Phio Pharmaceuticals Initiates Commercial-Scale API Manufacturing for siRNA Candidate PH-762 Ahead of FDA Meeting

Commercial-scale API manufacturing for a siRNA therapeutic signals a meaningful shift in Phio Pharmaceuticals' development posture for PH-762, moving the program from clinical-stage proof-of-concept toward the process validation demands that precede late-phase studies. The company initiated the manufacturing run in Q2 2026, alongside a long-term nonclinical toxicology study, with both activities expected to complete by year-end.

PH-762 is a siRNA compound delivered via intratumoral injection, evaluated in a U.S. multi-center Phase 1b dose-escalation trial (NCT 06014086) across 22 patients with cutaneous squamous cell carcinoma, melanoma, and Merkel cell carcinoma. The trial completed enrollment in March 2026. Final comprehensive clinical study documentation is in preparation for submission to the FDA, and Phio intends to request an FDA meeting in Q3 2026 to align on next-step clinical trial design and development strategy.

For CMC and QA teams tracking emerging gene-silencing modalities, the concurrent initiation of commercial-scale API and long-term toxicology reflects a compressed parallel-track strategy rather than a sequential one. That approach carries process characterization obligations early, particularly around comparability between clinical and commercial-scale batches under ICH Q10 and relevant sections of 21 CFR Part 211. The R&D spend increase supports the read: research and development expenses for Q2 2026 reached $3.1 million, up $2.0 million or 187% year-over-year, driven primarily by a $0.9 million increase in nonclinical toxicology study costs.

On the IP front, Phio received three notices of allowance and one grant decision across the United States, Canada, and Japan, strengthening the global portfolio around its INTASYL platform. The company also appointed Dr. R. Todd Plott, a board-certified dermatologist and former FDA advisory committee member, to its Board of Directors.

Cash and cash equivalents stood at $13.0 million as of June 30, 2026, down from $21.0 million at December 31, 2025. The company projects existing funds will support planned operations into the second half of 2027, supplemented by an at-the-market equity offering program of up to $6.36 million established in April 2026 through H.C. Wainwright & Co.

The FDA meeting request in Q3 2026 and the completion of commercial-scale API manufacturing by year-end represent the near-term checkpoints that will define the regulatory and manufacturing trajectory for PH-762 into 2027.

Source: Phio Pharmaceuticals Corp. via company press release, August 6, 2026.