Engineered CAR-T cells targeting CD19 or CD20 antigens are emerging as powerful therapies in hematologic B-malignancies, and CAR-T cells were found in CSF of several patients recruited to dedicated trials.81,82 CAR-T cells presence in CSF might be due to the enhanced cell trafficking through BBB promoted by IL6 release following CART infusion.83 Alternatively, authors have claimed that some cross-reactivity or undetectable expression of CD19 in the brain might trig CAR-T cells migration to CSF81. This evidence concerns the gene CD19 and cancer.