OS Therapies Seeks FDA Alignment on 3-Year Survival Endpoint and OST-400 Arm
OSTX•OS Therapies requested a Type B FDA meeting to validate 3-year overall survival as the Accelerated Approval endpoint and submitted pharmacodynamic biomarker data to BEST for its OST-HER2 BLA in resected pulmonary metastatic osteosarcoma. OST-400 synthetic control arm recruitment provides a comparator for review of Rolling Review, RMAT and BTD.
1. FDA Type B Meeting Request
OS Therapies has requested a Type B meeting with the FDA to review its 2.5-year overall survival data for OST-HER2 and confirm that 3-year overall survival will serve as the primary clinical efficacy endpoint for its Accelerated Approval BLA in resected pulmonary metastatic osteosarcoma. The company aims to align FDA’s statistical analysis methods with those previously agreed upon by MHRA and EMA.
2. Biomarker and Synthetic Control Data Submission
The company submitted pharmacodynamic biomarker data to the FDA’s BEST program to qualify these biomarkers as surrogate efficacy endpoints, and has begun assembling its OST-400 natural history study as a synthetic control arm. Recruitment for OST-400 now meets the criteria for a secondary comparator to bolster the single-arm trial design under the Accelerated Approval pathway.
3. Regulatory Review and Designation Status
OS Therapies will also use the meeting to discuss outstanding Rolling Review, Regenerative Medicine Advanced Therapy and Breakthrough Therapy designation requests. The FDA, EMA and MHRA have started joint coordination on the OST-HER2 dossier to facilitate early market access across major regions.
