Oncolytic viruses can selectively kill cancer cells and cancer-promoting cells, either directly by binding and infecting them, or indirectly by eliciting a targeted immune response against them. UPCI investigators have been examining the anti-cancer efficacy of an immune-stimulating vaccinia virus, vvDD, and found it to be safe in humans in a phase I clinical trial. However, the overall anti-cancer effects of this treatment were limited, especially in certain tumor types that are not commonly infiltrated by immune cells, such as colorectal cancer.
In recent pre-clinical studies, a research team led by David Bartlett, MD, Bernard Fisher Professor of Surgery, Professor of Clinical and Translational Science, Vice Chairman of Surgical Oncology and Gastrointestinal Services, and Director of the David C. Koch Regional Perfusion Cancer Therapy Center, demonstrated that vvDD treatment caused tumor and immune cells to increase production of the protein PD-L1, which is involved in immune suppression. When the investigators then combined vvDD therapy with a targeted checkpoint inhibitor that blocks PD-L1, they observed a synergistic effect in which over 40% of aggressive colon and ovarian cancers were cured in mice.