Qingrehuoxue formula enhances anti-PD-1 immunotherapy in NSCLC by remodeling the tumor immune microenvironment via TREM2 signaling.

OBJECTIVE: This study evaluated the anti-cancer effect of the Qingrehuoxue Formula (QRHXF) and explored its synergistic mechanisms with anti-programmed cell death protein 1 (anti-PD-1), focusing on the tumor mircroenvironment (TME) in non-small cell lung cancer (NSCLC). METHODS: The major components of QRHXF were quantified using mass spectrometry. Subcutaneous tumor mice models of Lewis lung carcinoma (LLC) were established. Mice were divided into five groups identified for pharmacodynamics: model, QRHXF (low-dose and high-dose), anti-PD-1, and anti-PD-1 + QRHXF. Tumor pathology was assessed using hematoxylin and eosin staining. Inflammatory factors were evaluated via ELISA and q-PCR. Flow cytometry was employed to quantify tumor-infiltrating immune cells. Immunofluorescence staining and western blotting (WB) were used to assess tumor angiogenesis and metastasis and confirm molecular targets and pathways. RESULTS: Animal experiments showed that QRHXF inhibited subcutaneous tumor growth in NSCLC, with the combined therapy of QRHXF and anti-PD-1 showing superior efficacy. Particularly, QRHXF reduced extracellular matrix deposition and tumor angiogenesis to inhibit tumor metastasis. Furthermore, QRHXF downregulated tumor-infiltrating M2 macrophages and enhanced T-cell cytokine activity, upregulating the antitumor immune response. The combination of QRHXF and anti-PD-1 could augment the effects of immunotherapy. Mechanistically, QRHXF exerted its antitumor activity by inhibiting targeting triggering receptor expressed on myeloid cells 2 (TREM2) and PI3K/AKT/STAT6 pathways. CONCLUSION: QRHXF enhanced antitumor immune responses in NSCLC via TREM2 and modulation of the PI3K/AKT/STAT6 signaling pathway, reducing chemotactic infiltration of M2 tumor-associated macrophages within the TME. This suggests its potential as an adjuvant immune therapy for improved patient outcomes.