PDCD1 and neoplasm: In addition to enhanced antitumor immunity and ameliorated tumor immunosuppressive microenvironment, DOX@3D-MPs treatment obviously upregulated the PD-1 expression of tumor-infiltrating CD8+ T lymphocytes (Supplementary Fig. 25a, c) and PD-L1 expression of tumor cells (Supplementary Fig. 25b, e) derived from H22 and 4T1 tumor-bearing mice.