Immune-related adverse events from immune checkpoint inhibitors: a retrospective analysis in a single-center veteran population

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Journal of Hematology Oncology Pharmacy





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BACKGROUND: Immune checkpoint inhibitors can cause immune-related adverse events. The incidence of and onset time to immune-related adverse events vary across therapies and clinical trials. Evidence is emerging regarding the real-world incidence of immune-related adverse events, but data are lacking for the US veteran population. OBJECTIVES: To analyze the incidence and time to immune-related adverse event onset after the start of immune checkpoint inhibitor therapy in the US veteran population, and to identify factors that may predict immune-related adverse event occurrence. METHODS: This was a retrospective study of US veterans who received at least 1 dose of an immune checkpoint inhibitor, alone or in combination, between January 1, 2014, and October 31, 2019, at the Veterans Affairs (VA) Long Beach Healthcare System in Long Beach, CA. Chart reviews were conducted using the Computerized Patient Record System to assess if any immune-related adverse events occurred after receiving a checkpoint inhibitor. The immune-related adverse events that were evaluated in the study included diarrhea/colitis, kidney injury, pneumonitis, thyroid disorder, and transaminitis, based on the National Comprehensive Cancer Network guidelines for the management of immunotherapy-related toxicities, version 1.2020. RESULTS: Of 140 patients who received checkpoint inhibitors during the study period, 31 had at least 1 immune-related adverse event, for a total of 37 events. The baseline characteristics among patients with immune-related adverse events and patients without such adverse events were not significantly different, except for thoracic cancer (19.4% vs 45%, respectively; P = .01) and the number of checkpoint inhibitor doses received (median, 9 vs 5 doses, respectively; P = .01). The severity of immune-related adverse events found in our study ranged from grade 1 to grade 3, with a median time to onset of 18 weeks. A logistic regression analysis did not uncover significant predictors for immune-related adverse event occurrence. Our findings showed incidence rates of immune-related adverse events that are similar to those in the literature, but our patients generally had a longer time to onset of adverse events. CONCLUSION: The incidence of immune-related adverse events in the veteran population at VA Long Beach Healthcare System is generally consistent with the incidence reported in the current literature. The longer time to the onset of adverse events in our study underscores the importance of ongoing monitoring during immune checkpoint inhibitor therapy, because the associated adverse events can occur at any time, and no patient factors were found to help predict such events.