2 Delivering on the promise of Prime Editing Corporate Presentation March 2026 1 Forward Looking Statements This presentation contains forward-looking statements of Prime Medicine, Inc. ("Prime", "we" or "our") within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. These forward-looking statements contain information about our current and future prospects and our operations, which are based on currently available information. All statements other than statements of historica ...

Delivering on the promise of Prime Editing Corporate Presentation January 2026 1 Forward Looking Statements This presentation contains forward-looking statements of Prime Medicine, Inc. ("Prime", "we" or "our") within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. These forward-looking statements contain information about our current and future prospects and our operations, which are based on currently available information. All statements other than statements of historica ...

Core Insights - Prime Medicine is advancing its pipeline with new preclinical data for PM577 in Wilson's Disease (WD) to be presented at AASLD, with plans to file an IND and/or CTA in the first half of 2026 and initial clinical data expected in 2027 [1][4][5] - The company has nominated PM647 as a development candidate for Alpha-1 Antitrypsin Deficiency (AATD), also on track to file an IND and/or CTA in mid-2026, with initial clinical data anticipated in 2027 [1][5] - The leadership team has been strengthened with the appointment of Matthew Hawryluk, Ph.D., M.B.A. as Chief Business Officer [1][4] Pipeline Developments - Prime Medicine is focused on in vivo programs targeting Wilson's Disease and Alpha-1 Antitrypsin Deficiency, with IND and/or CTA filings expected in 2026 and initial clinical data in 2027 [5][6] - The company is also advancing a Cystic Fibrosis program supported by the Cystic Fibrosis Foundation and developing Prime Edited CAR-T products in partnership with Bristol Myers Squibb [6] Financial Performance - For the quarter ended September 30, 2025, R&D expenses were $44.0 million, up from $40.3 million in the same period of 2024, primarily due to license and intellectual property costs [10][12] - General and Administrative expenses decreased to $11.2 million from $14.1 million year-over-year, attributed to reduced personnel costs [10][12] - The net loss for the quarter was $50.6 million, compared to a net loss of $52.5 million in the prior year [10][12] Cash Position - As of September 30, 2025, the company reported cash, cash equivalents, and investments totaling $213.3 million, which is expected to fund operations into 2027 [10][21]

Core Insights - Prime Medicine is advancing its pipeline with new preclinical data for PM577 in Wilson's Disease and has nominated PM647 for Alpha-1 Antitrypsin Deficiency, with both expected to file IND and/or CTA applications in the coming years [1][2][3] Pipeline Developments - The company is focused on liver-targeted programs for Wilson's Disease and Alpha-1 Antitrypsin Deficiency, with IND filings anticipated in H1 2026 for AATD and H1 2027 for WD, and initial clinical data expected in 2027 [3][4] - Prime Medicine is also developing a Cystic Fibrosis program and exploring collaborations, including a partnership with Bristol Myers Squibb for Prime Edited CAR-T products [4][11] Leadership and Corporate Updates - Matthew Hawryluk, Ph.D., M.B.A., has been appointed as Chief Business Officer to enhance business development and strategic collaborations [1][10] - A virtual KOL event is scheduled for November 12, 2025, to discuss the company's strategy for Wilson's Disease [1][10] Financial Performance - For Q3 2025, Prime Medicine reported R&D expenses of $44.0 million, up from $40.3 million in Q3 2024, primarily due to increased license and intellectual property costs [10][20] - General and Administrative expenses decreased to $11.2 million from $14.1 million year-over-year, attributed to workforce reductions [10][20] - The net loss for Q3 2025 was $50.6 million, slightly improved from a net loss of $52.5 million in Q3 2024 [10][20] - As of September 30, 2025, the company had cash and investments totaling $213.3 million, sufficient to fund operations into 2027 [8][18]