated deficit of $888.4 million and we expect to generate operating losses and negative operating cash flows for the foreseeable future. As stated above, as of December 31, 2025, we maintained cash, cash equivalents, short-term investments, and related party short-term investments of $177.7 million.

In accordance with Accounting Standards Codification, or ASC, 205-40, Going Concern, or ASC 205-40, we evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about our ability to continue as a going concern within one year after the date on which this Annual Report on Form 10-K is filed. Based on the our cash, cash equivalents, and short-term investments as of December 31, 2025, our current and forecasted level of operations and forecasted cash flows, our ability to continue as a going concern is dependent upon our ability to obtain the necessary financing to meet our obligations and repay our liabilities arising from normal business operations when they come due. Management plans to provide for capital requirements through financing or other transactions, and selling shares under our “at the market offering” program. There can be no assurance that we will be able to raise additional capital to fund operations with terms acceptable to us, or at all. Because certain elements of our plans to mitigate the conditions that raised substantial doubt about our ability to continue as a going concern are outside of our control, including the ability to raise capital through an equity or other financing, those elements cannot be considered probable according to ASC 205-40, and therefore cannot be considered in the evaluation of mitigating factors. As a result, we concluded that substantial doubt exists about our ability to continue as a going concern for 12 months from the date these consolidated financial statements are issued.

The consolidated financial statements as of December 31, 2025 have been prepared under the assumption that we will continue as a going concern for the next 12 months and that contemplates the realization of assets and satisfaction of liabilities and commitments in the normal course of business. Our ability to continue as a going concern is dependent upon our uncertain ability to obtain additional capital, reduce expenditures and/or execute on its business plan. These consolidated financial statements do not include any adjustments that might result from the outcome of this uncertainty.

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Cash Flows

The following table summarizes our sources and uses of cash for each of the periods presented:

Year ended December 31,

Net change in cash, cash equivalents, and restricted cash

Net cash used in operating activities $ (162,564) $ (122,865)

Net cash (used in) provided by investing activities (108,763) 68,457

Net change in cash, cash equivalents, and restricted cash $ (119,815) $ 141,468

Operating Activities

Net cash used in operating activities for the year ended December 31, 2025 was driven primarily by the following uses of cash:

•$201.1 million net loss;

•$5.4 million change in lease liabilities;

•$4.4 million change in deferred revenue; and

•$1.2 million change in accrued expenses and other assets.

These were offset by:

•$43.9 million of non-cash amounts included in net loss, which consisted primarily of stock-based compensation expense, non-cash lease expense, and depreciation and amortization expense; and

•$4.5 million change in prepaid expenses and other current assets;

Net cash used in operating activities for the year ended December 31, 2024 was driven primarily by the following uses of cash:

•$195.9 million net loss;

•$15.9 million change in prepaid expenses and other current assets;

•$13.5 million change in accrued settlement payment — related party;

•$6.5 million change in lease liabilities; and

•$5.3 million change in accounts payable.

These were offset by:

•$70.3 million change in deferred revenue;

•$41.9 million of non-cash amounts included in net loss, which consisted primarily of stock-based compensation expense, non-cash lease expense, depreciation and amortization expense, and change in fair value of short-term investment — related party; and

Investing Activities

Net cash used in investing activities for the year ended December 31, 2025 was driven primarily by the following:

•$109.6 million of purchases of short-term investments, net of maturities; and

•$4.5 million of purchases of property and equipment.

These were offset by $5.4 million from sales of investments — related party.

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Net cash provided by investing activities for the year ended December 31, 2024 was driven primarily by the following:

•$74.8 million of maturities of short-term investments, net of purchases; offset by

•$7.3 million of purchases of property and equipment.

Financing Activities

Net cash provided by financing activities for the year ended December 31, 2025 was driven primarily by the following:

•$138.4 million of proceeds from issuances of common stock with our August 2025 public offering; and

•$12.0 million of proceeds received under the CFF Agreement.

Net cash provided by financing activities for the year ended December 31, 2024 was driven primarily by the following:

•$132.1 million of proceeds from issuances of common stock with our February 2024 public offering;

•$38.1 million of proceeds from issuance of common stock to BMS in September 2024;

•$18.8 million of proceeds from issuance of pre-funded warrants contemporaneous with our February 2024 public offering; and

•$6.0 million of proceeds received under the CFF Agreement.

Funding Requirements

To date, we have not generated any revenue from product sales. We do not expect to generate revenue from product sales unless and until we successfully complete preclinical and clinical development of, receive regulatory approval for, and commercialize a product candidate and we do not know when, or if at all, that will occur. We expect our expenses to increase substantially in connection with our ongoing activities, particularly as we advance the preclinical activities and studies and initiate clinical trials. In addition, if we obtain regulatory approval for any product candidates, we expect to incur significant expenses related to product sales, marketing, and distribution to the extent that such sales, marketing and distribution are not the responsibility of potential collaborators. Further, we have incurred, and expect to continue to incur, costs associated with operating as a public company. The timing and amount of our operating expenditures will depend largely on the factors set out above. For more information, see “Risk Factors—Risks Related To Our Financial Position and Need for Additional Capital.”

We believe our existing cash, cash equivalents, and investments will be sufficient to fund our operating expenses and capital expenditure requirements into 2027. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect. We expect that we will require additional funding to:

•continue our current research development activities;

•identify product candidates;

•evaluate strategic alternatives and potential partnership opportunities for PM359, including our ability to execute and realize the anticipated benefits of any strategic alternatives we may pursue;

•develop, maintain, expand and protect our intellectual property portfolio and defend intellectual property-related claims;

•maintain existing collaborations or strategic relationships and identify and enter into future license agreements and collaborations with third parties;

•initiate preclinical testing and clinical trials for our future product candidates we identify;

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•further develop our Prime Editing platform; and

•hire additional personnel to support our strategic priorities.

If we receive regulatory approval for any of our product candidates, we expect to incur significant commercialization expenses related to product manufacturing, sales, marketing and distribution, depending on where we choose to commercialize ourselves.

Until such time, if ever, as we can generate substantial product revenue, we expect to finance our cash needs through a combination of private and public equity offerings, debt financings, additional collaborations, strategic alliances, and marketing, distribution or licensing arrangements with third parties. To the extent that we raise additional capital through the sale of equity or convertible debt securities, ownership interest may be materially diluted, and the terms of such securities could include liquidation or other preferences that adversely affect your rights as a common stockholder. Debt financing and preferred equity financing, if available, may involve agreements that include restrictive covenants that limit our ability to take specified actions, such as incurring additional debt, making capital expenditures or declaring dividends. If we raise funds through collaborations, strategic alliances or marketing, or distribution or licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies, any future revenue streams, research programs or product candidates or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds through equity or debt financings or other arrangements when needed, we may be required to delay, reduce or eliminate our product development or future commercialization efforts, or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Contractual Obligations and Other Commitments

Leases

Refer to Note 6, Leases, to our consolidated financial statements appearing elsewhere within this Annual Report on Form 10-K for information on our lease obligations.

Under our license and collaboration agreements, we are potentially obligated to pay certain milestones, royalty fees, licensing maintenance fees, and reimbursement of patent maintenance costs. These amounts are contingent upon the occurrence of future events and the timing and likelihood of such potential obligations are not known with certainty.

Critical Accounting Policies and Significant Judgments and Estimates

Our management’s discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with generally accepted accounting principles in the United States, or GAAP. The preparation of these consolidated financial statements requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosures of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses incurred during the reporting periods. We base our estimates on historical experience, known trends and events, and various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities recorded revenues and expenses that are not readily apparent from other sources. We evaluate our estimates and assumptions on an ongoing basis. Actual results may differ from these estimates.

While our significant accounting policies are described in more detail in Note 2, Summary of Significant Accounting Policies, to our consolidated financial statements appearing within this Annual Report on Form 10-K, we believe that the following accounting policies are those most critical to the judgments and estimates used in the preparation of our consolidated financial statements.

Stock-Based Compensation Expense

We measure stock-based awards granted to employees, directors, and non-employees based on their fair value on the date of the grant using the Black-Scholes option-pricing model for stock options. Compensation expense for those awards is recognized over the requisite service period, which is generally the vesting period of the respective award, using the straight-line method. We account for forfeitures of stock-based awards as they occur.

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The Black-Scholes option pricing model used to determine the fair value of our stock options includes various assumptions, including the expected term of the award, the expected volatility, and the expected risk-free interest rate, expected dividend payments, and the fair value of the common stock underlying the stock-based award.

We consider the expected volatility to be a critical accounting estimate. As we do not have sufficient trading history, we use the average historical volatility of a representative group of publicly traded biopharmaceutical companies to calculate the expected volatility for use in the Black-Scholes option pricing model. This assumption reflects our best estimate; but determining a representative peer group involves subjective considerations. As a result, if a different peer group is used to estimate volatility, the resulting volatility could have a material impact on our stock-based compensation expense.

Prepaid and Accrued Research and Development Expenses

As part of preparing our consolidated financial statements, we are required to estimate research and development expenses. This process involves reviewing quotations and contracts, identifying services that have been performed on our behalf and estimating the level of service performed and the associated cost incurred for the service when we have not yet been invoiced or otherwise notified of the actual cost. These estimates of the expenses incurred are based on facts and circumstances known to us at that time. Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and could have a significant impact on reported amounts.

If the payments made exceed the expenses incurred, the excess amount is reflected as prepaid expenses and other current assets. If the expenses incurred exceed payments made, the difference is reflected as accrued expenses and other current liabilities.

Non-refundable advance payments for goods or services to be received in the future for use in research and development activities are deferred and capitalized in prepaid expenses and other current assets. The capitalized amounts are expensed as the related goods are delivered or services are performed.

Revenues from contracts

We account for our revenue in accordance with ASC, 606, Revenue from Contracts with Customers, or ASC 606. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, we perform the following five steps at inception of the agreement or upon material modification of the agreement: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation.

We consider the pattern of satisfaction of the performance obligations under step (v) above to be a critical accounting estimate. More specifically, the determination of the level of achievement of research and development service performance obligations, whose pattern of satisfaction is measured using costs incurred to date as compared to total costs incurred and expected to be incurred in the future is driven by a critical accounting estimate.

In estimating the costs expected to be incurred in the future, we use our most recent budget and long-range plan, adjusted for any pertinent information. While this is our best estimate as of the reporting period, costs expected to be incurred in the future require management judgment as the scope and timing of research and development activities may change significantly over time. Change in our estimate of the scope and timing of research and development services performed relative to the actual scope and timing may have a significant impact on revenue recognition.

Recently Issued and Adopted Accounting Pronouncements

A description of recently issued accounting pronouncements that may potentially impact our financial position and results of operations is disclosed in Note 2, Summary of Significant Accounting Policies, to our consolidated financial statements appearing within this Annual Report on Form 10-K.

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Emerging Growth Company and Smaller Reporting Company Status

The JOBS Act permits an “emerging growth company” such as us to take advantage of an extended transition period to comply with new or revised accounting standards applicable to public companies until those standards would otherwise apply to private companies. We have elected not to “opt out” of such extended transition period, which means that when a standard is issued or revised and it has different application dates for public or private companies, we will adopt the new or revised standard at the time private companies adopt the new or revised standard and will do so until such time that we either (i) irrevocably elect to “opt out” of such extended transition period or (ii) no longer qualify as an emerging growth company. As a result of this election, our consolidated financial statements may not be comparable to other public companies that comply with new or revised accounting pronouncements as of public company effective dates. We may choose to early adopt any new or revised accounting standards whenever such early adoption is permitted for private companies.

We are also a “smaller reporting company,” meaning that the market value of our stock held by non-affiliates is less than $700 million and our annual revenue was less than $100 million during the most recently completed fiscal year. We may continue to be a smaller reporting company if either (i) the market value of our stock held by non-affiliates is less than $250 million or (ii) our annual revenue was less than $100 million during the most recently completed fiscal year and the market value of our stock held by non-affiliates is less than $700 million. If we are a smaller reporting company at the time we cease to be an emerging growth company, we may continue to rely on exemptions from certain disclosure requirements that are available to smaller reporting companies. Specifically, as a smaller reporting company we may choose to present only the two most recent fiscal years of audited financial statements in our Annual Report on Form 10-K and, similar to emerging growth companies, smaller reporting companies have reduced disclosure obligations regarding executive compensation.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Interest Rate Risk

We are exposed to market risk related to changes in interest rates of our investment portfolio of cash equivalents and short-term investments. As of December 31, 2025, we held cash and cash equivalents, investments, and restricted cash, which are exposed to interest income sensitivity affected by changes in the general level of U.S. interest rates. The fair value of our cash equivalents, consisted of our money market funds, and investments are subject to change as a result of potential changes in market interest rates. Due to the short-term maturities of our cash equivalents and investments and the low risk profile of our investments, an immediate 10 percent change in interest rates would not have a material effect on the fair market value of our cash equivalents or investments.

