Addition Therapeutics Emerges from Stealth with $100 Million to Advance All-RNA Gene Insertion Technology

SOUTH SAN FRANCISCO, CA – December 17, 2025 — Addition Therapeutics officially launched today, announcing $100 million in financing to accelerate its PRINT™ (Precise RNA-Mediated Insertion of Transgenes) platform. A spin-out from the University of California, Berkeley, the company aims to redefine genomic medicine by delivering durable, one-time therapies using an all-RNA, non-viral approach.

The PRINT™ platform utilizes a clinically validated lipid nanoparticle (LNP) delivery system to overcome the technical and safety limitations of traditional viral-based gene therapies.

A Breakthrough in Precise Gene Insertion

The foundational technology, developed in the laboratory of Professor Kathleen Collins, leverages the natural mechanism of retrotransposition. Unlike traditional methods that may result in random gene placement, PRINT™ enables the accurate insertion of transgenes into specific “safe-harbor” sites within the genome.

• Mechanism of Action: A retrotransposase encoded within the medicine converts a template RNA into a DNA transgene.

• Safe-Harbor Targeting: The transgene is directed to a highly conserved ribosomal DNA site, ensuring it does not interfere with other essential cellular functions.

• Plug-and-Play Versatility: The technology is highly adaptable; only the genetic sequence of interest changes between different therapeutic programs, while the delivery machinery remains constant.

Pipeline and Global Strategic Support

Addition is advancing a diverse pipeline of “PRINTed” therapeutics targeting both chronic and rare diseases. The company’s progress is bolstered by partnerships with major pharmaceutical companies and significant grant funding.

• HIV Prevention: The Gates Foundation has awarded a grant for a program designed to enable the lifelong endogenous production of antibodies against HIV with a single dose.

• Future Milestones: Addition plans to initiate initial disease-related non-human primate (NHP) studies in 2026.

• Blue-Chip Backing: The $100 million in funding stems from a syndicate including SR One, Pivotal Life Sciences, Abingworth, Osage University Partners, the Gates Foundation, and BEVC.

“Harnessing retrotransposon machinery to achieve precise transgene insertion… is an elegant and versatile new drug mechanism,” said Dr. Kathleen Collins. Addition Therapeutics anticipates sharing more details on its lead pipeline programs as development continues.