Background：Durvalumab dur val" ue mab is a human recombinant monoclonal IgG1 kappa-isotype antibody to the ligand for programmed cell death receptor-1 PD-L1 which leads to enhanced T cell responses against cancer cells and is used in cancer immunotherapy. PD-1 is an important checkpoint molecule that modulates and down regulates T cell responses. Inhibition of the PD-L1 prevents its binding to the programmed cell death receptor 1 which is responsible for down regulating T cell responses. Inhibition of this pathway allows for a continued activation and proliferation of T cells. The subsequent enhancement of cytotoxic reactivity may play a beneficial role in cancer immunotherapy by breaking immunological tolerance to cancer cell neo-antigens. In several large multicenter studies, durvalumab therapy resulted in a prolongation of survival in patients with advanced, metastatic or unresectable urothelial carcinoma, and a proportion of patients had a long term remission.
