-- Presentations include new preclinical data for PM359, further demonstrating ability of Prime Editors to efficiently, reproducibly and durably correct causative mutation of CGD; on track to enter clinical development in 2024, with initial data expected in 2025 --

-- Prime Medicine Co-Founder, David Liu, Ph.D., Awarded ASGCT Outstanding Achievement Award --

CAMBRIDGE, Mass., April 23, 2024 (GLOBE NEWSWIRE) -- Prime Medicine, Inc. (Nasdaq: PRME), a biotechnology company committed to delivering a new class of differentiated, one-time curative genetic therapies, today announced that the Company will present preclinical data highlighting the broad potential of its Prime Editing technology and supporting the advancement of its programs at the 3^rd Annual LNP Formulation and Process Development Summit (Boston, April 29-May 2, 2024); the American Society of Cell & Gene Therapy 27^th Annual Meeting (Baltimore, May 7-11, 2024); and TIDES USA Oligonucleotide & Peptide Therapeutics Conference (Boston, May 14-17, 2024).

"In the short time since Prime Editing was first discovered, we have made incredible strides advancing this technology, developing and optimizing Prime Editors for programs across our core areas of focus, and creating new delivery systems that we believe will permit our Prime Editors to safely and effectively access target tissue," said Keith Gottesdiener, M.D., President and Chief Executive Officer of Prime Medicine. "This progress is underscored by our upcoming presentations, which will feature new findings from across our platform and initial pipeline, including new preclinical data for our first program expected to enter clinical development – PM359 for chronic granulomatous disease (CGD), a serious, life-threatening rare disease. In addition to our presentations, we congratulate our Co-Founder, David Liu, on receiving the ASGCT Outstanding Achievement Award, highlighting his work in the gene editing field, including his contributions to the discovery and advancement of Prime Editing. We look forward to coming together with the scientific research community and highlighting our leading position in the field of next-generation gene editing."

Details of the presentations are as follows.

3^rd Annual LNP Formulation and Process Development Summit (Boston)

• Presentation Name: Advancing LNP Screening to Incorporate Automated, High-Throughput Readouts
  • Date & Time: Wednesday, May 1, 2024, 2:00 p.m. ET
  • Presenter: Marine Hatit, Ph.D.

American Society of Cell & Gene Therapy (ASGCT) 27^th Annual Meeting (Baltimore)

• Presentation Name: Development and Delivery of Prime Editors
  • Date & Time: Tuesday, May 7, 2024, 9:45 a.m. ET
  • Presenter: Jonathan Levy, Ph.D.
• Poster Name: Exon Reframing by Prime Editors Restores Dystrophin
  • Date & Time: Wednesday, May 8, 2024, 12:00 p.m. ET (poster session)
  • Presenter: Michelle O'Connor, Ph.D.
• Presentation Name: Development of a Prime Edited CD34+ cell Drug Product for the Treatment of P47phox Chronic Granulomatous Disease
  • Date & Time: Wednesday, May 8, 2024, 5:15 p.m. ET
  • Presenter: Jennifer Gori, Ph.D.
• Presentation Name: Off-Target Analysis Shows Favorable Safety Profile of Prime Editing
  • Date & Time: Friday, May 10, 2024, 2:45 p.m. ET
  • Presenter: Maria Collier, Ph.D.
• Presentation Name: Prime Editors Precisely Correct Pathogenic RHO Mutations and Preserve Photoreceptors In Vivo
  • Date & Time: Wednesday, May 8, 2024, 3:45 p.m. ET
  • Presenter: Deepak Reyon, Ph.D.

TIDES USA Oligonucleotide & Peptide Therapeutics Conference (Boston)

• Workshop: Introduction to Genome Editing
  • Date & Time: Tuesday, May 14, 2024, 9:00 a.m. ET
  • Presenter: Jeffrey Hussman, Ph.D.
• Presentation Name: Gene Editing, Regulatory and Delivery Challenges and Perspectives
  • Date & Time: Tuesday, May 14, 2024, 4:15 p.m. ET
  • Presenter: Luis Santos, Ph.D.
• Presentation Name: RNA-Based Approach to Delivering Prime Editing
  • Date & Time: Thursday, May 16, 2024, 10:45 a.m. ET
  • Presenter: Seth Alexander, Ph.D.
• Presentation Name: Analytical Development for Prime Editing Guide (peg)RNAs
  • Date & Time: Friday, May 17, 2024, 11:45 a.m. ET
  • Presenter: Xiangkun Yang, Ph.D.

About Prime Medicine

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.

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.

Forward Looking Statements

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; its expectations regarding the breadth and potential of Prime Editing technology; 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; the anticipated maturation into a clinical-stage company by bringing PM359 into clinical development in 2024 with initial data expected in 2025; and the potential for Prime Editors to repair genetic mutations and offer curative genetic therapies for a wide spectrum of diseases. 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 an IND or CTA filing and 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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