Abstract
With combination immunotherapy, the 5-year survival of patients with advanced melanoma is now approximately 50%. Outcomes can still be further improved, and evaluating new immune checkpoint targets is an attractive possibility. Patients with advanced melanoma have a reduced immune response to tumors, owing to an elevated expression of inhibitory receptors on tumor antigen–specific T cells, combined with exhaustion of the immune system by persistent antigenic stimulation. An immune checkpoint is a regulator of the immune system that is important for maintaining self-tolerance (the ability of the immune system to recognize self antigens as harmless while appropriately mounting a response to . . .