With regards to dosage and efficacy, Barrett et al. (34) showed that human mRNA-electroporated CD19-specific CAR-engineered CTLs had potent in vitro antileukemic killing activity against CD19+ cell lines and reduced disease burden within 1 day after injection of a single dose in a mouse model xenografted with human CD19+ leukemia cells. This evidence concerns the gene CD19 and leukemia.