PDCD1 and neoplasm: Anti-PD-1 × CTLA-4 BsAbs, including AK104,156 MEDI5752,157 and MGD019,158 are expected to synergistically inhibit checkpoint signaling pathways in PD-1/CTLA-4 double-positive tumor-infiltrated lymphocytes (TILs) while enhancing PD-1 degradation and CTLA-4 inhibition in the TME.157