Chai Discovery, a fledgling AI biotech startup founded in 2024, has quickly emerged as one of the most talked-about names in the race to revolutionize drug development. In just over a year, the company has raised hundreds of millions of dollars, secured a $1.3 billion valuation after its Series B round, and landed a high-profile partnership with pharmaceutical giant Eli Lilly. The deal marks a pivotal moment for Chai, which aims to use artificial intelligence to accelerate the discovery of new medicines by designing novel antibodies and molecules from the ground up. At the heart of Chai’s approach is Chai-2, a proprietary generative AI system designed to function as a kind of “computer-aided design suite” for biologics. Unlike traditional drug discovery, which relies on slow, expensive trial-and-error methods, Chai’s platform uses advanced machine learning models to predict and generate molecular structures with desired therapeutic properties. This allows researchers to explore vast chemical spaces more efficiently and identify promising drug candidates faster. The partnership with Eli Lilly underscores growing confidence in AI-driven drug discovery. Under the agreement, Lilly will use Chai’s software to advance its own pipeline of biologic therapies. Aliza Apple, head of Lilly’s TuneLab program, said the collaboration brings together Chai’s cutting-edge generative models with Lilly’s deep expertise in biologics and proprietary data, aiming to create better medicines from the outset. Chai’s rapid rise is especially notable given the intense competition in the space. Just days before the Eli Lilly announcement, Eli Lilly revealed a separate $1 billion collaboration with Nvidia to launch a co-innovation lab in San Francisco. The lab will combine AI, high-performance computing, and scientific research to speed up the development of new therapies. Despite skepticism from some industry veterans who argue that AI may not overcome the inherent complexities of drug development, supporters like Elena Viboch of General Catalyst believe the technology is poised to make a real impact. “The biopharma companies that move fastest to partner with innovators like Chai will be the first to get molecules into clinical trials,” she said, predicting that first-in-class medicines could enter trials by 2027. Chai’s roots trace back to conversations between its co-founders and Sam Altman, CEO of OpenAI, as early as 2018. One of the founders, Josh Meier, worked at OpenAI before joining Facebook, where he helped develop ESM1, one of the first transformer-based models for protein language. After stints at Absci and other AI biotech firms, Meier and his co-founder Jack Dent reconnected with Altman in 2024, reigniting their vision for a proteomics-focused startup. They officially launched Chai in OpenAI’s San Francisco offices, which provided space and support during the early days. The company’s core technology is entirely custom-built — not based on off-the-shelf large language models, but on highly specialized architectures developed in-house. Dent emphasized that Chai’s success stems from assembling a team of elite talent and pushing the boundaries of what AI can do in biology. “Every line of code is homegrown,” he said. “We’re not just fine-tuning existing models — we’re building new ones from the ground up.” With strong backing from investors like General Catalyst and OpenAI, and now a major alliance with Eli Lilly, Chai is positioning itself at the forefront of a new era in medicine — one where AI doesn’t just assist in drug discovery, but actively shapes the future of therapeutic innovation.