Overview

• OST-HER2 achieved a 2-year overall survival rate of 75% in 36 evaluable patients versus 40% in historical controls (p < 0.0001).
• All patients who reached 12-month event-free survival were alive at two years, compared with 59% among those with an event before 12 months.
• A Dutch rapporteur aligned with the company on safety, non-clinical, and CMC packages and signaled that overall survival could serve as the primary endpoint for a conditional application.
• OS Therapies plans to file a conditional MAA with the UK MHRA in December 2025, an FDA BLA under Accelerated Approval in January 2026, and an EMA MAA in the first quarter of 2026.
• Investigators described the therapy as safe and well tolerated, though the single-arm design with historical controls and five patients lost to follow-up temper the strength of the evidence.