Predictive factors for immunotherapy in melanoma

Immunotherapy has emerged as an exciting strategy for cancer treatment. Therapeutic blockade of immune checkpoint regulators favors the ability of T cell responses to increase anti-tumor immunity. The cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed cell death-1 (PD-1) are two T cell-inhibitory receptors with independent mechanisms of action. Immune checkpoint inhibitors targeting either CTLA-4, PD-1 or its ligand PD-L1 are currently yielding promising results in terms of efficacy in several clinical studies with melanoma patients and are being developed and tested as immunotherapy agents for multiple cancer types. To date, no reliable predictors of activity and efficacy of immunotherapy have yet been identified or validated. Even so, determining which patients derive clinical benefit from immune checkpoint agents remains an important clinical question and efforts to identify predictive markers of response are ongoing. This article reviews the current potential predictive factors for CTLA-4 and PD-1/PD-L1 immune checkpoints inhibitors in melanoma.