If you are a regular reader of nutrition news, you have likely heard of the “microbiome.” This is the community of bacteria that live on and in us, many of which are located in our digestive tracts. These bacteria perform many functions in our body – they help us absorb and produce nutrients and can also help to protect us from harmful bacteria.
Researchers are now beginning to understand that these bacteria may also be involved in how the immune system responds to cancer, and they may even influence whether a form of cancer treatment known as immunotherapy is successful.
Adoptive T cell transfer (ACT) is one form of immunotherapy in which immune cells from a person with cancer are isolated and grown to very large numbers in the lab to be re-injected into the person they came from.
Researchers from Pennsylvania recently published a study suggesting that the make-up of an individual’s microbiome can change how the body responds to ACT. This discovery may impact how the therapy is delivered, in order to make it more effective.
Make-up of microbiome influences success of immunotherapy
In this study, the researchers examined mice that were genetically identical but had come from 2 different locations, resulting in different species of bacteria found in their digestive tracts.
The mice had lung and cervical tumours, and all were treated with ACT. But the researchers found that the cancer in mice from one location stopped growing after treatment with ACT, while cancer in the mice from the other location continued to grow.
To further explore how the bacteria could be involved in this different response, the researchers gave the mice a commonly used antibiotic called vancomycin, which is used to treat a variety of infections including C. difficile, a gut infection often found in hospital settings. Vancomycin targets one subtype of bacteria.
The combination of vancomycin and ACT stopped cancer from growing in the group that had initially not responded well to ACT alone, but it didn’t improve ACT in the group that had initially responded well to the treatment on its own. In addition, using a combination of 2 different antibiotics also had no effect, suggesting that the group of bacteria targeted by vancomycin influences whether ACT is successful.
Study offers opportunities to personalize and improve therapy
When the researchers tried to understand how the bacteria impacts ACT, they found that the make-up of the microbiome seems to influence how immune cells locate and enter the tumour, which ultimately affects how well ACT works.
This research is still in very early stages and researchers have a lot to learn about the connection between the microbiome and the immune system, but this research suggests that it may be possible to learn who would benefit most from ACT based on their microbiome, or even improve the effectiveness of ACT by combining it with vancomycin.
While the potential impact of this research is still unclear, it highlights that – without a doubt – immunotherapy, and how bodies respond to it, is more complex than previously thought.
Eileen Hoftyzer, BSc