CD19 and chronic myelogenous leukemia, BCR-ABL1 positive: To investigate whether the reduction of TOX2 that impairs TCM cell outgrowth can decrease the proliferative potency of CAR T cells, we performed a serial stimulation experiment using CAR T cells and irradiated K562 chronic myeloid leukemia (CML) cells engineered to express the CD19 extracellular domain.