PDCD1 and neoplasm: Therapeutic window and optimal schedule uncertain; cytokine-related toxicities remain possible; manufacturing and analytics complex; evidence mostly preclinical or early phase, so long-term benefit vs standard PD-1/PD-L1 mAbs unclear;Degree and consistency of tumor-selective activation still being defined; added molecular complexity and potential immunogenicity; distribution remains IgG-like, so deep-tissue penetration is still constrained; optimal combinations and long-term outcomes vs standard PD-1/PD-L1 blockade not established