Poop Transplants Could Improve Cancer Treatment

A volume of donated stool may be exactly what some cancer patients need. A small clinical trial found evidence that fecal microbiota transplantation can increase the effectiveness of immunotherapy in patients with advanced gastric cancer. The findings could pave the way for combination therapy for some of the most difficult cancers.

Scientists from South Korea conducted the research as part of an ongoing effort to improve the use of immune checkpoint inhibitors. The drugs target specific proteins that block the immune system’s ability to recognize cancer cells as a serious threat. These inhibitors and other types of immunotherapy have become a powerful treatment strategy over the years, allowing doctors to treat advanced cancers that were once thought to be almost incurable. But they have their limitations, the main one of which is that only certain patients respond to treatment, while others may become resistant to the medication.

Some research has suggested that the gut microbiome, the community of bacteria that live around our digestive tract, may influence people’s response to immunotherapy. That has led some scientists to test whether fecal microbiota transplants can increase the chances of immunotherapy success by resetting people’s microbiomes. Phase I test published last year has already shown promising results using these implants in melanoma patients. But this latest study appears to be the first to test them in other types of metastatic solid tumors.

The scientists recruited 13 patients with various types of stomach cancer in their study, all of whom had developed resistance to anti-PD-1 inhibitors. Patients were given transplants from people who had responded to immunotherapy, and were given another course of inhibitors. Of these, half of the patients (six in total) showed a visible response, and five patients’ cancers stabilized.

“Our results suggest that [fecal microbiota transplantation] with beneficial microbiota can overcome resistance to anti-PD-1 inhibitors in advanced solid cancers, especially colon cancer,” the scientists wrote in their paper. published earlier this month in the journal Cell Host & Microbe.

This is only one small trial, so more research will be needed to know if these tumors could be an effective adjunct to immunotherapy. But the findings of this study may already provide important insights into how the gut microbiome affects human immunotherapy. Scientists were able to identify specific strains of certain bacteria that were associated with a better or worse response to the inhibitors. That information should help these and other researchers refine these treatments in the future.

“By examining the complex interactions within the microbiome, we hope to identify relevant microbial communities that can be used to improve the results of cancer treatment,” said study researcher Hansoo Park, a scientist in the study. The Gwangju Institute of Science and Technology, in a statement from Cell Press, the journal’s publishers. “This comprehensive approach will help us understand how the entire microbial ecosystem contributes to therapeutic success.”