Biomimetic Tumor Cell Membrane‐Encapsulated Nanoparticles Combine NIR‐II Photothermal Therapy and Chemotherapy for Enhanced Immunotherapy in Triple‐Negative Breast Cancer

Abstract To advance the understanding and potential treatment strategies for triple‐negative breast cancer (TNBC), particularly focusing on its high metastatic propensity and uncertain molecular targets, a biomimetic tumor cell membrane‐encapsulated nanodelivery system is developed for enhanced immunotherapy. This system is assembled with the second near‐infrared (NIR‐II) photothermal agent, chemotherapeutic drug, and programmed death‐ligand 1 (PD‐L1) inhibitors camouflaged by TNBC cell membranes. An NIR‐II Ag₂S quantum dots (QDs) is introduced for not only realizing pronounced imaging‐guided photothermal therapy (PTT), but also co‐activating immunogenic cell death (ICD) with chemotherapy. Homologous targeting and camouflage properties endowed the nanodelivery system with excellent biocompatibility and efficient delivery ability to the tumor site, demonstrating excellent synergistic therapeutic efficacy. The release of damage‐associated molecular patterns (DAMP) marked the induction of ICD, crucial for reshaping the immune microenvironment. Further integration of α‐PD‐L1 achieved a 56.5% immune checkpoint inhibition rate, synergistically amplifying immune response to ultimately activate key cytokines, thereby achieving pronounced anti‐tumor immunotherapy effects. Notably, this approach realized a considerable reduction of metastatic nodules by 51.2% in the TNBC lung metastasis model. The proposed nanodelivery system extended tumor remission and effectively reduced lung metastasis, paving the way for a reliable and promising approach in TNBC immunotherapy.