UK's Oyster Tx rebrands and raises $60m for Alzheimer's R&D

UK-based startup Oyster Therapeutics has raised $60 million in first-round financing that will be used to advance its tau protein-targeting drug for Alzheimer's disease.

Formerly known as Kesmalea, London-based Oyster will use the proceeds to push its lead candidate – an oral, brain-penetrant tau degrader identified using its SELFTAC discovery platform.

While a lot of protein degraders are bispecific molecules, which are bulky, need to be administered using a needle, and cannot penetrate the central nervous system (CNS), Oyster's SELFTAC candidates are small enough to be dosed orally. Another form of degrader, molecular glues, are smaller molecules but – according to Oyster – lack the rational, modular design approach afforded by its platform.

SELFTAC gets around the problems of its rivals by allowing its degraders to split into two small molecules in the body, which circulate and then self-assemble into the active form that can remove tau and other target proteins using cells' innate protein-clearance machinery.

In Alzheimer's and other neurodegenerative disorders, tau can clump together to form the neurofibrillary tangles that are one of the hallmarks of the disease, along with the amyloid plaques targeted by the current generation of disease-modifying therapies.

Like amyloid, the pathway to develop tau-targeting drugs for Alzheimer's is littered with failed trials and projects, including Johnson & Johnson's antibody-based posdinemab, Eli Lilly's zagotenemab antibody and OGA inhibitor LY3372689, although many more are still in clinical testing.

"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, Oyster's chief executive.

"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," he added.

In conjunction with the financing, Oyster has also entered into a sponsored research agreement with Massachusetts General Hospital in the US to access the tau biology expertise of leading tau researcher Dr Catarina Silva.

The financing was led by 4BIO Capital, with participation from new investors, including Lilly, alongside existing investors. Lilly is a player in the Alzheimer's category with Kisunla (donanemab), a drug that targets amyloid rather than tau and – after a slow start – generated $484 million in worldwide sales during the first nine months of 2026.

There is speculation that the limited efficacy shown by intravenously administered Kisunla and Eisai/Biogen's competing amyloid inhibitor Leqembi (lecanemab), available in IV and subcutaneous formulations, could be improved by also addressing 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," said Oyster in a statement.

Other backers of the Series A included CE Ventures, Actium Group, TOHO Ventures (managed by Global Brain), Syncona, Oxford Science Enterprises, Mission BioCapital, and MGB Ventures.