Predicting the response to anti-PD1 therapy in metastatic melanoma

Checkpoint inhibitor therapy has proven effective in metastatic melanoma and a range of other tumor entities including non-small cell lung carcinoma, Hodgkin lymphoma and renal cell carcinoma. Despite the impressive and often durable induction of tumor regression, 60–70% of patients with metastatic melanoma do not respond to single agent therapy with the anti-programmed death (PD)-1 antibodies pembrolizumab (1) or nivolumab (2). Combination treatment with ipilimumab, an anti-cytotoxic T-lymphocyte-associated protein (CTLA)-4 antibody, has resulted in higher response rates of 58%; however, this benefit comes with around 55% grade 3/4 side effects (2).