Business Description

Nature of the Business and Basis of Presentation Prime Medicine, Inc., together with its consolidated subsidiary, or the Company, is a biotechnology company committed to delivering a new class of differentiated one-time curative treatments. The Company is deploying Prime Editing technology, which it believes is a versatile, precise, and efficient gene editing technology. The Company was incorporated in the State of Delaware in September 2019. Its principal offices are in Cambridge, Massachusetts. Liquidity and Capital Resources Since its inception, the Company has devoted substantially all of its resources to building its Prime editing platform and advancing development of its portfolio of programs, establishing and protecting its intellectual property, conducting research and development activities, organizing and staffing the company, business planning, raising capital and providing general and administrative support for these operations. To date, the Company has funded its operations primarily with proceeds from sales of preferred stock, public offerings of its common stock, and through payments from our collaboration partners. In August 2025, the Company issued and sold 43,700,000 shares of its 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, the Company received approximately $138.4 million in net proceeds, after deducting underwriting discounts, commissions and offering costs of $5.8 million. Since its inception, the Company has incurred substantial losses. As of December 31, 2025, the Company had an accumulated deficit of $888.4 million and expects to generate operating losses and negative operating cash flows for the foreseeable future. As of December 31, 2025, the Company maintains cash, cash equivalents, short-term investments, and related party short-term investments of $177.7 million. Going Concern In accordance with Accounting Standards Codification, or ASC, 205-40, Going Concern , or ASC 205-40, the Company evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s 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 Company's cash, cash equivalents, and short-term investments as of December 31, 2025, the Company's current and forecasted level of operations, and its forecasted cash flows, the Company’s ability to continue as a going concern is dependent upon its ability to obtain the necessary financing to meet its obligations and repay its liabilities arising from normal business operations when they come due. Management plans to provide for the Company’s capital requirements through financing or other transactions, and selling shares under the Company's “at the market offering” program. There can be no assurance that the Company will be able to raise additional capital to fund operations with terms acceptable to the Company, or at all. Because certain elements of management’s plans to mitigate the conditions that raised substantial doubt about the Company’s ability to continue as a going concern are outside of the Company’s 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, management has concluded that substantial doubt exists about the Company’s 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 the Company 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. The Company’s ability to continue as a going concern is dependent upon its 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.…