Harnessing the Immune System as a Therapeutic Tool in Virus-Associated Cancers.

IMPORTANCE: There are at least 7 viruses implicated in the pathogenesis of 10% to 15% of all human cancers worldwide. Despite a high prevalence of infection with these viruses, only a minority of infected individuals develop a subsequent malignant tumor, underscoring the important role that host and environmental factors have in cancer development. This article reviews the mechanisms of viral carcinogenesis, with an emphasis on the viral evasion of the host immune system, and discusses how to harness the immune system effectively as a therapeutic tool in select cancers. OBSERVATIONS: Immune evasion mechanisms of these viral infections have an important role in carcinogenesis. Increased understanding of these mechanisms has paved the way for using immunotherapy to treat virus-associated cancers. This study summarizes the use of adoptive cell therapy, tumor vaccines, immune checkpoint inhibitors, and combination immunotherapies in the treatment of select virus-associated cancers. CONCLUSIONS AND RELEVANCE: Immunotherapy is proving to be a useful strategy in the treatment of virus-associated cancers. A greater understanding of the processes of immune evasion in chronic infections and malignant tumors will continue to help in the goal of optimizing immunotherapy, which will in turn translate into remission and long-term survival in this patient population.