Stylus Medicine

Stylus Medicine, a biotechnology firm established in 2022, is focused on developing in vivo genetic medicines to address significant challenges in cell and gene therapy. The company emerged from stealth in May 2025 with $85 million in Series A financing, co-founded by RA Capital's healthcare incubator, Raven, and Khosla Ventures. The funding round also saw participation from new investors, including Chugai Venture Fund, Eli Lilly and Company, and Johnson & Johnson Innovation—JJDC.

The scientific foundation of Stylus Medicine is rooted in the work of its academic founders: Patrick Hsu, Ph.D., of the Arc Institute and UC Berkeley, and Stanford University professors Ami S. Bhatt, M.D., Ph.D., Michael C. Bassik, Ph.D., and Lacramioara Bintu, Ph.D. Their research, particularly Hsu's work on viral proteins called recombinases, forms the basis of the company's core technology. The leadership team includes Chairman and CEO Emile Nuwaysir, Ph.D., a veteran with over 25 years in cell and gene therapy, and Chief Scientific Officer Jason Fontenot, Ph.D., who brings experience from roles at Sangamo Therapeutics and Juno Therapeutics.

Stylus Medicine's business model centers on the development and eventual commercialization of a proprietary therapeutic platform. This platform uniquely combines engineered, therapeutic-grade recombinases with non-viral, cell-targeted lipid nanoparticle (LNP) delivery systems. The core of the technology is its ability to perform sequence-specific genome integration, allowing for the precise insertion of large, multi-kilobase genetic payloads directly within the patient's body (*in vivo*). This approach circumvents the complex and costly manufacturing processes associated with traditional *ex vivo* cell therapies, where a patient's cells are extracted, modified, and then reinfused. By simplifying the treatment workflow, Stylus aims to create scalable, "off-the-shelf" genetic therapies, thereby expanding patient access.

The company's initial focus is on the oncology market, specifically on developing *in vivo* CAR-T cell therapies. This involves delivering a recombinase and a DNA payload that encodes for a Chimeric Antigen Receptor (CAR) directly to a patient's T-cells using an LNP infusion. This process effectively turns the patient's own body into a CAR-T cell factory. The platform's modularity allows for the adaptation of CAR constructs to target different antigens, opening pathways to treat various cancer types. Beyond oncology, the technology's versatility holds potential for applications in treating autoimmune and other genetic diseases.

Keywords: in vivo gene editing, genetic medicines, recombinases, lipid nanoparticles, LNP delivery, CAR-T therapy, cell therapy, genome engineering, non-viral delivery, RA Capital, Khosla Ventures, Patrick Hsu, Emile Nuwaysir, gene insertion, therapeutic payloads, oncology, autoimmune diseases, ex vivo manufacturing, biotherapeutics, genomic medicine, targeted gene therapy, molecular engineering