Phio Pharmaceuticals Corp.

PH-762 Development Update

PH-762 was evaluated in a U.S. multicenter Phase 1b dose-escalation clinical trial assessing intratumoral administration in patients with cutaneous squamous cell carcinoma (cSCC), melanoma, and Merkel cell carcinoma. The study (NCT 06014086) was designed to evaluate the safety and tolerability of neoadjuvant treatment with PH-762, assess tumor response, and identify a dose or dose range for further clinical development. The study enrolled 22 patients, consisting of 20 patients with cutaneous squamous cell carcinoma, one patient with melanoma, and one patient with Merkel cell carcinoma.

The clinical trial was completed in June 2026, and the final clinical study report was submitted to FDA with a meeting request and briefing document outlining the nonclinical and clinical pharmacology programs, scientific rationale for continued development, completed Phase 1b results, and details of the planned Phase 2b neoadjuvant study in cSCC. The submission seeks FDA feedback on the proposed development strategy and next steps, with a response expected from the FDA by the end of November 2026.

The Company also announced the successful release of its first commercial-scale cGMP batch of PH-762 drug substance (active pharmaceutical ingredient), representing an important CMC (chemistry, manufacturing and controls) milestone that supports the planned Phase 2b clinical program, which is expected to be initiated in the first quarter of 2027.