Influence of the gut microbiota on the immunotherapy of melanoma

This is the most comprehensive study to date of the relationship between the gut microbiota and immunotherapy

The microbiome, the group of microorganisms that live in our gut, may affect the effectiveness of treating cancer with immunotherapy. This is evidenced by the most comprehensive research to date into the relationship between gut flora and immunotherapy. At UMCG, Geke Hospers of the Department of Medical Oncology and Rinse Weersma of the Department of Gastrointestinal Hepatology began this research years ago, which has evolved into a large European study. The results of the work were published February 28 in the official journal Nature Medicine.

Previous studies in mice and small groups of patients indicated that the microbiome, through its effect on the immune system, plays a role in patients’ response to immunotherapy. This is especially true for the treatment of skin cancer (melanoma). The purpose of this large study was to find more evidence for this. To date, immunotherapy is effective in about half of patients with advanced melanoma. Since there are ways to adjust the composition of the gut flora prior to initiation of oncology therapy, this could have a significant impact on the effect of these therapies in the future.

The relationship between the intestinal microflora and the effectiveness of skin cancer treatment
Five medical centers participated in this study; Three in the UK, UMCG in the Netherlands and one in Spain. “This allowed us to collect the largest group of patients with melanoma and samples of their gut microbiome,” explains Laura Bolt, one of the first authors. This study allowed us to establish that there is indeed a relationship between the composition and function of the gut microbiota and the efficacy of antitumor therapy with immunotherapy in patients with melanoma. In particular, three types of bacteria (Bifidobacterium pseudocatenulatum, Roseburia spp., and Akkermansia muciniphila) appear to be more associated with a better anti-tumor response.

Continued research to improve the effect of immunotherapy
The composition of the intestinal flora can be modified. This can be done, for example, through diet or through fecal transplants. Weersma: “The cool thing about our results is that they mean that if you modify the gut flora, the effectiveness of cancer treatment can improve. We haven’t shown this yet in this study, but other exploratory studies have already been done with positive results and are now the subject of several follow-up studies. It is then necessary to accurately identify and understand the specific properties of the intestinal flora that increase the efficacy of immunotherapy.We are convinced that these follow-up studies will offer new possibilities for cancer control, even for advanced-stage tumours, says Geke Hospers.