A team of Canadian researchers is among the first in the world to test whether fecal transplants could help treat the deadliest form of skin cancer, melanoma.
Twenty patients with advanced stage disease are part of the phase one study out of the Lawson Health Research Institute in London, Ont. Participants have been prescribed pills filled with purified fecal bacteria, and they will then undergo immunotherapy in hopes of stimulating their bodies to kill cancer.
The hope is that transplanting healthy gut bacteria to cancer patients will boost their immune systems and make the immunotherapy drugs more effective. In turn, their bodies will be primed to destroy cancer cells.
The study is still in its early stages, but scientists have already seen promising signs the immune cells are revving up in the first two patients.
“We are getting some signs that the immune system is responding to these transplants,” said Dr. Michael Silverman, an associate scientist with the hospital. “We’re excited but we don’t want to give off the impression that this is a proven phenomenon yet, because it’s too early.”
Typically, immunotherapy with checkpoint inhibitors or PD-1 drugs is only successful in about half of patients. But preliminary research has shown that a person’s gut bacteria may play a role in whether their body responds to the treatment.
“Our hope is that every one of our patients will have a complete cure,” said Dr. John Lenehan, an associate scientist and oncologist with the hospital. “Although we’d be very happy if we had more than just 50 per cent responding to the treatment.”
Gut bacteria is having a bit of a moment in the medical world. Previous research has shown that the multitude of microorganisms in the human gut -- known among scientists as the microbiome -- have wider implications on a person’s overall health. Multiple sclerosis, inflammatory bowel disease and Alzheimer’s disease have all been linked to gut bacteria.
“Historically, the poop that comes out was felt to be either leftover food, or stuff that was not important, just bacteria that had no impact. Now we’re realizing that the organisms within the gut -- the gut microbiome -- are critically important in maintaining human health,” Silverman said.
Treating cancer with another person’s fecal matter may seem odd, and possibly even gross. But Emma Allen-Vercoe, a microbiologist at the University of Guelph, says the treatment doesn’t seem unusual to her. Instead, she calls it “a very smart strategy.”
“What I don’t think a lot of people realize is that the microbiome in the gut does an awful lot of talking to us … and so the idea that the microbiome might be used to help fine tune some of the treatments that we use to modulate the immune system and cancer treatment is not very far-fetched to people like me who understand the microbiome. But I think to the general public it comes as a bit of a shock,” she said.
Patients involved in the London study don’t seem fazed by the idea, either. Stool samples are gathered from healthy donors and undergo special treatment. The pills, which are taken orally, are tasteless and do not resemble human feces.
“If they have to swallow a bunch of pills they don’t seem that bothered by that. Even knowing that there’s stool inside, that’s fine with them. They want to live longer,” Lenehan said.
The study is the first of its kind in Canada to conduct full fecal transplants in cancer patients in hopes of boosting their responses to immunotherapy.
Research is expected to take two years. Doctors will monitor whether the gut bacteria is successful at repairing the immune system and helping shrink tumours.
If the method is effective, fecal transplants could be studied on a variety of cancers.
“We’re excited, we think it is a whole new field,” Silverman said.
A similar study is underway in Toronto. Researchers at Princess Margaret Hospital are using select microbes isolated from health donors and testing them on patients with several different kinds of solid tumours. The study is also in its early stages.
Allen-Vercoe, who is involved in the Toronto study, says research into the microbiome is a “very hot new area” of medicine that is gathering plenty of attention.
“I think it’s an area of such high excitement for the research community that I wouldn’t be surprised if this is going on quite widely around the world,” she said.
The London study is looking for young, healthy donors to provide fecal transplants. Anyone in the London, Ont. region interested in participating is asked to contact researchers at 519-646-6100 ext. 61726.