Stylus Medicine Launches with $85 Million to Tackle Major Cell & Gene Therapy Challenges with Novel Gene Editing Technology

Cambridge, MA – May 12, 2025 – Founded by Patrick Hsu, ambitious startup Stylus Medicine has emerged with $85 million in funding to develop a suite of innovative technologies aimed at overcoming key hurdles in cell and gene therapy, utilizing a novel gene editing approach. The company is focused on achieving targeted gene insertion, non-viral DNA delivery, and off-the-shelf solutions for cell therapy – long-sought-after goals in the field.

Led by CEO Emile Nuwaysir (formerly of Ensoma and BlueRock Therapeutics), Stylus is taking on these significant challenges with a new gene editing technology based on engineered viral proteins called recombinases. Leveraging machine learning, Stylus has designed recombinases that can precisely target specific regions of the human genome for gene insertion.

This approach, based on Hsu’s work at the Arc Institute and UC Berkeley, offers a potentially simpler and safer alternative to CRISPR-based gene insertion methods, requiring only the recombinase (encoded in mRNA) and the therapeutic DNA, delivered via a single lipid nanoparticle infusion. The initial focus is on developing in vivo cell therapies that reprogram immune cells to target tumors.

Stylus has raised a total of $85 million, including a previously undisclosed $40 million Series A and a recent $45 million extension. Investors include RA Capital Management, Khosla Ventures, Chugai Venture Fund, Eli Lilly, and Johnson & Johnson Innovation.

Stylus Medicine believes its novel recombinase-based technology offers crucial advantages for in vivo cell therapies by enabling direct cellular engineering within the body, minimizing the complexity of the process, utilizing non-viral delivery to reduce immune responses and manufacturing hurdles, ensuring durable therapeutic effects through permanent genetic modifications, and accommodating the delivery of large genetic payloads.

While acknowledging the challenges and the recent struggles of other gene editing startups like Tome Biosciences, Stylus and its investors are optimistic that their unique technology represents a significant advancement, potentially marking a new era in gene writing and offering transformative solutions for complex diseases. The company, currently with 30-40 employees, plans a focused approach on cancer initially.