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The idea that the trillions of microorganisms inside us could hold the key to better health has inspired a booming field of scientific research — and a burgeoning economy around it.

You can buy self-help books, yogurts, and cosmetics purported to help you strike just the right balance in your unique microbiome. And now drug makers are getting in on the action, aiming to target microbes to treat everything from type 2 diabetes to inflammatory bowel disorders — though some scientists caution that the hype may be outpacing the science.

The latest drug company to enter the market is Evelo Therapeutics, which launched on Wednesday. The Massachusetts company, born out of Flagship Ventures’ in-house incubator and backed with $35 million from the venture capital firm, wants to develop drugs made of bacteria to target cancers of the lung, skin, prostate, and colon.


Some of the bacteria that are part of the human microbiome have been linked to certain cancers, though those relationships are not fully understood. Evelo’s spin on cancer therapy aims to recalibrate a patient’s microbiome to fight cancer.

Those efforts take a few different forms. One approach would use certain kinds of bacteria as a drug to interfere with the metabolism of the tumor by competing with it for nutrients. Another approach would use infusions of bacteria to make the tumor’s immediate surroundings, known as its microenvironment, more hostile to the cancer’s growth. A third tactic the company is exploring would use bacteria to activate the immune system to attack tumor cells. The company frames that method as a “next-generation approach” in the growing field of immuno-oncology.


“The rising understanding of immunotherapy and the rising knowledge of the microbiome just really present an unprecedented opportunity to have a massive impact on cancer,” said Evelo chief executive Simba Gill.

Gill, a biotech veteran, said Evelo is advancing a number of pre-clinical drug candidates, which might take the form of a pill, or, for some types of cancers, an inhalant or cream. He expects the company to move into human testing “relatively soon.”

“The cat’s out of the bag with regard to how important the microbiota is to human health.”

Justin Sonnenburg, a microbiologist at Stanford University

As evidence for how bacteria can treat cancer, Gill points to the longtime use of one particular strain of bacteria, Mycobacterium bovis, as one of the most effective treatments for early-stage bladder cancer.

But Harvard epidemiologist Bill Hanage said the science behind such approaches is inconclusive. He voiced skepticism of the prospect of “trying to manipulate the big and complicated immune system by using the big and complicated microbiome.”

That complexity hasn’t stopped commercial activity. The worldwide market for products — ranging from foods to drugs to devices — that leverage the human microbiome is projected to grow to nearly $300 million by 2019 and surpass $650 million by 2023, according to MarketsandMarkets, a consulting firm.

“The cat’s out of the bag with regard to how important the microbiota is to human health,” said Justin Sonnenburg, a Stanford microbiologist who sits on the scientific advisory board of another Flagship Ventures startup, VL32.

Evelo’s launch comes a week after prominent researchers issued a call for government-led research on the workings of the human microbiome and those of other ecosystems, like the ocean or the soil.

Flagship Ventures is investing heavily in the science, backing Symbiota, which is working on the plant microbiome, and Seres Therapeutics, which raised $140 million in an initial public offering this summer and is testing a drug that would prevent the recurrence of a bacterial infection in the colon.

Evelo is not the only company looking to harness microbiome research for oncology. UK-based Origin Sciences and US-based Metabiomics, for instance, are developing microbiome-based diagnostics for colorectal cancer.