Monoclonal antibodies have always been the hot spot for immunotherapy and the front line of competition for pharmaceutical giants because monoclonal drugs are very lucrative. From the FDA-approved rituximab against CD20 in 1997, to later monoclonal antibodies against HER2, CD52, EGFR and VGFR, each one is a heavyweight bomb. The hottest antibodies in 2014 were BMS’s and Merk’s monoclonal antibody against PD-1, the star molecule of immunotherapy, which was approved in Japan for advanced melanoma, and Merk’s monoclonal antibody, which was approved by the FDA in the US, also for advanced melanoma. Roche’s antibody against PD-1’s ligand, PD-L1, is also in clinical trials and is expected to be approved for clinical use soon as well. PD-1 is mainly expressed in activated T and B cells and functions to inhibit cell activation, which is a normal self-stabilizing mechanism of the immune system, as excessive T/B cell activation can cause autoimmune disease, so PD-1 is a talisman for our body. However, the tumor microenvironment induces infiltrating T cells to overexpress PD-1 molecules, and tumor cells overexpress PD-L1 and PD-L2, ligands of PD-1, resulting in continuous activation of the PD-1 pathway in the tumor microenvironment and suppression of T cell function to kill tumor cells. antibodies to PD-1 can block this pathway and partially restore the function of T cells so that these cells can continue to kill tumor cells. The anti-cancer effects of PD-1 antibodies are unprecedented and have time and again created a black whirlwind at the annual American Clinical Oncology Conference. According to the editorial board of the prestigious journal New England Journal of Medicine, the effect of PD-1 antibodies is the best anti-cancer effect in the past 30 years. According to current clinical trials, PD-1 antibodies control cancer progression in 50% of skin cancer patients and cure about 10% of skin cancer patients; they also control 24% of patients with recalcitrant non-small cell lung cancer, and BMS’s latest clinical trial showed that their PD-1 monoclonal antibody kept 41% of patients alive for more than a year. Clinical trials are also underway using PD-1 antibodies against kidney, stomach, breast, bladder, blood, head and neck, bowel and brain cancers. Some analysts believe that the market for PD-1 antibodies could reach $35 billion.