The immunotherapy it is one of the most promising new families of cancer treatments. However, some of these drugs do not always seem to work for all patients. Recently, researchers seem to be figuring out why this is happening, and perhaps a way to fix it.

And it is that, as pointed out by the North American media The Washington Postthe composition of the gut microbiome of people (a huge community of microorganisms of various species that coexist in our intestine) seems to determine the effectiveness of immunotherapeutic treatments.

A diet to nourish the microbiome

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Specifically, there is increasing evidence that patients who harbor certain species of gut bacteria show better responses to immunotherapy than patients who do not. And even better: it seems that, with a high fiber diet (and therefore, with significant amounts of fruits, vegetables, legumes, whole grains and nuts) to nourish the microbiome the chances that the treatment will be effective could increase.

A clinical trial for this theory is currently underway at the University of Texas MD Anderson Cancer Center in Houston. In it, some patients who are receiving immunotherapeutic treatments together with diets very rich in fiber. The idea is to test the effect of diet with the same rigor with which tests for drugs are made.

Up to 80% of immune cells live in the intestine

It was already known that the microbiome of our body, and more specifically that of the intestine, has a crucial relationship with the immune system. By some estimates, between 60 to 80% of immune cells of the organism live in the intestine.

However, it has only been more recently that it has become clear that these microbes can affect the outcome of cancer. For example, a study from the University of Chicago and published in the scientific medium Science recently demonstrated that mice carrying a certain type of bacteria called bifidobacterium they showed a more robust immune response against melanoma than those who did not; and that giving the bacteria to mice that did not have it slowed tumor growth. Not only that: if an immunotherapy drug was added to the bacteria, the tumors they practically disappeared.

Another approach is to try to improve the response to immunotherapy by practicing fecal transplants to patients. A recently conducted clinical trial also published in Science It showed that the patients treated in this way responded better to the drugs than would be expected based on their medical histories.

More than twice the recommended fiber

It is all this evidence that leads the authors of M.D. Anderson to explore the diet route. The idea is based on the fact that many of these bacterial species that enhance the immune response seem eat fiberso a diet rich in this food should increase its population.

Previously, they examined the diets of 128 melanoma patients and found that those who regularly they ate large amounts fiber from fruits, vegetables and other plant foods had better results on immunotherapy than those who did not eat as much fiber, they published in Science.

In the current trial, patients are given food containing up to 50 grams of fiber dailyalmost twice the recommended amount.

References

Anahad O’Connor. Eating fiber alters the microbiome. It may boost cancer treatment, too. The Washington Post (2022). Consulted online at https://www.washingtonpost.com/wellness/2022/11/08/microbiome-fiber-immunotherapy-cancer/ on 11/23/2022.

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Christine N. Spencer, Jennifer L. McQuade, Vancheswaran Gopalakrishnan, John A. McCulloch, Marie Vetizou, Alexandria P. Cogdill, A. Wadud Khan, Xiaotao Zhang, Michael G. White, Jennifer Wargo et al. Dietary fiber and probiotics influence the gut microbiome and melanoma immunotherapy response. Science (2021). DOI: 10.1126/science.aaz7015