Tillman BF, et al. - Researchers conducted a systematic review of infectious events with the Bruton tyrosine kinase (BTK) inhibitor ibrutinib in the treatment of haematologic malignancies. Based on the findings, they recommended prudent consideration of the impacts of ibrutinib use on host immunity. Within prospective clinical trials, a high rate of serious adverse infectious events was observed. A role of both BTK and interleukin-2-inducible T-cell kinase (ITK) inhibition for the increased events was suggested. The reporting of adverse events between trials, journals, and conference reports showed considerable variability.