Rare irAEs associated with immune checkpoint inhibitor therapy

INTRODUCTION: Immune checkpoint inhibitors (ICIs), although revolutionary in the field of oncology, have been associated with immune-related adverse events (irAEs) that affect nearly every organ of the body. Many common AEs are well documented, but in this review, we highlight some rare irAEs that are mostly limited to reports of observational or case studies. Although these irAEs can be difficult to associate with ICI use due to their scarcity and often delayed onset, understanding and characterizing these rare irAEs is crucial to refining treatment strategies and improving outcomes for patients with cancer receiving ICIs. AREAS COVERED: This review covers the rare irAEs affecting various organ systems, including cardiac, dermatological, endocrine, gastrointestinal, hematological, hepatobiliary, neurological, ocular, pancreatic, renal, and rheumatological. Information regarding irAEs compiled in this review are largely derived from case reports and case series and includes discussion surrounding proposed etiology, phenotype, and treatment of AEs. EXPERT OPINION: Rare irAEs can occur in nearly all organ systems. Although it is difficult to attribute causation of an AE to ICIs, it is important for clinicians to be aware of possible AEs to rapidly diagnose and treat potential symptoms. Further research should focus on strategies to improve recognition of rare irAEs.