In recent years, there has been a lot of buzz about gut bacteria, also known as the gut microbiome, and the critical role it plays in health.
According to the Cleveland Clinic, the gut – inside the intestines – is a miniature biome “populated by trillions of microscopic organisms.” These microorganisms include over a thousand species of bacteria, along with viruses, fungi and parasites.
But the primary reason that the gut microbiome has garnered so much attention is due to the key functions it preforms in the body, such as digestion, nutrient production, immune system regulation, and even organ development.
According to researchers in the UK, one of these functions – immune system regulation – plays a crucial role in determining whether or not a patient’s immune system is successful in fighting a particularly aggressive form of cancer, mesothelioma, via a treatment that relies on the body’s immune system, immunotherapy.
Mesothelioma is a very rate cancer, with roughly 20,000 cases diagnosed per year in the US. It develops in the lining of the lungs or abdomen and most mesotheliomas are believed to be related to asbestos exposure.
The disease is typically difficult to treat as it is an aggressive cancer that is often diagnosed at an advanced stage. In the absence of a cure for mesothelioma, most treatments are designed to extend and improve the quality of life.
Given these factors, findings related to gut bacteria that suggest that dietary changes could improve the benefits of treatment for the disease represent a significant development in the fight against mesothelioma.
The Study
In a study funded by the British Government’s National Institute for Health and Care Research (NIHR) Leicester Biomedical Research Centre (BRC) and Asthma + Lung UK, researchers worked to identify personalized treatment pathways for patients with relapsed mesothelioma.
Specifically, they identified “which patients are likely to get the greatest benefit from different types of drug therapies, using the genetics of the cancer to lend insights.”
The team evaluated the impact of two immunotherapies, atezolizumab and bevacizumab, in 26 patients with relapsed mesothelioma.
In the study, which was published in Nature Communications, the average age of the participants was 68 and they received an average of 4.5 cycles of immunotherapy. Their disease control rate was then assessed after 12 weeks.
“The ecosystem of bacteria that live in everyone’s intestines have emerged in recent years as a significant factor associated with the body’s sensitivity to immunotherapy,” said Dean Fennell, Professor of Thoracic Oncology at the University of Leicester and a fellow of the Academy of Medical Sciences. “We wanted to find out how factors both inside and outside of the cancer per se, were influencing a patient’s response to immunotherapy.”
“We therefore sequenced the genetic code of the gut bacteria from patients in this study, to establish whether there was a relationship with their responsiveness to treatment.”
The researchers found that a positive patient response was more likely if there were more anti-cancer immune cells seen in the mesothelioma, which the team associated with the presence or absence of specific gut bacteria; primarily Provetella, eubacterium ventriosum group and biophilia.
“Our work builds on a growing understanding that factors outside of the cancer per se, in this case bacteria, which live with us in the gut, can be critical to the success of immunotherapy,” said Professor Fennell.
“A key implication of our work is that changing the gut microbiome might improve the odds of patient benefit to immunotherapy. This could be, for example, through specific changes to the diet such as increased fiber intake; something that can be actioned by the patient.”
Next, the team plans to test their hypothesis that changing the gut microbiome can positively impact the effectiveness of immunotherapy through clinical trials, which have now completed the patient enrollment phase.
