Immunotherapy even more effective thanks to gut microbiota of seniors

Stimulating and remobilizing the immune system to recognize and eliminate cancer cells: this is the principle behind immunotherapy, which has been revolutionizing cancer treatment since the 2010s. There is, however, one limitation: in some patients, it is not very effective.

Studies suggest that the gut microbiota may influence the outcome of this treatment, with certain bacteria living in our digestive tract secreting molecules capable of boosting our immune system in its fight against the proliferation of cancer cells. Some researchers have attempted to modify their patients’ gut flora prior to immunotherapy so as to stimulate the treatment. One way of doing this is via fecal microbiota transplantation.

Microbiota of seniors is preferable

If you were to receive a fecal microbiota transplantation (now a recognized therapeutic solution, or under study as such, for many diseases), you would tend to choose a young, healthy donor. So would researchers. However, they may have to revise this position and instead opt for stools from healthy eighty-year-old donors.

A recent study ¹ has shown that people over sixty respond better to immunotherapy, and that the older they are, the more their survival defies prognosis. But why?

Since with age, their gut microbiota seems to evolve towards a set of bacteria more favorable to the outcome of immunotherapy. In fact, by transplanting these bacteria typical of senior citizens into cancer-stricken mice prior to immunotherapy, tumor growth was reduced to a greater extent than without fecal transplantation.

What explains these results? At first glance, because these “elderly” bacteria give a “youthful” boost to an immune system that tends to become depleted with age. In this respect, it seems that the value of healthy microbiota increases with age.