OS Therapies Inc. (NYSE:OSTX), a clinical-stage cancer immunotherapy and antibody drug conjugate biotechnology company, released survival data on Friday from the Phase 2b trial of its off-the-shelf immunotherapy candidate, OST-HER2, for pulmonary metastatic osteosarcoma, an aggressive type of bone cancer.
The data showed statistically significant positive final 2-year overall survival data in the prevention or delay of recurrent, fully resected, pulmonary metastatic osteosarcoma.
Seventy-five percent (27 out of 36 evaluable patients; 5 patients were lost to follow-up) of OST-HER2-treated patients achieved 2-year overall survival as measured from the most recent pulmonary resection, compared with 40% of historical control patients (p < 0.0001).
Subgroup analyses showed that 100% of patients who achieved 12-month Event Free Survival (EFS) achieved 2-year overall survival, whereas 59% of patients who did not achieve EFS achieved 2-year overall survival.
“The overall survival data in this non-randomized OST-HER2 study is encouraging as the results show it was safe and well-tolerated,” said Dr. Peter Anderson, pediatric oncologist at Cleveland Clinic Children’s.
Dr. Robert Petit, chief medical & scientific officer for OS Therapies: “We expect that data to be available to us in November 2025, in time for our meetings we expect to hold with each of these regulatory agencies in December 2025. We remain on track to file a conditional Marketing Authorization Application to MHRA in December 2025, a Biologics Licensing Application under the Accelerated Approval Program to FDA in January 2026, and an MAA to EMA in the first quarter of 2026.”
Recently, during the meeting, OS Therapies and the Dutch Rapporteur aligned on key areas, including safety, non-clinical and chemistry, manufacturing, and controls (CMC) data in support of the company’s ongoing OST-HER2 Phase 2b clinical trial.
The Rapporteur advised that the overall survival results, demonstrating statistically significant, final two-year data, may serve as an appropriate primary endpoint for consideration of conditional marketing authorization.
OSTX Price Action: OS Therapies shares were down 0.98% at $2.02 at the time of publication on Friday, according to Benzinga Pro data.
Read Next:
Photo: Shutterstock
© 2025 Benzinga.com. Benzinga does not provide investment advice. All rights reserved.
