Kesmalea Therapeutics Announces $60 Million Series A Financing to Advance Next- Generation Targeted Protein Degraders for Alzheimer’s and Other Neurodegenerative Diseases and Rebrands as Oyster Therapeutics

‍LONDON, UK – November 10, 2026 – Oyster Therapeutics (previously known as Kesmalea Therapeutics),a pharmaceutical company developing next-generation targeted protein degraderswith an initial focus on tau-driven diseases like Alzheimer’s, today announcedthe closing of a $60 million Series A-2 financing. The financing was led by4BIO Capital, a London-based specialist life science venture capital fund, withparticipation from new investors including Eli Lilly and Company, CE Ventures, ActiumGroup, and TOHO Ventures (managed by Global Brain). Existing investors Syncona,Oxford Science Enterprises (OSE), Mission BioCapital, and MGB Ventures alsoparticipated.

“This financing accelerates our progress towards the clinicand enables us to validate a new approach to targeted protein degradation, orTPD, that solves some of its major limitations through the use of smallermolecules,” said Rob Johnson, Chief Executive Officer of Oyster Therapeutics. “Millionsof people living with diseases such as Alzheimer’s need new approaches such asTPD to address the root cause of disease. At Oyster we are definingnext-generation TPD medicines that can reliably reach the brain and are orallyavailable to better meet the needs of global patient populations. We welcomethis support from both new and existing investors for our vision of buildingthe world’s leading neuroscience TPD company.”

Targeted protein degradation is a major area of therapeuticdevelopment that involves guiding the natural ‘waste removal’ machinery of thecell to target disease-causing proteins. Oyster is focused on bringing thepotential of TPD to the central nervous system (CNS). Devastatingneurodegenerative diseases such as Alzheimer’s and Parkinson’s involve proteinsthat appear well-suited to clearance via TPD. However, the dominant approach toTPD involves larger molecules that have difficulty penetrating the CNS.

Oral Tau Degrader Is Lead Program

Oyster’s most advanced program is a small, oral degradertargeting the protein tau, one of the highest-priority targets in neurodegenerativedisease. Abnormal tau buildup is the main feature of diseases called‘tauopathies’, the best known of which is Alzheimer’s. Oyster’s tau degrader isdesigned to be small enough to enter the CNS and selectively removepathological forms of tau while preserving healthy tau. An oral formulation isthe preferred approach to diseases affecting large populations such asAlzheimer’s, due to the convenience of oral administration, room-temperaturestorage and lower-cost manufacturing.

MGH Collaboration with Leading Tau Researcher

The company has entered into a sponsored research agreementwith Massachusetts General Hospital (MGH) to access world-class tau biologycapabilities, including patient-derived neuronal cell lines and techniques togenerate and detect oligomeric tau, which is widely considered the most neurotoxicform of tau. This research is being conducted under the supervision of Dr.Catarina Silva, investigator at the Mass General Brigham NeuroscienceInstitute, Assistant Professor of Neurology at Harvard Medical School, and aleading tau researcher.

“Alzheimer’s and other tau-driven diseases remain among thehardest problems in medicine and Oyster is taking them on with a clearscientific rationale,” said Owen Smith, Partner at 4BIO Capital. “Targetedprotein degradation has real promise and SELFTAC is an ambitious effort tosolve its critical technical challenges so that degraders can reach the brain.Alongside it, Oyster’s lead program aims to remove disease-associated tau whilepreserving healthy tau. Much remains to be shown in the clinic, but this iswhere science meets unmet medical need. At 4BIO Capital we back teams like thiswith conviction before every question is answered, helping to build companieswith 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 generatedby its proprietary SELFTAC^® platform which is designed to transformlarge bifunctional protein degraders into small molecules. Larger bifunctional degradersrepresent the majority of targeted protein degraders in development. Bifunctionaldegraders consist of two ‘warheads’ which bind to the target protein and to theprotein that recruits the cell’s ‘waste removal’ machinery, respectively. It isa highly versatile approach, and these molecules can be designed rationally, orpredictably.

The core of a SELFTAC degrader is a reversible linkerbetween the two warheads which enables the molecule to exist in two forms: astwo small molecules that more easily penetrate biological membranes such as theblood-brain barrier that surrounds the CNS, and, after self-assembly, asbifunctional degraders which deliver powerful degradation. The SELFTAC platformprovides a repeatable engine for new degrader discovery. Its modular designenables high-throughput combinatorial hit screening, delivering candidate moleculesmore rapidly and more cost-effectively than conventional degrader approaches.

Rebranding Marks New Chapter for Oyster Therapeutics

Oyster’s rebranding reflects its new phase of developmentand a strong ambition to turn deep scientific insight into medicines thatchange people’s lives. Just as an oyster builds a rare pearl around a singularfocus, Oyster Therapeutics builds on deep scientific insight to shape valuable,next-generation medicines.

About Oyster Therapeutics

Oyster is a pharmaceutical companydeveloping next-generation targeted protein degraders with an initial focus on neurodegenerativediseases such as Alzheimer’s. Oyster’s proprietary SELFTAC^® platformis designed to solve the fundamental size limitations of many conventional degradersby transforming them into small molecules. This breakthrough is intended to enableroutine oral bioavailability and central nervous system (CNS) penetration,significantly expanding the therapeutic potential of the class. Oyster is basedin London, UK. For more information, visit www.oyster-tx.com.

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