WHO Approves International Name for OS Therapies' Osteosarcoma Immunotherapy Ahead of Regulatory Submissions
Key Insights
The World Health Organization's International Nonproprietary Names Expert Committee approved 'daznelimgene lisbac (search)' as the official non-proprietary name for OS Therapies' HER2 (search)-targeted listeria-based cancer immunotherapy OST-HER2.
OST-HER2 demonstrated statistically significant benefit in 12-month event-free survival in a Phase 2b trial for recurrent, fully resected, pulmonary metastatic osteosarcoma (search) patients.
The company plans to seek regulatory feedback from US, UK, and European authorities in December 2025 and submit a Biologics License Application to the FDA in early 2026.
OS Therapies Inc. announced that the World Health Organization's International Nonproprietary Names Expert Committee has approved 'daznelimgene lisbac (search)' as the official non-proprietary name for OST-HER2, the company's HER2 (search)-targeted Listeria monocytogenes-based cancer immunotherapy. The milestone comes as the clinical-stage oncology company prepares for regulatory submissions across multiple jurisdictions for its lead osteosarcoma (search) treatment candidate.
Regulatory Milestone Achieved
The INN approval represents a critical step in the drug development process, as each active pharmaceutical ingredient must receive a unique, globally accepted name to ensure clear identification and safe prescribing. OS Therapies will begin transitioning to use daznelimgene lisbac (search) alongside OST-HER2 in future communications.
"We are pleased to have completed this milestone on our path towards gaining regulatory approval for OST-HER2, now called daznelimgene lisbac (search)," said Paul Romness, MPH, Chairman & CEO of OS Therapies. "We remain on track to get regulatory feedback from the US, UK and European regulatory authorities in December 2025 and file for regulatory approvals beginning in January 2026."
Clinical Development Progress
OST-HER2 is currently being developed for the prevention or delay of recurrent, fully resected, pulmonary metastatic osteosarcoma (search). The immunotherapy leverages the immune-stimulatory effects of Listeria bacteria to initiate a strong immune response targeting the HER2 (search) protein.
The company reported positive data from its Phase 2b clinical trial of OST-HER2 in recurrent, fully resected, lung metastatic osteosarcoma (search), demonstrating statistically significant benefit in the 12-month event-free survival primary endpoint. OST-HER2 has also completed a Phase 1 clinical study primarily in breast cancer (search) patients and has shown preclinical efficacy data in various breast cancer models.
Regulatory Designations and Market Potential
OST-HER2 has received multiple regulatory designations that could accelerate its path to market. The therapy holds Rare Pediatric Disease Designation from the U.S. Food and Drug Administration (search), as well as Fast-Track and Orphan Drug designations from both the FDA and European Medicines Agency (search).
OS Therapies anticipates submitting a Biologics License Application to the FDA for OST-HER2 in osteosarcoma (search) in early 2026. If approved, the company would become eligible to receive a Priority Review Voucher that it could then sell, adding potential commercial value beyond the therapy itself.
Expanding Platform Technology
Beyond OST-HER2, OS Therapies is advancing its next-generation Antibody Drug Conjugate and Drug Conjugates platform, known as tunable ADC (tADC). This platform features tunable, tailored antibody-linker-payload candidates and leverages the company's proprietary silicone Si-Linker and Conditionally Active Payload technology, enabling the delivery of multiple payloads per linker.
The company has also received conditional approval from the U.S. Department of Agriculture for OST-HER2 in the treatment of canines with osteosarcoma (search), expanding its potential market applications.