CD19 and leukemia: In trial NCT02822326, a TLR2 Toll/IL-1 domain is incorporated in CAR-T, and the results showed that the tumor-targeting CD19-CAR-T2 cells augmented anti-leukemia responses in relapsed or refractory B cell acute lymphoblastic leukemia (B-ALL) patients with extramedullary involvement, competent in the eradication of extramedullary leukemia cells (257).