Your gut bacteria could play a role in determining whether cancer therapy will work

Cancer patients respond best to treatment when they have the right cocktail of bacteria in their guts, new research indicates.

Two separate studies found the “microbiome” of the gut – the bacteria, viruses and other bugs in the digestive system – can determine whether tumours will shrink when treated with immunotherapy drugs.

The studies carried out by scientists in the US and France relate to PD-1 inhibitors, which prevent tumours hoodwinking the body’s immune system into thinking they are healthy cells.

Both found that certain gut bacteria can boost the likelihood of a patient responding to a drug, Science magazine reported.

PD-1 inhibitors can hold certain cancers at bay for many years, but currently only about 25% of all patients respond to the drugs.

Now, the teams behind both studies are hopeful that this figure could be significantly boosted if they are able to manipulate the make-up of bacteria in the gut.

The team at the Gustave Roussy Cancer Campus in Paris also discovered that immunotherapy patients taking antibiotics, which disrupt gut bacteria, relapsed sooner or did not live as long as others.

Immunologist Laurence Zitvogel, the leader of the study, believes that by simply avoiding antibiotics the number of patients responding to immunotherapy could be boosted to 40%.

In the US, Jennifer Wargo, of the MD Anderson Cancer Centre in Houston, Texas, found that patients with a more diverse range of bacteria in their gut and more specific bacteria were more likely to respond well to the treatment.

She is now planning to test whether altering the gut’s microbiome with faecal transplants in pill form or bacterial treatment could help melanoma patients respond to PD-1 blockers.


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