Prime Medicine (PRME) 8-KPrime Medicine Reports Third Quarter 2024 Financial Results and Provides Business Updates

Dr. Gottesdiener continued, “Also in recent months, we announced our decision to strategically prioritize a set of high value programs, each with a clear path to value inflection and the potential to unlock multiple follow-on opportunities. This includes our wholly owned efforts in CGD and Wilson’s Disease, as well as our efforts in cell therapy and cystic fibrosis, which we are advancing with support from Bristol Myers Squibb and the Cystic Fibrosis Foundation, respectively. We believe partnerships like these will continue to play a critical role as we build Prime Medicine, allowing us access to best-in-class expertise and non-dilutive capital and enabling us to more rapidly realize the full potential of Prime Editing.”

In September 2024, Prime Medicine unveiled its strategically focused pipeline and plans to prioritize a set of high value programs, each targeting a disease with well-understood biology and a clearly defined clinical development and regulatory path. Each prioritized program is also intended to serve as a beachhead, in that the modularity of the Prime Editing platform is expected to allow Prime Medicine to generate follow-on candidates rapidly and efficiently.

identifying partnership opportunities to advance its other programs, including those for neurological diseases, cell therapy, ocular diseases and hearing loss.

Based on its current operating plans, Prime Medicine expects that its pro-forma cash, cash equivalents and investments as of September 30, 2024 will be sufficient to fund its operating expenses and capital expenditure requirements into the first half of 2026.

Prime Medicine is a leading biotechnology company dedicated to creating and delivering the next generation of gene editing therapies to patients. The Company is deploying its proprietary Prime Editing platform, a versatile, precise and efficient gene editing technology, to develop a new class of differentiated one-time curative genetic therapies. Designed to make only the right edit at the right position within a gene while minimizing unwanted DNA modifications, Prime Editors have the potential to repair almost all types of genetic mutations and work in many different tissues, organs and cell types. Taken together, Prime Editing’s versatile gene editing capabilities could unlock opportunities across thousands of potential indications.

Prime Medicine is currently progressing a diversified portfolio of investigational therapeutic programs organized around our core areas of focus: hematology, immunology and oncology, liver and lung. Across each core area, Prime Medicine is focused initially on a set of high value programs, each targeting a disease with well-understood biology and a clearly defined clinical development and regulatory path, and each expected to provide the foundation for expansion into additional opportunities. Over time, the Company intends to maximize Prime Editing’s broad and versatile therapeutic potential, as well as the modularity of the Prime Editing platform, to rapidly and efficiently expand beyond the diseases in its current pipeline, potentially including additional genetic diseases, immunological diseases, cancers, infectious diseases, and targeting genetic risk factors in common diseases, which collectively impact millions of people. For more information, please visit www.primemedicine.com.

© 2024 Prime Medicine, Inc. All rights reserved. PRIME MEDICINE, the Prime Medicine logos, and PASSIGE are trademarks of Prime Medicine, Inc. All other trademarks referred to herein are the property of their respective owners.

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, implied and express statements about Prime Medicine’s beliefs and expectations regarding: the timing, progress, and results of its Wilson’s Disease program, including the timing of the release of updated data and filing of an IND and/or CTA application in the first half of 2026; the potential for its modular universal LNP platform to precisely deliver Prime Editors, correct disease-causing mutations in the liver, and deliver transformative treatments for Wilson’s Disease, GSD1b, and other rare and non-rare liver indications; the modular universal LNP platform’s ability to be used repeatedly to generate candidates that offer an improved safety profile and biodistribution compared to other LNPs in development; the anticipated maturation into a clinical-stage company by bringing PM359 into clinical development in 2024 with initial clinical data from the ongoing Phase 1/2 clinical trial of PM359 expected in 2025; the collaboration with Bristol Myers Squibb and the intended and potential benefits thereof, including the receipt of potential milestone and royalty payments from commercial product sales, if any; the safety profile, tolerability, and durability of its universal LNP; the initiation, timing, progress, and results of its research and development programs, preclinical studies and future clinical trials; the modularity of the Prime Editing platform and the benefits thereof; the potential for Prime Editors to more precisely and effectively achieve genetic modification; the potential for Prime Editors to

repair genetic mutations and offer curative genetic therapies for a wide spectrum of diseases; its continued development and optimization of various non-viral and viral delivery systems; its ability to demonstrate superior off-target profiles for Prime Editing programs; the expansion of Prime Editing’s therapeutic potential and the creation of value through strategic business development to extend the reach and impact of Prime Editing to areas beyond Prime Medicine’s current core areas of focus; exploring business development opportunities that could accelerate existing work and the benefits thereof; its expectations regarding the breadth of Prime Editing technology and the implementation of its strategic plans for its business, programs, and technology; and the potential of Prime Editing to unlock opportunities across thousands of potential indications. The words “may,” “might,” “will,” “could,” “would,” “should,” “expect,” “plan,” “anticipate,” “intend,” “believe,” “expect,” “estimate,” “seek,” “predict,” “future,” “project,” “potential,” “continue,” “target” and similar words or expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

Any forward-looking statements in this press release are based on management’s current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially from those expressed or implied by any forward-looking statements contained in this press release, including, without limitation, risks associated with: uncertainties related to Prime Medicine’s product candidates entering clinical trials; the authorization, initiation, and conduct of preclinical and IND-enabling studies and other development requirements for potential product candidates, including uncertainties related to opening INDs and obtaining regulatory approvals; risks related to the development and optimization of new technologies, the results of preclinical studies, or clinical studies not being predictive of future results in connection with future studies; the scope of protection Prime Medicine is able to establish and maintain for intellectual property rights covering its Prime Editing technology; Prime Medicine’s ability to identify and enter into future license agreements and collaborations; and general economic, industry and market conditions. These and other risks and uncertainties are described in greater detail in the section entitled “Risk Factors” in Prime Medicine’s most recent Annual Report on Form 10-K, as well as any subsequent filings with the Securities and Exchange Commission. In addition, any forward-looking statements represent Prime Medicine’s views only as of today and should not be relied upon as representing its views as of any subsequent date. Prime Medicine explicitly disclaims any obligation to update any forward-looking statements subject to any obligations under applicable law. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements.

dan@1ABmedia.com