Huayu Wan enhances immune checkpoint inhibitor efficacy in triple-negative breast cancer by normalizing tumor vasculature and remodeling the tumor immune microenvironment.

BACKGROUND

Huayu Wan (HYW), a Traditional Chinese Medicine (TCM) formulation widely used in the clinical treatment of cancer, has demonstrated anti-tumor activity and augments chemotherapy efficacy by improving intratumoral drug delivery in non-small cell lung cancer. However, its efficacy and role in enhancing the response to immune checkpoint inhibitors (ICIs) for the treatment of triple-negative breast cancer (TNBC) remain unclear.

OBJECTIVE

To study the underlying mechanisms of HYW in enhancing the efficacy of ICIs for TNBC treatment.

MATERIALS AND

METHODS

In the 4T1 TNBC model, tumor growth, vascular structure/function, immune cell infiltration, angiogenic factors and effector cytokines were evaluated using ultrasound imaging, immunohistochemistry, immunofluorescence, and ELISA. HYW's effects on angiogenesis were validated via in vitro assays (HUVEC proliferation, tube formation, wound healing and transwell invasion) under normal oxygen/hypoxic conditions.

RESULTS

TCGA data and network pharmacology identified VEGFA and the PI3K-Akt/HIF-1 signaling axis as key targets of HYW. HYW significantly enhanced ICIs efficacy, with a tumor inhibition rate of 36.55% (vs. 5.01% for ICIs alone). Mechanistically, HYW: Normalized tumor vasculature: Restored the balance between proangiogenic and antiangiogenic factors (reduced VEGFA/bFGF, increased TSP-1/PF4), enhanced pericyte coverage and improved vascular maturity, and enhanced intratumoral perfusion (ultrasound imaging). Alleviated hypoxia: Inhibited HIF-1α and reduced hypoxic regions (Hypoxyprobe staining). Remodeled the TME: Promoted CD8+ T cell infiltration, increased effector cytokines (GZMB, IFN-γ, TNF-α), and inhibited CD8+ T cell exhaustion, downregulated exhaustion markers (Tim3, CD244, CD101, PD-L1). Inhibited PI3K-Akt-mTOR signaling: Reduced downstream HIF-1α/VEGFA expression, breaking the hypoxia-angiogenesis-immunosuppression cycle.

CONCLUSION

HYW enhances ICIs efficacy in TNBC by normalizing tumor vasculature and remodeling the tumor immune microenvironment (TIME), which provides a novel rationale for combining TCM with ICIs to improve TNBC treatment outcomes.