Effect of multifunctional biocatalytic nanoenzyme AuC@SCOF-Mn on photodynamic-immunoactivation cascade response and antitumor efficacy in triple negative breast cancer.

Abstract

e13139 Background: Triple-negative breast cancer (TNBC) is an aggressive subtype with no specific molecular targets and an immunosuppressive tumor microenvironment (TME). While immune checkpoint inhibitors (ICIs) show promise, their effectiveness is limited by immune evasion mechanisms. Photodynamic therapy (PDT) induces localized tumor cell death but has suboptimal effects on the immune system and TME. We developed AuC@SCOF-Mn, a novel nanoenzyme, to enhance PDT efficacy and activate antitumor immunity. Methods: AuC@SCOF-Mn is a multifunctional nanoenzyme composed of gold nanoclusters (AuNCs) integrated into the covalent organic framework (COF) with metallosalphen Mn centers. The AuNCs generate reactive oxygen species (ROS) under light exposure, enhancing PDT, while Mn centers catalyze ROS generation and modulate the immune response. In vitro , we evaluated the ability of AuC@SCOF-Mn to induce glutathione depletion, mitochondrial dysfunction, DNA damage, and apoptosis in 4T1 tumor cells. In vivo , its impact on tumor growth, immune cell infiltration, and recurrence was assessed in the TNBC mouse models. RNA-seq was conducted to reveal potential mechanisms. The potential for synergistic immune activation when combined with ICIs to against lung metastasis was also explored. Results: AuC@SCOF-Mn enhanced the ability of PDT to deplete GSH, inducing mitochondrial dysfunction as well as DNA damage, leading to extensive apoptosis of cancer cells in vitro . Besides, AuC@SCOF-Mn significantly inhibited tumor growth and enhanced CD8 + T cell and dendritic cell (DC) infiltration into the TME under light irradiation in vivo . It also polarized macrophages toward the pro-inflammatory M1 phenotype and reduced immunosuppressive regulatory T cells (T regs ) and myeloid-derived suppressor cells (MDSCs). RNA-seq revealed the significant upregulation of the cytokines-cytokines interaction signaling pathway to promote immune cell chemotaxis. The pro-inflammatory cytokine levels in both the TME and circulation were higher in the AuC@SCOF-Mn and PDT combined group than in the control and PDT-only groups, which helped inhibit tumor recurrence by long-term antitumor immunity. Moreover, combined with ICIs, AuC@SCOF-Mn suppressed lung metastasis via improving systemic immune responses in metastatic TNBC mice models. Furthermore, AuC@SCOF-Mn showed limited toxicity to the main organs and circulation system. Conclusions: The findings of this study suggest AuC@SCOF-Mn, as a promising nanoenzyme, can enhance PDT effects and activate the potent immune response to inhibit TNBC growth and recurrence with good biocompatibility. Its ability to promote immune cell infiltration and synergize with ICIs provides a novel strategy to improve metastatic TNBC outcomes with the potential for clinical translation.