A drug that binds to the protein PD-L1 to help immune cells kill cancer cells better and is used to treat many different types of cancer, including cancers that express PD-L1. Atezolizumab is used alone or with other drugs to treat certain types of hepatocellular carcinoma (a type of liver cancer), non-small cell lung cancer, small cell lung cancer, breast cancer, and urothelial cancer (a type of bladder cancer). It is also being studied in the treatment of other types of cancer. Atezolizumab 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 Tecentriq.