PDCD1 and neoplasm: Thus, the use of immune checkpoint inhibitors can counteract the PD-1/PD-L1-mediated immunosuppressive effects of radiotherapy, and in many tumors, such as breast cancer [72], melanoma [73], kidney cancer [74], and colorectal cancer [74,75,76], immunotherapies and radiation synergize to inhibit tumor growth and improve survival in mice.