In vivo antileukemia effects by CD44v6.CAR28z⁺ T cells coexpressing a suicide gene. (A) T cells from AML (n = 3) and MM patients (n = 3) were transduced with the bidirectional LV and cultured with autologous leukemic blasts (left) or malignant plasma cells (right) in the presence (+) or absence (−) of MSCs. After 4 days, residual tumor cells were counted and analyzed by FACS. Antileukemia and antimyeloma effects by CD44v6.CAR28z⁺ T cells were measured as the elimination index for each case. (B) At the time of AML#4 leukemia appearance in the peripheral blood (arrow), NSG mice were treated with either bidirectional LV-transduced autologous CD44v6.CAR28z⁺ or with CTR.CAR28z⁺ T cells (n = 5 mice per group). Left: percentage of circulating CD33⁺/CD45dim leukemic blasts at different time points by FACS (mean ± SD). Middle: percentages of BM leukemic blasts from representative mice. Right: percentages of BM leukemic blasts from each mouse at 5 weeks. Results from an unpaired Student t test are shown for each time point (**P < .01).