Pembrolizumab (MK-3475) is a monoclonal antibody that binds to the PD-1 receptor on T cells and prevents binding to its ligands PD-L1 and PD-L2. Blocking this receptor frees T cells from the inhibitory effects of PD-L1 and allows them to mediate antitumor effects against cancer cells. In a large Phase I study of 411 patients with melanoma, high durable response rates over a range of doses and schedules have been shown with very little toxicity. A Phase III study of pembrolizumab comparing two schedules of administration with the current standard treatment with the anti-CTLA-4 monoclonal antibody is in progress. Combinations with other checkpoint inhibitors as well as other anticancer agents are also being evaluated. Approval of pembrolizumab for the treatment of melanoma is expected.
Keywords: 1-year survival; PD-L1; PD1 checkpoint inhibitors; PFS; melanoma; response rates.