Effects of Inflation

Inflation generally affects us by increasing our cost of labor and research and development costs. Although we do not believe that inflation has had a material impact on our financial position or results of operations to date, we may experience some effect in the future due to an impact on the costs to conduct research and development, labor costs we incur to attract and retain qualified personnel, and other operational costs.

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Item 8. Financial Statements and Supplementary Data

The financial statements required to be filed pursuant to this Item 8 are appended to this Annual Report on Form 10-K. An index of those financial statements is found in Item 15, Exhibits and Financial Statement Schedules, of this Annual Report on Form 10-K.

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Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

None.

Item 9A. Controls and Procedures

Evaluation of Disclosure Controls and Procedures

Our management, with the participation of our Chief Executive Officer (who serves as both our principal executive officer and our principal financial officer), evaluated, as of the end of the period covered by this Annual Report on Form 10-K, the effectiveness of our disclosure controls and procedures as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act. The term “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act, means controls and other procedures of a company that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is accumulated and communicated to the company’s management, including its principal executive and principal financial officers, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure. Management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures.

Based on the evaluation of our disclosure controls and procedures as of December 31, 2025, our Chief Executive Officer concluded that our disclosure controls and procedures as of such date are effective at the reasonable assurance level.

Management’s Annual Report on Internal Controls Over Financial Reporting

Our management is responsible for establishing and maintaining adequate internal control over our financial reporting. Internal control over financial reporting is defined in Rules 13a-15(f) and 15d-15(f) promulgated under the Exchange Act as a process designed by, or under the supervision of, our principal executive and principal financial officers and effected by our board of directors, management, and other personnel to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with United States GAAP. Our internal control over financial reporting includes those policies and procedures that:

•pertain to the maintenance of records that, in reasonable detail, accurately, and fairly reflect our transactions and dispositions of our assets;

•provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with United States GAAP, and that our receipts and expenditures are being made only in accordance with authorizations of our management and directors; and

•provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use or disposition of our assets that could have a material effect on our financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Our management assessed the effectiveness of our internal control over financial reporting as of December 31, 2025. In making this assessment, management used the criteria set forth by the Committee of Sponsoring Organizations of the Treadway Commission in its 2013 Internal Control – Integrated Framework. Based on our assessment, our management has concluded that, as of December 31, 2025, our internal control over financial reporting is effective based on those criteria.

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Attestation Report of the Registered Public Accounting Firm

This Annual Report does not include an attestation report of out registered public accounting firm regarding our internal control over financial reporting due to an exemption provided by the JOBS Act for “emerging growth companies.”

Changes in Internal Control over Financial Reporting

We continuously seek to improve the efficiency and effectiveness of our internal controls, which may result in changes to our systems and refinements to our processes. However, there were no changes in our internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) during the fiscal quarter ended December 31, 2025 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Item 9B. Other Information

(a)

None.

(b)

From time to time, our officers (as defined in Rule 16a–1(f)) and directors may enter into Rule 10b5-1 or non-Rule 10b5-1 trading arrangements (as each such term is defined in Item 408 of Regulation S-K). During the three months ended December 31, 2025, none of our directors or officers adopted, modified or terminated a plan or other arrangement intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) or any non-Rule 10b5-1 trading arrangements (as defined in Item 408(c) of Regulation S-K).

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

Not applicable.

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PART III

Item 10. Directors, Executive Officers and Corporate Governance

Executive officers and directors

Our executive officers and directors, and their ages and positions as of March 3, 2026, are as set forth below.

Name Age Position

Allan Reine, M.D. 51 Chief Executive Officer and Director (Class II)

Ann Lee, Ph.D. 64 Chief Technical Officer

Thomas Cahill, M.D., Ph.D. 39 Director (Class III)

Wendy Chung, M.D., Ph.D. 57 Director (Class II)

Kaye Foster 66 Director (Class II)

Michael Kelly 69 Director (Class I)

Jeffrey Marrazzo 47 Director (Class II)

Robert Nelsen 62 Director (Class III)

David Schenkein, M.D. 68 Director (Class I)

Executive Officers

Allan Reine, M.D. has served as our Chief Executive Officer and a member of our board of directors since May 2025. He previously served as our former Chief Financial Officer from January 2024 to May 2025. Prior to joining Prime, Dr. Reine served as Chief Financial Officer of Foghorn Therapeutics Inc. from September 2019 to January 2024, and as Chief Financial Officer of Pieris Pharmaceuticals, Inc. from August 2017 to September 2019. From August 2012 through August 2017, Dr. Reine was a portfolio manager at Lombard Odier Asset Management, where he ran a healthcare portfolio focused on biotechnology and pharmaceutical companies. Before joining Lombard Odier, from 2003 through August 2012, Dr. Reine served as a healthcare portfolio manager at various funds, including Citi Principal Strategies, SAC Capital, Trivium Capital and Alexandra Investment Management. Dr. Reine began his career in 2001 at CIBC World Markets where he worked in both biotechnology investment banking and biotechnology equity research. Dr. Reine received his M.D. from the University of Toronto and his B.Sc. in Statistical Sciences from the University of Western Ontario. We believe that Dr. Reine is qualified to serve on our board of directors based on his extensive experience as a senior executive in the pharmaceutical industry, his public company experience, as well as his knowledge of our company based on his role as our former Chief Financial Officer and current Chief Executive Officer.

Ann L. Lee, Ph.D. has served as our Chief Technical Officer since October 2021. Prior to that, Dr. Lee served as Senior Vice President and Head of Cell Therapy Development and Operations at BMS from November 2019 to July 2021, as Executive Vice President of Cell Therapy Development and Operations at Celgene Corporation, a biopharmaceutical company, from April 2018 to November 2019 and as Executive Vice President of Technical Operations at Juno from November 2017 to April 2018. From April 2009 to November 2017, Dr. Lee served as Senior Vice President and Global Head of Pharma Technical Development at Genentech, Inc., a Roche Group subsidiary and a biotechnology company. She currently serves on the board of directors and audit and compensation committees of Coya Therapeutics, Inc. Dr. Lee received her Ph.D. in biochemical engineering from Yale University and her B.S. in chemical engineering from Cornell University.

Non-employee directors

Thomas Cahill, M.D., Ph.D. has served as a member of our board of directors since November 2021. Dr. Cahill is the Founder and has served as the Managing Partner of Newpath Partners, a Boston-based life science venture fund focused on therapeutic companies, since October 2018. Dr. Cahill is the founding investor and director of nChroma Bio, Inc., Exo Therapeutics, Inc., Kisbee Therapeutics, Inc., Magnet Biomedicine, Inc., Myeloid Therapeutics, Inc., or Myeloid, Convergence Bio, Inc., Autobahn Therapeutics, Inc., Leal Therapeutics, Inc. and Amplitude Therapeutics, Inc. Prior to Newpath Partners, Dr. Cahill served as an Advisor at Raptor Group Holdings, where he

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helped further establish and lead the life science and technology investment portfolio, from September 2016 to May 2018. Dr. Cahill received both his M.D. and Ph.D. from Duke University and his M.S. from Stanford University. We believe that Dr. Cahill is qualified to serve on our board of directors based on his experience in the medical and venture capital industries.

Wendy Chung, M.D., Ph.D. has served as a member of our board of directors since November 2021. Dr. Chung is an American Board of Medical Genetics certified clinical and molecular geneticist and serves as the Chair of the Department of Pediatrics at Boston Children’s Hospital, a position she has held since July 2023. Previously, she led the Precision Medicine Resource in the Irving Institute at Columbia University from February 2014 to June 2023. Dr. Chung was on the faculty at Columbia University from 2002 to June 2023, most recently as the Kennedy Family Professor of Pediatrics and Medicine at Columbia University. Prior to that, she was an Associate Professor at Columbia University. Dr. Chung has served as a member of the board of directors of Rallybio Corporation, a public biotechnology company, since August 2022. She received her B.A. in Biochemistry from Cornell University, her M.D. from Cornell University Medical College, and her Ph.D. in Genetics from The Rockefeller University. We believe that Dr. Chung is qualified to serve on our board of directors because of her extensive experience in medicine and genetics research.

Kaye Foster has served as a member of our board of directors since December 2021. Ms. Foster has been a Senior Advisor at the Boston Consulting Group since August 2014 and a Venture Partner at ARCH since January 2022. Previously, she was Senior Vice President, Global Human Resources at Onyx Pharmaceuticals, Inc., an Amgen, Inc. subsidiary and a biopharmaceutical company, from October 2010 to January 2014. At Onyx, she led all aspects of human resources for U.S. and global operations. Prior to joining Onyx, Ms. Foster was Global Vice President of Human Resources and an Executive Committee member at Johnson and Johnson Corporation, a healthcare company, from May 2003 to March 2010. Before Johnson and Johnson, Ms. Foster held several senior human resources executive positions with Pfizer Inc., a pharmaceuticals company. She currently serves on the board of directors and compensation committee of National Resilience Inc.; on the board of directors and the compensation and nominating and corporate governance committees of Agios Pharmaceuticals, Inc.; and on the board of trustees and the human resources committee of Spelman College. Ms. Foster previously served on the board of directors and real estate and nominations committees of Stanford Health Care, a hospital and healthcare system, and chaired the Glide Memorial Foundation Board of Trustees. She received her B.B.A. in Business Administration from Baruch College of the City University of New York and her M.B.A. from Columbia University, Graduate School of Business. We believe Ms. Foster is qualified to serve on our board of directors because of her extensive experience as an executive in the pharmaceuticals industry, including her experience in people management, compensation planning and driving and maintaining corporate culture.

Michael A. Kelly has served as a member of our board of directors since November 2021. Mr. Kelly is currently acting as Founder & President of Sentry Hill Partners, LLC, a global life sciences transformation and management consulting business founded by Mr. Kelly in January 2018. From February 2003 to December 2017, he was a senior executive of Amgen, Inc., a biotechnology company, where he most recently served as Senior Vice President, Global Business Services and Vice President & Chief Financial Officer, International Commercial Operations. He also serves on the boards of directors of: Amicus Therapeutics, Inc., a biotechnology company, which he joined in December 2020; DMC Global Inc., a composite materials and oil field products company, which he joined in July 2020; NeoGenomics Laboratories, Inc., a genetics testing company, which he joined in July 2020, and nChroma Bio, Inc., a biotechnology company, which he joined in December 2024. Mr. Kelly previously served on the boards of directors of Aprea Therapeutics, Inc., a biotechnology company, from September 2020 to May 2022, Hookipa Pharma Inc., a biopharmaceutical company, from February 2019 to April 2023, and Chroma Medicine (which merged with Nvelop Therapeutics in December 2024 to form nChroma Bio, Inc.), a biotechnology company, from February 2023 to December 2024. Mr. Kelly has also held positions at Tanox, Inc., Biogen, Inc., and Nutrasweet Kelco Company, a division of Monsanto Life Sciences. He also serves on the Council of Advisors and was the former audit committee chairman for Direct Relief, a humanitarian aid organization focused on health outcomes and disaster relief. Mr. Kelly received his B.Sc. in Business Administration from Florida A&M University, concentrating in Finance and Industrial Relations. We believe that Mr. Kelly is qualified to serve on our board of directors because of his extensive experience in managing and growing global healthcare and biotechnology companies.

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Jeffrey D. Marrazzo has served as a member of our board of directors since May 2023 and as Executive Chair of our board of directors since May 2025. Currently, Mr. Marrazzo chairs the board of directors of several privately-held biotechnology companies including Dispatch Biotherapeutics and nChroma Bio. Previously, Mr. Marrazzo served as co-founder and Chief Executive Officer of Spark Therapeutics, Inc. from May 2013 to April 2022 and as a member of its board of directors from May 2013 to December 2019. In addition, Mr. Marrazzo launched and was Chief Business Officer of the U.S. division of Molecular Health, Inc. from 2011 to 2013. Mr. Marrazzo was part of the founding management of Generation Health from 2009 to 2011, up to and through the acquisition of a majority of the company’s shares by CVS Caremark. From 2008 to 2009, Mr. Marrazzo served as an employee and independent consultant to the business development and finance teams at Tengion Inc. and, from 2011 to 2013, Mr. Marrazzo served as an independent consultant to the Children’s Hospital of Philadelphia, or CHOP. Previously, Mr. Marrazzo served as healthcare advisor to former Pennsylvania Governor Edward G. Rendell and as an IBM management consultant to global pharmaceutical companies. Mr. Marrazzo holds a B.S.E. and B.A. in Systems Science and Engineering and Economics from the University of Pennsylvania and a dual M.B.A./M.P.A. from The Wharton School and Harvard University. We believe that Mr. Marrazzo is qualified to serve on our board of directors because of his extensive leadership experience in the life sciences industry.

