Coultreon Biopharma raises $125M Series A to advance oral immunology drug from Galapagos
What’s the deal? Coultreon Biopharma, formerly Onco3R Therapeutics, has closed an oversubscribed $125M Series A. The round was led by Sofinnova InvestmentsDealroom has a profile for this one. Try Dealroom →, with ForbionDealroom has a profile for this one. Try Dealroom → and Novo HoldingsDealroom has a profile for this one. Try Dealroom → as co-leads. They were joined by Galapagos, Regeneron VenturesDealroom has a profile for this one. Try Dealroom →, Balyasny Asset ManagementDealroom has a profile for this one. Try Dealroom →, Luma GroupDealroom has a profile for this one. Try Dealroom →, Samsara BioCapitalDealroom has a profile for this one. Try Dealroom →, Longwood FundDealroom has a profile for this one. Try Dealroom →, and Finchley Healthcare VenturesDealroom has a profile for this one. Try Dealroom →.
The Leuven, Belgium-based biotech will use the capital to push its lead drug, COL-5671, into Phase 2 trials for psoriasis and ulcerative colitis, with initial proof-of-concept data expected in 2027.
Why now? Autoimmune diseases like psoriasis, ulcerative colitis, Crohn’s disease, and rheumatoid arthritis are commonly treated with injectable biologic drugs that broadly suppress the immune system. These treatments often lose effectiveness over time and leave patients vulnerable to infections. Many patients cycle through multiple therapies without lasting relief.
Coultreon is pursuing a different mechanism. Its drug targets a protein called SIK3 — a “salt-inducible kinase” that acts as a central switch in the immune pathways that drive inflammation. By blocking SIK3 with a once-daily pill, COL-5671 simultaneously dials down multiple inflammation-causing signals (including IL-23 and TNFα, both established drug targets) while boosting the body’s own anti-inflammatory response through IL-10. The company argues this could deliver broader, more durable disease control than existing treatments.
Galapagos originally developed the drug but transferred it to Coultreon in April 2025 as part of a broader pipeline restructuring. CEO and founder Pierre Raboisson saw the asset’s potential and built Coultreon around it.
What could go wrong? COL-5671 is still in Phase 1 — no efficacy data in patients has been published. The SIK3 mechanism is novel, which means there is no clinical precedent to benchmark against. Immunology is one of the most competitive areas in drug development: companies like AbbVieDealroom has a profile for this one. Try Dealroom →, Johnson & JohnsonDealroom has a profile for this one. Try Dealroom →, and dozens of biotechs are all racing to build the next generation of autoimmune treatments.
The gap between a promising mechanism in preclinical models and a successful drug in humans is wide. Phase 2 data in 2027 will be the real test.
The signal: The round’s investor lineup — Sofinnova, Novo Holdings, Forbion, Regeneron Ventures, and Galapagos itself — signals deep conviction from specialist healthcare investors that SIK inhibition could become a new class of immunology therapy. The oversubscription at $125M for a Phase 1 asset reflects the premium the market places on oral drugs with the potential to replace or improve on biologics.
If COL-5671’s multi-target approach works in humans, it could offer a single pill that addresses diseases currently requiring multiple injectable treatments — a meaningful shift for patients and for the $100B+ autoimmune drug market.
Sources:
BioPharma Dive
BioSpace
Fierce Biotech
GlobeNewswire
Novo Holdings
Forbion
Coultreon
FinSMEs
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Coultreon Biopharma
J.V.
