Autologous T cells engineered to express a humanized anti-CD22 chimeric antigen receptor redirect T cells to CD22 on B-ALL blasts. CAR engagement triggers CD3ζ signaling (with costimulatory signaling), leading to T-cell activation, cytokine release, proliferation, and perforin/granzyme-mediated cytotoxic killing of CD22+ leukemia cells; used sequentially with CD19 CAR T cells to reduce antigen-loss escape.