Pathology data indicate 70% overall response rate for squamous cell carcinomas: 100% clearance in 10 out of 14 responders Favorable safety and tolerability at all dose escalations King of Prussia, Pennsylvania--(Newsfile Corp. - 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 announced today a summary of the pathology results and safety ...

Core Insights - Phio Pharmaceuticals Corp. has received FDA acceptance for a nonclinical protocol study design, marking a significant advancement in the drug development pathway for PH-762, a treatment for skin cancer [1][3] - The company plans to commence a toxicology study in the first quarter of 2026, which is a prerequisite for initiating human pivotal trials [1] - Positive interim results from an ongoing Phase 1b clinical trial of PH-762 show promising safety and efficacy, with no dose-limiting toxicities reported [2] Group 1: Drug Development Progress - The FDA has accepted the nonclinical protocol study design for PH-762, allowing the company to move forward with necessary studies [1][3] - A toxicology study is set to begin in Q1 2026, which is essential for progressing to human trials [1] - The company is also working on delivering a commercially viable drug product by 2026, adhering to FDA's Good Manufacturing Practices [1][3] Group 2: Clinical Trial Results - The Phase 1b trial has treated 18 patients with cutaneous carcinomas, showing a cumulative pathologic response in 16 patients, including six with complete response (100% clearance) [2] - No patients exhibited clinical progression of disease during the trial, and PH-762 was well tolerated across all dose cohorts [2] - The trial results indicate a promising safety profile, with no dose-limiting toxicities or clinically relevant adverse effects reported [2] Group 3: Company Overview - Phio Pharmaceuticals Corp. is focused on developing therapeutics using its proprietary INTASYL® gene silencing technology, particularly in the field of immuno-oncology [4] - The lead clinical program, PH-762, targets the PD-1 gene associated with various skin cancers, positioning it as a potential non-surgical treatment option [4] - The ongoing Phase 1b trial is evaluating PH-762 for cutaneous squamous cell carcinoma, melanoma, and Merkel cell carcinoma [4]

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].