Merck & Co. launched a multi-target AI drug discovery collaboration with Protillion Biosciences using Protillion’s “lab-in-the-loop” antibody discovery and on-chip protein display platform. The deal is structured around upfront and potentially large milestone payments, with total milestone opportunity reported at up to $510 million. Protillion’s Prot-MaP system is designed to rapidly generate high-dimensional binding datasets by measuring millions of antibody variants per run, which the partners say supports more reliable AI optimization without overfitting. Merck will apply its therapeutic development expertise to discover candidate programs emerging from the platform. The transaction adds to a growing set of pharma-led investments in AI-enabled wet-lab iteration, aiming to compress discovery cycles and improve candidate selection quality before expensive clinical development.