CTLA-4 and PD-1/PD-L1 Blockade: New Immunotherapeutic Modalities with Durable Clinical Benefit in Melanoma Patients

Immune checkpoint blockade with monoclonal antibodies directed at the inhibitory immune receptors CTLA-4, PD-1, and PD-L1 has emerged as a successful treatment approach for patients with advanced melanoma. Ipilimumab is the first agent associated with a documented improved overall survival benefit in this patient population. A striking attribute of CTLA-4 blockade is the durability of objective responses, leading to speculation of a possible cure for some patients. Many tumor responses achieved with PD-1 and PD-L1 inhibition were durable in the phase I trials and were seen in a higher proportion of patients with melanoma than typically observed with ipilimumab. Biomarker development to identify the subset of…