Robert Nelsenhas served as a member of our board of directors since September 2020. Mr. Nelsen co-founded ARCH Venture Partners, L.P., a venture capital firm focused on early-stage technology companies, in 1986 and has served as a Managing Director of ARCH Venture Partners or its affiliated entities since 1994. Mr. Nelsen currently serves on the board of directors of Sana Biotechnology, Inc. and Hua Medicine, Inc., each a public biotechnology company, and currently serves on the board of directors of a number of private companies. Mr. Nelsen previously served on the board of directors of a number of public biotechnology companies, including Vir Biotechnology, Inc., from 2017 to May 2025, Lyell Immunopharma, Inc. from 2018 to May 2025, Brii Biosciences Limited from 2019 to June 2024, Revolution Healthcare Acquisition Corp. from 2021 to April 2022, Denali Therapeutics Inc. from 2015 to June 2022, Beam from 2017 to June 2021, Karuna Therapeutics, Inc. from 2018 to June 2021, Unity Biotechnology, Inc. from 2015 to December 2020, Agios Pharmaceuticals, Inc. from 2007 to June 2017, Syros Pharmaceuticals, Inc. from 2012 to June 2018, Juno Therapeutics, Inc. (acquired by Celgene Corporation in January 2018) from 2013 to March 2018, Sienna Biopharmaceuticals, Inc. from 2015 to September 2018 and Gossamer Bio, Inc. from 2017 to December 2018 (prior to its initial public offering). Mr. Nelsen received his M.B.A. from the University of Chicago and his B.S. from the University of Puget Sound in Economics and Biology. We believe that Mr. Nelsen is qualified to serve on our board of directors because of his extensive experience as a venture capitalist, building and serving boards of many public and private emerging companies, including multiple life sciences, biotechnology and pharmaceutical companies.

David Schenkein, M.D. has served as a member of our board of directors since September 2019. Dr. Schenkein currently serves as a partner in GV, the venture capital investment arm of Alphabet Inc., which he joined in February 2019. Previously, Dr. Schenkein served as President and Chief Executive Officer of Agios Pharmaceuticals, Inc. from August 2009 to February 2019. From April 2006 to July 2009, Dr. Schenkein served as a Senior Vice President of Oncology Development at Genentech Inc. Dr. Schenkein currently serves on the board of directors of Denali Therapeutics Inc. and Regeneron Pharmaceuticals, Inc. He is also on the boards of the private companies Leyden Laboratories B.V., Aera Therapeutics, Inc. and Treeline Biosciences, Inc. Previously, Dr. Schenkein served on the board of directors of Agios Pharmaceuticals, Inc. from 2009 to February 2025 and bluebird bio, Inc. from 2013 to 2021. He also currently serves as an adjunct attending physician in hematology at Tufts Medical Center. Dr. Schenkein received his M.D. from the State University of New York Upstate Medical School and his B.A. in Chemistry from Wesleyan University. We believe that Dr. Schenkein is qualified to serve on our board of directors because of his extensive background in the biotechnology industry and leadership experience as a senior executive and director of biotechnology companies.

We believe that all of our current board of directors members possess the professional and personal qualifications necessary for service on our board of directors and have highlighted particularly noteworthy attributes for each board of directors member in the individual biographies above.

Role of Board in Risk Oversight Process

Our board of directors has an active role, as a whole and also at the committee level, in overseeing the management of our risks. Our board of directors is responsible for general oversight of risks and regular review of information

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regarding our risks, including credit risks, liquidity risks, operational risks and cybersecurity. The audit committee is responsible for overseeing the management of risks relating to accounting matters and financial reporting. The compensation committee is responsible for overseeing the management of risks relating to our executive compensation plans and arrangements. The nominating and corporate governance committee is responsible for overseeing the management of risks associated with the independence of our board of directors and potential conflicts of interest. Although each committee is responsible for evaluating certain risks and overseeing the management of such risks, the entire board of directors is regularly informed through discussions from committee members about such risks. Our board of directors believes its administration of its risk oversight function has not negatively affected our board of director’s leadership structure.

Board Committees

Our board of directors has established an audit committee, a compensation committee, and a nominating and corporate governance committee, each of which operates pursuant to a charter adopted by our board of directors. We believe that the composition and functioning of all of our committees comply with the applicable requirements of Nasdaq, the Sarbanes-Oxley Act of 2002, and SEC rules and regulations that are applicable to us. We intend to comply with future requirements to the extent they become applicable to us.

The full text of our audit committee charter, compensation committee charter and nominating and corporate governance committee charter are posted on the “Corporate Governance” portion of our website at https://www.primemedicine.com. We do not incorporate the information contained on, or accessible through, our corporate website into this Annual Report on Form 10-K, and you should not consider it a part of this Annual Report on Form 10-K.

The following table describes which directors serve on each of our board of directors’s committees as of March 3, 2026.

Thomas Cahill, M.D., Ph.D. Member Member

Wendy Chung, M.D., Ph.D. Member Member

Kaye Foster Chair

Michael Kelly Chair

Robert Nelsen Member

David Schenkein, M.D. Member Chair

Audit Committee

Among other things, our audit committee’s responsibilities include:

•appointing, approving the compensation of, and assessing the independence of our independent registered public accounting firm;

•pre-approving auditing and permissible non-audit services, and the terms of such services, to be provided by our independent registered public accounting firm;

•reviewing the overall audit plan with our independent registered public accounting firm and members of management responsible for preparing our financial statements;

•reviewing and discussing with management and our independent registered public accounting firm our annual and quarterly financial statements and related disclosures as well as critical accounting policies and practices used by us;

•coordinating the oversight and reviewing the adequacy of our internal control over financial reporting;

•establishing policies and procedures for the receipt and retention of accounting-related complaints and concerns;

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•recommending based upon the audit committee’s review and discussions with management and our independent registered public accounting firm whether our audited financial statements shall be included in our Annual Report on Form 10-K;

•monitoring the integrity of our financial statements and our compliance with legal and regulatory requirements as they relate to our financial statements and accounting matters;

•preparing the audit committee report required by SEC rules to be included in our annual proxy statement;

•reviewing all related person transactions for potential conflict of interest situations and approving all such transactions;

•discussing and reviewing items of enterprise risk management and considering major risk exposures, including financial, operational, privacy, security, cybersecurity, competition, legal, regulatory, hedging and accounting risk exposures;

•evaluating the performance, responsibilities, budget and staffing of our internal audit function and reviewing the internal audit plan; and

•reviewing quarterly earnings releases.

All audit services and all permitted non-audit services to be provided to us by our independent registered public accounting firm must be approved in advance by our audit committee.

The members of our audit committee are Michael Kelly, Thomas Cahill and Wendy Chung. Mr. Kelly chairs the audit committee. All members of our audit committee meet the requirements for financial literacy under the applicable rules and regulations of the SEC and the Nasdaq listing rules. Our board of directors has determined that Mr. Kelly qualifies as an “audit committee financial expert” within the meaning of applicable SEC regulations. In making this determination, our board of directors considered the nature and scope of experience that Michael Kelly has previously had with public reporting companies, including service as a principal financial officer and principal accounting officer. Our board of directors has determined that all of the members of our audit committee satisfy the relevant independence requirements for service on the audit committee set forth in the rules of the SEC and the Nasdaq listing rules. Both our independent registered public accounting firm and management periodically meet privately with our audit committee. Our audit committee charter, which has been adopted by our board of directors, is available on our website.

Compensation Committee

Among other things, our compensation committee’s responsibilities include:

•reviewing and reassessing periodically (and making recommendations to our board of directors if advisable) our processes and procedures for the consideration and determination of director and executive officer compensation;

•annually reviewing and approving the corporate goals and objectives relevant to the compensation of our Chief Executive Officer;

•evaluating the performance of our Chief Executive Officer in light of such corporate goals and objectives and based on such evaluation (i) recommending to our board of directors the cash compensation of our Chief Executive Officer and (ii) recommending to our board of directors any grants and awards to our Chief Executive Officer under equity-based plans;

•reviewing and approving the compensation of our other executive officers;

•providing oversight of management’s decisions regarding the compensation of our other members of senior management;

•overseeing and administering our incentive-based compensation and equity-based plans;

•evaluating and assessing potential and current compensation consultants or advisors in accordance with the independence standards identified in the applicable Nasdaq listing rules;

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•reviewing and approving grants and awards under incentive-based compensation plans and equity-based plans, in each case consistent with the terms of such plans;

•reviewing and recommending to our board of directors our policies and procedures for the grant of equity-based awards;

•administering our compensation recovery policy;

•reviewing and recommending to our board of directors the compensation of our directors;

•preparing our compensation committee report if and when required by SEC rules, to be included in our annual proxy statement or Annual Report on Form 10-K in accordance with the rules and regulations of the SEC, the Nasdaq Stock Market rules and any other rules and regulations applicable to us;

•reviewing and discussing annually with management our “Compensation Discussion and Analysis,” if and when required, to be included in our annual proxy statement or Annual Report on Form 10-K; and

•reviewing and approving the retention or termination of any consulting firm or outside advisor to assist in the evaluation of compensation matters.

The members of our compensation committee are Kaye Foster, David Schenkein and Robert Nelsen. Ms. Foster chairs the compensation committee. Each member of our compensation committee is a non-employee director, as defined in Rule 16b-3 promulgated under the Exchange Act. Our compensation committee may delegate any of the responsibilities of the full committee to subcommittees and may delegate certain responsibilities of the full committee to our executive officers and other persons as may be permitted by applicable laws, rules or regulations and in accordance with the listing standards set forth by Nasdaq. Accordingly, our compensation committee has delegated authority to our Chief Executive Officer to make certain equity awards under our 2022 Stock Option and Incentive Plan, or the 2022 Plan, to our new hires and our existing employees at the senior vice president level and below who are not (and are not reasonably expected to be upon hiring) officers (as defined in Section 16 of the Exchange Act and Rule 16a-1 promulgated thereunder) in connection with promotions, market adjustments, employee recognition or retention, in each case, subject to certain limitations. Our compensation committee charter, which has been adopted by our board of directors, is available on our website.

Compensation Consultant

Our compensation committee has engaged Alpine Rewards, LLC, or Alpine Rewards, as its independent compensation consultant. When requested, Alpine Rewards consultants attend meetings of our compensation committee, including executive sessions in which executive compensation-related matters are discussed without the presence of our management. Alpine Rewards reports to our compensation committee and not to our management, although Alpine Rewards meets with our management for purposes of gathering information for its analyses and recommendations.

Our compensation committee assessed the independence of Alpine Rewards from management, taking into consideration relevant factors, including the other services provided to our Company by Alpine Rewards, the amount of fees our Company paid to Alpine Rewards as a percentage of Alpine Rewards’ total revenue, the policies and procedures of Alpine Rewards that are designed to prevent conflicts of interest, any business or personal relationship of the individual compensation advisors employed by Alpine Rewards with any executive officer of the Company, any business or personal relationship the individual compensation advisors employed by Alpine Rewards have with any member of our compensation committee and any stock of our Company owned by Alpine Rewards or the individual compensation advisors employed by Alpine Rewards. On the basis of that assessment and taking into consideration the independence factors that are required to be considered under applicable stock exchange rules, our compensation committee determined that no relationships existed that would create a conflict of interest or that would compromise Alpine Rewards’ independence, and that Alpine Rewards is independent pursuant to the independence standards set forth in the Nasdaq listing standards promulgated pursuant to Section 10C of the Exchange Act.

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Nominating and Corporate Governance Committee

Among other things, our nominating and corporate governance committee’s responsibilities include:

•developing and recommending to our board of directors criteria for our board of directors and committee membership;

•establishing procedures for identifying and evaluating our board of director candidates, including nominees recommended by stockholders;

•to the extent deemed appropriate, retaining third-party search firms or other advisors to identify and evaluate director nominee candidates;

•reviewing the composition of our board of directors to ensure that it is composed of members containing the appropriate skills and expertise to advise us;

•identifying individuals qualified to become members of our board of directors;

•recommending to our board of directors the persons to be nominated for election as directors and to each of the committees of our board of directors;

•developing, recommending to our board of directors and periodically assessing the adequacy of a set of corporate governance guidelines and a code of conduct and business ethics;

•overseeing the evaluation of our board of directors; and

•reviewing and discussing with our board of directors corporate succession plans for our Chief Executive Officer and our other key officers.

The members of our nominating and corporate governance committee are David Schenkein, Wendy Chung and Thomas Cahill. Dr. Schenkein chairs our nominating and corporate governance committee. Our board of directors has determined that each member of our nominating and corporate governance committee satisfies the independence standards of the applicable rules of Nasdaq. Our nominating and corporate governance committee charter, which has been adopted by our board of directors, is available on our website.

Code of Business Conduct and Ethics

Our board of directors adopted a Code of Business Conduct and Ethics, which applies to all of our employees, officers (including our principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions), agents and representatives, including directors and consultants.

If we make any substantive future amendments to certain provisions of our Code of Business Conduct and Ethics, or grant any waivers from our Code of Business Conduct and Ethics for any officer or director, we will disclose the nature of such amendment or waiver on our website identified below or in a Current Report on Form 8-K. The full text of our Code of Business Conduct and Ethics and our Code of Ethics is posted on our website at https://www.primemedicine.com. The inclusion of our website address in this Annual Statement on Form 10-K does not include or incorporate by reference the information on our website into this Annual Report on Form 10-K, and you should not consider that information a part of this Annual Report on Form 10-K.

