Photo credit: University of Texas

We find ourselves living in an era that houses the best possible medical technology. With that in mind, two new studies have been published showing how the gut microbiome of different patients can affect the success of cancer treatments.

The studies have identified similar gut bacteria discrepancies in human cancer patients. Both of the studies examined the gut microbiome of cancer patients undergoing treatment with PD-1 inhibitors, a new type of cancer therapy that for an unknown reason is only successful in 25% of patients. 

The first study, published in Science, was carried out in France, and discovered that cancer patients recently treated with antibiotics exhibited significantly less success with PD-1 treatment than patients who hadn’t recently taken antibiotics. When examining the gut bacteria of these subjects the researchers identified one particular species, Akkermansia muciniphila, as substantially lacking in the group treated with antibiotics. 

Follow up experiments involving mice confirmed the correlation by fecal microbiota transplants. Interestingly, the study revealed that after the non-responsive mice were fed a supplement of Akkermansia muciniphila, they increased their positive response to the PD-1 treatment.

In addition, the second study, also published in Science, led by the University of Texas, focused more at the bacterial diversity of patients who successfully responses to PD-1 treatment versus those who did not. They found significant differences in the diversity of gut bacteria between the two groups, but identified different relevant bacteria than to the first study. 

As a result, the subjects with a high volume of Faecalibacterium had a more positive response to the treatment, while an abundance of Bacteriodales was found in subjects with a low response to the treatment. Just like the first study, fecal transplants were delivered to mice to verify the specific gut bacteria having an effect on the outcome of the PD-1 drugs. 

Jennifer Wargo, leader of the University of Texas study, explained, “You can change your microbiome, it’s really not that difficult, so we think these findings open up huge new opportunities. Our studies in patients and subsequent mouse research really drive home that our gut microbiomes modulate both systematic and anti-tumour immunity.”

The successful nature of both studies alone has the potential to increase positive patient responses to PD-1 treatment from 25%-40%.