The Latest Cancer Treatments Rely on Bacteria

The discovery of immunotherapy brought hope to cancer research for a potential cure; however, researchers soon discovered it wasn’t as effective as originally anticipated. After decades of research, scientists have finally found effective ways of turning the immune system against tumors: the gut microbiome. End-stage kidney cancers and melanomas have been cured in patients. Immunotherapy coupled with bacteria might be an effective cure.

Two teams of researchers have shown that the presence of certain gut microbes can significantly influence the immune system's ability to deal with cancer in mice, showing promise for future human studies. These microbes may predict an individual's susceptibility to cancer, and how well they respond to immunotherapy drugs. In addition, certain species of bacteria are especially potent at directing anti-tumor immunity, proposing novel cancer drugs that are more potent.

Although both studies were done in mice, they may reveal why checkpoint inhibitors work so well in some cancer patients. That subset may harbor certain gut microbes, including Bacteroides and Bifidobacterium, which make these drugs more effective.

If what researchers suggest is true, sequencing a patient’s microbiome may predict how they will respond to ipilmumab and other immunotherapies. If their odds are not optimistic, doctors might prescribe next-generation probiotics that include Bacteroides or Bifidobacterium species, or other immune-stimulating bacteria. Fecal transplants from patients who are responding well to the drugs may also be administered. These treatments may lead to greater drug effectiveness and better results for groups diagnosed with certain cancers.


Ed, Yong. "The Hottest New Cancer Drugs Depend on Gut Microbes." The Atlantic. November 1, 2015.

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