Human PD-1 (CD279), Fc fusion, Biotin-labeled. The understanding of the checkpoint signaling pathway involving the programmed death 1 (PD-1) receptor and its ligands (PD-L1/2) in tumor-induced immune suppression has been a critical advancement in immunotherapeutic drug development. Tumors that express PD-L1 can often be aggressive and carry a poor prognosis. The anti-PD-1 and anti-PD-L1 agents have a good safety profile and have resulted in durable responses in a variety of cancers, including melanoma, kidney cancer, and lung cancer. The PD-1/PD-L1 pathway in cancer is implicated in tumors escaping immune destruction and is a promising therapeutic target. The development of anti-PD-1 and anti-PD-L1 agents marks a new era in the treatment of cancer with immunotherapies.