Chai Discovery partners with Eli Lilly to accelerate biologics design with AI

Chai Discovery has entered a collaboration with Eli Lilly and Company to accelerate the design of biologic therapeutics using artificial intelligence.

Under the agreement, Lilly will deploy Chai’s AI platform to design novel biologic drugs across multiple targets. In parallel, Chai will build an exclusive, purpose-built model trained on large-scale proprietary Lilly data and tailored specifically to Lilly’s discovery workflows, the companies said.

Chai said the partnership builds on evaluation work in which Lilly assessed a range of model-designed candidates generated by Chai’s systems. The collaboration is intended to move beyond general-purpose tools towards tightly integrated AI models embedded directly in pharmaceutical research and development processes.

At the core of the deal is Chai-2, which the company describes as the first zero-shot antibody design platform to deliver double-digit experimental hit rates while producing molecules with drug-like properties. Chai said the system can reduce early-stage discovery timelines from months to weeks, a shift that could materially change how biologics pipelines are built and prioritised.

Josh Meier, chief executive of Chai Discovery, said the partnership combines complementary strengths. “Our collaboration with Lilly brings together the strengths of both organisations, combining Chai’s expertise in building frontier models with Lilly’s ability to deploy technology to accelerate their efforts to make a positive impact on the lives of patients,” he said. Meier added that training custom models on Lilly’s proprietary data could push the boundaries of AI-enabled early-stage drug discovery and development.

For Lilly, the deal reflects a broader industry move to apply AI not just as an analytical aid, but as a core engine for molecule design. Large pharmaceutical groups have increasingly sought exclusive or semi-exclusive partnerships that allow them to capture more of the upside from AI-driven productivity gains.

The collaboration follows a period of rapid growth for Chai. The company said it completed a Series B funding round in December, co-led by Oak HC/FT and General Catalyst, valuing the business at $1.3 billion. Chai has raised nearly $230 million to date.

Annie Lamont, co-founder and managing partner at Oak HC/FT, framed the partnership as a signal of where drug discovery is heading. “Drug discovery is one of the areas that stands to benefit most from AI transformation, and Chai is the leader in building frontier models to reshape the category,” she said. Lamont added that the collaboration suggests a future in which new medicines are increasingly designed computationally rather than discovered through slower, trial-heavy processes.

The deal underscores how artificial intelligence is moving from pilot projects to deeply embedded systems within pharmaceutical research, as companies race to improve hit rates, shorten timelines and bring complex biologic therapies to patients faster.

The Recap

• Chai Discovery and Eli Lilly will collaborate on biologics design.
• Chai’s Chai-2 platform achieves double-digit experimental hit rates.
• Lilly will deploy Chai’s platform and receive an exclusive model.