We next examined the effects of PD-L1 on CAR-T cells or CAR exosomes in vivo, and injection of CAR exosomes notably inhibited the growth of tumours derived from MDA-MB-231 cells or SK-BR-3 cells, with or without combined PD-L1 treatment, whereas combined treatment of the CAR-T cells with the PD-L1 protein, but not with IgG isotype antibodies, inhibited the antitumour effect (Fig. 6f). The gene discussed is CD274; the disease is neoplasm.