Parabilis filed for an IPO shortly after signing a collaboration with Regeneron worth up to $2.3B-plus and covering an initial set of five antibody-Helicon conjugate candidates. In a concurrent private placement, Regeneron agreed to buy about $75M of Parabilis common stock at 90% of the IPO price per share. Parabilis said its planned clinical priorities include continued development of its lead Helicon peptide candidate zolucatetide (FOG-001) across desmoid tumors and additional expansion into familial adenomatous polyposis and hepatocellular carcinoma, with modeling pointing toward a Phase III registrational trial. The sequence—deal plus IPO filing—signals Parabilis’ attempt to close an early development capital gap while anchoring financing around a defined pipeline milestone and companion partner backing.