LONDON–Oyster Therapeutics, formerly known as Kesmalea Therapeutics, has raised $60 million in Series A-2 financing to advance the development of experimental treatments for Alzheimer’s disease and other neurodegenerative disorders, while establishing a research collaboration with Massachusetts General Hospital.
The financing was led by London-based life sciences investment firm 4BIO Capital, with participation from new investors 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 in the funding round.
The company said the proceeds will support the clinical development of its lead drug candidate, an oral treatment designed to selectively eliminate abnormal tau proteins associated with Alzheimer’s disease and related neurological conditions.
The investment will also fund continued development of Oyster’s proprietary SELFTAC platform, which is designed to create smaller targeted protein degraders capable of reaching the brain.
“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 an emerging therapeutic approach that uses the body’s natural cellular machinery to break down and eliminate proteins associated with disease.
The technology has attracted growing interest as a potential treatment strategy for neurological disorders, including Alzheimer’s and Parkinson’s diseases, where abnormal protein accumulation contributes to disease progression.
However, many conventional protein degraders are relatively large molecules, making it difficult for them to cross the blood-brain barrier and reach the central nervous system.
Oyster is developing smaller compounds intended to overcome that challenge.
The company’s lead program targets tau, a protein that can accumulate abnormally in the brain and is closely associated with Alzheimer’s disease and other conditions known as tauopathies.
Its investigational tau degrader is designed to enter the central nervous system and selectively remove disease-associated forms of tau while preserving the protein’s normal functions.
The company is pursuing an oral formulation, which could offer advantages in convenience, manufacturing costs and storage compared with treatments requiring injections or infusions.
As part of its development strategy, Oyster has entered into a sponsored research agreement with Massachusetts General Hospital to expand its understanding of tau biology and support its drug discovery efforts.
The collaboration will provide access to patient-derived neuronal cell lines and specialized techniques for generating and detecting oligomeric tau, a form of the protein considered particularly toxic to neurons.
The research will be conducted under the supervision of Catarina Silva, Ph.D., an Investigator at the Mass General Brigham Neuroscience Institute and Assistant Professor of Neurology at Harvard Medical School.
The collaboration is expected to strengthen the scientific foundation of Oyster’s tau-targeting programs and provide additional tools for studying the biological mechanisms underlying neurodegenerative diseases.
“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.”
Oyster’s SELFTAC platform is designed to address a key limitation of traditional targeted protein degradation technologies by enabling the development of smaller molecules with improved drug-like properties.
Conventional bifunctional protein degraders typically contain two molecular components connected by a linker. One component binds to the disease-associated protein, while the other recruits the cellular machinery responsible for breaking it down.
The SELFTAC technology uses a reversible linker that allows the components to exist as smaller molecules capable of passing more easily through biological barriers, including the blood-brain barrier.
Once inside the target environment, the molecules are designed to reassemble into functional protein degraders.
According to Oyster, the platform’s modular design also supports high-throughput screening of potential drug candidates, which could accelerate discovery and reduce development costs.
The company’s transition from Kesmalea Therapeutics to Oyster Therapeutics reflects its expanded focus on developing targeted protein degradation medicines for neurological diseases.
Although the company is preparing to advance its lead tau degrader into clinical development, the treatment remains investigational, and its safety and effectiveness in humans have not yet been established.
