Immunotherapy of melanoma: Present options and future promises

Metastatic melanoma is notorious for its immune evasion and resistance to conventional chemotherapy. The recent success of ipilimumab, a human monoclonal antibody against cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), in increasing the median survival time and stabilizing the disease progression renewed, hopes in treatment for melanoma. Currently, ipilimumab and high-dose interleukin-2 (IL-2; Aldesleukin) are approved as monotherapies for the treatment of patients with unresectable advanced melanoma, and pegylated interferon-alpha 2b (p-IFN-alpha 2b) is approved as an adjuvant for the treatment of patients with surgically resected high-risk melanoma. The present review describes the currently approved immune-modulators and the promising immune-based interventions that are currently in clinical trials. We present the four commonly used strategies to boost immune responses against the tumors; monoclonal antibodies, cytokines, cancer vaccines, and adoptive T cell transfer. The corresponding lists of ongoing clinical trials include details of the trial phase, target patients, intervention details, status of the study, and expected date of completion. Further, our review discusses the challenges faced by immunotherapy and the various strategies adopted to overcome them.