A Tetramethylpyrazine-Releasing Hydrogel Potentiates CAR-T Cell Therapy Against Triple Negative Breast Cancer by Reprogramming Tumor Vasculatures

Background and Purpose:

Chimeric antigen receptor T (CAR-T) cell therapy has shown limited efficacy in solid tumors like triple-negative breast cancer (TNBC), largely due to the immunosuppressive tumor microenvironment characterized by hypoxia resulting from abnormal vasculature. Tetramethylpyrazine (TMP), an active component of the traditional Chinese medicine Ligusticum wallichii, possesses vasomodulatory properties, yet its potential to enhance CAR-T therapy via vascular remodeling remains unexplored. This study aims to investigate whether sustained intratumoral release of TMP can reprogram tumor vasculature to potentiate HER1-CAR-T cell therapy against TNBC.

Experimental Approach:

An injectable, hydrogen peroxide-responsive hydrogel (PEGDMA/FeCl₂) was developed for sustained intratumoral delivery of TMP (TMP@PEGgel). Its effects on vascular endothelial cells were assessed by evaluating VEGF expression, eNOS phosphorylation, and NO production. In TNBC-bearing mice, TMP@PEGgel was intratumorally injected, followed by intravenous administration of HER1-CAR-T cells. Tumor vascular normalization, hypoxia relief, CAR-T cell infiltration, survival, effector function, and therapeutic efficacy were comprehensively evaluated.

Results:

TMP treatment activated VEGF expression and the eNOS/NO axis in endothelial cells, promoting angiogenesis and vascular maturation. TMP@PEGgel enabled sustained intratumoral release of TMP, leading to prolonged vascular remodeling and significant alleviation of tumor hypoxia. This improved tumor microenvironment facilitated enhanced infiltration, prolonged survival, and augmented effector cytokine secretion (IL-2, TNF-α, IFN-γ) of HER1-CAR-T cells. Consequently, TMP@PEGgel-assisted HER1-CAR-T therapy synergistically suppressed TNBC tumor growth, achieving complete regression in some cases, without notable toxicity.

Conclusions and Implications:

TMP@PEGgel-mediated tumor vascular reprogramming effectively relieves hypoxia and enhances the therapeutic potency of HER1-CAR-T cells against TNBC. This study presents a novel and translatable strategy to potentiate adoptive cell therapy by remodeling the tumor vasculature using a traditional medicine-derived agent.