Engineered oncolytic viruses to treat melanoma: where are we now and what comes next?

INTRODUCTION: Melanoma treatments have evolved rapidly in the past decade and have included the use of intratumoral injections of engineered oncolytic viruses. One such oncolytic virus is talimogene laherparepvec (T-VEC), which is the first approved therapy of its kind for use in recurrent, unresectable stage IIIB-IVM1a melanoma. Additional oncolytic viruses and their uses in combination with other interventions are currently under investigation. Areas Covered: Oncolytic viruses are being evaluated as immunotherapies for a variety of advanced malignancies. In this article we review T-VEC, the only FDA-approved engineered oncolytic virus, in addition to ongoing research regarding other oncolytic viruses for treatment of advanced melanomas. Finally, we discuss opportunities to improve these therapies through viral, host, and tumor-related modifications. Expert Opinion: Engineered and naturally oncolytic viruses have demonstrable local and systemic efficacy as immunotherapies in cancer. T-VEC leads the way with improved survival outcomes for unresectable, stage IIIB - IVM1a melanoma as a monotherapy, and is demonstrating superior results in combination with systemic checkpoint inhibitors. Additional viral vectors show acceptable safety profiles and varying degrees of efficacy in targeting melanoma. The indications for use of oncolytic viruses will expand as their efficacy and appropriate usage is better understood in coming years.