8-K: Phio Pharma's PH-762 Shows Strong Tumor Response in Skin Cancer Trial

Phio Pharmaceuticals announced positive key tumor response data from its intratumoral PH-762 dose escalation cutaneous carcinoma trial, showing a 70% overall response rate for squamous cell carcinomas.

Summary

• Phio Pharmaceuticals Corp. reported key tumor response data from all cohorts in its intratumoral PH-762 dose escalation cutaneous carcinoma trial.
• The Phase 1b trial evaluated 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.
• A total of 22 patients with cutaneous carcinomas completed treatment across five cohorts.
• Pathology data indicated a 70% overall response rate for squamous cell carcinomas (cSCC), with 14 out of 20 cSCC patients determined to be pathologic responders.
• Among the cSCC responders, 10 patients achieved a complete response (100% clearance), 2 patients had a major/near clear response (greater than 90% clearance), and 2 patients showed a partial response (greater than 50% clearance).
• A single patient with metastatic Merkel cell carcinoma also had a partial response with greater than 50% clearance.
• Six cSCC patients and one melanoma patient had responses of less than 50%, but none experienced disease progression.
• The trial demonstrated favorable safety and tolerability at all dose escalations, with no dose-limiting toxicities or clinically relevant treatment-emergent adverse effects reported across a 20-fold increase in drug concentration.

Sentiment

Score: 9

Explanation: The filing reports exceptionally strong positive clinical trial data for a Phase 1b study, including a high overall response rate and complete responses, coupled with an excellent safety profile. This significantly de-risks the asset and provides a clear path forward for development.

Positives

• PH-762 achieved a remarkable 70% overall response rate for squamous cell carcinomas in the Phase 1b trial.
• 10 out of 14 cSCC responders reported 100% clearance of their tumors.
• The drug demonstrated favorable safety and tolerability across all five dose escalation cohorts, with no dose-limiting toxicities or clinically relevant treatment-emergent adverse effects.
• PH-762 was well tolerated in all enrolled patients, even with a 20-fold increase in drug concentration from the first to the final cohort.
• No patients experienced progression of the disease, even those with responses less than 50%.

Risks

• Actual results may differ materially from forward-looking statements due to various factors, including results from preclinical and clinical activities.
• The ability to execute on business strategies, the timing or likelihood of regulatory filings and approvals, and the ability to manufacture and supply product candidates for clinical and commercial use are uncertain.
• The scope of protection for intellectual property rights covering the technology platform is a factor.
• The ability to obtain future financing is a risk.
• General market and other conditions can impact outcomes.

Future Outlook

We are actively beginning the design of a follow-on clinical trial, representing the next step in the regulatory development pathway for PH-762. Extended follow-up safety data from the current Phase 1b trial is expected to be reported in the second quarter of 2026. PH-762 is positioned as a potential non-surgical treatment for various forms of skin cancer.

Management Comments

• "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." Robert Bitterman, CEO and Chairman of the Board, Phio Pharmaceuticals.

Industry Context

Phio Pharmaceuticals operates as a clinical-stage siRNA biopharmaceutical company, specializing in immuno-oncology therapeutics. Its INTASYL gene silencing technology aims to enhance the body's immune cells to combat cancer. The positive Phase 1b data for PH-762 in cutaneous carcinomas positions the company within the competitive landscape of novel cancer therapies, particularly for skin cancers, where non-surgical options are highly sought after.

Stakeholder Impact

• Shareholders: Positive clinical data is likely to increase investor confidence and potentially the company's valuation.
• Patients: The promising results offer hope for a potential non-surgical treatment option for various skin cancers.
• Employees: Advancement of the lead clinical program strengthens the company's pipeline and strategic direction.

Next Steps

• Actively beginning the design of a follow-on clinical trial for PH-762.
• Reporting of safety data through an extended follow-up period for the Phase 1b trial is expected in the second quarter of 2026.

Key Dates

Recommendation

The reported Phase 1b clinical trial data for PH-762 is highly encouraging, demonstrating a 70% overall response rate in squamous cell carcinomas, with a significant number of complete responses (100% clearance), alongside a favorable safety and tolerability profile. For a clinical-stage biopharmaceutical company, such strong early-stage efficacy and safety data significantly de-risks the asset and provides a clear pathway for further development. This positive outcome warrants a 'buy' recommendation, as it suggests strong potential for PH-762 to become a valuable therapeutic, driving future growth and shareholder value.

Keywords

PHIO, PH-762, INTASYL, siRNA, immuno-oncology, skin cancer, cutaneous carcinoma, squamous cell carcinoma, melanoma, Merkel cell carcinoma, clinical trial, Phase 1b, biopharmaceutical, tumor response, gene silencing