CD19 and neoplasm: Differently from moAbs, T-cells can cross the BBB and traffic to brain tissue and cerebrospinal fluid from blood flow to recognize tumor cells, as demonstrated by clinical response of melanoma brain metastasis after intravenous infusion of adoptive tumor-infiltrating lymphocytes and by the detection of CD19-CAR-T in cerebrospinal fluids of patients with ALL (19, 20).