First, at least one co-stimulatory signaling domain in the CAR is necessary; second, differential expression of target antigen on tumor and normal tissue is required; third, tumor antigens that are targeted by CAR-T cells could be suppressed, which leads to therapeutic failure (i.e., CD19 antigen loss after anti-CD19 CAR-T cell exposure in hematologic malignancies); fourth, lymphodepletion prior to CAR-T cell infusion is considered to be necessary at present; finally, significant side effects can occur, including cytokine release syndrome (CRS) and neurotoxicity [4]. The gene discussed is CD19; the disease is hematologic disorder.