Director Nomination Process

No material changes have been made to the procedures by which our stockholders may recommend nominees to our board of directors from those that were described in our annual proxy statement filed with the SEC on April 22, 2025.

Policy on Trading, Pledging and Hedging of Company Stock

Certain transactions in our securities (such as purchases and sales of publicly traded put and call options, and short sales) create a heightened compliance risk or could create the appearance of misalignment between management and stockholders. In addition, securities held in a margin account or pledged as collateral may be sold without consent if the owner fails to meet a margin call or defaults on the loan, thus creating the risk that a sale may occur at a time

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when an officer or director is aware of material, non-public information or otherwise is not permitted to trade in our securities. Our insider trading policy expressly prohibits short sales and derivative transactions of our stock and purchases or sales of puts, calls, or our other derivative securities or any derivative securities that provide the economic equivalent of ownership of any of our securities or an opportunity, direct or indirect, to profit from any change in the value of our securities or engage in any other hedging transaction with respect to our securities, at any time, by our executive officers, directors and employees.

Insider Trading Policy

We have adopted an Insider Trading Policy governing the purchase, sale, and/or other dispositions of our securities by directors, officers, employees and designated consultants and contractors that we believe is reasonably designed to promote compliance with insider trading laws, rules and regulations, and the Nasdaq Stock Market listing standards that are applicable to us. A copy of our Second Amended and Restated Insider Trading Policy is included as Exhibit 19.1 in this Annual Report on Form 10-K.

Our Insider Trading Policy permits our officers, directors, employees and certain other persons to enter into trading plans complying with Rule 10b5-1 under the Exchange Act. Generally, under these trading plans, the individual relinquishes control over the transactions once the trading plan is put into place and can only put such plans into place while the individual is not in possession of material non-public information. Accordingly, sales under these plans may occur at any time, including possibly before, simultaneously with, or immediately after significant events involving us.

A copy of our Second Amended and Restated Insider Trading Policy is filed as Exhibit 19.1 to this Annual Report on Form 10-K.

In addition, with regard to trading in our own securities, it is the our policy to comply with applicable insider trading laws, rules and regulations, and any exchange listing standards when engaging in transactions in our securities.

Compensation Recovery Policy

In accordance with the requirements of the SEC and Nasdaq listing rules, our board of directors adopted a compensation recovery policy on September 15, 2023, effective as of October 2, 2023. The compensation recovery policy provides that in the event we are required to prepare a restatement of financial statements due to material noncompliance with any financial reporting requirement under securities laws, we will seek to recover any incentive-based compensation that was based upon the attainment of a financial reporting measure and that was received by any current or former executive officer during the three-year period preceding the date that the restatement was required if such compensation exceeds the amount that the executive officers would have received based on the restated financial statements.

Policies and Practices Related to the Grant of Certain Equity Awards

We have adopted an Equity Award Grant Policy that sets forth the process and timing for us to follow when we grant equity awards for shares of our common stock to our employees or advisors or consultants (other than our non-employee directors) pursuant to our equity compensation plans. All grants of equity awards must be approved in advance by our board of directors, the compensation committee or, subject to the delegation requirements in the policy, our Chief Executive Officer. The equity award granting authority delegated to our Chief Executive Officer applies to employees at the senior vice president level and below who are not (and are not reasonably expected to be upon hiring) officers (as defined in Section 16 of the Exchange Act and Rule 16a-1 promulgated thereunder) and to equity awards within the specific ranges and subject to a maximum annual aggregate amount as may be set forth in the policy, as approved by the compensation committee from time to time.

Generally, equity awards are granted on the following regularly scheduled basis as set forth in the Equity Award Grant Policy: (a) equity awards granted in connection with the hiring of a new employee or the promotion of an existing employee or the engagement of a new consultant will generally be granted, if at all, regularly (either monthly or quarterly) and will be effective on the first day of the month immediately following the month in which such individual’s employment or consulting term begins or promotion occurs, as applicable; (b) equity awards granted to existing employees (other than in connection with a promotion or other special grant) will generally be

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granted, if at all, on an annual basis and will be effective on the date such grant is approved or such future date as approved by our board of directors, compensation committee or Chief Executive Officer, as applicable; and (c) any special grants to existing employees will be made, if at all, periodically and will be effective on the date such grant is approved or such future date as approved by our board of directors, compensation committee or Chief Executive Officer, as applicable.

Our board of directors, compensation committee and Chief Executive Officer do not take into account any material nonpublic information when determining the timing and terms of equity awards. We do not time our equity award grants either to take advantage of a depressed stock price, or an anticipated increase in stock price, and we have limited the amount of discretion that can be exercised in connection with the timing of equity award grants. We also do not time the release of material nonpublic information based on equity award grant dates.

The following table contains information required by Item 402(x)(2) of Regulation S-K about stock options granted to the our named executive officers, or NEOs, in the last completed fiscal year during the period beginning four business days before and ending one business day after the filing of our Annual Report on Form 10-K, our Quarterly Reports on Form 10-Q, or the filing or furnishing of any of our Current Reports on Form 8-K that discloses material nonpublic information.

(1)Amounts reflect the aggregate grant date fair value of option awards granted during the applicable year calculated in accordance with the provisions of Financial Accounting Standards Board, or FASB, Accounting Standards Codification, or ASC, Topic 718, Compensation—Stock Compensation. Such grant date fair values do not take into account any estimated forfeitures. Refer to Note 2, Summary of Significant Accounting Policies, to our consolidated financial statements appearing elsewhere within this Annual Report on Form 10-K for assumptions underlying the valuation of equity awards. The grant date fair value of Dr. Reine’s performance-based stock options grant for 500,000 shares, based on probable achievement of the applicable performance metrics, was $0; the grant date fair value of such performance-based stock option grant, based on maximum achievement of the applicable performance metrics, was $556,800. The amounts reported in this column reflect the accounting cost for these options and do not correspond to the actual economic value that may be received by our NEOs upon the exercise of the options or any sale of the underlying shares of common stock.

(2)These options were repriced on August 1, 2025 under our stockholder approved option repricing plan, which is discussed in greater detail in Note 8, Stock-based Compensation, to our consolidated financial statements appearing elsewhere within this Annual Report on Form 10-K. Amounts reflect the aggregate incremental fair value of the repriced options, calculated in accordance with the provisions of FASB ASC Topic 718. Such grant date fair values do not take into account any estimated forfeitures. Refer to Note 2, Summary of Significant

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Accounting Policies, to our consolidated financial statements appearing elsewhere within this Annual Report on Form 10-K for assumptions underlying the valuation of equity awards. The amounts reported in this column reflect the accounting cost for these options and do not correspond to the actual economic value that may be received by our NEOs upon the exercise of the options or any sale of the underlying shares of common stock.

Director Compensation

The following table presents the total compensation for each person who served as a non-employee member of our board of directors during the fiscal year ended December 31, 2025. Other than as set forth in the table and described more above, we did not pay any compensation, grant any equity awards or non-equity awards to, or pay any other compensation to any of the non-employee members of our board of directors during the fiscal year ended December 31, 2025. Dr. Reine, who is our Chief Executive Officer, and Dr. Gottesdiener, who was our former Chief Executive Officer, did not receive any additional compensation for their services as directors. The compensation received by Dr. Reine and Dr. Gottesdiener, as NEOs of the Company, are presented in the “2025 Summary Compensation Table”.

(1)Amounts represent annual cash compensation earned for services rendered as directors by non-employee members of our board of directors and the committees thereof during the fiscal year ended December 31, 2025.

(2)Amounts reflect the aggregate grant date fair value of option awards granted during 2025 in accordance with our Non-employee Director Compensation Policy, described below, calculated in accordance with the provisions of FASB ASC Topic 718, Compensation—Stock Compensation. Such grant date fair values do not take into account any estimated forfeitures. The grant date fair value of Mr. Marrazzo’s performance-based stock option grant for 200,000 shares, based on probable achievement of the applicable performance metrics, was $0; the grant date fair value of such performance-based stock option grants, based on maximum achievement of the applicable performance metrics, was $223,900. In addition to grant date fair value of options granted during 2025, the amounts also include the incremental fair value of options repriced during 2025. The aggregate incremental fair value of repriced options were $83,456 for each of Dr. Cahill, Mr. Nelsen, and Dr. Schenkein; $111,611 for each of Dr. Chung and Mr. Kelly; $111,891 for Ms. Foster; and $348,821 for Mr. Marrazzo. Refer to Note 2, Summary of Significant Accounting Policies, to our consolidated financial statements appearing elsewhere within this Annual Report on Form 10-K for assumptions underlying the valuation of equity awards. The amounts reported in this column reflect the accounting cost for these options and do not correspond to the actual economic value that may be received by our directors upon the exercise of the options or any sale of the underlying shares of common stock.

(3)As part of the annual board of directors member grants, Dr. Cahill, Dr. Chung, Ms. Foster, Mr. Kelly, Mr. Nelsen, and Dr. Schenkein received options to purchase 55,000 shares of our common stock. As of December 31, 2025, Dr. Cahill, Mr. Nelsen, and Dr. Schenkein each held options to purchase an aggregate of 139,062 shares of common stock, and Dr. Chung, Ms. Foster, and Mr. Kelly each held options to purchase an aggregate of 161,578 shares of common stock.

(4)Upon his appointment as the Executive Chair of the our board of directors, Mr. Marrazzo received options to purchase 1,000,000 shares of our common stock. In addition, for his services as a director, as part of the annual board of directors member grants, Mr. Marrazzo received options to purchase an additional 55,000 shares of our common stock. Under his advisory services agreement with the Company, the details of which are discussed in

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the “Item 13. Certain Relationships and Related Transactions, and Director Independence”, Mr. Marrazzo also received fees totaling $95,161 during the year ended December 31, 2025. As of December 31, 2025, Mr. Marrazzo held options to purchase an aggregate of 1,442,000 shares of common stock.

Non-Employee Director Compensation Policy

We adopted a non-employee director compensation policy in May 2022 designed to enable us to attract and retain, on a long-term basis, highly qualified non-employee directors, which was amended and restated on May 17, 2024. On May 16, 2025, our board of directors approved a second amended and restated non-employee director compensation policy based upon the recommendations of our compensation committee and Alpine Rewards, our independent compensation consultant.

Under the second amended and restated policy, our non-employee directors are eligible to receive annual cash retainers (which are payable quarterly in arrears and prorated for partial years of service) and equity awards as set forth below:

Annual Retainer for Board of Directors

All non-employee members $ 45,000

Additional Retainer for Board Chair $ 30,000

Additional Retainer for Audit Committee

Non-chair members $ 10,000

Additional Retainer for Compensation Committee

Non-chair members $ 7,500

Additional Retainer for Nominating and Corporate Governance Committee

Non-chair members $ 5,000

In addition, our policy provides that, upon initial election or appointment to our board of directors, each new non-employee director will be granted a one-time grant of a non-statutory stock option to purchase 110,000 shares of our common stock on the date of such director’s election or appointment to our board of directors (the “Initial Director Grant”). The Initial Director Grant will vest in substantially equal annual installments over three years, subject to the non-employee director’s continued services to the Company. On the date of each annual meeting of stockholders of the Company, each non-employee director who will continue as a non-employee director following such meeting, other than a non-employee director receiving an Initial Director Grant, will be granted an annual award of a non-statutory stock option to purchase 55,000 shares of common stock (the “Annual Director Grant”). Notwithstanding the foregoing, if a non-employee director was initially elected to our board of directors on a date other than the date of an annual meeting, then upon such initial election or appointment, the non-employee director shall receive, in lieu of an Annual Director Grant, a grant that is pro-rated on a monthly basis for time served as a non-employee director between the date of the non-employee director’s initial election or appointment and the date of the next annual meeting. The Annual Director Grant (including any pro-rated amount) will vest in full on the earlier of the one-year anniversary of the grant date or on the date of our next annual meeting of stockholders, subject to the non-employee director’s continued services to the Company. Such awards are subject to fully accelerated vesting upon the sale of the Company. All vested options remain exercisable for twelve months if a non-employee director resigns from the board of directors or otherwise ceases to serve as a director.

The aggregate amount of compensation, including both equity compensation and cash compensation, paid to any non-employee director for service as a non-employee director in a calendar year period will not exceed $1,600,000 in the first calendar year such individual becomes a non-employee director and $1,000,000 in any other calendar year.

We reimburse all reasonable out-of-pocket expenses incurred by directors for their attendance at meetings of our board of directors or any committee thereof.

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Employee directors receive no additional compensation for their service as a director.

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Item 11. Executive Compensation

Our NEOs for the fiscal year ended December 31, 2025 were:

•Allan Reine, M.D., our current Chief Executive Officer;

•Keith Gottesdiener, M.D., our former President and Chief Executive Officer from January to May 2025;

•Ann Lee, Ph.D., our Chief Technical Officer; and

•Jeremy Duffield, M.D., Ph.D., FRCP, our former Chief Scientific Officer from January to July 2025.

2025 Summary Compensation Table

The following table sets forth the compensation provided to our NEOs for the fiscal years ended December 31, 2025 and 2024.

