Microbiome and Cancer
April 25, 2016
What would you say if I told you that your gut bacteria have now been shown to affect your response to a cancer that has begun to proliferate in your body!
We all know that I am beyond the normal when it comes to my excitement about human health and the benefit that a stable micro biome plays. My partner, Ed Cody, routinely asks the medical students that we train how many times a day they hear the word "micro biome". Then he apologizes for me.
Alas, here goes more "micro biome"!
In April's issue of Scientific American, M. Alegre and T. Gajewski have written a provocative article entitled Germ Warfare. The article starts with the statement, "why do some patients respond well to the new cancer immunotherapies and others don't?" What they found in their Chicago lab is that the makeup of the microbial communities of the gut dictate the immune system's response to cancer cells.
They studied genetically identical mice with different intestinal microbial species makeups. They then injected the mice with cancer cells that cause melanoma. The two mice groupings had differential gut bacteria and were kept apart from each other. One group had a slower tumor progression and a more vigorous T cell immune response than the other. When they analyzed the micro biome, they noted that the mice species with more
bifidobacter had a better outcome. (bifidobacter is the species that we are colonized with when we breast-feed.)
They followed this up by transplanting the micro biome to the less well performing group and they subsequently had a more robust response proving proof of concept that the microbial flora is driving immune function against cancer proliferation.
The final phase of the research aimed to see the effect of chemotherapy in these groupings. Sure enough, the
bifidobacter predominant grouping tolerated the chemotherapy with a better cancer killing response.
Even more interesting is that adding bifidobacteria to the mice orally had a positive benefit. Leading one to believe that probiotic supplementation has a future in cancer care!
Couple this information with Dr. Zitvogel's publication in November 5, 2015 Science where mice had differential responses to cancer chemotherapy based on the microbial makeup and we are on to something big.
The papers in science demonstrate that the microbiome and immunology are tightly linked and that gut bacteria can activate mammalian anti-tumor responses,
M. Vétizou et al., "Anticancer immunotherapy by CTLA-4 blockade relies on the gut microbiota," Science, doi:10.1126/aad1329, 2015.
A. Sivan et al., "Commensal Bifidobacterium promotes antitumor immunity and facilitates anti-PD-L1 efficacy," Science, doi:0.1126/science.aac4255, 2015.