Design and in vitro characterization of bispecific CARs. (A) Schematics of bispecific CAR T-cell formats. (B) Top panels: lysis of the indicated tumor cell lines by CD19, CD79a, and bispecific CD79a-CD19 CAR T cells. tCD79a-CD19 refers to tandem CAR; bCD19-CD79a refers to bicistronic CAR. Bottom panel: lysis of the indicated tumor cell lines by CD19, CD79b, and bispecific CD79b-CD19 CAR T cells. tCD79b-CD19 refers to tandem CAR; bCD19-CD7b refers to bicistronic CAR. (C) CAR T-cell IL-2 and IFN-γ production measured by ELISA. Data given in (A-B) are means ± SEM from 3 independent experiments. ELISA, enzyme-linked immunosorbent assay; SEM, standard error of the mean.