On January 20, 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 reported a summary of the pathology results and safety outcomes across all cohorts in its Phase 1b dose escalation clinical trial with the INTASYL compound PH-762 for the treatment of skin cancer.
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A total of 22 patients with cutaneous carcinomas completed treatment across five cohorts in the Phase 1b trial and underwent excision of the treated lesional site. Among the 20 patients with cSCC, 14 patients were determined to be pathologic responders, including 10 patients with complete response (100% clearance), 2 patients with major/near clear response (greater than 90% clearance), and 2 patients with partial response (greater than 50% clearance). A single patient with metastatic Merkel cell carcinoma had a partial response with greater than 50% clearance. Six cSCC patients and one melanoma patient had responses of less than 50%, however, none of the patients experienced a progression of the disease.
There were no dose-limiting toxicities or clinically relevant treatment-emergent adverse effects in any patients who received intratumoral PH-762 in this trial. PH-762 has been well tolerated in all enrolled patients in each of the five dose escalating cohorts, increasing drug concentration 20-fold from the first to the final cohort. Safety data through an extended follow-up period is expected to be reported in the second quarter of 2026.
"The pathology data is remarkable with an overall response rate of 70%, complemented by a favorable safety data. With this data in hand, we are now actively beginning the follow-on clinical trial design in the next step in the regulatory development pathway." said Robert Bitterman, CEO and Chairman of the Board, Phio Pharmaceuticals.
The Phase 1b clinical trial is designed to evaluate the safety and tolerability of neoadjuvant use of intratumoral PH-762 in Stages 1, 2 and 4 cSCC, Stage 4 melanoma, and Stage 4 Merkel cell carcinoma. Per the trial’s protocol, patients received four injections of PH-762 at weekly intervals and pathologic response was assessed 2 weeks following the final injection of PH-762.
(Press release, Phio Pharmaceuticals, JAN 20, 2026, View Source [SID1234662097])