Lilly (formerly known as Eli Lilly and Company) has acquired Engage Biologics Inc., a San Carlos, California-based preclinical biotechnology company developing the Tethosome™ platform for non-viral DNA delivery. The deal is valued at up to $202 million in cash, including an upfront payment and development milestone payments. An upfront purchase price was not disclosed.
Engage Bio’s Tethosome platform combines engineered DNA payloads with lipid nanoparticle delivery and an mRNA-encoded proprietary protein to improve nuclear localization, expression, potency, tolerability, and redosability of non-viral DNA therapies. The technology targets limitations in current non-viral approaches while retaining advantages of DNA-based modalities such as durability and programmability. The company, founded in 2021, was backed by seed investors including Y Combinator, SciFounders and the Cystic Fibrosis Foundation, along with non-dilutive funding from the Gates Foundation and NIH-NCATS.
The acquisition accelerates Lilly’s efforts to develop next-generation genetic medicines by integrating Engage’s platform with Lilly’s existing capabilities and portfolio. Will Olsen, Co-Founder and CEO of Engage Bio, will transition with the team.
Cooley LLP served as legal counsel to Engage Bio in the transaction process.
According to data in the LevinPro HC database, this deal represents the 58th Biotechnology transaction of the year. There were 136 Biotechnology acquisitions reported in 2025, and 139 in 2024. The largest Biotechnology deal by purchase price this year has been Gilead Sciences‘ acquisition of Arcellx for an implied equity value of $7.8 billion.
