Did You Know Gut Microbes Can Affect Cancer Treatment Response?


The gut microbiome is vital to our overall health – it's part pharmacy, part powerhouse, and part immune system. Scientists have also found that certain gut microbes determine whether or not you'll respond to disease treatments and drugs well. Meaning, one day in the future it could be possible to manipulate the gut microbiome so you respond to treatments better.

Imagine going in for a disease treatment but your doctor also prescribed you certain probiotics so you’d have a better response. Interestingly, that’s the direction cancer treatment is heading. When it comes to cancer, some studies suggest certain gut bacteria can determine how well a treatment can improve a person’s health outcome. For example, one recent human study on cancer patients found that certain bacteria are essential to the success of cancer treatment in patients. 1 Exactly how this happens isn't clear yet, but its implications are exciting nevertheless!

What we do know is that our gut microbiome can help breakdown hard to digest nutrients found in our diet. However, they also breakdown drugs we take - like many prescription medications. Sometimes, the reason a drug is so effective is thanks to the help of our gut microbiome. Now researchers believe they might be influencing how certain cancer treatments are metabolized as well.

Certain Bacteria Boost the Effectiveness of Cancer Treatment

New cancer drugs called, ‘immune checkpoint inhibitors’ help the immune system identify tumor cells and attack them. Oncologists have been trying out these new drugs on cancer patients who don't respond well to the powerful immunotherapies commonly used.

What they found is that certain microbes in the gut help boost the efficacy of these new immune checkpoint inhibitors. A recent clinical trial has been examining the effects of the gut microbiome composition on the efficacy of these new cancer drugs in melanoma patients and have found incredible results.

Normally, our immune system does a great job of identifying and capturing rogue invaders or mutated cells. However, when cells become cancerous, they can develop a strong self-defense system to help them avoid destruction. This can mean that even when the immune system comes into contact with cancerous cells, it fails to notice them and lets them pass by. Moreover, cancer cells can even send out messengers and signals that convince immune cells to avoid the areas where they’re thriving, preventing their detection. What’s worse, cancer cells can not only hide from the immune system, but they can also hijack our immune cells and recruit them for their own use! 2

Gut Microbes Unmask Hiding Cancer Cells

One way cancer cells are so good at hiding is due to two proteins called PD-1 and PD-L1. Cancer cells may produce PD-L1, which allows them to slip-by undetected from the immune system. PD-1 and PD-L1I inhibitors block the PD-L1 created by the cancer cell and the PD-1 receptors in the immune system. 3 This allows the immune system to suddenly recognize the cancer cells for what they are: an attack.

Theoretically, these drugs get the T-cells (our most valiant immune defenders) of the immune system to do their job by shining a light on cancer cells and removing their invisibility cloak. However, this study found that this process only occurs if the patient has a balanced gut microbiome. PD-1 inhibitors only work in about 30-40% of melanoma patients but for those who have gut dysbiosis - or gut microbiome imbalance - they just don’t work at all. 4

A study that profiled the gut microbiome of lung and kidney cancer patients found that they had low levels of the bacterium Akkermansia muciniphila. Researchers found that patients with a greater abundance of this good bacteria had a great response to PD-1 blocking immunotherapy. 5

Alongside this observation, the same researchers used oral transplantation of the Akkermansia muciniphila bacteria to restore the gut microbiomes of mice with cancer who had been treated with antibiotics. They found that the transplantation improved their immune system response to the cancer, suggesting that manipulating the gut microbiota of cancer patients and improving the activity of beneficial microbes can improve their responses to treatment. 5

The Future of Cancer Treatments Involves the Gut

An exciting next step to this research is happening right now. In an ongoing human trial, scientists are collecting gut microbiome samples from cancer patients who are responding extremely well PD-1 immunotherapy. 6 Using fecal microbiota transplants, they are restoring the gut microbiome of those who are not responding, hoping this improves their health outcome.

We're living in exciting times for new and innovative treatments of all sorts of diseases.

This includes learning how our gut microbiome plays a role in many different aspects of our health. Everyday new disease research unmasks more evidence that our microbes are essential to living a healthy, happy life.

*The information on the Viome website is provided for informational purposes only and with the understanding that Viome is not engaged in rendering medical advice or recommendations. Viome is providing this educational information to share the exciting developments being reported in the scientific literature about the human microbiome and your health. Viome products are not intended to diagnose, treat, or prevent any disease.


  1. http://science.sciencemag.org/content/early/2017/11/01/science.aan4236

  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6068015/

  3. https://www.scientificamerican.com/article/gut-microbes-can-shape-responses-to-cancer-immunotherapy/

  4. https://jamanetwork.com/journals/jamaoncology/fullarticle/2293945

  5. http://science.sciencemag.org/content/359/6371/91

  6. https://www.clinicaltrials.gov/ct2/show/NCT03341143