Mannose enhances anti-PD-1 therapy efficacy in ovarian cancer via modulating gut microbial metabolite [CD8]

The gut microbiome plays a critical role in enhancing the effectiveness of immune checkpoint blockade (ICB) therapy. Here, we demonstrate that oral supplementation with the prebiotics mannose slows tumor growth in immunocompetent mice in a manner dependent on the gut microbiota. This effect is associated with an increase in the abundance of Faecalibaculum. Mannose generates an immune-stimulatory tumor microenvironment (TME), characterized by a higher percentage of effector and memory CD8+ T cells, along with a notable immunoreactive gene expression signature. Crucially, mannose modulates the stemness program of CD8+ T cells and promotes the generation of progenitor exhausted CD8+ T cells (Tpex). Mechanistically, mannose enhances the production of the short-chain fatty acids (SCFA) propionate and butyrate by the gut microbiota. Administration of propionate and butyrate suppresses tumor progression and stimulates the expansion and differentiation of Tpex both in vivo and in vitro. Furthermore, mannose works synergistically with PD-1 blockade, resulting in tumor regression and enhanced differentiation of intratumoral Tpex into intermediate exhausted CD8+ T cells (Tex-int) and terminally exhausted CD8+ T cells (Tex-term). We also identified a gene signature related to mannose therapy that correlates with favorable responses to ICB across various cancers. Overall, our findings support the combination of mannose dietary supplementation with anti-PD-1 immunotherapy in treating ovarian cancer and suggest its potential for clinical application. Seven CD8+ T cells samples isolated from ascites of mouse models of peritoneal metastasis treated with or without co-treatment with propionate and butyrate.