We found that in NSG xenograft models, the CD19/20/22CAR T-cells were able to overcome the inability of CD19CAR T-cells to control growth of CD19(−) leukemia cells from patients who failed CD19CAR T-cell therapy, as well as of the genetically-modeled CD19(−) escape variants (Raji.CD19KO). The gene discussed is CD19; the disease is leukemia.