Combination of APS, HMGN1, and anti-TNFR2 antibody remodels the tumor immune microenvironment to enhance antitumor immunity in colorectal cancer

• Astragalus polysaccharide synergizes with HMGN1 and anti-TNFR2 antibody in a colorectal cancer model. • Combination therapy markedly suppresses tumor growth in murine colorectal cancer. • Enhances CD8 + T cell activation and reduces treg-mediated immunosuppression. • Induces durable and tumor-specific immune memory responses. • Provides a promising immunotherapeutic strategy for CRC treatment. Astragalus polysaccharide (APS), a major bioactive component of Astragalus membranaceus , has shown antitumor potential through modulation of the tumor microenvironment (TME) and immune responses. High mobility group nucleosome binding domain 1 (HMGN1), a natural agonist of TLR4, promotes dendritic cell (DC) maturation, whereas an anti-TNFR2 antibody relieves immunosuppression by targeting regulatory T cells (Tregs). Although immunotherapy holds promise for the treatment of colorectal cancer (CRC), more effective combination strategies are still needed. Here, we investigated the therapeutic efficacy of APS in combination with HMGN1 and an anti-TNFR2 antibody in a murine CRC model. This triple combination regimen eradicated CT26 tumors and induced durable, tumor specific immune memory. Mechanistic analyses showed that the treatment activated DCs in vitro and induced profound remodeling of the TME in vivo, including increased CD8 + T cell infiltration and reduced Treg abundance. The therapy was also associated with altered cytokine production profiles and downregulation of Tim-3, a marker of T-cell exhaustion. These findings indicate that APS combined with HMGN1 and an anti-TNFR2 antibody exerts a synergistic antitumor effect by simultaneously enhancing antigen presentation, relieving immunosuppression, and restoring T-cell function. In conclusion, this therapeutic approach holds promise as a novel and effective treatment strategy for CRC.