OS Therapies is a buy, this analyst says

Roth Capital Markets analyst Adam Walsh says OS Therapies’ (OS Therapies Incorporated Stock Quote, Chart, News, Analysts, Financials NYSE:OSTX) OST-HER2 has shown enough survival benefit to make approval more a question of timing.

In a July 9 report, Walsh initiated coverage of OS Therapies with a “Buy” rating and $7.00 target.

Walsh said OST-HER2, a Listeria-based immunotherapy, achieved 75% 2.5-year overall survival in recurrent, fully resected, pulmonary metastatic osteosarcoma, compared with 47% for a pooled historical control.

“We believe OST-HER2 works and approval is more a question of timing,” Walsh said.

He said the survival advantage emerges later and widens after 24 months, which he views as consistent with a durable antigen-specific immune effect. Walsh also said the therapy’s flu-shot-like tolerability supports the benefit-risk profile in a pediatric cancer with no approved therapy.

“The regulatory path is well advanced, in our view,” Walsh said.

The analyst said four agencies have aligned on the Phase 3 design, CMC plan and biomarker, while the MHRA, EMA and TGA have accepted three-year overall survival as an approvable endpoint. FDA alignment on the endpoint and comparator remains the key gating item.

Walsh expects a three-year overall survival update in early fall 2026 and models U.S. accelerated approval in late Q4 2026, with a 70% probability of approval.

He also expects OS Therapies to receive and sell a Priority Review Voucher for US$180-million in Q1 2027, which he said would exceed the company’s current market capitalization and fund its path to cash-flow positivity.

Walsh said orphan-level pricing and a worldwide addressable population of about 990 patients annually could support peak sales of US$420-million in 2029. He also pointed to manufacturing patents through 2040, along with biologic and orphan exclusivity.

Key milestones include an FDA Type B Statistical Methods meeting expected in the coming weeks, the three-year overall survival update in early fall 2026, a pre-BLA meeting and potential U.S. accelerated approval late in Q4 2026.

Walsh said the main risks are the three-year survival update, FDA acceptance of the external-control comparator, financing, CMC execution and commercialization.

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