The composition of the intestinal flora can predict the effectiveness and toxicity of immunotherapy in patients with melanoma, according to a French study.
The arrival of immunotherapy has revolutionized the management of certain cancers. But this innovative therapy targeting the immune system is not effective in all patients, although we do not understand why. A French study reveals that the microbiota plays a key role in the response as well as in the tolerance of patients to these treatments. These jobs resulting from the collaboration between scientists and doctors from AP-HP, INRA and the Gustave Roussy Institute are presented in the scientific journal Annals of Oncology.
“These drugs have good sides because they treat cancer patients, but they also have a bad side because they trigger inflammatory diseases, in particular chronic inflammatory bowel diseases”, explains Prof. Franck Carbonnel, lead author of the study and head of the gastroenterology service at Bicêtre hospital, AP-HP. However, in these intestinal pathologies such as Crohn’s disease, the intestinal flora plays an important role. It is also now established that the billions of bacteria present in our intestines contribute to the development of the immune system. The researchers therefore assumed that the microbiota could influence the action of immunotherapy.
The advantage of a varied microbiota
To verify their hypothesis, the scientists studied the intestinal flora of 26 patients with melanoma with metastases, and treated with ipilimumab, a monoclonal antibody. Analyzes were done before they received treatment and then after. And it appears that the composition of the microbiota makes it possible to predict the effectiveness of the treatment but also to determine which patients are at risk of experiencing serious adverse effects linked to immunotherapy.
Indeed, scientists have discovered that patients with flora rich in bacteria Faecalibacterium and others Firmicutes respond better to treatment than patients whose microbiota is rich in bacteria of the Bacteroides type. They also demonstrated that the patients who respond best to treatment are also those who are more prone to enterocolitis.
Optimizing the effectiveness of the treatment
Besides the possibility of identifying the patients who could benefit from this treatment, the scientists suggest that it will be possible to optimize the effectiveness of this treatment by modifying the intestinal flora. “There are several ways to manipulate flora, the best known being antibiotics, but we can also influence it more selectively by administering phages (viruses that kill bacteria, editor’s note) or by faecal transplantation ”, describes Prof. Carbonnel.
Currently, research on immunotherapy and the levers of action capable of improving its effectiveness and reducing its adverse effects is bubbling up all over the world. Recently, the role of these intestinal bacteria has also been shown in the success of chemotherapy.
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