Immunotherapy and antibiotics don’t get along

The success of immunotherapy in cancer treatment may be linked to the composition of the patients’ intestinal microbiota, according to a French study.

Immunotherapy, despite representing a real revolution in the treatment for certain cancers (malignant melanoma, lung, kidney, or bladder cancer), still fails in some cases.

To understand why, French researchers from several public organizations worked together and observed that patients treated with immunotherapy who had previously taken antibiotics to fight infection had a poorer overall survival rate than patients who had not taken antibiotics. Their hypothesis? That these medications caused dysbiosis in the intestinal microbiota, which made the immunotherapy less effective. They analyzed the patients’ microbiota before and during immunotherapy treatment, and observed that intestinal flora rich in Akkermansia muciniphila went hand in hand with a good response to treatment. Their hypothesis about the role played by this bacteria in the effectiveness of immunotherapy was confirmed by a study in mice who were given fecal transplants: only animals transplanted with a favorable microbiota had a positive progression when they were given immunotherapy treatment.

The authors conclude that the composition of the microbiota in patients with malignant melanoma can predict their response to immunotherapy. This discovery confirms the value of developing a therapeutic approach that combines bacteria and immunotherapy.

Sources:

Routy B  et al. Gut microbiome influences efficacy of PD-1 based-immunotherapy against epithelial tumors. Science (2 novembre 2017)

http://science.sciencemag.org/lookup/doi/10.1126/science.aan3706