Seethapathy H, Zhao S, Chute DF, et al. - Among 1,016 patients who received checkpoint inhibitor therapy from May 2011 to December 2016 at Massachusetts General Hospital, researchers undertook this inquiry to define the frequency, severity, cause, as well as the factors predictive of AKI in this real-world population. They compared baseline serum creatinine, averaged 6 months prior to checkpoint inhibitor initiation date, vs all subsequent creatinine values within 12 months of commencing treatment. The study sample had an average age of 63 (SD 13) years (61% men, and 91% white). AKI development was reported in 169 patients (17%) and sustained AKI was detected in 82 patients (8%). Potential checkpoint inhibitor–related AKI was detected in 30 patients (3%). A link was identified between proton pump inhibitor (PPI) use at baseline and sustained AKI. Findings revealed a common occurrence of AKI in patients receiving checkpoint inhibitor therapy. In these patients, the reasons for sustained AKI were heterogenous and deserve a thorough assessment. There is a necessity to better determine the role of PPI and other nephritis-inducing drugs in the development of sustained AKI.