OS Therapies Targets FDA Approval for Bone Cancer Drug, Plans Animal Health IPO and $160M Voucher

OS Therapies Inc. (NYSE:OSTX) ("OS Therapies" or "the Company"), the world leader in listeria-based cancer immunotherapies, today provided stakeholders with a corporate outlook for the first half 2026.

The outlook highlights planned submissions to seek regulatory approval for the Company's lead candidate OST-HER2 in the U.S., U.K. and Europe, the expected release of Phase 2b biomarker data from the Company's Metastatic Osteosarcoma Program in the first half of January 2026, as well as additional pipeline and corporate milestones.

"OS Therapies is potentially at the cusp of improving the standard of care for patients with metastatic osteosarcoma," said Chairman & CEO Paul Romness. "2025 was a transformational year in which we announced promising OST-HER2 clinical trial results and had significant interactions with regulatory agencies in the U.S., U.K. and Europe regarding the path toward conditional marketing authorizations in 2026. We have incorporated the guidance received from those meetings into a clear regulatory plan that aligns our strategy with each regulatory agency's specific feedback."

Mr. Romness added, "In parallel, with much of the work related to OST-HER2 regulatory submissions winding down in the second half of Q1 2026, we expect to start making regulatory progress in our human OST-503 and OST-504 programs. We also look forward to completing a go-public transaction for our OS Animal Health subsidiary in the first half of 2026, with a confidential filing with the SEC expected in the very near future."

The Company expects to release biomarker data from its Phase 2b human clinical trial of OST-HER2 in the prevention or delay of recurrent, fully resected, pulmonary metastatic osteosarcoma during the week of the J.P. Morgan Healthcare Conference 2026.

The Company reiterates its intention to file a BLA with the U.S. FDA under the Accelerated Approval Program (Accelerated Approval) by the end of January 2026. The Company intends to complete MAA submissions seeking conditional marketing authorization with the U.K. MHRA and Europe's EMA by end of February 2026 and March 2026, respectively.
Following these submissions, the Company expects to engage in multiple meetings with regulatory authorities in the U.S., U.K., and Europe during the first half of 2026. These discussions are expected to address proposed surrogate clinical efficacy endpoints, confirmatory trial design, and post-market authorization monitoring plans in support of regulatory review. Following these additional meetings requested by the FDA, MHRA and EMA, the Company anticipates the potential to receive regulatory approval for OST-HER2 in the U.K. in Q2 2026, in the United States in Q3 2026 and in Europe by the end of Q4 2026.

OST-HER2 has received Orphan Disease Designation (ODD) and Fast Track Designation from the FDA and EMA, and has received Rare Pediatric Disease Designation (RPDD) from FDA. Under the RPDD program, if the Company receives Accelerated Approval prior to September 30, 2026, it will become eligible to receive a Priority Review Voucher (PRV) that it intends to sell. The most recent PRV sale valued at $160 million occurred in June 2025.

The Company expects to advance a go-public transaction for its OS Animal Health subsidiary, with a confidential filing with the U.S. Securities and Exchange Commission expected in early January 2026. OS Animal Health is seeking to gain regulatory approval for OST-HER2 from the United States Department of Agriculture (USDA) for the treatment of pulmonary metastatic osteosarcoma, as well as frontline osteosarcoma. OST-HER2 was featured in the Emmy-nominated documentary 'Shelter Me: Cancer Pioneers' streaming on PBS.

Beyond OST-HER2, the Company expects to advance additional human oncology programs. The Company expects delayed data from its OST-504 Phase 1 trial in castration resistant prostate cancer in the first quarter of 2026 after prioritizing biomarker lab partner resources for osteosarcoma data analysis, with an End of Phase 1 meeting with the FDA expected in Q2 2026. The Company also expects an End of Phase 2 meeting with the FDA in the Q2 2026 to review OST-503 non-small cell lung cancer frontline trial results in combination with Keytruda®.