A research team from the Japan Advanced Institute published a research paper this month describing an innovative and promising approach to cancer treatment. They report on a bacterial species extracted from the gut of the Japanese Tree Frog that demonstrated a 100% cure rate in a mouse model of human colon cancer. All the untreated mice died; all the treated mice lived, and became resistant to this cancer thereafter. The bacteria (Ewingella americana) were handily cleared from the body of the mice, and they are unlikely to pose a danger to humans when this therapy is translated. 

Crucially important — the bacteria not only attack the tumor but also enlist the body’s own immune system to aid in the assault. It may be that the bacteria are well-adapted to reproduce inside the tumor, and they grow to a critical mass where the body’s immune system comes in to pounce on them; only then does the immune system notice and attack the cancer. “The underlying therapeutic mechanism encompasses selective tumor colonization and proliferation by this facultative anaerobic bacterium, coupled with potent direct cytotoxic effects against cancer cells and comprehensive immune-mediated tumor suppression through coordinated activation of neutrophils, T cells, and B cells.”

When the episode is ended, the tumor resorbed and the bacteria eliminated from the mouse system, the mouse immune system is left primed to prevent recurrence. Contrast this to the action of chemotherapy. Chemotherapy targets any cells that reproduce rapidly, not only the tumor but (visibly) the patient’s hair follicles and (invisibly) the patient’s immune system. When the dust clears, the patient is left in an immune-impaired condition, vulnerable not only to infection but to recurrence of the same cancer or a more aggressive one. Chemotherapy accelerates the GrimAge clock, and we all have anecdotal experience that it ages patients visibly.

The team knew just what they were looking for. They were systematically exploring bacteria strains from the microbiomes of amphibians and reptiles for anti-tumor activity. All the tested bacterial strains were pre-tested for pathogenicity in mammals, and three candidates advanced to a stage of optimizing treatment protocols in mice. Ewingella was the best of the three.

In the past, this same Japanese group has looked inside tumors for “oncolytic” bacterial strains that might already be well-adapted to parasitizing a particular cancer. The enemy of your enemy is your friend. These results, too, have been promising. “Based on these considerations, we hypothesize that the gut microbiome represents a vast reservoir of bacterial diversity, encompassing strains with potentially exceptional antitumor properties that remain largely unexplored.”

The human microbiome is known to have major effects on susceptibility to disease, including cancer, and remains an opportunity for exploring new therapeutic potential. Our gut bacteria manufacture many of the proteins that keep us healthy, as well as some that can make us sick. The Japanese authors point out in their introduction that there is already a literature on human gut biota in relation to cancer. “The mechanisms underlying these microbiome-cancer interactions are remarkably diverse, encompassing direct genotoxic effects, chronic inflammatory processes, immune system modulation, and metabolic reprogramming of the tumor microenvironment.” 

A small number of researchers have become interested in the intestinal microbiome, but so far, we don’t have enough understanding of interrelationships among species to be the basis for effective treatments. 

These spectacular, early results for the effectiveness of a bacterial strains in fighting cancer remain in a backwater of medical literature. You can be sure that if any molecule had shown such promise, the public relations machine would be in full gear, promoting the breakthrough in Science Magazine and in the news media as well. 

The universe of bacteria and fungi with potential for treating human disease remains an untapped resource which could be seminal for the future of medicine. 

Our American for-profit model of medical research has introduced distortions into the field, and whole areas of possibility are being neglected. Lifestyle changes, exosomes, natural hormones, traditional herbs — all of these are non-patentable, so no company is motivated to invest in researching their potential. 

It’s not just that pharma companies fund their own in-house research as well as research at medical schools. Government-funded research is overwhelmingly the same model. Everyone is looking for one molecule for one disease, preferably a new molecule that can be patented.

Through the last century of medical research, we have come to view the body through a biochemical lens. Our bodies are also ecosystems of symbionts, commensals, and parasites, each with multiple counter-balancing and reinforcing effects. We look for biochemical imbalances as the root of disease, when some diseases are better understood as ecological imbalances. 

Lifespan.io article by Arkadi Mazin
Original research article from the journal Gut Microbes