OS Therapies Inc. (NYSE: OSTX) has moved its lead candidate, OST-HER2, materially closer to global approval in recurrent, fully resected, pulmonary metastatic osteosarcoma, according to an update from Stonegate Capital Partners. The key development is greater regulatory clarity: the European Medicines Agency (EMA) has initiated rolling review of the OST-HER2 Conditional Marketing Authorization dossier, while the EMA and Australia’s Therapeutic Goods Administration (TGA) have aligned on 3-year overall survival (OS) as the approvable efficacy endpoint.
This alignment shifts OST-HER2 from Phase 2b-supported planning toward a more defined global approval pathway. Management has also positioned seroconversion biomarker data as supportive surrogate efficacy evidence, reframing the investment debate from early proof-of-concept toward execution across a dense 2026 catalyst calendar.
The company expects to report 2.5-year OS data in mid-second quarter 2026, followed by meetings with the U.S. Food and Drug Administration (FDA) and the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) in the same quarter. Phase 3 initiation in Australia is planned for the third quarter, with 3-year OS data expected in early fourth quarter. A potential EMA Conditional Marketing Authorization decision could come in the fourth quarter of 2026.
Stonegate highlighted that regulatory clarity is the core value inflection. The EMA rolling review, TGA endpoint alignment, MHRA Advanced Therapy Medicinal Product (ATMP) designation, and upcoming FDA/MHRA meetings shift OST-HER2 from Phase 2b validation toward an executable global approval pathway.
Survival data remain the key catalyst stack. The mid-2026 2.5-year OS data and early-fourth quarter 3-year OS data should determine whether OS Therapies can complete the EMA submission and sustain accelerated-access momentum. Financing and Priority Review Voucher (PRV) optionality bridges the regulatory window. The company raised $5.25 million and expects an additional $4.0 million in non-dilutive funding to support 2026 catalysts. A potential PRV remains a meaningful approval-contingent valuation lever, with the latest public transaction at $205 million.
Stonegate Capital Partners is a capital markets advisory firm providing investor relations, equity research, and institutional investor outreach services for public companies. Its affiliate, Stonegate Capital Markets (member FINRA), offers investment banking services. The full announcement, including downloadable images and bios, is available here.
