Macrophage Membrane-Coated Nano- Gemcitabine Promotes Lymphocyte Infiltration and Synergizes AntiPD-L1 to Restore the Tumoricidal Function

The limited lymphocyte infiltration and exhaus-tion of tumoricidal functions in solid tumors remain a formidable obstacle to cancer immunotherapy. Herein, we designed a macrophage membrane-coated nano-gemcitabine system (MNGs) to promote lymphocyte infiltration and then synergized anti-programmed death ligand 1 (antiPD-L1) to reinvigorate the exhausted lymphocytes. MNGs exhibited effective intratumor-permeating and responsive drug-releasing capacity, produced notable elimination of versatile immuno-suppressive cells, and promoted lymphocyte infiltration into cancer cell regions in tumors, but over 50% of these infiltrated lymphocytes were in the exhausted state. Compared with MNG monotherapy, the MNGs+antiPD-L1 combination produced 31.77% and 30.63% reduction of exhausted CD3+CD8+ T cells and natural triller (NK) cells and 2.83-and 3.17-fold increases of interferon-gamma (IFN-gamma)-positive subtypes, respectively, thereby resulting in considerable therapeutic benefits in several tumor models. Thus, MNGs provide an encouraging strategy to promote lymphocyte infiltration and synergize antiPD-L1 to restore their tumoricidal function for cancer immunotherapy.