Our gut flora determines with the outcome of cancer treatment

Certain bacteria in the gut affect the success of a treatment for cancer

There are several reasons why certain therapies do not work very effectively against cancer. Of course, this also applies to the treatment of skin cancer and other types of cancer. Even new treatment regimens do not appear to affect one quarter of the disease. The reason is probably the presence of certain bacteria in the intestine.

Independently, two groups of scientists from the US and France found that our diverse gut flora can greatly influence the success of cancer immunotherapy. The experts published the results of their studies in the English-language journal "Science".

Experts found that bacteria in our gut have a significant impact on the likelihood of successfully treating skin cancer. (Image: Africa Studio / fotolia.com)

Antibiotics should never be taken before immunotherapy against cancer

The human microbiome decisively influences the treatment success of therapies for cancer. The physicians explained that it was urgent to avoid taking antibiotics before cancer immunotherapy. It should be better an additional treatment, such as a so-called fecal grafting performed. This will help many affected people more effectively, explain the scientists. The results of the current studies could lead to improved immunotherapy in the near future, the experts speculate.

Checkpoint inhibitor therapy in melanoma affects only a few patients

Immunotherapy for cancer has been well established for several years. In the treatment of so-called black skin cancer (melanoma), a checkpoint inhibitor therapy is now used as a standard. In such treatment, an antibody is used to help the immune system detect and permanently fight the tumor. However, only about one-quarter of patients with metastatic melanoma have the form of therapy, the researchers from the University of Texas's Anderson Cancer Center in Houston said in a press release.

Microorganisms in the mouth did not affect the treatment

For their analysis, the experts analyzed data from a total of 112 melanoma patients who had oral and intestinal microbiome. These had participated in a so-called checkpoint inhibitor therapy. The physicians found that microorganisms in the mouth had no influence on the treatment success of the therapy. When the prescribed treatment started with the patients, it was possible to detect a much richer flora in the intestine of those affected. This particularly affected the bacteria in the intestine, which came from the group of Ruminococcaceae.

Success of the treatment is often influenced by the microbiome

The French scientists from a working group around Laurence Zitvogel from the French Gustave Roussy Cancer Center (GRCC) in Villejuif came to a similar conclusion. These researchers studied nearly 250 subjects with bladder cancer, non-small cell lung cancer (NSCLC) and renal cell carcinoma (RCC). For these types of cancer, the physicians also found that the success of the therapy is influenced by the microbiome.

Antibiotics can trigger relapses in treatment

A certain germ named Akkermansia muciniphila, which lives in the intestinal mucosa of humans, is associated with a good response to immunotherapy, the researchers explain. However, when sick people take antibiotics, relapses in treatment are more likely. In addition, the affected patients died earlier.

Results were checked on mice

In both studies, the effect of intestinal flora on immunotherapy was also investigated in mice. For intestinal germs of patients were transplanted into previously germ-free mice, explain the scientists from the United States. When these laboratory mice received microorganisms from patients on whom therapy was well struck, existing tumors grew significantly more slowly.

Akkermansia muciniphila improves treatment success

The study of the French experts found the same results. When the bacterium Akkermansia muciniphila was administered to mice that did not normally respond to cancer therapy, the likelihood of treatment success improved. Apparently, such a gut microbiome can significantly improve the outcome of a checkpoint inhibitor therapy in mice and patients, the researchers explain.

Further research is needed

The experts from the USA now want to initiate a new study and check whether and how a manipulation of the intestinal flora could lead to improved immunotherapy. The microbiome can be manipulated relatively easily. The results of the studies could therefore provide great opportunities for further treatment, the researchers say. (As)