Abstract
The number of patients with cancer qualifying for treatment with immune checkpoint inhibitors (ICIs) continues to increase, and a clearer understanding of the mechanisms underlying their activity-driven side effects, or immune-related adverse events (irAEs), has become crucial. Patients receiving ICIs can develop irAEs in any organ, and numerous studies have suggested that irAE development may be associated with improved ICI efficacy. However, the robustness and magnitude of such associations are unclear, and little is known about the relationship between irAE development and ICI efficacy at the individual organ level. A precise understanding of these links could improve patient care and provide further insight into the immunological mechanisms underlying both irAE development and ICI efficacy. We herein review the prognostic implications of irAEs occurring in patients with cancer treated with ICIs and discuss outstanding issues that should be addressed in future studies.