Although the therapeutic effects of CAR-T cells on hematological malignancies, especially CAR-T cells targeting CD-19, have been elucidated, the development of CARs for the treatment of solid tumors has been hindered by the paucity of optimal antigens, the inability of T cells to migrate to and infiltrate primary lesions, transgene immunogenicity and toxicity, ongoing evolution of cancer cells, possible existence of CSC populations, and the immunosuppressive tumor microenvironment. The gene discussed is CD19; the disease is neoplasm.