Flagship Pioneering Appoints Mary Beth Harler President of Pioneering Medicines

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Sep 17, 2025, 11:31 ET

Dr. Harler Joins to Lead Effort to Create New Medicines Built from Flagship's Innovative Bioplatforms and Novel Modalities

CAMBRIDGE, Mass., Sept. 17, 2025 /PRNewswire/ -- Flagship Pioneering, a scientific innovation engine for platforms and products, today announced the appointment of Mary Beth Harler, M.D., as President of Pioneering Medicines, Flagship's in-house drug discovery and development unit. Dr. Harler comes to Flagship with more than two decades of senior leadership experience across the biotechnology and global pharmaceutical industries, spanning clinical development, organizational building, and corporate strategy.

In this role, Dr. Harler will lead efforts to accelerate the creation of novel therapeutics and maximize the patient impact and value of Flagship's first-in-category bioplatforms. She will work closely with Flagship-founded companies and leaders, as well as external collaborators through the company's Innovation Supply Chain partnerships. Dr. Harler will report to Paul Biondi, Managing Partner at Flagship Pioneering, who will chair the Pioneering Medicines Oversight Board.

"We are thrilled to welcome Mary Beth as President of Pioneering Medicines," said Biondi. "She combines world-class pharma R&D expertise, including responsibility for key drug approvals and experience developing and delivering programs across therapeutic areas and modalities, with entrepreneurial experience in scaling biotech organizations. Her proven ability to advance complex portfolios and align science, strategy, and execution will be invaluable as Pioneering Medicines enters its next phase of growth and impact."

Most recently, Dr. Harler served as Chief Executive Officer of IGM Biosciences, where she led a comprehensive scientific and strategic re-evaluation of the company's portfolio, restructured operations, and established a high-performing executive team and culture. Before joining IGM, she spent more than a decade at Bristol Myers Squibb, ultimately serving as Senior Vice President, Head of Immunology and Fibrosis Development, where she oversaw a late-stage portfolio of 10–12 assets across immunology, fibrosis, and rare diseases.

"I am honored to join Flagship Pioneering to lead Pioneering Medicines in this unique role," said Dr. Harler. "The opportunity to transform groundbreaking bioplatforms into medicines across multiple areas of unmet need is very exciting. I look forward to working with the broader Flagship ecosystem to advance a new generation of transformative therapies for patients."

Dr. Harler earned her medical degree from Marshall University School of Medicine and completed surgical training at Brown University, where she also held a faculty appointment as Clinical Instructor of General Surgery.

About Pioneering Medicines

Pioneering Medicines, Flagship Pioneering's in house drug development unit, is dedicated to conceiving and developing a broad portfolio of life-changing treatments for patients built from Flagship's innovative platforms. Harnessing the drug development expertise of its team together with the power of Flagship's multiple scientific platforms, Pioneering Medicines explores and identifies new product concepts which are then advanced jointly with Flagship's bioplatform companies. Within Flagship's Innovation Supply Chain partnerships, Pioneering Medicines works with external collaborators to apply its unique approach to partners' R&D priorities. These partnerships are highly co-creative strategic alliances that accelerate therapeutic innovation by bringing together partners spanning the full spectrum of drug discovery, development, and production.

About Flagship Pioneering

Flagship Pioneering invents and builds platform companies, each with the potential for multiple products that transform human health, sustainability and beyond. Since its launch in 2000, Flagship has originated and fostered more than 100 scientific ventures, operating with $14 billion of current assets under its direction as of its latest capital raise, announced in July 2024. The current Flagship ecosystem comprises more than 40 companies, including Foghorn Therapeutics, Generate Biomedicines, Inari, Indigo Agriculture, Lila Sciences, Moderna, Sana Biotechnology, Tessera Therapeutics and Valo Health. 