CD274 and neoplasm: Since CD28 is a co-stimulatory molecule on the process of T-cell activation while PD-L1 is a co-inhibitory molecule expressed on the surface of tumor cells, co-targeting CD28 and PD-L1 using bsAbs may enhance antitumor activity via the dual pathway mechanism, compared with monospecific CD28 or PD-L1 antibodies alone.