CD19 and hematologic disorder: In this review, we summarize the short- and long-term toxicity, such as secondary T-cell tumors and lethal CAR tumors, of patients with hematologic malignancies treated with CD19-CAR-T cells, including cytokine release syndrome (CRS), ICANS, and secondary malignancies with low occurrence rates but high mortality, such as secondary T cell tumors and lethal CAR tumors, which may be related to the gene modification mechanism of viral vectors currently approved for CAR-T cells.