{"entity":{"id":"chai-1","kind":"technology","name":"Chai-1 / Chai-2","aka":[],"tldr":"Structure and antibody-design models from Chai Discovery, with Chai-2 reporting high zero-shot antibody hit rates.","summary":"Chai-1 and Chai-2 are structure prediction and protein design models from Chai Discovery. Chai-1 (2024) is a diffusion model for biomolecular structure prediction released with open weights, and Chai-2 (2025) adds generative design conditioned on a chosen target epitope, producing antibodies and other binders from scratch. Chai-2 reported roughly 16% zero-shot binder hit rates across dozens of targets in wet-lab tests, meaning a meaningful fraction of computer-designed antibodies bound their target without experimental optimisation. The intended users are biologics teams seeking new antibodies, including against cancer antigens. Independent replication of the Chai-2 hit rates is pending, and developability of the designed antibodies has not been reported. For a newcomer: Chai-2 claims it can design a working antibody from a target's structure on the first try in about one attempt in six.","status":"emerging","asOf":"2026-09-08","links":[{"label":"Chai Discovery","url":"https://www.chaidiscovery.com"}],"tags":["foundation-model","protein-design"],"related":[],"cancers":[],"sections":["drug-discovery","ai-computation"],"technologies":["ai-drug-design","monoclonal-antibody"],"targets":[],"drugs":[],"companies":["chai-discovery"],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"principle":"Diffusion structure prediction; generative design conditioned on target epitope.","strengths":["De novo antibody design"],"limitations":["Independent replication pending"],"since":2024},"route":"/technologies/chai-1/","neighbours":{"section":[{"id":"ai-computation","kind":"section","name":"AI & Computation","route":"/fronts/ai-computation/"},{"id":"drug-discovery","kind":"section","name":"Drug Discovery Platforms","route":"/fronts/drug-discovery/"}],"technology":[{"id":"ai-drug-design","kind":"technology","name":"AI-driven drug & target discovery","route":"/technologies/ai-drug-design/"},{"id":"monoclonal-antibody","kind":"technology","name":"Monoclonal antibodies","route":"/technologies/monoclonal-antibody/"}],"company":[{"id":"chai-discovery","kind":"company","name":"Chai Discovery","route":"/companies/chai-discovery/"}],"roadmap":[{"id":"ai-oncology-roadmap","kind":"roadmap","name":"AI in oncology roadmap: pattern readers → foundation models → agents in the workflow","route":"/roadmaps/ai-oncology-roadmap/"},{"id":"drug-discovery-roadmap","kind":"roadmap","name":"Drug discovery roadmap: screening in mice → maps of dependency → designing in silico","route":"/roadmaps/drug-discovery-roadmap/"}]}}