Gut microbiome may help improve cancer immunotherapy response

Bacteria living inside the digestive system may alter how cancer drugs work, a study suggests, and could improve cancer immunotherapy response.

The human body is home to a vast number of micro-organisms. Indeed, estimates suggest that tissues are so heavily outnumbered by microbes that the body is in fact only 10% human. A growing body of research has shown that these microbes can influence the immune system and they have been implicated in auto-immune diseases and allergies.

Immunotherapies are one of the most exciting breakthroughs in treating cancer. They work by allowing the immune system to help it to attack tumours more easily. However, not everyone responds to these treatments, and researchers are trying to understand why.

Now a small study by the University of Texas has found that people harbouring a more diverse community of gut bugs are more likely to benefit.

Scientists studied over 200 mouth and over 100 gut microbiome samples from people who had advanced melanoma. They discovered that people whose cancer responded to immunotherapy treatment had more diversity in the types of bacteria found in their gut. They also found significant differences in the type of bacteria found in the gut of people whose cancer responded versus those who didn't.

This research suggests that adapting people's gut bacteria, such as by giving antibiotics, probiotics or a faecal transplant before immunotherapy, could increase the benefits already achieved with the new immunotherapy drugs already being used to treat several different types of cancer.

Understanding role of microbes has great potential

The study was presented at the National Cancer Reserach Institute's Cancer Conference in Liverpool.

Dr Jennifer Wargo, lead researcher at the University of Texas, said: "Our research shows a really interesting link that may mean the immune system is aided by gut bacteria when responding to these drugs. Not all patients respond to immunotherapy drugs and it's hard to know who will benefit from the treatment prior to it being given.

"The gut microbiome can be changed through a number of different strategies, so there is real potential here to modify the gut microbiome to boost an immunotherapy response."

Sir Harpal Kumar, Chief Executive of Cancer Research UK, said: "Our bodies are filled with trillions of bacteria, and we are just beginning to scratch the surface of understanding their great potential."

"It's really interesting and exciting to see new evidence emerge on the close connection between the immune system and the bacteria living in our guts. As this, and several other studies, have shown, manipulating these bacteria could be exploited in future to help patients respond better to treatment."

Medication to treat infections caused by microbes (organisms that can't be seen with the naked eye), such as bacteria. Full medical glossary
A group of organisms too small to be seen with the naked eye, which are usually made up of just a single cell. Full medical glossary
Abnormal, uncontrolled cell division resulting in a malignant tumour that may invade surrounding tissues or spread to distant parts of the body. Full medical glossary
A viral infection affecting the respiratory system. Full medical glossary
The organs specialised to fight infection. Full medical glossary
A treatment that modifies the immune response for the prevention or treatment of disease. Full medical glossary
A malignant tumour arising from pigmented cells or melanocytes, most often in the skin Full medical glossary
Dietary supplements containing bacteria believed to be necessary for proper gut function. Full medical glossary
A group of cells with a similar structure and a specialised function. Full medical glossary
An abnormal swelling. Full medical glossary