PDCD1 and cancer: PD-L1/TIGIT nanobodies augment T-cell activation by 40% in vitro, while VISTA/PD-L1 BsAbs promote enhanced cancer cell lysis (40–50%) through effector cytokines, and polymeric PD-1/PD-L1 BsAbs attain 90% tumor suppression in preclinical studies [73–76].