Oyster Therapeutics (previously known as Kesmalea Therapeutics), a pharmaceutical company developing next-generation targeted protein degraders with an initial focus on tau-driven diseases like Alzheimer’s, today announced the closing of a $60 million Series A-2 financing. The financing was led by 4BIO Capital, a London-based specialist life science venture capital fund, with participation from new investors including Eli Lilly and Company, CE Ventures, Actium Group, and TOHO Ventures (managed by Global Brain). Existing investors Syncona, Oxford Science Enterprises (OSE), Mission BioCapital, and MGB Ventures also participated.
“This financing accelerates our progress towards the clinic and enables us to validate a new approach to targeted protein degradation, or TPD, that solves some of its major limitations through the use of smaller molecules,” said Rob Johnson, Chief Executive Officer of Oyster Therapeutics. “Millions of people living with diseases such as Alzheimer’s need new approaches such as TPD to address the root cause of disease. At Oyster we are defining next-generation TPD medicines that can reliably reach the brain and are orally available to better meet the needs of global patient populations. We welcome this support from both new and existing investors for our vision of building the world’s leading neuroscience TPD company.”
Targeted protein degradation is a major area of therapeutic development that involves guiding the natural ‘waste removal’ machinery of the cell to target disease-causing proteins. Oyster is focused on bringing the potential of TPD to the central nervous system (CNS). Devastating neurodegenerative diseases such as Alzheimer’s and Parkinson’s involve proteins that appear well-suited to clearance via TPD. However, the dominant approach to TPD involves larger molecules that have difficulty penetrating the CNS.
Oral Tau Degrader Is Lead Program
Oyster’s most advanced program is a small, oral degrader targeting the protein tau, one of the highest-priority targets in neurodegenerative disease. Abnormal tau buildup is the main feature of diseases called ‘tauopathies’, the best known of which is Alzheimer’s. Oyster’s tau degrader is designed to be small enough to enter the CNS and selectively remove pathological forms of tau while preserving healthy tau. An oral formulation is the preferred approach to diseases affecting large populations such as Alzheimer’s, due to the convenience of oral administration, room-temperature storage and lower-cost manufacturing.
MGH Collaboration with Leading Tau Researcher
The company has entered into a sponsored research agreement with Massachusetts General Hospital (MGH) to access world-class tau biology capabilities, including patient-derived neuronal cell lines and techniques to generate and detect oligomeric tau, which is widely considered the most neurotoxic form of tau. This research is being conducted under the supervision of Dr. Catarina Silva, investigator at the Mass General Brigham Neuroscience Institute, Assistant Professor of Neurology at Harvard Medical School, and a leading tau researcher.
“Alzheimer’s and other tau-driven diseases remain among the hardest problems in medicine and Oyster is taking them on with a clear scientific rationale,” said Owen Smith, Partner at 4BIO Capital. “Targeted protein degradation has real promise and SELFTAC is an ambitious effort to solve its critical technical challenges so that degraders can reach the brain. Alongside it, Oyster’s lead program aims to remove disease-associated tau while preserving healthy tau. Much remains to be shown in the clinic, but this is where science meets unmet medical need. At 4BIO Capital we back teams like this with conviction before every question is answered, helping to build companies with the potential to make a real difference in medicine.”
SELFTAC Platform Delivers Benefits of Smaller Size, including Brain Penetrance
Oyster’s broader pipeline is based on candidates generated by its proprietary SELFTAC® platform which is designed to transform large bifunctional protein degraders into small molecules. Larger bifunctional degraders represent the majority of targeted protein degraders in development. Bifunctional degraders consist of two ‘warheads’ which bind to the target protein and to the protein that recruits the cell’s ‘waste removal’ machinery, respectively. It is a highly versatile approach, and these molecules can be designed rationally, or predictably.
The core of a SELFTAC degrader is a reversible linker between the two warheads which enables the molecule to exist in two forms: as two small molecules that more easily penetrate biological membranes such as the blood-brain barrier that surrounds the CNS, and, after self-assembly, as bifunctional degraders which deliver powerful degradation. The SELFTAC platform provides a repeatable engine for new degrader discovery. Its modular design enables high-throughput combinatorial hit screening, delivering candidate molecules more rapidly and more cost-effectively than conventional degrader approaches.
Rebranding Marks New Chapter for Oyster Therapeutics
Oyster’s rebranding reflects its new phase of development and a strong ambition to turn deep scientific insight into medicines that change people’s lives. Just as an oyster builds a rare pearl around a singular focus, Oyster Therapeutics builds on deep scientific insight to shape valuable, next-generation medicines.
About Oyster Therapeutics
Oyster is a pharmaceutical company developing next-generation targeted protein degraders with an initial focus on neurodegenerative diseases such as Alzheimer’s. Oyster’s proprietary SELFTAC® platform is designed to solve the fundamental size limitations of many conventional degraders by transforming them into small molecules. This breakthrough is intended to enable routine oral bioavailability and central nervous system (CNS) penetration, significantly expanding the therapeutic potential of the class. Oyster is based in London, UK. For more information, visit www.oyster-tx.com.
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