Parabilis filed for an initial public offering just a day after signing a strategic research collaboration with Regeneron, positioning the company to raise growth capital to advance its Helicon-based antibody-drug conjugate platform. The collaboration supports an initial set of five antibody–Helicon conjugate candidates, and Regeneron will buy roughly $75 million of Parabilis common stock in a concurrent private placement. The IPO plan centers on continued development of zolucatetide (formerly FOG-001), including dose expansion and a planned phase 3 registrational trial in desmoid tumors, plus expansion into additional indications such as familial adenomatous polyposis and hepatocellular carcinoma. Overall, the filing reflects how platform biotechs with long-horizon pipelines are using partnership validation to support public-market entry, even as biotech IPO windows remain selective.