Oyster Therapeutics announced on November 10 the closing of a 60 million dollar Series A-2 financing, alongside a rebrand: the London company was previously called Kesmalea Therapeutics. The round was led by 4BIO Capital, with new investors including Eli Lilly and Company, CE Ventures, Actium Group and TOHO Ventures, managed by Global Brain, and participation from existing investors Syncona, Oxford Science Enterprises, Mission BioCapital and MGB Ventures.
Oyster works on targeted protein degradation, using the cell’s own disposal machinery to remove disease proteins rather than block them. Its proprietary SELFTAC platform is designed to convert large bifunctional degrader molecules into small molecules, addressing the size problem that has kept conventional degraders out of the brain. The lead programme is a small, oral, brain-penetrant degrader of tau, designed to remove pathological forms of the protein while preserving healthy tau. Abnormal tau accumulation defines the tauopathies, of which Alzheimer’s disease is the best known. The financing proceeds will advance the tau degrader into clinical development and support the platform.
The company has also signed a sponsored research agreement with Massachusetts General Hospital, supervised by tau researcher Dr Catarina Silva of the Mass General Brigham Neuroscience Institute, covering patient-derived neuronal cell lines and methods for generating and detecting oligomeric tau, the form Oyster regards as most neurotoxic.
Nothing here is clinical yet. BioPharma Dive noted the company has not disclosed when its lead drug will enter the clinic, and tau has absorbed decades of failed programmes from larger sponsors. What the round establishes is syndicate quality at the preclinical stage: a strategic investor in Lilly, which sells its own Alzheimer’s therapy, backing a degrader approach to the same target biology.