Can swallowing a pill containing probiotic bacteria help destroy deadly cancers? That is the hope that a new clinical trial will be conducted by a British life sciences company at a leading university in London.
Probiotic yogurt, which promises to promote healthy gut bacteria, has been in UK stores since the 1990s, but scientists are divided on whether commercially sold probiotics can offer real benefits.
NHS guidelines say that there is & # 39; some evidence & # 39; is that probiotics help prevent diarrhea when taking antibiotics and can alleviate some symptoms of irritable bowel syndrome (IBS).
But there is little to support many of the other health claims about them – for example, that they can help treat eczema.
Oncologists at University College London are testing a probiotic bacterial strain in 120 patients with conditions such as breast, prostate, bladder, lung and kidney cancer (dossier photo)
However, emerging scientific knowledge shows that having a variety of microbes in our gut, derived from food, encourages the immune system to work more effectively.
It is on this theory – that microbes can be used to improve cancer care – that the new British study is based on.
Scientists from 4D Pharma Plc and oncologists from University College London are testing a probiotic bacterial strain, Enterococcus gallinarum, in 120 patients with conditions such as breast, prostate, bladder, lung and kidney cancer.
The bacterium is found in the gut and in foods such as cheese and olives. The medication version, called MRx0518, is made from samples taken from healthy entrails.
Researchers say that it seems that E. gallinarum can stimulate the body to secrete specialized immune cells that can attack tumors.
This is crucial, since MRx0518 is designed to be used with a cancer treatment called immunotherapy, which helps patients' own immune systems identify and destroy cancer cells. This approach has taken decades to refine, since it has proved a challenge to manipulate the immune system without harming patients.
Immunotherapy drugs such as pembrolizumab (Keytruda) have achieved a number of notable successes against melanoma, non-small cell lung cancer, kidney cancer, bladder cancer, head and neck cancer and Hodgkin's lymphoma.
Recent figures show that nearly 25 percent of patients who received pembrolizumab as an initial treatment for advanced non-small cell lung cancer were still alive after five years – a huge gain over the historic five-year survival of just 5 percent.
However, despite this success, many patients' immune systems do not respond effectively to therapy or are only stimulated for a limited time before the benefit disappears and the cancer returns.
It is hoped that a targeted probiotic could improve these results. Patients get the probiotic in the month or so between those who are diagnosed with cancer and undergo surgery to remove the tumor. Biopsies at these points are compared to see how much the tumor has shrunk or not.
Tests have previously identified the potential benefit of healthy gut bacteria in beating cancers (file photo)
The study will also look at whether MRx0518 can reactivate the effects of pembrolizumab in cancer patients who initially showed an advantage but then stopped responding to the drug.
Studies have already identified the potential benefit of healthy gut bacteria in beating cancers. In 2017, the journal Science reported that patients with melanoma who had more diverse beneficial bacteria in their intestines had better success with their cancer treatment.
Earlier this year, however, American scientists warned against taking freely available probiotics to stimulate immunotherapy because they appear to be hampering their effects by disrupting the healthy balance of intestinal bacteria in the patient.
Their study of 113 patients with metastatic melanoma discovered that those who regularly used freely available probiotics had a 70 percent lower chance than normal to respond to immunotherapy.
"The general perception is (that probiotics) make your gut microbiome healthier," reports the study, which was presented at the American Association for Cancer Research conference.
"Our data suggests that this may not be the case for cancer patients."
These different results can be explained by a study published in the journal Cell Host & Microbe in March, which suggests that, under certain circumstances, probiotics can be harmful due to their ability to evolve.
Scientists at the Washington University School of Medicine in St. Louis, in the US, investigated the behavior of a strain of E. coli (presumably anti-diarrhea properties) in mice. After five weeks, the bacterium had evolved to become harmful in mice with a low bacterial diversity in their gut, eating the protective layer that covered the gut.
Aura Ferreiro, who led the study, warns: "We often use probiotics in sick people with an unhealthy microbiome with low diversity. That seems to be the condition when the probiotic is most likely to evolve. & # 39;
Instead of buying probiotics, cancer patients may be better off with a diet that is as healthy as possible because it is best to promote a healthy balance of bacteria in their gut.
Jane Clarke, a leading dietitian, told Good Health: "Probiotics are an exciting area of research. But the answers will never be as simple as just taking a pill. & # 39;
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