PDCD1 and gastric cancer: Overall, response rates to anti-PDL1 therapy appear to be lower than to anti-PD-1 for patients with gastric cancer, and it is possible that enhancing response rates by using a combination approach such as mitogen-acivated protein kinase (MEK) inhibition plus anti-PDL1 therapy in colorectal cancer may be required in order to further develop this class of compound [35].