Cancer treatment and microflora
Antibiotics have weakened the effect of immunotherapy against cancer
Anna Kaznadzei, N+1
Two studies have shown the effect of the intestinal microbiota on the effectiveness of immunotherapy in the treatment of cancer. One of them reports that taking antibiotics reduces its effect. In the second study, it was shown that, in turn, the "correct" composition of the intestinal microflora, rich in representatives of Faecalibacterium and Clostridiales, provides a more positive response of the body to immunotherapy. The articles are published in Science.
The object of both studies were cancer patients suffering from kidney or lung cancer who underwent immunotherapy while taking PD-1 inhibitors. This therapy activates the body's immune system through T-lymphocytes, encourages it to fight tumors. During the first study, it turned out that patients who had been taking antibiotics for the last two months to fight infections of the urethra, lungs or teeth (there were 28 percent of the total) perceived therapy worse, and the percentage of mortality among them was higher.
The analysis of the intestinal microflora of patients showed that people who had significant amounts of Akkermansia muciniphila bacteria in their intestinal microbiome reacted best to immunotherapy. In patients who did not respond well to immunotherapy, they were twice as rare. With an additional, more detailed analysis, a positive correlation with the effect of immunotherapy was also shown by Enterococcus hirae bacteria.
Scientists conducted an experimental study, the object of which was mice deprived of their own intestinal microflora with the help of antibiotics. During the experiment, they were injected with colonies of A.muciniphila or simultaneously A.muciniphila and E.hirae. It turned out that such a procedure significantly increased the activity of mouse immune cells and improved their own response to immunotherapy. In addition, it turned out that with the introduction of "bad" microflora from patients who did not respond to therapy, this response worsened, but additional administration after that of the aforementioned "good" bacteria reactivated the immune response. In the case of lung cancer (NSLCL), similar results were achieved with colonies of bacteria Alistipes indistinctus.
In the second study, the researchers collected samples from melanoma patients who were also taking PD-1 inhibitors. They found out that the best results in terms of therapy were shown by people whose microflora was diverse and rich in representatives of Faecalibacterium and Clostridiales, in particular, the Ruminococcaceae family. For such patients, the probability of stopping tumor growth also increased and life expectancy increased. The opposite effect was observed in many patients in whose microflora the predominance of Bacteroidales species was observed.
In general, people with "good" microflora had more immune cells, the activity of which led to a decrease in tumors. In this study, we also conducted an experiment with mice, transplanting the microflora of different patients to them, and observed similar results – mice with "good" microflora responded better to immunotherapy.
The results of both studies suggest that the composition and diversity of human microflora have an important impact on the course of immunotherapy, which, of course, should be taken into account in the treatment of oncological diseases in the future.
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