PGAM1 suppression remodels the tumor microenvironment in triple-negative breast cancer and synergizes with anti–PD-1 immunotherapy

Abstract Triple-negative breast cancer is a high-risk form of breast cancer with a high metastatic potential and lack of effective therapies. Immunotherapy has shown encouraging clinical benefits, and its efficacy in triple-negative breast cancer is affected by immunocyte infiltration in the tumor microenvironment. PGAM1 is a key enzyme involved in cancer metabolism; however, its role in the tumor microenvironment remains unclear. In this study, we aimed to investigate the role of PGAM1 in triple-negative breast cancer and determine the potential of PGAM1 inhibition in combination with anti–PD-1 immunotherapy. Our results showed that PGAM1 is highly expressed in triple-negative breast cancer and is associated with poor prognosis. In vivo experiments demonstrated that PGAM1 inhibition synergizes with anti–PD-1 immunotherapy, significantly remodeling the tumor microenvironment and leading to an increase in antitumor immunocytes, such as CD8+ T cells and M1 macrophages, and a reduction in immunosuppressive cell infiltration, including myeloid-derived suppressor cells, M2 macrophages, and regulatory T cells. Functional and animal experiments showed that this synergistic mechanism inhibited tumor growth in vitro and in vivo. We identified PGAM1 as a novel target that exhibits an antitumor effect via the regulation of immunocyte infiltration. Our results show that PGAM1 can synergize with anti–PD-1 immunotherapy, providing a novel treatment strategy for triple-negative breast cancer.