Autologous T cells are genetically engineered to express dual chimeric antigen receptors recognizing CD19 and CD20 on B cells. Antigen binding triggers CAR signaling (CD3ζ with costimulatory domains), driving T‑cell activation, expansion, cytokine release, and perforin/granzyme‑mediated cytotoxic killing of malignant B cells. Dual targeting aims to reduce antigen‑loss escape; on‑target effects include B‑cell aplasia.