Chief Technical Officer

(1)Amounts reflect the aggregate grant date fair value of option awards granted during the applicable year calculated in accordance with the provisions of FASB ASC Topic 718, Compensation—Stock Compensation. Such grant date fair values do not take into account any estimated forfeitures. Refer to Note 2, Summary of Significant Accounting Policies, to our consolidated financial statements appearing elsewhere within this Annual Report on Form 10-K for assumptions underlying the valuation of equity awards. The amounts reported in this column reflect the accounting cost for these options and do not correspond to the actual economic value that may be received by our NEOs upon the exercise of the options or any sale of the underlying shares of common stock. For the year ended December 31, 2025, Dr. Reine was granted time-based and performance-based stock options. The grant date fair value of Dr. Reine’s time-based stock option grant was $2,382,997. The grant date fair value of Dr. Reine’s performance-based stock option grant, based on probable achievement of the applicable performance metrics, was $0; the grant date fair value of such performance-based stock option grant, based on maximum achievement of the applicable performance metrics, was $556,800. Dr. Gottesdiener, Dr. Lee, and Dr. Duffield were granted only time-based stock options during the year ended December 31, 2025. Additionally, the aggregate incremental fair value, calculated in accordance with FASB ASC Topic 718, for the repricing of certain options in 2025 were $445,801 for Dr. Reine and $318,478 for Dr. Lee. Dr. Gottesdiener and Dr. Duffield were not eligible to participate in our option repricing program. Furthermore, the aggregate incremental fair value, calculated in accordance with FASB ASC Topic 718, with respect to the extension of the post-termination exercise period in 2025 for certain options held by Dr. Gottesdiener and Dr. Duffield were $293,602 and $197,002, respectively.

(2)The amounts reflect the annual cash incentive compensation earned by our NEOs for the applicable year based on our achievement of certain corporate performance goals.

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(3)Dr. Reine was appointed as our Chief Executive Officer in May 2025. Prior to his appointment, Dr. Reine served as our Chief Financial Officer. Dr. Reine’s 2025 base salary represents his salary as our former Chief Financial Officer through his transition to Chief Executive Officer and, subsequently, his salary in the role as our Chief Executive Officer. Similarly, Dr. Reine’s annual bonus includes a proration for his tenure as our former Chief Financial Officer.

(4)All other compensation for Dr. Reine for 2025 consists of (i) $32,965 in reimbursements for housing expenses, which includes $8,965 for related tax gross-ups, (ii) $13,352 in reimbursement for commuting expenses, which includes $1,702 related tax gross-ups, (iii) $10,500 for matching contributions under our 401(k) plan, and (iv) $360 in wellness reimbursements.

(5)All other compensation for Dr. Gottesdiener for 2025 consists of (i) $646,067 of severance, which includes $10,000 of legal reimbursements, (ii) $99,299 in consulting fees under the KMG Consulting Agreement, which is described in greater detail below, (iii) $6,534 in reimbursements for commuting expenses, which includes $846 for related tax gross-ups, and (iv) $10,500 for matching contributions under our 401(k) plan.

(6)Dr. Lee was not an NEO for 2024. All other compensation for Dr. Lee for 2025 consists of (i) $10,500 for matching contributions under our 401(k) plan, and (ii) $206 in reimbursements for commuting expense.

(7)All other compensation for Dr. Duffield for 2025 consists of (i) $321,154 of severance payments, (ii) $48,900 in consulting fees under the Duffield Consulting Agreement, which is described in greater detail below, (iii) $10,500 for matching contributions under our 401(k) plan, and (iv) $372 in reimbursements for commuting expense.

Overview

Our executive compensation program is designed to attract, motivate and retain key employees who we believe best represent our values and can make significant contributions towards achieving our purpose of delivering a new class of differentiated one-time curative genetic therapies to address the widest spectrum of diseases by deploying our Prime Editing technology. Our program’s purpose is to incentivize them based on the achievement of key performance goals, and to align their interests with the interests of our stockholders. Under this program, our NEOs’ compensation is based on the achievement of key strategic and business goals that were developed based on our mission. The program consists of a combination of base salary, an annual cash bonus, long-term equity incentive compensation and other employee benefits generally available to our employees, and is designed to align our executive compensation program with the interests of our stockholders by reflecting a pay-for-performance philosophy that supports our business strategy. At the same time, our board of directors believes that the program does not encourage excessive risk-taking by management.

Our compensation committee is generally responsible for determining the compensation of our executive officers (and recommending to our board of directors such compensation for our Chief Executive Officer). In setting executive base salaries and bonuses and granting equity incentive awards, the compensation committee considers compensation for comparable positions in the market, the historical compensation levels of our executive officers, internal equity, our desire to motivate our employees to achieve short- and long-term results that are in the best interests of our stockholders, and a long-term commitment to us. We target a general competitive position, based on independent third-party benchmark analytics to inform the mix of compensation of base salary, bonus and long-term incentives. Our compensation committee typically reviews and discusses management’s proposed compensation with our Chief Executive Officer for all executives other than the Chief Executive Officer. Based on those discussions and its discretion, taking into account the factors noted above, the compensation committee then sets the compensation for each executive officer other than the Chief Executive Officer. For the Chief Executive Officer, our compensation committee recommends our Chief Executive Officer’s compensation for approval by our board of directors. Our compensation committee may delegate certain authorities to one of our officers, as described above in “Corporate Governance—Compensation Committee”.

Our compensation committee has the authority to engage the services of a consulting firm or other outside advisor to assist it in designing our executive compensation programs and in making compensation decisions.

During the fiscal year ended December 31, 2025, our compensation committee engaged Alpine Rewards to assist it in evaluating our executive and director compensation practices, including program design, identification of an

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appropriate peer group for compensation comparison purposes and providing pay benchmarking data. Alpine Rewards also provided (i) analysis and recommendations to our compensation committee regarding trends and emerging topics with respect to executive compensation; (ii) compensation programs for executives, directors and our employees generally; and (iii) stock utilization and related metrics. For further information, see “Corporate Governance—Compensation Committee—Compensation Consultant.”

Alpine Rewards reports directly to our compensation committee and did not provide any additional services other than as described above. Our compensation committee annually assesses its independence consistent with Nasdaq listing standards and concluded that the engagement of such consultant did not raise any conflict of interest.

2025 Base Salary

Our NEOs each receive a base salary to compensate them for services rendered to us. The base salary payable to each NEO is intended to provide a fixed component of compensation reflecting the executive’s skill set, experience, role and responsibilities. Base salaries may be adjusted from time to time to realign salaries with market levels after taking into account individual responsibilities, performance and experience. For the fiscal year ended December 31, 2025, the annual base salaries for our NEOs were as follows:

(1)Dr. Reine was appointed as our Chief Executive Officer effective May 19, 2025. Prior to May 19, 2025, Dr. Reine served as our Chief Financial Officer.

(2)Dr. Gottesdiener’s employment with us ceased on May 18, 2025 and Dr. Duffield’s employment with us ceased on July 15, 2025. These NEOs’ base salaries were pro-rated accordingly.

2025 Annual Bonus

For the fiscal year ended December 31, 2025, each of the NEOs was eligible to earn an annual cash bonus determined by our compensation committee for NEOs other than the Chief Executive Officer and by our board of directors on the recommendation of our compensation committee, for our principal executive officer, based on our corporate performance. The target annual bonus for each of our NEOs for the fiscal year ended December 31, 2025 was equal to the percentage of the executive’s respective annual base salary as of December 31, 2025 specified below:

Name Target Bonus Percentage

Allan Reine, M.D. (1) 60%

Keith Gottesdiener, M.D. 60%

Ann Lee, Ph.D. 40%

Jeremy Duffield, M.D., Ph.D., FRCP 40%

(1) During his tenure as our former Chief Financial Officer, Dr. Reine’s target bonus percentage was 40%. Upon becoming our Chief Executive Officer, Dr. Reine’s target bonus percentage increased to 60%.

In 2025, annual bonuses for our Chief Executive Officer and Chief Technical Officer were based entirely on the level of corporate achievement against our 2025 corporate objectives. With respect to the fiscal year ended December 31, 2025, our compensation committee approved a cash bonus payout in an amount of 120% of target for Dr. Lee and our board of directors approved a cash bonus payout in an amount of 120% of target for Dr. Reine. Dr. Gottesdiener and Dr. Duffield did not earn any annual bonuses for 2025 as a result of their separations from us.

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Equity-Based Compensation

We believe that long-term equity incentives provide our executives with a strong link to our long-term performance and create an ownership culture. These equity awards are a key aspect of our compensation philosophy and serve to align the interests of our executive officers with our stockholders, as they are tied to future increases in the value of our stock. Further, we believe that equity awards with a time-based vesting feature promote retention because this feature incentivizes our NEOs to remain in our employment during the vesting period. Additionally, we believe that equity awards with a performance-based vesting feature further incentivize our executive officers to achieve important milestones. Accordingly, our compensation committee periodically reviews the equity incentive compensation of our NEOs and may grant equity incentive awards to them from time to time. For additional information regarding outstanding equity awards held by our NEOs as of December 31, 2025, see the “Outstanding Equity Awards at Fiscal Year End” table below.

Perquisites/Personal Benefits

We do not provide significant perquisites or other personal benefits to our executive officers, including our NEOs, except for reimbursements for wellness, commuting and/or housing for certain NEOs, as well as certain related tax gross-ups as described above in the “2025 Summary Compensation Table.”

401(k) Plan

We maintain a retirement savings plan, or the 401(k) plan, that is intended to qualify for favorable tax treatment under Section 401(a) of the Code and contains a cash or deferred feature that is intended to meet the requirements of Section 401(k) of the Code. U.S. employees are generally eligible to participate in the 401(k) plan, subject to certain criteria. Participants may make pre-tax and certain after-tax (Roth) salary deferral contributions to the plan from their eligible earnings up to the statutorily prescribed annual limit under the Code. Participants who are 50 years of age or older may contribute additional amounts based on the statutory limits for catch-up contributions. Participants who are 60 to 63 years of age may also contribute additional amounts based on the statutory limits for super catch-up contributions. All deferrals made to the standard catch-up or the super catch-up may only be made on Roth contributions. Participant contributions are held in trust as required by law. We provide matching contributions equal to 50% of an employee’s contributions, subject to a maximum of six percent of eligible compensation.

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Outstanding Equity Awards at 2025 Fiscal Year-End Table

The following table lists all outstanding equity awards held by our NEOs as of December 31, 2025. Equity awards granted prior to our IPO in October 2022 were under our 2019 Stock Option and Grant Plan, as amended from time to time, or the 2019 Plan, and equity awards granted following our IPO were under our 2022 Plan.

Options

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(1)The shares underlying these options vest as follows: 25 percent vest on the 1-year anniversary of the vesting commencement date, and 1/48th of the shares vest on a monthly basis thereafter, in each case subject to the applicable NEO’s continuous service relationship with us through each applicable vesting date. The stock options are also subject to certain acceleration of vesting provisions as provided in the applicable NEO’s employment agreement.

(2)The underlying shares vest upon the achievement of pre-determined milestone(s), subject to the applicable NEO’s continuous service relationship with us through the applicable vesting date. As of December 31, 2025, the applicable milestone(s) have not been satisfied.

(3)The shares underlying these options vest in equal monthly installments over 48 months commencing on the vesting commencement date, subject to the applicable NEO’s continuous service relationship with us through each applicable vesting date. The stock options are also subject to certain acceleration of vesting provisions as provided in the applicable NEO’s employment agreement.

(4)The underlying shares are fully vested as of December 31, 2025.

(5)The shares underlying these options vest in equal monthly installments over 48 months commencing on the vesting commencement date. Under the terms of the Gottesdiener Separation Agreement, as defined and described in greater detail below, options granted to Dr. Gottesdiener while an employee will continue to vest for one additional year following the cessation of his employment, subject to Dr. Gottesdiener’s continued service relationship with us through each applicable vesting date.

(6)The underlying shares vest in four tranches (consisting of 100,000 shares each) upon the achievement of a pre-determined milestone for each tranche prior to one year additional vesting period provided for under the defined the Gottesdiener Separation Agreement, subject to Dr. Gottesdiener’s continued service relationship with us through each applicable vesting date. As of December 31, 2025, two of the four tranches have not vested.

(7)The shares underlying these options vest in equal monthly installments over 48 months commencing on the vesting commencement date and through March 31, 2026, the last date of Duffield Consulting Agreement, as defined and described in detail below, subject to Dr. Duffield’s continued service relationship with us through each applicable vesting date.

(8)All options issued under the 2019 Plan and 2022 Plan to Dr. Lee and Dr. Reine with an exercise price greater than $4.04 were repriced on August 1, 2025, as approved by our stockholders. Refer to Note 8, Stock-based Compensation, to our consolidated financial statements appearing elsewhere within this Annual Report on Form 10-K for greater detail.

