Key Takeaways
- • Oyster Therapeutics (formerly Kesmalea Therapeutics) closed a $60 million Series A-2 financing led by 4BIO Capital, a London-based specialist life science venture fund, according to a Business Wire release.
- • New investors include Eli Lilly and Company, CE Ventures, Actium Group, and TOHO Ventures (managed by Global Brain); existing investors Syncona, Oxford Science Enterprises, Mission BioCapital, and MGB Ventures also participated.
- • Proceeds will advance an oral, brain-penetrant tau degrader toward clinical development as a potential treatment for tau-driven diseases such as Alzheimer's.
- • The company's proprietary SELFTAC platform aims to convert large bifunctional protein degraders into small molecules that can cross the blood-brain barrier.
- • Oyster has entered a sponsored research agreement with Massachusetts General Hospital, with work supervised by tau researcher Dr. Catarina Silva.
Summary
Oyster Therapeutics, previously known as Kesmalea Therapeutics and headquartered in London, has announced the closing of a $60 million Series A-2 financing, according to a Business Wire release. The round was led by 4BIO Capital, a London-based specialist life science venture capital fund. New investors Eli Lilly and Company, CE Ventures, Actium Group, and TOHO Ventures (managed by Global Brain) joined, while existing backers Syncona, Oxford Science Enterprises (OSE), Mission BioCapital, and MGB Ventures also participated. The company is rebranding as Oyster Therapeutics to reflect its new phase of development.
The company is developing next-generation targeted protein degraders with an initial focus on neurodegenerative diseases. Its most advanced program is a small, oral degrader targeting tau, a protein whose abnormal buildup is the main feature of tauopathies, including Alzheimer's. The company says the compound is designed to enter the central nervous system and selectively remove pathological tau while preserving healthy tau. Oyster argues that an oral formulation suits large patient populations because of convenience, room-temperature storage and lower-cost manufacturing. CEO Rob Johnson said the financing "accelerates our progress towards the clinic" and allows the company to validate a smaller-molecule approach to targeted protein degradation, which has been limited by the size of dominant degrader molecules that struggle to penetrate the CNS.
Oyster's broader pipeline rests on its SELFTAC platform, which the company says transforms large bifunctional degraders into small molecules that can more easily cross biological membranes, including the blood-brain barrier, before self-assembling into active degraders. The company describes the platform as a repeatable discovery engine with modular design enabling high-throughput combinatorial screening. To support its tau work, Oyster has entered a sponsored research agreement with Massachusetts General Hospital, giving it access to patient-derived neuronal cell lines and techniques for generating and detecting oligomeric tau, which is widely regarded as the most neurotoxic form. The research is supervised by Dr. Catarina Silva of the Mass General Brigham Neuroscience Institute and Harvard Medical School.
Owen Smith, Partner at 4BIO Capital, said the firm backs teams "with conviction before every question is answered," while cautioning that much remains to be shown in the clinic. The release does not disclose clinical timelines or the company's valuation.
The company is developing next-generation targeted protein degraders with an initial focus on neurodegenerative diseases. Its most advanced program is a small, oral degrader targeting tau, a protein whose abnormal buildup is the main feature of tauopathies, including Alzheimer's. The company says the compound is designed to enter the central nervous system and selectively remove pathological tau while preserving healthy tau. Oyster argues that an oral formulation suits large patient populations because of convenience, room-temperature storage and lower-cost manufacturing. CEO Rob Johnson said the financing "accelerates our progress towards the clinic" and allows the company to validate a smaller-molecule approach to targeted protein degradation, which has been limited by the size of dominant degrader molecules that struggle to penetrate the CNS.
Oyster's broader pipeline rests on its SELFTAC platform, which the company says transforms large bifunctional degraders into small molecules that can more easily cross biological membranes, including the blood-brain barrier, before self-assembling into active degraders. The company describes the platform as a repeatable discovery engine with modular design enabling high-throughput combinatorial screening. To support its tau work, Oyster has entered a sponsored research agreement with Massachusetts General Hospital, giving it access to patient-derived neuronal cell lines and techniques for generating and detecting oligomeric tau, which is widely regarded as the most neurotoxic form. The research is supervised by Dr. Catarina Silva of the Mass General Brigham Neuroscience Institute and Harvard Medical School.
Owen Smith, Partner at 4BIO Capital, said the firm backs teams "with conviction before every question is answered," while cautioning that much remains to be shown in the clinic. The release does not disclose clinical timelines or the company's valuation.
Go deeper than the headline
Research every firm in this story, track the ones that matter and get the daily briefing — free for 7 days.