Domestic researchers have proven for the first time in the world a new treatment strategy that can enhance the effect of immunotherapy for brain tumors by utilizing gut microbiota and their metabolites.
Professor Lee Heung-kyu from the Korea Advanced Institute of Science and Technology (KAIST) and his research team noted on 1st that they discovered a method to significantly improve the efficiency of glioblastoma immunotherapy by focusing on changes in the gut microbiome. The research findings were published online in the international journal 'Cell Reports' on June 26.
The advanced therapy known as 'immuno-oncology therapy,' which activates T cells—immune cells in our body—to remove cancer cells, has previously shown limited effectiveness against the most deadly brain tumor, glioblastoma, due to high resistance to treatment.
The research team focused on the fact that as glioblastoma progresses, the concentration of the important amino acid 'tryptophan' decreases sharply in the gut, leading to changes in the gut microbiome. They revealed that supplementing tryptophan can restore microbial diversity, activating specific beneficial strains that induce one of the immune cells, CD8 T cells, back into the tumor tissue.
Through a mouse model of glioblastoma, the research team confirmed that supplementing tryptophan enhances the response of T cells that attack cancer, particularly the CD8 T cells, which migrate more to the lymph nodes and areas with tumors such as the brain.
They also revealed that the beneficial symbiotic bacteria 'Duncaniella dubosii' that exist in the gut play a key role in this process. This strain helped T cells effectively redistribute in the body, and its use in conjunction with the immuno-oncology therapy (anti-PD-1) significantly improved survival rates.
Furthermore, even introducing the symbiotic bacteria alone to germ-free mice, which have no gut microbiota, increased survival rates against glioblastoma, proving that this strain utilizes tryptophan to regulate the gut environment, and the metabolites produced in this process enhance the ability of CD8 T cells to attack cancer cells.
Professor Lee Heung-kyu explained, 'This research demonstrates a significant achievement by showing that even in intractable brain tumors where immune checkpoint inhibitors have not been effective, the therapeutic response can be significantly enhanced through a combination strategy utilizing gut microbiota.'
References
Cell Reports (2025), DOI: https://doi.org/10.1016/j.celrep.2025.115825