Company Proposes Planned Phase 2b Neoadjuvant Study Following Successful Completion of Phase 1b Trial

King of Prussia, Pennsylvania--(Newsfile Corp. - September 14, 2026) - Phio Pharmaceuticals Corp. (NASDAQ: PHIO) is a clinical-stage siRNA biopharmaceutical company developing therapeutics using its proprietary INTASYL^® gene silencing technology to eliminate cancer. Phio announced today that, following the formal completion of the Phase 1b clinical study, it has submitted a meeting request and comprehensive briefing package to the U.S. Food and Drug Administration (FDA).

The submission describes the nonclinical development program and integrated clinical pharmacology data for PH-762 and provides details of the completed Phase 1b study as well as the next planned Phase 2b neoadjuvant clinical study in cutaneous squamous cell carcinoma. The briefing package includes the scientific rationale, study design, and pharmacokinetic strategy intended to support the next stage of clinical development.

"Delivering this comprehensive briefing package to the FDA is a key achievement for the PH-762 program and an important step toward unlocking its clinical potential in cutaneous squamous cell carcinoma," said Robert J. Bitterman, President and CEO of Phio Pharmaceuticals. "We are encouraged by the Phase 1b findings and look forward to working with the FDA as we pursue the next phase of development."

Phio is currently preparing to manufacture clinical supplies for the next planned study, which are expected to be available in the first quarter of 2027. In addition, the dosing phase of the company's nonclinical toxicology study has been completed. Final activities supporting the next phase of clinical development are expected to be completed during the first quarter of 2027.