Phio Pharmaceuticals Achieves 100% Tumor Clearance in Skin Cancer Trial as FDA Accepts PH-762 Development Protocol
核心洞察
Phio Pharmaceuticals' PH-762 demonstrated 100% tumor clearance in one patient and greater than 90% clearance in another patient at the maximum dose in its Phase 1b skin cancer (搜索) trial.
The FDA has accepted the company's nonclinical protocol study design for PH-762, with toxicology studies planned to begin in Q1 2026.
The INTASYL (搜索) siRNA therapy has shown no dose-limiting toxicities across 18 patients treated in five escalating dose cohorts for cutaneous squamous cell carcinoma (搜索), melanoma (搜索), and Merkel cell carcinoma (搜索).
Phio Pharmaceuticals Corp. has reported promising efficacy results from its Phase 1b clinical trial of PH-762, an INTASYL (搜索) siRNA therapy for skin cancers, with one patient achieving complete tumor clearance at the maximum dose. The FDA has also accepted the company's nonclinical protocol study design, marking a significant regulatory milestone for the experimental treatment.
Strong Efficacy Signals at Maximum Dose
In the fifth and final cohort of the Phase 1b dose escalation trial (NCT 06014086), PH-762 demonstrated notable pathologic responses at day 36 following treatment initiation. Among three patients treated at the maximum dose, one achieved 100% tumor clearance (complete response), a second patient showed greater than 90% clearance (near complete response), and a third patient had greater than 50% clearance (partial response).
The trial is evaluating neoadjuvant intratumoral PH-762 in patients with Stages 1, 2 and 4 cutaneous squamous cell carcinoma (搜索) (cSCC), Stage 4 melanoma (搜索), and Stage 4 Merkel cell carcinoma (搜索). Patients receive four weekly injections of PH-762, with pathologic response assessed 36 days after the initial injection.
Cumulative Trial Results Show Consistent Activity
Across all five dose-escalating cohorts, 18 patients with cutaneous carcinomas have completed treatment. Among 16 patients with cSCC, six achieved complete response (100% clearance), two had near complete response (greater than 90% clearance), and two showed partial response (greater than 50% clearance). One patient with metastatic Merkel cell carcinoma (搜索) demonstrated a partial response.
While six patients with cSCC and one patient with metastatic melanoma (搜索) had pathologic non-response (less than 50% clearance), no patients in the study exhibited clinical progression of disease during the treatment period.
Safety Profile Remains Favorable
The Safety Monitoring Committee issued a favorable review of safety data at the maximum dose of PH-762. To date, there have been no dose-limiting toxicities or clinically relevant treatment-emergent adverse effects reported in patients receiving intratumoral PH-762. The therapy has been well tolerated across all enrolled patients in each escalating dose cohort.
FDA Regulatory Progress
On December 23, 2025, Phio announced that the FDA has accepted its nonclinical protocol study design for PH-762. The company plans to initiate toxicology studies in the first quarter of 2026, representing a critical step toward advancing the program through regulatory pathways.
Financial Position Strengthened
The company completed warrant inducement financings that raised approximately $12.1 million in November 2025, following an earlier $2.1 million raise in July 2025. As of the reporting date, Phio had estimated cash and cash equivalents of approximately $21.3 million, which is projected to sustain operations into the first half of 2027.
For the third quarter of 2025, research and development expenses increased to $1.2 million from $0.6 million in the prior year period, primarily driven by higher clinical trial costs and chemistry, manufacturing and controls costs for the PH-762 program.
INTASYL Technology Platform
PH-762 utilizes Phio's proprietary INTASYL (搜索) siRNA gene silencing technology, which is designed to silence the PD-1 (搜索) gene implicated in various forms of skin cancer (搜索). The INTASYL compounds are engineered to enhance the body's immune cells to more effectively eliminate cancer cells, potentially offering a non-surgical treatment alternative for skin cancers.