Two recent studies demonstrate that we can manipulate the microbiome to help improve responses to treatments for diseases like the skin cancer melanoma. Importantly these two studies were clinical trials – patient studies, not mice – and have clearly demonstrated that we can alter the microbiome to improve responses to cancer immunotherapies.
Understanding the Basics of our Microbiome
To better understand, let’s discuss the microbiome. To do that, it helps to have a cursory understanding of the human genome. A genome is a person’s complete set of DNA, made up of four base pairs (abbreviated A, T, G, C). As noted by the National Human Genome Research Institute, ‘the human genome contains approximately 3 billion of these base pairs, which reside in the 23 pairs of chromosomes within the nucleus of all of our cells. Each chromosome contains hundreds to thousands of genes, which carry the instructions for making proteins.” Experts estimate the human genome has 30,000 genes, each making an average of 3 proteins (so ~100,000 proteins).
Now on to the microbiome! While many readers have heard about the human genome, many might not know about the ‘microbiome’. Each human body contains many more microbes (including bacteria, viruses, fungi, and protozoa) living in, on, and as part of our bodies, including the gut, skin and throughout our bodies. Here is one great news article that gives a great description of the microbiome.
The genetic materials of the microbes making up our microbiome is approximately 200 times greater than the number of human genes in our body (6 million microbial genes versus 30,000 human genes, as part of our body composition. The challenging part is that our microbiome varies greatly – the microbes in our gut are not the same as on our skin. And, our microbiome is changing depending upon our local ‘body environment’ what we are eating, what new microbes we are exposed to, drugs we take like antibiotics, etc. can all lead to a change in the composition of the microbiome, especially in the gut.
Changing Microbiome to treat Cancer
In a recent clinical trial, researchers found they could manipulate the microbiome and improve melanoma patients’ response to therapy. The trial was conducted by scientists at the National Institutes of Health (NIH) in collaboration with investigators at the University of Pittsburgh Medical Center (UPMC) Hillman Cancer Center. In this study, doctors performed fecal microbiota transplants (FMT) taking samples from patients with melanoma that had favorable responses to immunotherapy. The material was transplanted into patients with melanoma that did not respond to immunotherapy. The results showed that 6 out of 15 FMT transplant recipients, who had not originally responded to immunotherapy drugs now responded, and experienced either tumor reduction or long-term disease stabilization.
The punchline is that changing the microbiome, via FMT, could turn a patient with melanoma from an immunotherapy non-responder to one who’s tumor now did respond to immune checkpoint inhibitors. This happened for 6 out of 15 patients in this small study.
Steps to Altering Your Microbiome through Diet
All of us – whether we’ve had cancer or are otherwise healthy, can take certain steps to make our microbiome more favorable and helpful to us. Making a “more favorable” microbiome is through the same recommendations we often hear – nutrition and exercise! You can learn more here.
High-fiber foods such as vegetables, whole grains and fruit feed the helpful bacteria in your colon. Probiotic foods – such as pickled vegetables, and yogurt – also deliver helpful bacteria to your gut.
Exercise – do your best to exercise nearly every day. The American Cancer Society recommends vigorous walking for at least 30 minutes, five days each week. Weight training and resistance exercise is also important.
If you have 5 minutes, I highly recommend this TED Ed video.