Artesunate modulates the tumor microenvironment via STAT1/IRF1-mediated TAM repolarization and T cell activation in non-small cell lung cancer.

Background: In non-small cell lung cancer (NSCLC), M2-polarized tumor-associated macrophages (TAMs) induce T cell dysfunction and correlate with poor clinical outcomes. Recent studies have demonstrated that artesunate (AS) enhances antitumor immunity, but the underlying mechanisms of AS reprogramming TAMs and boosting T cell anti-tumor activity in NSCLC need further clarification.

Purpose: This study aims to clarify the molecular mechanisms by which AS induces TAM repolarization and enhances T cell activity to remodel the tumor microenvironment (TME) in NSCLC.

Methods: Lewis lung carcinoma (LLC)-bearing mice were treated with AS, and the subsets and activation status of immune cells in tumor were extensively analyzed. Subsequently, the effects of AS on macrophage polarization and T cell activation were evaluated in vitro which is further validated with publicly available clinical data. Finally, the therapeutic efficacy of AS combined with anti-PD-1 antibody was assessed in vivo.

Results: In vivo studies demonstrated that AS inhibited LLC progression, enhanced T cell infiltration and activity, and reprogrammed TAMs into an inflammatory phenotype, thereby alleviating T cell exhaustion within the TME. RNA-Seq data from CD45 cells isolated from LLC tumors revealed that AS significantly upregulated genes involved in phagosome formation and antigen processing and presentation, with the interferon signaling emerging as one of the potential key pathways mediating these effects. In vitro experiments further confirmed that AS promoted macrophage reprogramming, enhancing their phagocytic activity, antigen cross-presentation, and tumoricidal capacity. Additionally, AS activated T cells directly or indirectly via STAT1/IRF1-driven macrophage repolarization. Finally, AS potentiated the tumoricidal efficacy of anti-PD-1 antibodies in the LLC mouse model.

Conclusion: Our study demonstrates that AS reprograms the TME through STAT1/IRF1-mediated M1 TAMs repolarization and T cell activation, broadening our understanding of the immunotherapeutic potential of AS and warranting further preclinical and clinical evaluations on combination of AS and PD-1 blockade for NSCLC treatment.