Gut check? Not such a bad idea, if you are going in for cancer chemotherapy. Because the microbial flora in our gut may been the difference between a successful chemo course- or not.
Some of the newer drugs (ipilimumab- for example) actually activate our immune system, rendering it more capable of treating the advanced melanoma. But, some folks administered the drug have gut flareups. So, Dr. Laurence Zitvogel (Villejuif, France) and some 35 researchers from France (plus one from New York and another from Singapore) tested their hypothesis that our gut bacteria have significant interactions with the drugs, which affect its performance.
They tested the drug’s effects on mice that lack gut bacteria. And, found that the drug was much less effective than when the mice had normal microbial flora populations. (The same results were obtained if the mice were fed antibiotics, which also wiped out their gut populations.) Futher studies found that Bacteriodales and Burkholderiales were the critical microbial species that affected drug performance. When these two speciaes were added to the microbial mix in the gut, the response to ipilimumab was restored.
Then, their studies progressed to humans. The 25 patients in the study were treated with ipilimumab. And, when their gut populations were transferred to the mice- those fecal transplants that had Bacteriodales present enabled much better mice response to the drug. These results were published in Science; Anticancer immunotherapy by CTLA-4 blockade relies on the gut microbiota
Dr. Thomas Gajewski, along with 11 colleagues from the University of Chicago, approached the issue from a different angle. Also published in Science, their article is entitled Commensal Bifidobacterium promotes antitumor immunity and facilitates anti–PD-L1 efficacy . The researchers found that tumors grew more quickly in mice dependent upon the different microbial populations. Those with Bifidobacteria had slower tumor growth and a stronger immune response. And, if they effected fecal transplants to the other group, tumor growth was arrested to virtually the same extent as if the anti-cancer drug were administered.
So, both these studies are more evidence that our gut bacteria are critical to the functionality of some anti-cancer drugs. The remaining questions are whether we need to vary the gut populations to ensure proper clinical therapeutic results, to avoid chemical toxicity, or to enhance populations that will actually reduce the incidence of cancer.
