OS Therapies Aligns with MHRA and EMA for Osteosarcoma Therapy

OS Therapies, Inc., a leader in gene-edited, Listeria-based cancer immunotherapies, has achieved a significant milestone in its regulatory journey. The company has secured full alignment with the U.K. Medicines and Healthcare products Regulatory Agency (MHRA) and the European Medicines Agency (EMA) for its pending Conditional Marketing Authorisation Application (CMAA) submission. This alignment is based on the use of comparable historical control data, derived from a systematic evaluation of all suitable available peer-reviewed literature by independent biostatistics advisors, presented in its most recent Scientific Advice Meeting (SAM).

According to the press release, the MHRA agreed that this approach was appropriate for the orphan indication of preventing or delaying the recurrence in fully resected, pulmonary metastatic osteosarcoma. Additionally, OS Therapies has finalized the design of its confirmatory Phase 3 trial, which is expected to commence in the fourth quarter of 2026. The trial will involve a specific proportion of patients dosed with remaining Phase 2 drug product versus the forthcoming Phase 3 material, ensuring a seamless transition from Phase 2 to Phase 3.

The company's lead asset, OST-HER2, has received multiple designations from regulatory bodies, including Orphan Drug Designation (ODD), Fast Track Designation (FTD), and Rare Pediatric Disease Designation (RPDD) from the U.S. Food and Drug Administration (FDA). Similarly, it has received ODD, FTD, and Advanced Therapy Medicinal Products (ATMP) designations from the EMA and MHRA. These designations are expected to streamline the regulatory approval process and provide early access to the market.

OS Therapies is currently in the process of completing its Biologics License Application (BLA) submission for OST-HER2 in osteosarcoma, which is scheduled for potential early market access under the Accelerated Approval Program. The company also intends to file Conditional Marketing Authorisation Applications (CMAAs) in Europe, the U.K., and Australia for OST-HER2 in the fourth quarter of 2026. The submission is expected to be completed in the coming weeks.

Paul Romness, MPH, Chairman and CEO of OS Therapies, expressed his satisfaction with the progress: "Achieving full alignment with MHRA and EMA, which paves the way for our upcoming CMAA submissions, and the initiation of our confirmatory Phase 3 trial is a major achievement. With this alignment now in hand, and with it the recognition from international regulators that the standard of care in osteosarcoma has not meaningfully changed in the last forty years, we are bringing this to the U.S. Food and Drug Administration (FDA)."

The company's next steps include rolling out site outreach for the confirmatory Phase 3 trial, which is expected to begin in the fourth quarter of 2026. OS Therapies has also completed the resubmission of a Regenerative Medicine Advanced Therapy (RMAT) request and has accepted a Commissioner's National Priority Review Voucher (CNPV) letter of intent from the FDA. The company is also seeking to obtain a BLA under the Accelerated Approval Program in the U.S. and CMAAs in Europe, the U.K., and Australia for OST-HER2 in metastatic osteosarcoma.

In conclusion, OS Therapies is making significant strides in its regulatory and clinical development efforts, positioning itself for potential early market access and approval of its lead asset, OST-HER2, in osteosarcoma.