ERBB2 and neoplasm: Similar to that in culture medium, HER2.28ζ/PD-L1.BB CAR-T cells showed superior tumor-killing activity, and formed obviously larger cell clusters when co-incubated with SKOV3PD-L1 cells for 24 h, as compared to HER2.28ζ CAR-T cells and PD-L1.BB CSR-T cells (Fig. 3e).