Inhibitors of Cytotoxic T Lymphocyte Antigen 4 and Programmed Death 1/Programmed Death 1 Ligand for Metastatic Melanoma, Dual Versus Monotherapy-Summary of Advances and Future Directions for Studying These Drugs.

Immense progress in the field of cancer immunotherapy has garnered several novel and successful treatments for metastatic melanoma. Beginning with therapies targeting cytotoxic T lymphocyte antigen 4 (CTLA-4), objective response rates, overall survival, and long-term survival were significantly increased when compared with glycoprotein 100 vaccine therapies. Expanding the breadth of therapies aimed to "release the breaks" on the active immune system, anti-programmed death 1 (PD-1) and anti-programmed death 1 ligand (PD-L1) therapies further improved overall survival, progression-free survival, and objective tumor response while exhibiting more favorable safety profiles compared with ipilimumab and to chemotherapy agents. Given the power of these agents as monotherapies, a combination approach sought to combine the anti-CTLA agent ipilimumab and anti-PD-1 agent, nivolumab, to form a double-pronged attack and target several mechanisms within the active immune system. Given the promise in elevated response rates and progression-free survival, the future appears promising along the immunotherapy front. Continuing the push for progress, biomarkers to uncover the profile of responders to the various therapies will become vital in the treatment of metastatic melanoma patients. Here, we highlight the advances of CTLA-4 and PD-1/PD-L1 inhibitors in the metastatic melanoma setting and discuss future directions for uncovering the full potential of these therapies.