Flagship Pioneering Launches Serif Biomedicines to Establish Modified DNA as a New Biotechnology

Following Flagship’s origination of generative protein and mRNA platforms, Serif is pioneering Modified DNA medicines to program the foundational information layer of biology

Serif to present data at an upcoming scientific meeting demonstrating tolerability in non-human primates and sustained gene expression with therapeutic effects in preclinical models after intravenous (IV) administration

Company emerges following five years of platform development and with an initial commitment of $50 million from Flagship Pioneering

CAMBRIDGE, Mass., April 21, 2026 — Flagship Pioneering, a scientific innovation engine for transformative platforms and products, today announced the launch of Serif Biomedicines, a biotechnology company pioneering Modified DNA as a new class of medicines. Modified DNA brings together the best features of mRNA and gene therapy, while mitigating their limitations, by enabling medicines that are programmable, scalable, durable, and redosable. Flagship has initially committed $50 million to develop the company’s platform and advance its first drug discovery programs.

Over the past several decades, enduring biotechnology companies have transformed stages of the central dogma of biology into powerful therapeutic platforms. Yet despite its central role as the code of life, DNA has not been translated into a therapeutic modality outside of gene therapy because of its immunogenicity and inefficient access to the cell’s nucleus. Addressing these fundamental barriers, Serif has reshaped the structural and chemical form of DNA, similar to how typographic serifs subtly refine how written language is expressed. These refinements enable Serif’s Modified DNA to, without altering the cell’s genome, express genes safely, durably, and programmably inside cells.

“When a foundational layer of biology becomes engineerable, new therapeutic categories are born that can redefine the possibilities for medicine,” said Noubar Afeyan, Ph.D., Founder and CEO of Flagship Pioneering and Co-Founder of Serif Biomedicines. “Serif builds upon our experience in prior category-originating Flagship companies to establish Modified DNA as a practical and broadly applicable therapeutic platform.”

Serif is building the complete technology stack to unlock non-viral DNA therapeutics in a capital-efficient manner, combining Modified DNA that minimizes innate immunogenicity, co-delivered mRNA Co-factors that enhance nuclear entry and gene expression, optimized lipid nanoparticles for redosing and targeted tissue delivery, AI-guided DNA sequence design for cell-specific programmable gene expression, and scalable manufacturing for accessible therapeutics. Unlike RNA therapies that are limited to transient gene expression, gene therapies that cannot be redosed, and genome engineering strategies that rely on DNA integration, Modified DNA enables a durable, redosable, and potentially safer therapeutic profile that supports broad medical applications with significant market opportunities. Serif’s initial drug discovery programs focus on rare diseases and immune programming where Modified DNA’s therapeutic properties offer clear advantages for fulfilling meaningful unmet clinical needs.

“More than 75 years after DNA was recognized as the key information molecule in biology, turning DNA into a reliable medicine remains one of our industry’s biggest opportunities,” said Jacob Rubens, Ph.D., Co-Founder and Chief Executive Officer of Serif Biomedicines and Origination Partner at Flagship Pioneering. “With Modified DNA, we are introducing a new therapeutic modality that can become an enduring biotechnology in the emerging era of programmable medicines.”

Serif will present preclinical data supporting its Modified DNA platform at an upcoming scientific meeting. The data show that, following systemic IV administration, Serif’s Modified DNA demonstrates tolerability in non-human primate studies and durable gene expression resulting in functional and therapeutic effects in vivo. Serif’s Modified DNA platform is protected by more than 20 patent families, including issued U.S. patents.

In addition to Afeyan and Rubens, Serif was co-founded by Geoffrey von Maltzahn, Ph.D., General Partner at Flagship Pioneering and Board Chair of Serif; Eric Keen, Ph.D., Principal at Flagship Pioneering; and Louisa Helms, Ph.D., Principal at Flagship Pioneering. The company’s leadership team includes Pete Smith, Ph.D., Chief Scientific Officer, and Andy Oh, Chief Financial Officer. Serif’s Board of Directors also includes Andrew Allen, M.D., Ph.D., former President and CEO of Gritstone bio; Avak Kahvejian, Ph.D., President, Flagship Labs and General Partner, Flagship Pioneering; and Michael Holmes, Ph.D., Chief Scientific Officer at Tessera Therapeutics.

Strategic advisors to the company include John Maraganore, Ph.D., former Chief Executive Officer of Alnylam Pharmaceuticals; Mike Nally, Chief Executive Officer of Generate: Biomedicines and CEO-Partner at Flagship Pioneering; and Rupert Vessey, Ph.D., Chief Scientist at Flagship Pioneering and former President of Research and Early Development at Bristol Myers Squibb.

About Serif Biomedicines

Serif Biomedicines is pioneering Modified DNA as a new class of biotechnology. Founded in 2021 within Flagship Labs, the innovation foundry of Flagship Pioneering, Serif integrates nucleic acid chemistry, synthetic biology, delivery science, and artificial intelligence to enable programmable, scalable, durable, and redosable DNA medicines. The company’s initial focus is on genetically defined diseases and reprogramming the immune system. For more information, visit www.serifbiomedicines.com.

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 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. For more information, visit www.flagshippioneering.com.