Phio Pharmaceuticals Corp. announced results of a new study showing that local treatment in vivo with INTASYL can cure tumors and generate systemic tumor immunity that is both durable and tumor specific. These data, which were presented at the European Society of Medical Oncology (ESMO) Congress 2021, highlight the potential of the Company's INTASYL technology in direct therapeutic applications. The study was performed to show the synergistic activity of co-targeting PD-1 and BRD4 with one INTASYL formulation (PH-3861) in a preclinical in vivo hepatocellular carcinoma model. The results show that up to 83% of the animals treated with PH-3861 had a complete response when treated at low doses, namely doses suboptimal for monotherapy. Moreover, this treatment induced a durable and specific systemic anti-tumor immune response, without requiring further treatment. In the study presented, subcutaneous Hepa1-6 tumors in mice were treated with a murine version of dual targeting INTASYL PH-3861 (mPH-3861) by local administration to the tumor, at low doses that are suboptimal for a single agent targeting either PD-1 or BRD4 alone. Mice showing complete cure of tumors with mPH-3861 were rechallenged by implanting hepatoma cancer cells at a different location to the previous tumor challenge up to 2.5 months after the initial treatment. All of the rechallenged mice previously cured by mPH-3861 were cured again without requiring further treatment, while tumors grew steadily in the control group as expected. These data show that treatment with mPH-3861 provides a durable and systemic anti-tumor immune response that can combat tumor growth.