I reached out to Dr. Michael Dougan. He is a GI physician and is a MAJOR member of our Severe Immunotherapy Toxicity Team at MGH. Here is his response to the question about probiotics.
“The current evidence in insufficient to support a recommendation for or against probiotic treatment during immunotherapy. Based on animal models, it is likely that the microbiome (the population of bacteria living in our gut) has an influence on the outcome of immunotherapy. However, at present we do not have enough information to know if the bacteria in probiotics will improve the antitumor response, or change the risk for developing diarrhea or colitis with ipilimumab or the PD-1/PD-L1 blocking antibodies. This is an ongoing area of active research and we will begin to have answers to this question in the near future. In the meantime, I recommend that providers not take a strong stand on this issue, but they can reassure their patients that it is unlikely that probiotics would be harmful”.
Michael Dougan, MD PhD
Assistant Professor of Medicine
Division of Gastroenterology
Massachusetts General Hospital