On February 20, 2025 OS Therapies, Inc. (NYSE-A: OSTX), a clinical-stage biotechnology company advancing immunotherapies and targeted drug conjugates for cancer treatment, reported that it received a Notice of Allowance from the United States Patent & Trademark Office (USPTO) that a patent will be issued covering the manufacturing methods required for the OST-HER2 commercial product (Press release, OS Therapies, FEB 20, 2025, View Source [SID1234650434]). The USPTO granted a Patent Term Adjustment of 572 days, providing market exclusivity for the OST-HER2 commercial drug product into 2040. OS Therapies is preparing to initiate discussions with the United States Food & Drug Administration (FDA) following the successful treatment phase of its Phase 2b clinical trial in the prevention of recurrent, resected, lung metastatic osteosarcoma with a view towards submitting a Biologics Licensing Application (BLA) and gaining conditional or accelerated FDA approval in 2025. The Company recently completed a $7.1 million financing in January 2025 and has sufficient capital into mid-2026.

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OST-HER2 has already received rare pediatric disease (RPDD), fast-track (FTD) and orphan drug (ODD) designations from the US FDA for osteosarcoma. The Company intends to (1) focus on gaining FDA BLA approval for OST-HER2 in osteosarcoma in late 2025, (2) sell the Priority Review Voucher (PRV) it would receive from the FDA BLA approval prior to the September 30, 2026 PRV deadline to a larger pharmaceutical company at prevailing market prices (most recent PRV sale transaction was $150 million), (3) commercialize OST-HER2 in osteosarcoma and (4) then expand the clinical development of OST-HER2 into breast cancer and other larger solid tumor indications for additional revenue potential.

OST-HER2 has successfully completed a Phase 1 trial in adult patients with HER2 overexpressing cancers, primarily breast cancer patients. Preclinical breast cancer results with OST-HER2 showed:

78% reduction in tumor size (3mm for OST-HER2 treated vs. 14mm for control arm) in FVB/N HER2 transgenic mouse model of breast cancer treatment at day 75
33% prevention of breast cancer in OST-HER2 treated mice vs. 0% prevention of breast cancer in FVB/N HER2 transgenic model of breast cancer prevention at week 50
20% reduction of tumor size for OST-HER2 plus HER2-targeted antibody vs. HER2-targeted antibody alone Tg tumor regression model of breast cancer at day 42
65% reduction cellular concentration of metastatic cells for OST-HER2-treated mice compared with controls in brain metastasis model of primary breast cancer
The osteosarcoma treatment market was estimated at $1.2 billion in 2022 according to Data Bridge Market Research. The Company believes the market opportunity for OST-HER2 in the prevention of lung metastases in osteosarcoma is over $500 million. The breast cancer treatment market was estimated at $29.2 billion in 2023 and expected to grow to $53.7 billion by 2030 according to Grandview Research. The Company believes the market opportunity for OST-HER2 in the treatment of breast cancer exceeds $1 billion.