PDCD1 and neoplasm: PD-1/Al@OV offered four advantages: (1) OVs can directly lyse cancer cells to kill tumor cells; (2) OVs can promote intratumoral T cell infiltration; (3) Released anti-PD-1 can block the PD-1/PD-L1 pathway in T cells to enhance the therapeutic effect of OVs; (4) Released alendronate can eliminate TAMs, thereby increasing OV concentration.