His cancer treatment was failing. A fecal transplant turned it around. Scientists are learning how to harness the power of the gut microbiome to make certain cancer drugs more potent.

In the spring of 2022, Tim Story’s doctor told him that he likely had just months to live.

Story, a high school football coach in Hattiesburg, Mississippi, had been diagnosed with Stage 3 small bowel cancer two years earlier, at the age of 49, after mysterious pains in his side turned out to be a tumor in his small intestine. Surgery and several grueling rounds of chemotherapy and immunotherapy had failed to stop the cancer, which had spread to other organs.

“I’m not a crying man, but my wife and I shed some tears on the couch that day,” said Story, now 53.

There was one final option, however: He could join an unusual clinical trial at MD Anderson Cancer Center in Houston that had just started recruiting patients. Highly experimental — and with no guarantee of success — the trial involved getting a so-called fecal transplant from a patient with advanced cancer who had been completely cured by immunotherapy. The idea was that the unique populations of gut bacteria found within the stool might help kick-start the immune system to better recognize and fight the cancer.

It came with its own risks, but Story agreed to enroll in the trial. “I knew I was kind of a guinea pig, but the only other option was staying at home, and I wasn’t going to make it,” he said.