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

Prime Medicine Reports First Quarter 2024 Financial Results and Provides Business Updates

-- Announced FDA clearance of first-ever IND application for a Prime Editing product, PM359, for the treatment of CGD; initial data from planned Phase 1/2 clinical trial expected in 2025 --

-- Presented new preclinical data demonstrating broad potential of Prime Editing technology at LNP Formulation and Process Development Summit and ASGCT 2024 --

-- Appointed Tony Coles, M.D. as senior advisor --

“In 2024, we expect to bring the first-ever Prime Editing-based product candidate to patients, while continuing to strengthen our modular Prime Editing platform and advance our next wave of programs across a range of target tissues,” said Keith Gottesdiener, M.D., President and Chief Executive Officer of Prime Medicine. “In recent months, we made meaningful progress toward this goal. In April, the U.S. Food and Drug Administration (FDA) cleared our investigational new drug (IND) application for PM359, our Prime Editor for the treatment of chronic granulomatous disease (CGD), and the first-ever Prime Editor product candidate to advance to the clinic. This represents a watershed moment for gene editing and for Prime Medicine, and we are eager to initiate our Phase 1/2 trial as we work to establish the potential for PM359 to correct the disease-causing mutation of CGD and ameliorate this devastating disease.”

Dr. Gottesdiener continued, “At recent scientific meetings, we also presented new preclinical data showcasing the safety and broad potential of our Prime Editing technology across our pipeline programs and highlighting our proprietary delivery capabilities. Together, these presentations reinforce efforts across our core areas of focus – hematology and immunology, liver, lung, ocular and neuromuscular disease – and support our plans to advance a diverse pipeline into the clinic. Finally, in March, we were fortunate to welcome Dr. Tony Coles as a senior advisor to Prime Medicine. Tony brings a wealth of strategic perspectives and company growth experience in innovative drug discovery and development, and we look forward to his many contributions as Prime Medicine enters its next phase of growth.”

Prime Medicine expects the following activities and next steps to drive Prime Medicine forward and support the Company’s maturation into a clinical-stage company:

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 core areas of focus: hematology and immunology, liver, lung, ocular and neuromuscular. Across each core area, Prime Medicine’s initial focus is on genetic diseases with a fast, direct path to treating patients, and those with high unmet need not currently addressable using other gene editing approaches. Over time, the Company intends to maximize Prime Editing’s broad and versatile therapeutic potential to expand beyond the genetic diseases in its initial pipeline, potentially including 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.

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 potential of PM359 to correct the causative mutation of CGD; the anticipated maturation into a clinical-stage company by bringing PM359 into clinical development in 2024 with initial clinical data expected in 2025; the initiation, timing, progress, and results of its research and development programs, preclinical studies and future clinical trials, and the release of data related thereto; the potential for Prime Editors to repair genetic mutations and offer curative genetic therapies for a wide spectrum of diseases; the potential of Prime Editors to reproducibly correct disease-causing genetic mutations across different tissues, organs and cell types, and the capacity of its PASSIGE technology to edit CAR-T cells for the treatment of certain cancers and immune 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; certain activities and next steps to support the Company’s maturation into a clinical-stage company, including opening IND and/or CTA applications, clinical data expectations, establishing proof of concept, advancing programs into lead optimization, advancing

preclinical studies and initiating IND-enabling activities, nominating development candidates, and establishing delivery platform and rout of administration; 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; the modularity of the Prime Editing platform 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, including rising interest rates, inflation, and adverse developments affecting the financial services industry. 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.

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