An autologous, gene-modified CAR T-cell therapy that co-targets CD19 and CD20. Patient T cells are engineered to express a chimeric antigen receptor recognizing CD19 and CD20 on B cells; antigen binding triggers T-cell activation, cytotoxic killing, cytokine release, and in vivo expansion, resulting in deep B-cell depletion and aiming to reduce antigen escape versus single-antigen approaches.