Agreements with our NEOs

We have entered into a new employment agreement with Dr. Reine that was effective as of May 2025. Previously, we entered into an employment agreement with Dr. Reine that was effective as of January 2024. We entered into employment agreements with Dr. Gottesdiener, Dr. Duffield, and Dr. Lee that were effective in July 2022. We entered into a separation agreement with Dr. Gottesdiener and a consulting agreement with a limited liability company managed by Dr. Gottesdiener in May 2025. We entered into a separation agreement and consulting agreement with Dr. Duffield in July 2025.

Each of our NEOs are subject to standard confidentiality and nondisclosure, assignment of intellectual property work product and post-termination non-solicitation of employees, consultants and customers covenants and, in certain circumstances, non-competition covenants.

Allan Reine, M.D.

CEO Agreement

In connection with Dr. Reine’s appointment as our Chief Executive Officer, we entered into an Amended and Restated Employment Agreement, or the Reine CEO Employment Agreement, effective May 19, 2025. The Reine CEO Employment Agreement provides for at-will employment.The agreement also sets forth initial base salary, initial annual target bonus and eligibility to participate in our benefit plans generally. In addition, Dr. Reine is

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entitled to reimbursement for commuting expenses, which include all reasonable costs for his commute between his residence in New York, New York and our corporate headquarters in Cambridge, Massachusetts, as well as reimbursement for housing expenses in or near Cambridge, Massachusetts.

Pursuant to the Reine CEO Employment Agreement, in the event Dr. Reine is terminated by us without “Cause” or he resigns for “Good Reason” (as such terms are defined in the Reine CEO Employment Agreement), in each case subject to the delivery of and compliance with a fully effective separation agreement that shall include, without limitation, a general release of claims, reaffirmation of applicable restrictive covenants and, in our discretion, a one year non-competition agreement, Dr. Reine will be entitled to (i) an amount equal to the sum of (A) twelve (12) months of his then-current base salary plus (B) 1.0 times his target annual bonus for the then current year, in each case subject to reductions by any amount received by him pursuant to a restrictive covenant agreement, and (ii) subject to Dr. Reine’s co-payment of premium amounts at the applicable active employees’ rate and proper election to continue COBRA health coverage, payment of the portion of the premium equal to the amount we would have paid to provide health insurance had he remained employed by us until the earliest of (A) twelve (12) months following his termination, (B) his eligibility for group medical plan benefits under any other employer’s group medical plan or (C) the end of his COBRA health continuation period. These amounts shall be paid out in substantially equal installments in accordance with our payroll practice over a period of twelve (12) months. In addition, subject to the delivery of the fully effective separation agreement, the bonus amount (if any) that Dr. Reine would have been paid if he had remained employed through the payment date, if such termination occurs on or after January 1 but before the date bonuses are paid for the prior year to our other executives, will be paid to Dr. Reine on the date our other executives receive their bonuses.

In the event Dr. Reine is terminated by us without “Cause” or he resigns for “Good Reason”, in each case within three months prior and 12 months following a “Change in Control” (as such terms are defined in the Reine CEO Employment Agreement), subject to the delivery of and compliance with a fully effective separation agreement (as described above), Dr. Reine will be entitled to the following, in lieu of the benefits above: (i) a lump sum cash payment equal to the sum of (A) 18 months of his then-current base salary (or his base salary in effect immediately prior to the “Change in Control,” if higher) plus (B) 1.5 times his target annual bonus for the then current year (or target in effect immediately prior to the “Change in Control,” if higher), in each case subject to reductions by any amount received by him pursuant to a restrictive covenant agreement, (ii) subject to Dr. Reine’s co-payment of premium amounts at the applicable active employees’ rate and proper election to continue COBRA health coverage, payment of the portion of the premium equal to the amount we would have paid to provide health insurance had he remained employed by us until the earliest of (A) 18 months from the date of his separation, (B) his eligibility for group medical plan benefits under any other employer’s group medical plan or (C) the end of his COBRA health continuation period, and (iii) the bonus amount (if any) that Dr. Reine would have been paid if he had remained employed through the payment date, if such termination occurs on or after January 1 but before the date bonuses are paid for the prior year to our other executives. In addition, in the event Dr. Reine is terminated by us without Cause or he resigns for Good Reason, in each case within three months prior and 12 months following a “Change in Control,” all of the then-outstanding and unvested portion of his stock options and other stock-based awards that are subject solely to time-based vesting shall become fully vested and exercisable or non-forfeitable immediately as of the date of termination, with any such performance-based awards vesting at target.

The payments and benefits provided under the Reine CEO Employment Agreement in connection with a “Change in Control” may not be eligible for federal income tax deduction for us pursuant to Section 280G of the Code. These payments and benefits may also be subject to an excise tax under Section 4999 of the Code. If the payments or benefits payable to Dr. Reine in connection with a “Change in Control” would be subject to the excise tax imposed under Section 4999 of the Code, then those payments or benefits will be reduced if such reduction would result in a higher net after-tax benefit to him.

CFO Agreement

In January 2024, we entered into an employment agreement with Dr. Reine pursuant to which we employed Dr. Reine as our former Chief Financial Officer, or the Reine CFO Employment Agreement.The agreement set forth Dr. Reine’s initial base salary, initial annual target bonus and eligibility to participate in our benefit plans generally. In addition, Dr. Reine was entitled to reimbursement for commuting expenses, which include all reasonable costs for his commute between his residence in New York, New York and our corporate headquarters in Cambridge,

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Massachusetts, as well as reimbursement for housing expenses in or near Cambridge, Massachusetts, for up to $2,000 per month for 12 months from the commencement of his employment.

Keith M. Gottesdiener, M.D.

Employment Agreement

The employment agreement with Dr. Gottesdiener, or the Gottesdiener Employment Agreement, provided for at-will employment. The agreement also set forth initial base salary, initial annual target bonus and eligibility to participate in our benefit plans generally. In addition, pursuant to Amendment No. 1 to the Gottesdiener Employment Agreement, Dr. Gottesdiener was entitled to reimbursement for commuting expenses, which include all reasonable costs for his commute between his family’s residence in New York, New York and our corporate headquarters in Cambridge, Massachusetts.

Separation Agreement

In May 2025, we entered into a separation agreement with Dr. Gottesdiener, or the Gottesdiener Separation Agreement, pursuant to which Dr. Gottesdiener is entitled to receive certain severance benefits in accordance with the terms of the Gottesdiener Employment Agreement.

Pursuant to the Gottesdiener Separation Agreement, in exchange for, among other things, a release of claims, reaffirmation of applicable restrictive covenants, and a one-year non-competition agreement, Dr. Gottesdiener is entitled to (i) an amount equal to the sum of (A) 12 months of his then-current base salary plus (B) one times his target bonus (as defined in the Gottesdiener Employment Agreement) for 2025, to be paid out in substantially equal installments in accordance with our payroll practices over a period of 12 months, (ii) subject to his copayment of premium amounts at the applicable active employees’ rate and his proper election to receive COBRA health coverage, payment of the portion of the premium equal to the amount we would have paid to provide health insurance had he remained employed by us until the earliest of (A) 12 months following his termination, (B) his eligibility for group medical plan benefits under any other employer’s group medical plan or (C) the end of his COBRA health continuation period.

The Gottesdiener Separation Agreement also provides that, if Dr. Gottesdiener enters into the Gottesdiener Advisor Agreement, as defined and described below, with us, he will continue to vest in his outstanding unvested equity awards during the advisory period (for up to one-year following the date of separation of employment), subject to the terms of the Gottesdiener Advisor Agreement, the applicable equity award agreements, and the 2019 Plan and 2022 Plan.

Consulting Agreement

In May 2025, pursuant to the Gottesdiener Separation Agreement and Gottesdiener Employment Agreement, we entered into a consulting agreement with KMG Strategic Consulting, LLC, or the KMG Consulting Agreement, a limited liability company managed by Dr. Gottesdiener, to provide for Dr. Gottesdiener’s continued consulting services to us.

Pursuant to the KMG Consulting Agreement, Dr. Gottesdiener will provide advice and assistance in the area of his expertise. In exchange, we agreed to pay KMG an hourly rate of $1,000 and reimburse KMG for any pre-approved actual expenses incurred. The KMG Consulting Agreement has a term of one-year unless (i) earlier terminated by one of the parties or (ii) extended upon mutual written agreement of the parties.

Advisory Services Agreement

In May 2025, pursuant to the Gottesdiener Separation Agreement and Gottesdiener Employment Agreement, we entered into an advisory services agreement with Dr. Gottesdiener, or the Gottesdiener Advisor Agreement, to retain certain non-exclusive, limited consulting and advisory services of Dr. Gottesdiener for a period of up to one year from the date of his separation.

Pursuant to the Gottesdiener Advisor Agreement, Dr. Gottesdiener will provide advice and assistance in the area of his expertise. In exchange, (i) Dr. Gottesdiener will continue to vest in his outstanding, unvested equity awards

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during the term of the Gottesdiener Advisor Agreement; (ii) following the termination of the Gottesdiener Advisor Agreement, the post-termination exercise period for any vested stock options as of the last date of the term of the Gottesdiener Advisor Agreement will be extended to the earlier of (A) the 48 month anniversary of the last date of the term, or (B) the original expiration of such stock options, as applicable; and (iii) we agreed to reimburse Dr. Gottesdiener for any pre-approved actual expenses incurred. The Gottesdiener Advisor Agreement has a term of one-year unless earlier terminated in accordance with the terms described therein.

Ann L. Lee, Ph.D.

The employment agreement with Dr. Lee, or the Lee Employment Agreement, provides for at-will employment. The agreement also sets forth initial base salary, initial annual target bonus and eligibility to participate in our benefit plans generally. The agreement also sets forth initial base salary, initial annual target bonus and eligibility to participate in our benefit plans generally.

Pursuant to the Lee Employment Agreement, in the event Dr. Lee is terminated by us without “Cause” or she resigns for “Good Reason” (as such terms are defined in the Lee Employment Agreement), in each case subject to the delivery of and compliance with a fully effective separation agreement that shall include, without limitation, a release of claims, reaffirmation of applicable restrictive covenants and, in our discretion, a one year non-competition agreement, Dr. Lee will be entitled to (i) an amount equal to the sum of (A) nine months of her then-current base salary plus (B) 0.75 times her target annual bonus for the then current year, in each case subject to reductions by any amount received by her pursuant to a restrictive covenant agreement, and (ii) subject to Dr. Lee’s co-payment of premium amounts at the applicable active employees’ rate and proper election to continue COBRA health coverage, payment of the portion of the premium equal to the amount we would have paid to provide health insurance had she remained employed by us until the earliest of (A) nine months following her termination, (B) her eligibility for group medical plan benefits under any other employer’s group medical plan or (C) the end of her COBRA health continuation period. These amounts shall be paid out in substantially equal installments in accordance with our payroll practice over a period of nine months. In addition, subject to the delivery of the fully effective separation agreement, the bonus amount (if any) that Dr. Lee would have been paid if she had remained employed through the payment date, if such termination occurs on or after January 1 but before the date bonuses are paid for the prior year to our other executives, will be paid to Dr. Lee on the date our other executives receive their bonuses.

In the event Dr. Lee is terminated by us without “Cause” or she resigns for “Good Reason”, in each case within 12 months following a ”Change in Control” (as defined in the Lee Employment Agreement), subject to the delivery of and compliance with a fully effective separation agreement (as described above), Dr. Lee will be entitled to the following, in lieu of the benefits above: (i) a lump sum cash payment equal to the sum of (A) 12 months of her then-current base salary (or her base salary in effect immediately prior to the “Change in Control,” if higher) plus (B) 1.0 times her target annual bonus for the then current year (or target in effect immediately prior to the “Change in Control,” if higher), in each case subject to reductions by any amount received by her pursuant to a restrictive covenant agreement, (ii) subject to Dr. Lee’s co-payment of premium amounts at the applicable active employees’ rate and proper election to continue COBRA health coverage, payment of the portion of the premium equal to the amount we would have paid to provide health insurance had she remained employed by us until the earliest of (A) 12 months from the date of her separation, (B) her eligibility for group medical plan benefits under any other employer’s group medical plan or (C) the end of her COBRA health continuation period, and (iii) the bonus amount (if any) that Dr. Lee would have been paid if she had remained employed through the payment date, if such termination occurs on or after January 1 but before the date bonuses are paid for the prior year to our other executives. In addition, in the event Dr. Lee is terminated by us without Cause or she resigns for Good Reason, in each case within 12 months following a “Change in Control” (as defined in the Lee Employment Agreement), all of the then-outstanding and unvested portion of her stock options and other stock-based awards that (i) are subject solely to time-based vesting or (ii) were granted to Dr. Lee prior to the effective date of the Lee Employment Agreement and are subject to performance-based vesting shall become fully vested and exercisable or non-forfeitable immediately as of the date of termination, with any such performance-based awards vesting at target.

The payments and benefits provided under the Lee Employment Agreement in connection with a “Change in Control” may not be eligible for federal income tax deduction for us pursuant to Section 280G of the Code. These payments and benefits may also be subject to an excise tax under Section 4999 of the Code. If the payments or benefits payable to Dr. Lee in connection with a “Change in Control” would be subject to the excise tax imposed

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under Section 4999 of the Code, then those payments or benefits will be reduced if such reduction would result in a higher net after-tax benefit to her.

