Intestinal microflora helps cancer treatment

Margarita Paimakova, Vesti 

Success in the treatment of cancer may depend, among other things, on the inhabitants of the patient's intestines. Two studies on mice have shown that bacteria in the intestines can affect the effectiveness of therapy.

Medications such as ipilimumab, used in the treatment of melanoma, skin cancer, activate the immune system to fight the disease. However, some patients taking the drug have inflammation in the intestines. Also, approximately 80% of patients demonstrate a better perception of treatment than others, all other things being equal.

These data prompted Mathias Chamaillard from the University of Lille in France to the idea that intestinal bacteria somehow interact with the drug being taken.

To study this issue, Shameyar and his colleagues gave ipilimumab to those mice that had no bacteria in their intestines (a specially bred sterile group). The drug did not show sufficient effectiveness in the treatment of cancers in these rodents compared to animals of the control group with normal intestinal microflora. The effectiveness of the drug also decreased if "normal" mice were injected with antibiotics that destroy intestinal bacteria.

The study of fecal samples showed that the use of ipilimumab reduces the populations of two types of bacteria in the intestine – representatives of the genera Bacteroidales and Burkholderiales. At the same time, the effectiveness of the drug decreases. However, the restoration of communities of these microbes in the organisms of mice led to an increase in the effectiveness of the drug.

Then the scientists took fecal samples from 25 people with diagnosed melanoma and tested them for the content of bacteria of the genus Bacteroidales. When the doctors transplanted the collected samples to mice without intestinal bacteria and began treating them with ipilimumab, those animals that received samples containing more bacteria of the genus Bacteroidales during transplantation received the treatment better. According to scientists, these bacteria somehow mitigate the side effects of taking the drug.

In the future, the French research team plans to test whether it is possible to predict how well a person will respond to treatment based on the bacterial profile of someone's intestine. The team's scientific paper was published by Science (Vétizou et al., Anticancer immunotherapy by CTLA-4 blockade relies on the gut microbiota).

In the second study, Thomas Gajewski of the University of Chicago and his colleagues noticed differences in how fast tumors grow in two groups of mice with different populations of intestinal microbes.

Scientists have found that bifidobacteria, apparently, are associated with the intensity of the immune response and slowing down the growth of the tumor.

When intestinal microbes were transplanted into another group of rodents, they slowed down the growth of the tumor to about the same extent as treatment with an anti-cancer drug currently used to treat humans.

The Americans also shared their results in the journal Science (Sivan et al., Commercial Bifidobacterium promotes antitumor immunity and facilitates anti–PD-L1 efficacy).

Exactly how gut bacteria affect the immune response and treatment of cancer is still not entirely clear. Gayevsky believes that doctors need to start analyzing the intestinal microflora of patients. This will help to identify the influence of some other types of bacteria on the clinical effect or toxicity of treatment. In the future, the data obtained will help to develop probiotic supplements that will increase the effectiveness of immunotherapy.

Shameyara, in turn, suggests that changing the diet of a sick person will help stimulate the growth of beneficial bacteria.

Portal "Eternal youth" http://vechnayamolodost.ru

09.11.2015