I want you to sit with this trajectory for a moment. Korsana Biosciences emerged from stealth in 2024. They raised a $25 million seed from Fairmount and Venrock Healthcare Capital Partners. Then a $150 million Series A co-led by Wellington Management and TCGX in February 2026. And now — barely a month later — a $380 million oversubscribed private financing tied to a merger with Cyclerion Therapeutics.

That’s $555 million raised in under two years. For a company whose lead asset hasn’t entered Phase 1 yet. Someone believes in this.

The “someone” is actually a lot of someones. The $380 million round was led by Fairmount and Venrock Healthcare Capital Partners (who’ve been there since seed), with General Atlantic, TCGX, Forbion, Wellington Management, RA Capital, RTW Investments, Vivo Capital, Janus Henderson, Foresite Capital, J.P. Morgan Life Sciences Private Capital, SR One, Sanofi Ventures, and more. That’s not a syndicate — that’s a roster.

So what are they building? KRSA-028 is a next-generation monoclonal antibody targeting amyloid beta for Alzheimer’s disease — but with a twist. It’s built on Korsana’s proprietary THETA platform, which uses engineered transferrin receptor 1 (TfR1) binding domains to shuttle the antibody across the blood-brain barrier. The Fc engineering also enables subcutaneous dosing, which would be a major convenience win over the IV infusions required by current anti-amyloid therapies.

The pitch: better brain penetration, potentially lower ARIA risk, and a subQ injection patients can get outside of an infusion center. Phase 1 is expected with proof-of-concept data by 2027.

The Cyclerion merger gives Korsana a public listing — Cyclerion had been pivoting away from its legacy sGC stimulator portfolio toward neuropsychiatry, but the real value here is the shell. The combined entity will operate under the Korsana name, and with $380 million in fresh capital and a runway through 2029, they’ve got time to prove the THETA platform works in humans.

Incubated by Paragon Therapeutics, led by CEO Jonathan Violin — this is a company that went from zero to half a billion in funding with an Alzheimer’s antibody that hasn’t dosed a single patient. The conviction is staggering. Now they have to deliver.