Checkpoint Inhibitor Pneumonitis: Mechanisms, Characteristics, Management Strategies, and Beyond.

Checkpoint inhibitor pneumonitis (CIP) is a toxicity of immune checkpoint blockade (ICB) that can be highly morbid and at times fatal. Here, we review the proposed biologic mechanisms of CIP, epidemiology and risk factors for CIP development, diagnostic work-up and management strategies for CIP, and future directions of CIP research. CIP incidence appears to be greater in real-world populations and may continue to rise as FDA approvals for ICB continue to expand to multiple malignancies. Multiple retrospective studies and case series have identified potential risk factors for CIP. Several society guidelines have helped to unify the classification of CIP severity and standardize treatment approaches but significant gaps remain, including formal validated diagnostic criteria for CIP. While significant strides have been made in enhancing the knowledge and management of CIP, ongoing research is needed to continue to advance our understanding of the biologic underpinnings of CIP, as well as optimize diagnostic and management strategies for this potentially devastating toxicity.