Immunotherapy is a promising approach in the treatment of metastatic melanoma, an aggressive and deadly form of skin cancer; but for most patients, immunotherapy drugs so far have so far failed to live up to their promise and provided little or no benefit. In a phase 1b clinical trial with 21 patients, researchers tested the safety and efficacy of combining the immunotherapy drug pembrolizumab with an oncolytic virus called T-VEC. The results suggest that this combination treatment, which had a 62% response rate, may work better than using either therapy on its own. The study was published in the September 7, 2017 issue of Cell. The article is titled “Oncolytic Virotherapy Promotes Intratumoral T Cell Infiltration and Improves Anti-PD-1 Immunotherapy.” "We had a hypothesis about how these treatments would work together, and when we did biopsies of patients' tumors we found that they were cooperating in just the way we thought they would," says lead author Dr. Antoni Ribas, Director of the Immunology Program at the UCLA Jonsson Comprehensive Cancer Center. Pembrolizumab is in a class of drugs called checkpoint inhibitors. These drugs are designed to get around one of the ways that cancer protects itself from the immune system: tumors can activate the body's natural protective response from autoimmunity, called a checkpoint, and thereby thwart cytotoxic T cells. The drugs work by taking the brakes off the checkpoint and allowing T cells to attack the tumor. "Some people put tumors into the categories of either 'hot' and 'cold,'" Dr. Ribas explains. "Hot tumors, also called inflamed tumors, have a lot of immune cells in and around them, but cold tumors do not." Drugs like pembrolizumab boost the response in tumors where immune cells are present but don't work in tumors where there is no immune response to boost. This is where T-VEC comes in.
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