Phio Pharmaceuticals has announced promising results from its ongoing Phase 1b clinical trial of PH-762, an investigational therapy for skin cancers. The trial (NCT 06014086) is evaluating the safety and tolerability of intratumoral PH-762 in patients with Stage 1, 2, and 4 cutaneous squamous cell carcinoma (cSCC), Stage 4 melanoma, and Stage 4 Merkel cell carcinoma. Interim data revealed complete tumor clearance in two patients with cSCC.
The Phase 1b study, which commenced in the second quarter of 2023, aims to assess PH-762, Phio's lead clinical compound, which targets programmed cell death protein 1 (PD-1). PD-1 is a protein that inhibits the immune system's ability to attack cancer cells. The trial has enrolled seven patients to date, including six with cSCC and one with metastatic melanoma.
Promising Results from Second Cohort
Data from the second cohort of four patients who completed treatment showed notable responses. Two patients with cSCC experienced a complete response, defined as 100% tumor clearance. One patient with cSCC achieved a partial response, demonstrating 90% tumor clearance. The remaining patient had stable disease, indicating no progression of the cancer.
According to Mary Spellman MD, Phio's acting Chief Medical Officer, the company is "pleased and encouraged by the profound tumor response in the second dose cohort, coupled with reassuring safety data." She added that continued enrollment will allow for assessment of higher dose concentrations of PH-762.
Safety and Tolerability
Importantly, the treatment has been well-tolerated, with no dose-limiting toxicities or clinically relevant treatment-emergent adverse events reported. This favorable safety profile is a crucial factor in the continued development of PH-762.
INTASYL Technology
PH-762 leverages Phio's proprietary INTASYL technology, which utilizes siRNA to silence specific genes, in this case, PD-1. By silencing PD-1, PH-762 aims to enhance the ability of immune cells to recognize and kill tumor cells. The INTASYL technology is designed to be self-delivering, targeting immuno-oncology therapeutics without the need for additional formulation.
Robert Bitterman, CEO of Phio Pharmaceuticals, commented on the early positive results, stating they "offer promise for our vision, 'striving for a cancer free future' using INTASYL technology."
