Insights into Intestinal T Cells in Cancer Immunotherapy

Two recent studies published in Science and Science Immunology have revealed insights into the role of intestinal T cells with α4β7 integrin receptors in the context of cancer immunotherapy. These studies, conducted in mice and corroborated with patient samples, offer valuable knowledge about how these T cells can influence the response to immune checkpoint blockade (ICB) therapy. 

The Science study, led by Marine Fidelle and colleagues, focuses on the immunosuppressive effects of these T cells within tumors, while the Science Immunology study, led by Virginie Feliu and colleagues, explores their potential to enhance anticancer responses.

Fidelle et al. found that broad-spectrum antibiotics reduced the expression of an adhesion molecule called MAdCAM-1, allowing α4β7+ Tr17 cells to migrate to tumors and impair anti-PD-1 immunotherapy. Fecal transplants prevented antibiotic-induced deficiency and reduced immunotherapy resistance.

Feliu et al. investigated how gut-resident α4β7+ T cells could enhance anticancer responses to metastatic tumors. By implanting colorectal carcinomas into the livers and guts of mice, representing primary and secondary sites of cancer, the researchers discovered that mice with tumors in both locations exhibited improved antimetastatic immunity and survival outcomes. These T cells, particularly CD8+ cytotoxic T cells, showed enhanced efficacy when combined with anti-PD-L1 treatment.

Targeting MAdCAM-1-α4β7 interactions could improve anti-PD-1 therapy, while leveraging α4β7+ T cells may enhance immunotherapy responses in metastatic tumors. These findings deepen our understanding of how antibiotics influence ICB responses, inspire novel therapeutic strategies for manipulating the tumor microenvironment, and may lead to identifying new biomarkers to guide immunotherapy use.

Intestinal T cells with α4β7 receptors have a dual role in cancer immunotherapy—either impairing or enhancing response. Understanding these mechanisms can help inform strategies to optimize treatment and personalize therapy for better patient outcomes.