Phio Pharmaceuticals Announces Completion of Enrollment in Phase 1b Clinical Trial of INTASYL siRNA Lead Compound PH-762November 25, 2025 11:30 AM EST | Source: Phio Pharmaceuticals Corp.King of Prussia, Pennsylvania--(Newsfile Corp. - November 25, 2025) - 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 the completion of enroll ...

Core Insights - Phio Pharmaceuticals Corp. announced promising pathologic results from its ongoing Phase 1b trial for PH-762, showing 100% tumor clearance in one patient, over 90% in another, and over 50% in a third patient with cutaneous squamous cell carcinoma (cSCC) [2][3] - The trial has treated a total of 18 patients with cutaneous carcinomas, with cumulative results indicating six complete responses, two near complete responses, and two partial responses [3] - The Safety Monitoring Committee confirmed no dose-limiting toxicities or clinically relevant adverse effects at the maximum dose concentration, indicating a favorable safety profile for PH-762 [6][7] Company Overview - Phio Pharmaceuticals is a clinical-stage siRNA biopharmaceutical company focused on developing therapeutics using its proprietary INTASYL® gene silencing technology aimed at treating various forms of skin cancer [9] - The lead clinical program, PH-762, targets the PD-1 gene and is being evaluated for its potential as a non-surgical treatment for skin cancers, including cSCC, melanoma, and Merkel cell carcinoma [9] Trial Design and Results - The Phase 1b trial is designed to assess the safety and tolerability of intratumoral PH-762 in patients with Stages 1, 2, and 4 cSCC, Stage 4 melanoma, and Stage 4 Merkel cell carcinoma, with pathologic responses evaluated approximately five weeks post-injection [4] - The trial has shown no clinical progression of disease in any patients treated thus far, and additional patients may continue to be screened and treated as part of the fifth cohort [3][5]

Core Insights - Phio Pharmaceuticals has reported promising pathology results from its ongoing Phase 1b clinical trial, indicating potential efficacy of its treatment PH-762 for skin cancers [2][3][5]. Group 1: Clinical Trial Results - In the fourth cohort of the trial, one patient with cutaneous squamous cell carcinoma (cSCC) achieved a complete pathologic response, indicating 100% tumor clearance [2][4]. - A patient with Stage 4 metastatic Merkel cell carcinoma showed a partial response with over 50% tumor clearance [2][4]. - Two patients with cSCC exhibited pathologic non-response, with less than 50% tumor clearance, while results for one remaining patient are still pending [2][4]. Group 2: Safety and Tolerability - The Phase 1b trial has treated a total of 15 patients across four cohorts, with no dose-limiting toxicities or significant treatment-emergent adverse effects reported [3][5]. - PH-762 has been well tolerated among all enrolled patients, with no clinical progression of disease observed [3][5]. Group 3: Future Directions - Phio Pharmaceuticals is currently enrolling patients for what is expected to be the fifth and final cohort in the Phase 1b study [5]. - The CEO of Phio Pharmaceuticals expressed optimism that the positive safety and efficacy outcomes suggest PH-762 could serve as a viable non-surgical alternative in the expanding skin cancer market [5][6]. Group 4: Company Overview - Phio Pharmaceuticals is a clinical-stage siRNA biopharmaceutical company focused on developing therapeutics using its proprietary INTASYL® gene silencing technology, particularly in the field of immuno-oncology [6]. - The lead clinical program, PH-762, targets the PD-1 gene associated with various skin cancers, including cSCC, melanoma, and Merkel cell carcinoma [6].

Core Insights - Phio Pharmaceuticals is launching a strategic initiative to increase awareness of its INTASYL siRNA portfolio, which includes around 30 compounds [1][5] - The company reported positive interim safety and efficacy results for its INTASYL compound PH-762 in an ongoing Phase 1b clinical trial targeting skin cancer [1][5] Leadership Changes - Robert Infarinato has been appointed as VP of Strategic Development, effective June 9, 2025, transitioning from his role as CFO [2] - Lisa Carson has been named VP of Finance and Administration, bringing over 20 years of finance experience [2][4] Product Development - Phio's lead clinical program, PH-762, aims to silence the PD-1 gene associated with various skin cancers and is currently in a Phase 1b trial [5] - The ongoing trial evaluates PH-762 for treating cutaneous squamous cell carcinoma, melanoma, and Merkel cell carcinoma, positioning it as a potential non-surgical treatment option [5]