Retrospective cohort study of late-onset immune-related adverse events after immune checkpoint inhibitor therapy for cancer

The use of immune checkpoint inhibitors (ICIs) is increasing. Little is known about the frequency of late-onset immune-related adverse events (ir AEs) and the patient-specific risk factors associated with their development. A retrospective cohort study at Massachusetts General Hospital (Boston) included 795 patients hospitalized for irAEs after use of ICI. Among these patients, 14.7% presented within 6 to 12 months after the initial ICI exposure, and 10.8% presented more than 12 months after exposure. The irAEs most likely to present late included those involving the kidney (31%) and hematologic organ systems (21.7%). The authors conclude that late irAEs are possible, with a subset admitted for irAE management years after ICI start, underscoring the need for ongoing health care professional vigilance for potential irAEs regardless of elapsed time from ICI therapy.