Seethapathy H, Zhao S, Chute DF, et al. - Among patients (n = 1,016, average age = 63 (SD 13) years, 61% were men, and 91% were white) who were treated with checkpoint inhibitor therapy from May 2011 to December 2016 at Massachusetts General Hospital, researchers focused on the frequency, severity, cause, and predictors of AKI. They compared baseline serum creatinine, averaged 6 months prior to checkpoint inhibitor commencement date, vs all subsequent creatinine values within 12 months of beginning treatment. The development of AKI was found in 169 patients (17%). Stage 3 sustained AKI developed in 16 (2%) patients and dialysis was needed in four patients. A link was identified between proton pump inhibitor use at baseline and sustained AKI. Experts concluded a common occurrence of AKI in patients taking checkpoint inhibitor treatment. There were heterogeneous causes of sustained AKI in this population, which merit thorough evaluation. There is a necessity to better explain the role of PPI and other nephritis-inducing drugs in the development of sustained AKI.