Jeremy Duffield, M.D. Ph.D., FRCP

Employment Agreement

The employment agreement with Dr. Duffield, or the Duffield Employment Agreement, provided for at-will employment. The agreement also set forth his initial base salary, initial annual target bonus and eligibility to participate in our benefit plans generally.

Separation Agreement

In July 2025, Dr. Duffield entered into a Separation Agreement with us, or the Duffield Separation Agreement, pursuant to which Dr. Duffield is entitled to receive certain severance benefits in accordance with the terms of the Duffield Employment Agreement.

Pursuant to the Duffield Separation Agreement, in exchange for, among other things, a release of claims, reaffirmation of applicable restrictive covenants, and a one-year noncompetition agreement, Dr. Duffield is entitled to (i) an amount equal to the sum of (A) nine months of his then-current base salary plus (B) 0.75 his target bonus (as defined in the Duffield Employment Agreement) for 2025, to be paid out in substantially equal installments in accordance with our payroll practices over a period of nine months, (ii) subject to his copayment of premium amounts at the applicable active employees’ rate and his proper election to receive COBRA health coverage, payment of the portion of the premium equal to the amount we would have paid to provide health insurance had he remained employed by us until the earliest of (A) 12 months following his termination, (B) his eligibility for group medical plan benefits under any other employer’s group medical plan or (C) the end of his COBRA health continuation period.

The Duffield Separation Agreement also provides that his service relationship for the purposes of vesting in any of the Company’s outstanding unvested stock options ends on the later of (i) the date his employment terminated, or (ii) the termination of a consulting agreement entered into between Dr. Duffield and us in July 2025, or the Duffield Consulting Agreement. The Duffield Separation Agreement further provides that upon the termination of the Duffield Consulting Agreement, any and all stock options held by him that are outstanding and vested shall be exercisable until the date that is four months following the termination of the Duffield Consulting Agreement. In July 2025, our compensation committee approved an extension of the post-termination exercise period for such options until 12 months following the termination of the Duffield Consulting Agreement.

Consulting Agreement

In July 2025, Dr. Duffield entered into the Duffield Consulting Agreement with us, pursuant to which Dr. Duffield will provide advice and assistance in the area of his expertise. In exchange, we agree to pay Dr. Duffield an hourly rate of $600 and reimburse him for any pre-approved actual expenses incurred. The Duffield Consulting Agreement will continue until March 31, 2026, unless (i) earlier terminated by one of the parties or (ii) extended upon mutual written agreement of the parties.

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Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.

Equity Compensation Plan Information

The following table provides information as of December 31, 2025 with respect to the shares of our common stock that may be issued under our existing equity compensation plans:

Equity compensation plans approved by security holders

Equity compensation plans not approved by security holders — — —

(1)Number of shares to be issued pursuant to outstanding options includes 15,637,303 time-based stock options with a weighted-average exercise price of $3.76 outstanding under our 2019 Plan and our 2022 Plan, 2,029,564 performance-based stock options with a weighted-average exercise price of $4.10 under our 2019 Plan and our 2022 Plan, and 300,000 market-based stock options with a weighted-average exercise price of $1.34 under our 2022 Plan.

(2)Shares of our common stock available for future issuance as of December 31, 2025 pursuant to the 2022 Plan excludes the 9,025,700 shares that were added to the plan as a result of the automatic annual increase on January 1, 2026. The 2022 Plan provides that the number of shares reserved and available for issuance under the 2022 Plan will automatically increase on January 1, 2023 and each January 1 thereafter, by five percent 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 compensation committee. The Company no longer makes grants under the 2019 Plan. The shares of common stock underlying any awards under the 2022 Plan and the 2019 Plan that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without the issuance of stock, expire or are otherwise terminated (other than by exercise) will be added back to the shares of common stock available for issuance under the 2022 Plan.

(3)Number of securities to be issued upon exercise of outstanding options, warrants and rights excludes purchase rights accruing under the 2022 Employee Stock Purchase Plan, as amended from time to time, or the 2022 ESPP, because the purchase rights (and, therefore, the number of shares to be purchased) will not be determined until the end of the offering period, which will occur after December 31, 2025.

(4)Shares of our common stock available for future issuance as of December 31, 2025 pursuant to the 2022 ESPP includes shares that are expected to be issued at the close of the ESPP offering period that was ongoing at December 31, 2025, as the exact number of shares to be issued will not be known until the end of the offering period, which will occur after December 31, 2025. The 2022 ESPP provides that the number of shares common stock that may be issued under the 2022 ESPP plan shall cumulatively increase beginning on January 1, 2023 and each January 1 thereafter through January 1, 2032, by the least of (i) 971,350 shares of common stock, (ii) one percent of the outstanding number of shares of common stock on the immediately preceding December 31 or (iii) such number of shares of common stock as determined by the administrator of the 2022 ESPP. The Company did not add shares to the 2022 ESPP on January 1, 2026.

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Security Ownership of Certain Beneficial Owners and Management

The following table sets forth information, as of February 12, 2026, unless otherwise indicated, regarding the beneficial ownership of our common stock for (i) stockholders who beneficially owned more than 5% of our common stock, (ii) each of our directors and NEOs, and (iii) all of our directors and executive officers as a group.

The number of shares beneficially owned by each stockholder is determined under rules issued by the SEC. Under these rules, a person is deemed to be a “beneficial” owner of a security if that person has or shares voting power or investment power, which includes the power to dispose of or to direct the disposition of such security. Except as indicated in the footnotes below, we believe, based on the information furnished to us, that the individuals and entities named in the table below have sole voting and investment power with respect to all shares of common stock beneficially owned by them, subject to any applicable community property laws.

In computing the number of shares beneficially owned by an individual or entity, shares of common stock subject to options, warrants, restricted stock units or other rights held by such person that are currently exercisable or have vested or that will become exercisable or will have vested within 60 days of February 12, 2026 are considered outstanding, although these shares are not considered outstanding for purposes of computing the percentage ownership of any other person. On February 12, 2026, there were 180,551,436 shares of our common stock outstanding. Unless noted otherwise, the address of all listed stockholders is c/o Prime Medicine, Inc., 60 First Street, Cambridge, MA 02141.

Shares of Common Stock Beneficially Owned Percentage of SharesBeneficially Owned

5% or Greater Stockholders

Entities affiliated with ARCH Venture Partners (2) 18,486,894 10.24 %

Directors and Named Executive Officers

All executive officers and directors as a group (11 persons) 28,190,988 15.61 %

* Less than one percent.

(1)Consists of: (a) 20,240,945 shares of common stock, and (b) 93,515 shares of common stock underlying options exercisable within 60 days of February 12, 2026.

(2)Information herein is based on Schedule 13D/A filed with the SEC on August 11, 2025 by (1) ARCH Venture Fund X, L.P., or AVF X, (2) ARCH Venture Partners X, L.P., or AVP X LP, which is the sole general partner of AVF X, (3) ARCH Venture Partners X, LLC, or AVP X LLC, which is the sole general partner of AVP X LP and AVP X Overage LP (defined below), (4) ARCH Venture Fund X Overage, L.P., or AVF X Overage, (5) ARCH Venture Partners X Overage, L.P., or AVP X Overage LP, which is the sole general partner of AVF X

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Overage, (6) ARCH Venture Fund XII, L.P., or AVF XII, (7) ARCH Venture Partners XII, L.P., or AVP XII LP, which is the sole general partner of AVF XII, (8) ARCH Venture Partners XII, LLC, or AVP XII LLC, which is the sole general partner of AVP XII LP, (9) Keith Crandell, or Crandell, (10) Robert Nelsen, or Nelsen, a member of our board of directors, (11) Kristina Burow, or Burow, and (12) Steven Gillis, or Gillis”, and together with Nelsen, Crandell and Burow, referred to individually as “Committee Member or collectively as either the “AVP X Investment Committee Members” or the “AVP XII Investment Committee Members. Each of the individuals and entities above shall be referred to herein as an “ARCH Reporting Person” and collectively as the “ARCH Reporting Persons.” AVP X LP and AVP X Overage LP may be deemed to beneficially own the shares held by AVF X and AVF X Overage, respectively; AVP X LLC may be deemed to beneficially own the shares held by AVF X; AVP XII LP may be deemed to beneficially own the shares held by AVF XII; AVP XII LLC may be deemed to beneficially own the shares held by AVF XII; and each of the Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by AVF X, AVF X Overage and AVF XII. The ARCH Reporting Persons each disclaims beneficial ownership except to any pecuniary interest therein.

Consists of: (a) 6,128,297 shares of common stock held by AVF X, (b) 6,128,297 shares of common stock held by AVF X Overage, and (c) 6,230,300 shares of common stock held by AVF XII.

The address of all entities and individuals referenced in this footnote is 8755 W. Higgins Road, Suite 1025, Chicago, IL 60631.

(3)Information herein is based on Schedule 13G/A filed with the SEC on November 12, 2025 by GV 2019, L.P., GV 2019 GP, L.P., GV 2019 GP, L.L.C., GV 2021, L.P., GV 2021 GP, L.P., GV 2021 GP, L.L.C., GV 2023, L.P., GV 2023 GP, L.P., GV 2023 GP, L.L.C., Alphabet Holdings LLC, XXVI Holdings Inc. and Alphabet Inc. Consists of: (a) 10,100,058 shares of common stock held by GV 2019, L.P., or GV 2019, (b) 3,262,440 shares of common stock held by GV 2021, L.P., or GV 2021, and (c) 3,200,000 shares of common stock held by GV 2023, L.P., or GV 2023.

The general partner of the GV 2019, L.P., or the 2019 Partnership, is GV 2019 GP, L.P., or 2019 GP. The general partner of 2019 GP is GV 2019 GP, L.L.C., or 2019 LLC. The sole member of 2019 LLC is Alphabet Holdings LLC, or Alphabet Holdings. The sole member of Alphabet Holdings is XXVI Holdings Inc., or XXVI. The controlling stockholder of XXVI is Alphabet Inc. (Alphabet Inc., together with 2019 GP, 2019 LLC, Alphabet Holdings, and XXVI may be collectively referred to as the 2019 Partnership Affiliates. Each of the 2019 Partnership Affiliates may be deemed to indirectly beneficially own (as that term is defined in Rule 13d-3 of the Exchange Act) the securities directly beneficially owned by the 2019 Partnership.

The general partner of the GV 2021, L.P., or the 2021 Partnership is GV 2021 GP, L.P., or 2021 GP. The general partner of 2021 GP is GV 2021 GP, L.L.C., or 2021 LLC. The sole member of 2021 LLC is Alphabet Holdings. The sole member of Alphabet Holdings is XXVI. The controlling stockholder of XXVI is Alphabet Inc. (Alphabet Inc., together with 2021 GP, 2021 LLC, Alphabet Holdings, and XXVI may be referred to as the 2021 Partnership Affiliates). Each of the 2021 Partnership Affiliates may be deemed to indirectly beneficially own (as that term is defined in Rule 13d-3 of the Exchange Act) the securities directly beneficially owned by the 2021 Partnership.

The general partner of the GV 2023, L.P., or the 2023 Partnership is GV 2023 GP, L.P., or 2023 GP. The general partner of 2023 GP is GV 2023 GP, L.L.C., or 2023 LLC. The sole member of 2023 LLC is Alphabet Holdings. The sole member of Alphabet Holdings is XXVI. The controlling stockholder of XXVI is Alphabet Inc. (Alphabet Inc., together with 2023 GP, 2023 LLC, Alphabet Holdings, and XXVI may be referred to as the 2023 Partnership Affiliates. Each of the 2023 Partnership Affiliates may be deemed to indirectly beneficially own (as that term is defined in Rule 13d-3 of the Exchange Act) the securities directly beneficially owned by the 2023 Partnership.

The principal business address for all entities referenced in this footnote is 1600 Amphitheatre Parkway, Mountain View, CA 94043.

(4)Information herein is based on Schedule 13G filed with the SEC on October 4, 2024 by BMS. The address of BMS is Route 206 & Province Line Road, Princeton, NJ 08543.

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(5)Consists of: (a) 125,000 shares of common stock held by Dr. Reine, and (b) 649,479 shares of common stock underlying options exercisable within 60 days of February 12, 2026.

(6)Information herein is based solely on Form 4 filed with the SEC on October 10, 2024 by the Company on behalf of Dr. Gottesdiener and on the Company’s records. Dr. Gottesdiener shareholdings consists of: (a) 2,310,837 shares of common stock held by Dr. Gottesdiener, (b) 50,241 shares of common stock held by Dr. Gottesdiener’s spouse, (c) 682,259 shares of common stock held by the Coolidge GST Trust-2022, or the Coolidge Trust Shares, and (d) 1,317,741 shares of common stock held by the Gottesdiener Family GST Trust, or the Gottesdiener Family Trust Shares. Dr. Gottesdiener disclaims beneficial ownership of the Coolidge Trust Shares and the Gottesdiener Family Trust Shares. In addition, this is also inclusive of 1,002,052 shares of common stock underlying options exercisable within 60 days of February 12, 2026.

