Abstract
Atezolizumab, a humanized antiprogrammed death ligand 1 monoclonal immunoglobulin G1 antibody, is a targeted therapeutic drug known as an immune checkpoint inhibitor. It is currently used to treat various types of cancer, including unresectable hepatocellular carcinoma (HCC), nonsmall cell lung cancer, urothelial cancer, and breast cancer, and is becoming a therapeutic option in the forefront of oncology treatment. However, it may sometimes lead to undesirable adverse reactions owing to the activation of immune responses in various organs. Cutaneous adverse reactions to atezolizumab are well known; however, cases of anaphylaxis are very rare. In this report, we present the first case of HCC who experienced near-fatal anaphylaxis to atezolizumab in South Korea.