OS Therapies Achieves Statistically Significant Final Three-Year Overall Survival Benefit for Herlystic(TM)-Treated Patients in Phase 2b Pulmonary Metastatic Osteosarcoma Trial

What the release reports

OS Therapies announced statistically significant final three-year overall survival data from its Phase 2b trial of OST-HER2 (Herlystic™) in fully resected, pulmonary metastatic osteosarcoma. The company reported a 72.7 percent three-year overall survival rate for treated patients versus a 45.8 percent comparable combined historical control and provided the trial sample size and follow-up details in the release.

Sources: S1

Trial results and sample

The Phase 2b analysis presented a three-year overall survival rate for OST-HER2-treated patients of 72.7 percent compared with 45.8 percent in a combined historical control (p = 0.0006). The company reported that the analysis covered 41 total enrolled patients, with four patients lost to follow-up.

Sources: S1

Regulatory and development plans described by the company

OS Therapies said it is preparing regulatory submissions in the U.S., U.K., Europe and Australia and intends to submit a Clinical Trial Authorisation (CTA) to the U.K. MHRA as the precursor to Phase 3 initiation. The company stated its intent to complete BLA and conditional marketing authorisation submissions in the fourth quarter of 2026 and referenced prior regulatory designations and eligibility for a Priority Review Voucher under the RPDD program.

Sources: S1

Context on designations and corporate statements

The release lists multiple regulatory designations awarded to OST-HER2 by the FDA and EMA and notes the company’s characterization of its platform and pipeline. The company also referenced a recent Priority Review Voucher sale for $220 million as context for potential PRV value, while cautioning there is no assurance of realizing comparable value in the future.

Sources: S1

What remains uncertain

• This article is based solely on an OS Therapies press release and does not independently verify the trial data or comparisons to the historical control.
• The press release contains forward-looking statements about planned regulatory submissions, trial initiation, and potential market access; regulatory outcomes and timing are not guaranteed.
• The historical control comparison is reported by the company; details about the composition and matching methodology of that combined historical control are not provided in the release.
• Statements about future eligibility to receive and the potential value of a Priority Review Voucher are conditional on future regulatory approval and a future sale, and the company explicitly stated there can be no assurance of realizing comparable value.