New Studies Link Our Microbiome to Cancer Treatment Response and Tooth Decay

We may not like to think of ourselves this way, but human bodies are essentially vast cargo vessels for microbes. The bacteria, fungi, and viruses that make themselves at home in and on our bodies aren’t just passengers enjoying the ride; they are a key contributor to our state of health. When these microbial populations get out of whack, we can experience a range of medical problems. When they’re in happy harmony, they can keep us healthier and give us functions we wouldn’t otherwise have, like digesting certain foods.

This week, several studies came out that underscore the importance of these communities of microorganisms, better known to scientists as our microbiome. Three papers were published in the highly regarded journal Nature Medicine, all reporting results from clinical trials where the microbiome played a key role.

All three trials focused on a relatively new class of cancer treatments known as immunotherapies — specifically, immune checkpoint inhibitors. These therapies are wonder drugs for some cancer patients, but bafflingly ineffective for others. Researchers around the world are trying to understand why the response to treatment varies so much, and how to improve results among current non-responders. In each of these trials, which focused on non-small cell lung cancer, melanoma, and renal cell carcinoma, researchers asked whether replenishing gut microbes using fecal transplants (yes, that’s a thing) could boost response to immunotherapy.

Short answer: it worked. Scientists believe the gut microbiome, which houses one of the most complex microbial communities in our body, is particularly important for a patient’s response to immunotherapy. (That’s because the gut microbiome is deeply connected to our immune system function.) Researchers theorized that the fecal microbe transplants replaced “bad” bacteria with “good” bacteria, enabling more people to have a better response to therapy. It’s important to note that all three of these clinical trials were small and early-stage, so much more research will be needed to determine whether microbial transplants are actually a viable means of improving outcomes for patients with cancer. (In other words, don’t try this at home.)

In a separate study, scientists analyzed genetic variation among people to understand how it influences the oral microbiome, which plays a role in our dental health. They found a link between certain human genes and the composition of the microbial population in the mouth, including one gene that appears associated with higher rates of tooth decay. The analysis also identified 11 different gene regions that have an impact on which bacteria are most common in the mouth. “It seems like there’s a lot of interaction between human genetics and the oral microbiome,” said Nolan Kamitaki, first author of the paper and a graduate student at the Broad Institute.

It’s exciting to see so much progress being made in figuring out long-reaching impacts of the trillions of microbes in our microbiomes. With luck, some of these insights will eventually translate into practical ways of boosting our health.

Short Takes

A new analysis shows that more than 10,000 PhD-level experts left or lost their jobs in the federal government last year. This is a massive increase from typical years, and reflects the current administration’s attack on science in our country. Overall, that’s a loss of more than 106,000 years of federal work experience.

The U.S. might have abandoned the World Health Organization, but California is trying to keep ties with this essential public health agency. The state is the first to become part of the WHO’s Global Outbreak Alert & Response Network, and it appears that Illinois may follow suit soon.