OS Therapies secures FDA statistical meeting on 2.5-year survival data

OS Therapies received an FDA Type C meeting to review 2.5-year overall survival data from its Phase 2b OST-HER2 trial in metastatic osteosarcoma.

"We are heartened that overall survival at the 2.5-year timepoint remained unchanged from the 2-year timepoint," Dr. Craig Eagle, Chief Medical Advisor and board member at OS Therapies, said.

The meeting is expected in mid-September 2026 with members from the Center for Biologics Evaluation and Research (CBER), running in parallel with a pending Biomarker Data Review Meeting scheduled with the Center for Drug Evaluation and Research's Biomarker Qualification Program. The company expects to announce interim 3-year overall survival data in early September 2026. Concurrently, the U.K. Medicines and Healthcare products Regulatory Agency granted a new Scientific Advice Meeting to review statistical methods supporting the company's pending Conditional Marketing Authorisation Application.

The FDA meeting will focus on whether pooled non-concurrent published historical control data or concurrent natural history data from OST-400 should be used to evaluate clinical efficacy from the OST-HER2 trial. Decisions on the company's pending Regenerative Medicine Advanced Therapy designation submission, FDA Rolling Review and Commissioner's National Priority Review Voucher are expected following the meeting, which could help a potential Biologics License Application under the Accelerated Approval Program by year-end 2026.

OST-HER2 has received Orphan Drug Designation, Fast Track Designation and Rare Pediatric Disease Designation from the FDA, along with ODD, FTD and ATMP from the EMA and MHRA. Under the RPDD program, a BLA approval would make the company eligible for a Priority Review Voucher it intends to sell. The company's Commissioner's National Priority Review Voucher letter of intent was accepted by the FDA, with a final decision expected after full BLA submission.

The company reported positive Phase 2b data demonstrating clinically significant benefit in the 12-month event-free survival primary endpoint and the overall survival secondary endpoint. OST-HER2 has also been conditionally approved by the U.S. Department of Agriculture for treating canines with osteosarcoma, and the company completed dosing in a Phase 1 study of OST-504 for castration-resistant prostate cancer.

The sustained survival benefit between the 2-year and 2.5-year timepoints strengthens the case for accelerated approval. Investors will watch the interim 3-year OS data in early September and the FDA Type C meeting outcome in mid-September as the next decision points for the stock.

This article is for informational purposes only and does not constitute investment advice.