CTLA4 and neoplasm: Recently, “immunovirotherapy” strategies to enhance the oncolytic efficacy of MeV have been developed with the introduction of immunomodulatory transgenes (GM-CSF, IFN-β, IL-12 and IL-15, etc.)and antibodies against immune checkpoint inhibitors (cytotoxic T-lymphocyte antigen-4, CTLA-4 and programmed cell death-1, PD-1) that stimulate the native anti-tumor immune response.