Oncolytic Viruses: T-VEC and Others

Immunotherapy has become a standard for treatment of several advanced cancers such as melanoma, lung cancer, and head and neck cancer. Lymphocyte-rich tumor microenvironment is a predictor factor for response to immunotherapy. Although, theoretically, these tumor-infiltrating lymphocytes should be highly immunogenic, it has been shown that the tumor microenvironment by itself is immunosuppressive, and the tumor-associated antigens (TAAs) are weakly immunogenic, thus limiting spontaneous antitumor immunologic activity in most tumor types. Therefore, strategies to shift the balance between tumor growth and immunosuppressive tumor microenvironment while at the same time enhancing the magnitude of antitumor immune response are highly desired. Much of the immunotherapies available currently such as ipilimumab, pembrolizumab, and nivolumab to name a few disrupt these immunoregulatory circuits such as CTLA-4 and PD-1 and enhance antitumor immunity.