A drug that binds to the protein PD-L1 to help immune cells kill cancer cells better and is used to treat different types of cancer. Imfinzi is used alone or with other drugs to treat adults with certain types of extensive-stage small cell lung cancer, stage III non-small cell lung cancer, or urothelial carcinoma (a type of bladder cancer) that is advanced or has spread to other parts of the body. It is also being studied in the treatment of other types of cancer. Imfinzi may block PD-L1 and help the immune system kill cancer cells. It is a type of monoclonal antibody and a type of immune checkpoint inhibitor. Also called durvalumab.