Bacterium may decrease effectiveness of immunotherapy (H. pylori)

Medical Xpress / University of Montreal / OncoImmunology ^ | Jan. 25, 2023 | Béatrice St-Cyr-Leroux / Marion Tonneau et al

[ConservativeMind]

Helicobacter pylori is a bacterium that colonizes the stomach lining and is found in more than half of the global population.

Most people with an H. pylori infection have no symptoms, but it can result in gastric ulcers and even stomach cancer.

A study has found that seropositivity for the bacteria—meaning a blood test has confirmed the presence of antibodies against a previous H. pylori infection—may decrease the response to immunotherapy in people with metastatic melanoma, an advanced skin cancer.

Dr. Marion Tonneau led the study as part of a team under Dr. Bertrand Routy.

They found that patients who tested positive for H. pylori tended to respond more poorly to immunotherapy than patients who were negative, and had significantly shorter overall survival rates.

The study subjects all received immune checkpoint inhibitors (ICI). ICI specifically stimulate the immune system to target cancer cells.

Routy's recent work has led researchers to take the microbiome into account in cancer research and treatments. Several studies to improve the efficacy of ICI by modifying intestinal microbiota—such as through fecal transplantation—are in the works.

Current research has been more broadly focused on intestinal microbiota, on the lower gastrointestinal tract, including the intestines, appendix and rectum. But Tonneau believes the new findings should encourage immuno-oncologists to take a keener interest in the upper gastrointestinal tract (the mouth, pharynx, esophagus, and stomach), as well.

"After all, H. pylori is found in the lining of the stomach, and it is present in over 50 percent of the world's population," she said. "Our study suggests that H. pylori, in addition to affecting the stomach, can potentially affect systemic immune response, notably by modifying the polarization of T lymphocytes. This is further evidence that microbiota play a role in the development of cancers, and not just intestinal cancers."

[ConservativeMind]

Beatrice did a disservice to the study, because she wrongly states it was seropositivity that matters—that is not true. The researchers did blood tests, which show if anyone ever had H. pylori at anytime in their lives (it’s an antibody test). However, the abstract clearly states they relied on fecal tests, which show CURRENT infection. So you had to have both to be “positive.”

So, this means if you need immunotherapy, you need to get rid of your H. pylori, first. That’s a pretty important thing to know.

If you had H. pylori in the past and eliminated it, you should likely be fine, according to this paper, it would seem.

[ConservativeMind]

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