Phio reports PH-762 FDA submission and planned Phase 2b study

Phio Pharmaceuticals Corp. (Nasdaq: PHIO) said on September 14, 2026 that it reached a key development milestone for PH-762, an INTASYL compound. The milestone includes the submission of materials to the FDA to support the next phase of clinical development in cutaneous cell carcinoma, and a planned Phase 2b neoadjuvant study. Phio disclosed the milestone in a Form 8-K filed the same day. The filing attaches the full press release as Exhibit 99.1 and incorporates it by reference.

What PH-762 is

Phio describes itself as a clinical stage biopharmaceutical company. Its proprietary INTASYL small interfering RNA gene silencing technology is designed to make immune cells more effective in killing tumor cells, according to its annual report on Form 10-K filed March 5, 2026. PH-762 is designed to reduce the expression of PD-1, a protein that inhibits T cells' ability to kill cancer cells. The report calls PD-1 a clinically validated target in immunotherapy.

The report says direct-to-tumor application of PH-762 produced potent anti-tumoral effects in preclinical models, including activity against distant untreated tumors. The company also said it had shown preclinical activity against multiple gene targets, including PD-1, BRD4, CTLA-4, TIGIT and CTGF.

Trial results to date

PH-762 is in a U.S. multi-center Phase 1b dose-escalating trial using intratumoral injection in patients with cutaneous squamous cell carcinoma, melanoma and Merkel cell carcinoma (NCT 06014086). The study was fully enrolled in November 2025 with 22 patients: 20 with cutaneous squamous cell carcinoma, one with melanoma and one with Merkel cell carcinoma. The report gives revised data supporting an overall response rate of 65% for squamous cell carcinomas. This is a small, uncontrolled dose-escalation study with 20 of 22 patients in one cancer type, and the 65% counts partial responders of greater than 50% clearance.

Among the 20 patients with cSCC, 13 were classified as pathologic responders. Nine had a complete response (100% clearance), two had a major or near clear response (greater than 90% clearance) and two had a partial response (greater than 50% clearance). The single patient with metastatic Merkel cell carcinoma had a partial response. Seven cSCC patients and one melanoma patient had responses of less than 50%. None of the patients experienced disease progression.

The report says intratumoral injection was well tolerated in all enrolled patients, with no dose-limiting toxicities and no clinically relevant treatment-emergent adverse effects in those who received intratumoral PH-762. The trial evaluated five dose-escalating cohorts, increasing drug concentration 20-fold from the first to the final cohort.

Financial position and next steps

Research and development expense was $4.6 million for 2025, up from $3.6 million for 2024, according to XBRL data from the 10-K. The net loss was $8.7 million for 2025 and $7.2 million for 2024. Cash used in operations was $8.0 million for 2025 and $7.1 million for 2024. Year-end cash and cash equivalents were $5.4 million at December 31, 2024. The company reported $13.0 million in cash and cash equivalents at June 30, 2026, in its quarterly report.

The annual report said final study data was still pending formal analysis. It also said an FDA submission intended to seek guidance on next steps in clinical study design for PH-762 was targeted for the second quarter of 2026. The company has $13.0 million in cash against $8.0 million used in operations in 2025, and the filings give no financing plan for a Phase 2b study. The 8-K groups the submission with the milestone announced on September 14, 2026, but it does not give the date of the submission. It also gives no start date for the Phase 2b study and no timing for any FDA response.

Report an error

Companies in this story

PHIOPhio Pharmaceuticals Corp.NASDAQ · United StatesOpen the starter desk