Park JH, et al. - Fifty-three adult patients with relapsed B-cell acute lymphoblastic leukemia (B-ALL) enrolled in phase I clinical trial at Memorial Sloan Kettering Cancer Center were investigated for infectious complications that followed CD19 chimeric antigen receptor (CAR) T-cell therapy. Observations suggest infections are a common occurrence in adult patients with relapsed B-ALL following CD19 CAR T-cell therapy. Cytokine release syndrome (CRS) grade 3 or higher had an independent correlation with an increased risk of subsequent infection, and with bloodstream infection, especially. Understanding these infectious complications is important for developing efficacious prophylactic and other supportive care measures.