Jun. 30 at 6:33 PM
OS Therapies (NYSE-A:
$OSTX) announced positive results from its Phase 2b trial of OST-HER2, showing statistically significant improvement in 1-year event free survival compared to historical controls.
OS Therapies is a B2i Digital Featured Company: https://b2idigital.com/os-therapies-1.
The clinical-stage oncology company develops immunotherapies and antibody drug conjugates for osteosarcoma and other solid tumors. In data presented at the MIB Factor Osteosarcoma Conference, 35% of OST-HER2-treated patients achieved 1-year event free survival compared with 20% from a peer-reviewed historical control group selected by Children’s Oncology Group (p = 0.0194).
The trial data also showed a favorable safety profile, with 13 out of 40 patients experiencing severe adverse events, of which 7 were treatment-related. All treatment-related adverse events were grade 3, with no grade 4 or 5 events reported, and no patients discontinued the study due to treatment-related adverse events.“
The feedback received from FDA regarding the use of external control comparators in settings where placebo-controlled randomization trials are not feasible increases the avenues available for OST-HER2 to gain Accelerated Approval,” said Paul Romness, Chairman & CEO of OS Therapies. “We have now responded to the follow-up questions from our recent positive Type D Meeting with FDA positioning us to soon be granted an End of Phase 2 meeting. We were also very pleased with the reception the presentation received from the osteosarcoma community. Recent interactions we have had with FDA are consistent with public statements from FDA leadership prioritizing the safety profile of potential new products under consideration for Accelerated Approval that are intended to treat deadly rare diseases where randomized trials may not be feasible, especially in pediatric cancer where no alternative treatment options are approved.”
OST-HER2 is a Listeria-based immunotherapy targeting HER2-positive cancers in pediatric osteosarcoma patients. The company also announced regulatory updates regarding its submission of external control data to support a potential Biologics License Application under the FDA’s Accelerated Approval Program.
Additionally, the UK’s Medicines and Healthcare products Regulatory Agency has agreed to support OS Therapies in utilizing its Clinical Practice Research Datalink to assist with data development for potential worldwide marketing authorizations.
Press release: https://ir.ostherapies.com/news-events/press-releases/detail/67/os-therapies-presents-statistically-significantly-positive
The company holds Rare Pediatric Disease Designation and could be eligible for a Priority Review Voucher if approved before September 30, 2026. The most recent PRV sale was valued at
$160 million in June 2025.
Os Therapies is led by Paul Romness and an experienced executive team including Chris Acevedo, Robert Petit, Jack Doll, and Gerald Commissiong.
Learn more about OS Therapies’ work at https://www.ostherapies.com and visit B2i Digital for updates. For investor-related questions, please see OS Therapies’ Investor Relations page or email
[email protected].
DISCLOSURE: As of June 30, 2025, the management of B2i Digital owns unrestricted shares of OSTX stock purchased in the open market. This post is not intended to solicit the sale of OSTX or any security, and it is not intended to offer any opinion on OSTX as an investment. Conduct your own research and consult with your own professional advisors prior to making any investment decisions. See the full disclosure in the Risks and Disclosures section of https://b2idigital.com/os-therapies-1.
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