CD274 and neoplasm: PD-L1-dependence in vitro and in vivo, tumor infiltration, cytokine release, BsTE:T killing activity, and IFN-γ production, in addition to PD-L1+ exosomes on the PD-L1 KO tumors (MO5 and MC38), suggest that tumor-derived exosomes with tumor antigens play an important role in the enhancement and infiltration of BsTE:T.