OS Therapies (NYSE: OSTX) dropped some encouraging numbers on Tuesday from its ongoing Phase 2b trial, and they're worth a closer look if you follow oncology plays.
The company is testing a therapy called OST-HER2 in patients with a specific type of bone cancer: fully resected, pulmonary metastatic osteosarcoma. That's a mouthful, but essentially it's for patients whose osteosarcoma has spread to the lungs and has been surgically removed. The goal is to keep the disease from coming back.
Osteosarcoma is the most common type of primary bone cancer, starting in the cells that form new bone tissue. It's a tough disease, so any signal of improved survival is meaningful.
In the interim analysis, patients treated with OST-HER2 showed a 71.2% overall survival rate at the three-year mark. That's against a combined published historical control group, which came in at 45.8%. The company says the difference is statistically significant, and they're using that historical data for regulatory discussions.
Only two study participants haven't yet hit their three-year anniversary since enrolling. OS Therapies has scheduled monitoring visits for those two patients in September 2026 and early October 2026, so we might get a final readout soon.
Funding the Next Step
Alongside the survival data, the company also shared some financial news that's directly tied to its next move. OS Therapies received $3.15 million in Value Added Tax refunds through its wholly-owned subsidiary, OS Therapies U.K., Ltd. And that's not the end of it—the subsidiary is eligible for at least $7.2 million more in VAT and research and development tax credits.
That money is earmarked for a specific purpose: launching a confirmatory Phase 3 clinical trial in the U.K. This trial is a key step for the company to become eligible for a Biologics License Application under the FDA's Accelerated Approval Program in the U.S. It will also support Conditional Marketing Authorization Applications in the U.K., Europe, and Australia.
So the strategy is pretty clear: use the tax credits to fund the Phase 3, which could open doors on both sides of the Atlantic.
Stock Reaction
Despite the positive data, shares of OS Therapies were down 3.72% to $1.81 at the time of publication on Tuesday. That's not unusual for biotech stocks, where the market often has already priced in expectations, or investors are focused on the dilution risk from future trials.
Still, for a small-cap biotech, these survival numbers are the kind of thing that can move the needle over time—especially if the Phase 3 trial confirms the benefit.
