Mechanistic insights into cordycepin-enhanced CTLA-4 blockade efficacy via Eubacterium rectale-mediated immunomodulation in colon cancer.

Colon cancer remains a therapeutic challenge due to limited efficacy of current treatments. This study investigates the synergistic antitumor effects of cordycepin combined with CTLA-4 inhibitors, focusing on their ability to reshape the gut microbiome. By integrating multi-omics approaches, we elucidate the mechanisms underlying the enhanced efficacy of this triple therapy. Our findings reveal that cordycepin combined with CTLA-4 inhibitors significantly improves antitumor efficacy in the MC38 colon cancer mouse model. This enhancement is mediated by the critical role of the Eubacterium brachy group in modulating the tumor immune microenvironment. Based on these results, we propose a "microbiome-immune" triple therapy strategy involving cordycepin, CTLA-4 inhibitors, and Eubacterium rectale. Non-targeted metabolomics analysis using LC-MS identified specific activation of the histidine metabolism pathway, with elevated levels of the key metabolite Cetirizine N-Oxide potentially contributing to enhanced immune activity. Single-cell transcriptomic analysis demonstrated that the triple therapy significantly increased the responsiveness of tumor antigen-specific CD8 T cells to CTLA-4 inhibitors, thereby boosting their antitumor activity. Moreover, the triple therapy not only enhanced the antitumor functionality of conventional effector CD4 T cells but also effectively prevented their exhaustion. Mechanistic studies further revealed that the triple therapy suppresses the activity of the Bcl6 regulatory network, thereby reducing the immunosuppressive function of Tregs and destroying the immunosuppressive interplay between myeloid immune cells and Tregs. These results demonstrate a promising "microbiome-immune" dual-targeting strategy for colon cancer with clinical translational potential.