CD19 and lymphoma: After promising preclinical results demonstrated that the blockade of PD-1 could increase the in vivo efficacy of CD19-specific CAR-T cells [51,52,53], seminal clinical experience on the combination of checkpoint blocking antibodies and CAR-T cells (Figure 5) was obtained in a B-cell lymphoma patient who evinced progressive lymphoma despite treatment with CD19-specific CAR-T cells [54].