(7)Consists of: (a) 100,000 shares of common stock held by Dr. Lee, and (b) 1,028,242 shares of common stock underlying options exercisable within 60 days of February 12, 2026.

(8)Information herein is based solely on Form 4 filed with the SEC on October 19, 2022 by the Company on behalf of Dr. Duffield and on the Company’s records. Dr. Duffield directly holds 965,001 shares of common stock. In addition, this is also inclusive of 320,576 shares of common stock underlying options exercisable within 60 days of February 12, 2026.

(9)Consists entirely of shares of common stock underlying options exercisable within 60 days of February 12, 2026.

(10)Consists of: (a) 84,062 shares of common stock underlying options exercisable within 60 days of February 12, 2026 and (b) 16,080 shares of common stock held by a trust for the benefit of Mr. Nelsen’s family members.

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Item 13. Certain Relationships and Related Transactions, and Director Independence

Other than the compensation arrangements for our NEOs and our directors described in Item 11, Executive Compensation, of this Annual Report on Form 10-K, set forth below is a description of transactions or series of transactions since January 1, 2024, to which we were or will be a party, and in which:

•the amount involved in the transaction exceeds, or will exceed, $120,000 (or, if less, 1% of the average of our total asset amounts at December 31, 2024 and 2025); and

•in which any of our executive officers, directors or holder of five percent or more of any class of our capital stock, including their immediate family members or affiliated entities, had or will have a direct or indirect material interest.

Participation in our Follow-on Public Offerings

Our 5% stockholders, their affiliates, and certain affiliated entities affiliated with our directors purchased an aggregate of (i) 7,200,000 shares of our common stock in our follow-on public offering in February 2024 at the public offering price, and (ii) an aggregate of 4,545,455 shares of our common stock in our follow-on public offering in August 2025 at the public offering price. The following table sets forth the number of shares of our common stock purchased by our 5% stockholders, their affiliates, and certain affiliated entities affiliated with our directors and the aggregate purchase price paid for such shares.

Stockholder(1) Shares of common stock Total purchase price

February 2024 follow-on public offering

August 2025 follow-on public offering

(1)Additional details regarding certain of these investors and their equity holdings are provided in Item 12, Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters, of this Annual Report on Form 10-K.

(2)David Schenkein serves as a member of our board of directors and is an affiliate of GV, of which GV 2021, L.P. and GV 2023, L.P. are affiliated funds. Entities affiliated with GV collectively hold more than five percent of our voting securities.

(3)Robert Nelsen serves as a member of our board of directors and is an affiliate of ARCH Venture Partners, of which ARCH Venture Fund X Overage, L.P., ARCH Venture Fund X, L.P., and ARCH Venture Fund XII, L.P. are affiliated funds. Entities affiliated with ARCH Venture Partners collectively hold more than five percent of our voting securities.

(4)Thomas Cahill serves as a member of our board of directors and is an affiliate of Newpath Partners, of which Newpath Partners, L.P. is an affiliated fund.

Agreements with BMS

Research Collaboration and License Agreement

In September 2024, we entered into the BMS Collaboration Agreement with Juno. BMS became a beneficial owner of more than 5% of our voting securities as a result of this transaction. Pursuant to the BMS Collaboration Agreement, we granted to BMS an exclusive worldwide license to certain Prime Editing technology for developing, manufacturing and commercializing ex vivo T-cell therapeutic products directed to select targets. Under the BMS Collaboration Agreement, we received a $55.0 million upfront payment and received a $55.0 million equity

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investment from BMS (as described below). We are also eligible to receive more than $3.5 billion in milestones, including up to $185.0 million in preclinical milestones, up to $1.2 billion in development milestones, and up to $2.1 billion in commercialization milestones, along with royalties on net sales.

Unless earlier terminated, the term of the BMS Collaboration Agreement continues until expiration of the last royalty term for the applicable product in the applicable country. The BMS Collaboration Agreement is subject to customary termination provisions, including termination by a party for the other party’s uncured, material breach.

Stock Purchase Agreement

In September 2024, we entered into a stock purchase agreement with BMS, or the BMS Purchase Agreement, pursuant to which we agreed to issue and sell, and BMS agreed to purchase, 11,006,163 shares of our common stock, or the BMS Shares, for an aggregate purchase price of $55.0 million pursuant to the terms and conditions thereof. Pursuant to the terms of the BMS Purchase Agreement, BMS has agreed not to, directly or indirectly, sell or transfer any of the BMS Shares until September 30, 2027 subject to specified conditions and exceptions. In addition, we agreed, among other things, to file with the SEC a registration statement covering the resale of the BMS Shares and to use commercially reasonable efforts to cause such registration statement to become effective on or prior to ninety (90) calendar days after closing. We filed the registration statement on Form S-3 covering the resale of the BMS Shares with the SEC on December 13, 2024, which became effective on December 20, 2024.

We have also agreed to customary indemnification obligations under the BMS Purchase Agreement.

Advisory Services Agreement with Jeffrey Marrazzo

Pursuant to an advisory services agreement with Jeffrey Marrazzo, a member of our board of directors, or the Marrazzo Agreement, dated February 29, 2024, Mr. Marrazzo agreed to provide certain professional services to the Company separate from and in addition to his service as a member of our board of directors, and we agreed to pay Mr. Marrazzo an annual fee of $50,000 per year in addition to the grant of an option to purchase 250,000 shares of the Company’s common stock.

The Marrazzo Agreement expired in February 2025. From January 1, 2024 through the termination date, we paid Mr. Marrazzo $50,000 and granted Mr. Marrazzo 250,000 stock options under the Marrazzo Agreement.

Executive Chair Agreement with Jeffrey Marrazzo

Pursuant to an executive chair agreement with Jeffrey Marrazzo, a member of our board of directors, or the Executive Chair Agreement, dated May 19, 2025, Mr. Marrazzo agreed to provide services as the executive chair of our board of directors, and we agreed to pay Mr. Marrazzo an annual fee of $100,000 per year in addition to the grant of options to purchase a total of 1,000,000 shares of the Company’s common stock consisting of (i) a time-based option to purchase 500,000 shares, (ii) a performance-based option to purchase 200,000 shares, and (iii) a stock price-based option to purchase 300,000 shares.

The Executive Chair Agreement will continue indefinitely until terminated in accordance with its terms. If the Executive Chair Agreement is terminated between six-months and one-year of its effective date, a minimum of 250,000 shares subject to the time-based option will vest.

In the event of a Sale Event (as defined in the 2022 Plan), all of the then-outstanding and unvested portions of the time-based option, 50% of the then-outstanding and unvested portions of the performance-based option, and any of the then-outstanding and unvested portions of the stock price-based option for which the applicable stock-price milestone has been satisfied in connection with the Sale Event, will become vested and exercisable.

Settlement Agreement with Myeloid

In December 2021, we entered into a research collaboration and exclusive option agreement, or the Myeloid Collaboration Agreement, with Myeloid, during which time we and Myeloid had one common board member, Dr. Cahill, who is also an affiliate of Newpath Partners, L.P. and holds more than 30% of Myeloid’s voting securities. In 2023, we terminated the Myeloid Collaboration Agreement.

In January 2024, we entered into a settlement agreement, or the Settlement Agreement, with Myeloid resolving two arbitration proceedings. Under the terms of the Settlement Agreement, the parties agreed to resolve and settle all

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disputes between the parties and release all claims between them relating to the Myeloid Collaboration Agreement and the arbitrations in exchange for our payment to Myeloid of $13.5 million, certain mutual covenants, and other consideration. Accordingly, for the year ended December 31, 2023, we recorded a charge of $13.5 million, and paid the $13.5 million during the year ended December 31, 2024.

Indemnification Agreements

We have entered into agreements to indemnify our directors and executive officers. These agreements, among other things, require us to indemnify these individuals for certain expenses (including attorneys’ fees), judgments, fines and settlement amounts reasonably incurred by such person in any action or proceeding, including any action by or in our right, on account of any services undertaken by such person on behalf of our company or that person’s status as a member of our board of directors or our executive officer to the maximum extent allowed under Delaware law.

Policies for Approval of Related Party Transactions

Our board of directors reviews and approves transactions with directors, officers and holders of 5 percent or more of our voting securities and their affiliates, each a related party. The material facts as to the related party’s relationship or interest in the transaction were disclosed to our board of directors prior to their consideration of such transaction, and the transaction was not considered approved by our board of directors unless a majority of the directors who are not interested in the transaction approved the transaction. Further, when stockholders were entitled to vote on a transaction with a related party, the material facts of the related party’s relationship or interest in the transaction were disclosed to the stockholders, who were obligated to approve the transaction in good faith.

We adopted a written related party transactions policy that provides that such transactions must be approved by our audit committee. Pursuant to this policy, the audit committee has the primary responsibility for reviewing and approving or disapproving “related party transactions,” which are transactions between us and related persons in which the aggregate amount involved exceeds or may be expected to exceed $120,000 and in which a related person has or will have a direct or indirect material interest. In reviewing any such proposal, our audit committee or other committee of independent directors are to consider the relevant facts of the transaction, including the risks, costs and benefits to us and whether the transaction is on terms no less favorable than terms generally available to an unaffiliated third party under the same or similar circumstances. For purposes of this policy, a related person is defined as a director, executive officer, nominee for director, or greater than 5 percent beneficial owner of our common stock, in each case since the beginning of the most recently completed year, and their immediate family members.

Director Independence

Our common stock is listed on the Nasdaq Global Market. Under the Nasdaq listing rules, independent directors must comprise a majority of a listed company’s board of directors within twelve months from the date of listing. In addition, the Nasdaq listing rules require that, subject to specified exceptions, each member of a listed company’s audit, compensation and nominating and corporate governance committees be independent within twelve months from the date of listing. Audit committee members must also satisfy additional independence criteria, including those set forth in Rule 10A-3 under the Exchange Act and compensation committee members must also satisfy the independence criteria set forth in Rule 10C-1 under the Exchange Act. Under Nasdaq listing rules, a director will only qualify as an “independent director” if, in the opinion of that company’s board of directors, that person does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director. In order to be considered independent for purposes of Rule 10A-3 under the Exchange Act, a member of an audit committee of a listed company may not, other than in his or her capacity as a member of the audit committee, the board of directors or any other board committee: (i) accept, directly or indirectly, any consulting, advisory or other compensatory fee from the listed company or any of its subsidiaries, other than compensation for board service; or (ii) be an affiliated person of the listed company or any of its subsidiaries. In order to be considered independent for purposes of Rule 10C-1, the board of directors must consider, for each member of a compensation committee of a listed company, all factors specifically relevant to determining whether a director has a relationship to such company which is material to that director’s ability to be independent from management in connection with the duties of a compensation committee member, including, but not limited to: the source of compensation of the director, including any consulting advisory or other compensatory fee paid by such

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company to the director, and whether the director is affiliated with the company or any of its subsidiaries or affiliates.

In February of 2026, our board of directors undertook a review of the composition of our board of directors and its committees and the independence of each director. Based upon information requested from and provided by each director concerning his or her background, employment and affiliations, including family relationships, our board of directors has determined that all members of our board of directors, except Allan Reine and Jeffrey Marrazzo, are independent directors, including for purposes of Nasdaq and the SEC rules. In making that determination, our board of directors considered the relationships that each director has with us and all other facts and circumstances the board of directors deemed relevant in determining independence, including the potential deemed beneficial ownership of our capital stock by each director, including non-employee directors that are affiliated with certain of our major stockholders. We believe that the composition and functioning of our board of directors and each of our committees complies with all applicable requirements of Nasdaq and the rules and regulations of the SEC. There are no family relationships between or among any of our executive officers and directors. The principal occupation and employment during the past five years of each of our directors was carried on, in each case except as specifically identified, with a corporation or organization that is not a parent, subsidiary or other affiliate of us. There is no arrangement or understanding between any of our directors and any other person or persons pursuant to which he or she is to be selected as a director.

There are no material legal proceedings to which any of our directors, executive officers, or affiliates is a party adverse to us or our subsidiary or in which any such person has a material interest adverse to us or our subsidiary.

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Item 14. Principal Accountant Fees and Services

PricewaterhouseCoopers LLP, or PwC, served as independent registered public accounting firm for our Company with respect to the audit of the Company’s consolidated financial statements for the fiscal year ended December 31, 2025 The aggregate fees billed by categories of services are as follows for each of the years ended December 31:

Audit-Related Fees — —

Tax Fees — —

(1)“Audit Fees” consist of fees billed for professional services performed by PwC for the audit of our annual consolidated financial statements, the review of interim consolidated financial statements, review of the registration statement on Form S-3 and Form S-8, comfort letters issued for financing, and related services that are normally provided in connection with statutory and regulatory filings or engagements.

(2)All other fees consist of database subscription fees.

Pre-Approval by Audit Committee of Principal Accountant Services