Startup profile · funding coverage
Oyster Therapeutics (formerly Kesmalea Therapeutics) funding, valuation and investors
London preclinical biotech developing small oral, brain-penetrant targeted protein degraders for tau-linked neurodegenerative diseases.
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Funding, valuation & investors
Answer-first snapshotLatest funding
Series A-2
$60M · November 10, 2026
Latest known valuation
Undisclosed
Series A-2 · November 10, 2026
Total disclosed equity funding
$60M
Excludes debt, grants, acquisitions, secondaries, and IPO proceeds.
Current status
private
series a · London, United Kingdom
Investors in latest funding
Lead: 4BIO Capital
Other: Eli Lilly and Company , CE Ventures , Actium Group , TOHO Ventures , Syncona , Oxford Science Enterprises , Mission BioCapital , MGB Ventures
Overview
Oyster Therapeutics, formerly Kesmalea Therapeutics, is a London-based drug developer founded in 2020. It develops SELFTAC, a self-assembly approach intended to make targeted protein degraders small enough for oral delivery and central nervous system exposure.
Its lead investigational candidate aims to remove disease-associated tau while sparing healthy tau, but selectivity, brain exposure, safety and human clinical benefit remain unproven. On November 10, 2026 Oyster announced a $60M Series A-2 led by 4BIO Capital, with new participants including Lilly, CE Ventures, Actium Group and TOHO Ventures and returning investors including Syncona and Oxford Science Enterprises.
Why Oyster Therapeutics (formerly Kesmalea Therapeutics) is interesting
November 10, 2026 company statement confirms a $60M Series A-2, led by 4BIO Capital, and a rebrand from Kesmalea. The separately issued lead-investor release shortens the stage to 'Series A'; these refer to the same financing. SELFTAC and the tau degrader remain preclinical; no human efficacy is established.
Product & use cases
SELFTAC is an experimental small-molecule targeted-protein-degradation platform. Developers select a disease-associated target such as pathological tau, design paired molecules intended to assemble into a functional degrader, test binding and degradation in model systems, then evaluate brain exposure, selectivity, safety, and pharmacology before an investigational clinical program. This is a research and drug development operation, not a marketed patient product, approved medicine, paid subscription, or demonstrated clinical treatment.
- Experimental oral tau degrader for Alzheimer's and other tauopathies; clinical trial not yet demonstrated.
- Screening and optimization of smaller, self-assembling degraders for central nervous system targets.
- Sponsored tau-biology research with Massachusetts General Hospital using patient-derived neuronal cell lines.
Key facts
- $60M Series A-2 announced Nov 10, 2026; do not relabel as a new Series B or a separate Series A.
- Rebranded from Kesmalea, the same legal company lineage; avoid creating two startups.
- Lead oral tau degrader at preclinical stage; no human efficacy or confirmed clinical start.
- Massachusetts General Hospital sponsored research collaboration disclosed, not clinical trial.
- Historical 2022 financing and 2023 extension exist and are distinct from this A-2; FX conversion required before public numeric backfill.
Funding history (newest first)
Series A-2
2026-11-10 $60M Valuation: Undisclosed- 4BIO Capital (lead)
- Eli Lilly and Company (participant)
- CE Ventures (participant)
- Actium Group (participant)
- TOHO Ventures (participant)
- Syncona (participant)
- Oxford Science Enterprises (participant)
- Mission BioCapital (participant)
- MGB Ventures (participant)
Source: Read source · businesswire.com
Competitive landscape
Edge: Company hypothesizes that smaller SELFTAC degraders could cross the blood-brain barrier and enable oral dosing where bulkier bifunctional degraders struggle; the key tradeoff is unproven CNS exposure, pathological-tau selectivity, human pharmacology and clinical efficacy.
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Arvinas adjacent
Established targeted protein degradation research; not an approved comparable tau drug.
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Nurix Therapeutics adjacent
Targeted protein degradation platform with distinct disease programs.
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Biogen adjacent
Tau-directed research programs demonstrate clinical-development uncertainty.
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Eisai alternative
Approved anti-amyloid Alzheimer's therapy represents a different disease mechanism and delivery route.
Market / IPO context
Editorial / static context — not a live quote.
FAQs about Oyster Therapeutics (formerly Kesmalea Therapeutics)
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