HEBP2-governed glutamine competition between tumor and macrophages dictates immunotherapy efficacy in triple-negative breast cancer.

Abstract

Immunotherapy demonstrates limited efficacy in triple-negative breast cancer (TNBC), influenced by intricate metabolic interactions within the tumor microenvironment. Here, we developed a single-cell RNA sequencing (scRNA-seq) immunotherapy cohort (N = 27) and a spatial transcriptomics cohort (N = 88) to elucidate metabolic crosstalk associated with therapeutic efficacy in TNBC. We illustrated that heme binding protein 2 (HEBP2)^high tumor cells (featured by active glutathione metabolism) and CCL3⁺ macrophages (characterized by oxidative metabolism) indicated immunotherapy efficacy and were quantitatively and spatially negatively correlated. HEBP2-mediated glutamine face-off between these cell types induced this phenomenon. Mechanistically, HEBP2 disrupted FOXA1 cytoplasmic phase separation, promoting its nuclear translocation to upregulate glutathione S-transferase P1 (GSTP1) expression and glutamine consumption in tumor cells. This metabolic shift induced ferroptosis of CCL3⁺ macrophages, impairing the antitumor immunity. The utilization of a GSTP1 inhibitor sensitized TNBC to immunotherapy. Collectively, we delineate a tumor-macrophage metabolic checkpoint governed by the HEBP2/GSTP1 axis and pioneer single-cell-level immunometabolism as a paradigm for evaluating immunotherapeutic vulnerabilities.