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

Triple-negative breast cancer (TNBC) 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 TNBC is affected by immunocyte infiltration in the tumor microenvironment (TME). Phosphoglycerate mutase 1 (PGAM1) is a key enzyme involved in cancer metabolism; however, its role in the TME remains unclear. In this study, we aimed to investigate the role of PGAM1 in TNBC and determine the potential of PGAM1 inhibition in combination with anti-PD-1 immunotherapy. Our results showed that PGAM1 is highly expressed in TNBC and is associated with poor prognosis. In vivo experiments demonstrated that PGAM1 inhibition synergizes with anti-PD-1 immunotherapy, significantly remodeling the TME and leading to an increase in anti-tumor immunocytes, such as CD8+ T cells and M1-macrophages, and a reduction in immunosuppressive cell infiltration, including myeloid-derived suppressor cells, M2-macrophage, and Tregs. 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 TNBC.