PDCD1 and melanoma: In a trial of solid tumors, including colorectal cancer, melanoma, and renal cell carcinoma, 17 patients who received a combination therapy of an anti-GITR antibody agonist (MK-1248) and humanized PD-1 monoclonal antibody pembrolizumab reached to an objective response rate of 18% versus no response in 20 patients who received MK-1248 monotherapy (Figure 2) (133).