PDCD1 and neoplasm: When considering the general efficacy of anti-PD-1/PD-L1 therapies, it is widely seen that these therapies have a greater response rate in tumors expressing PD-L1 (PD-L1+) than tumors without PD-L1 expression (PD-L1−) across various forms of anti-PD-1/PD-L1 inhibitor therapies and various tumor types [15,16].