Innovative ‘Poop Pills’ Dramatically Improve Cancer Treatment

Immunotherapy has transformed cancer care, but many patients either fail to respond or develop severe side effects that force treatment to stop early. In kidney cancer, lung cancer, and melanoma, immune-related complications such as colitis and diarrhea can significantly reduce quality of life and limit survival benefits. At the same time, response rates to immunotherapy remain inconsistent across cancer types. New clinical studies now show that modifying the gut microbiome can both reduce treatment toxicity and substantially improve patient response to immunotherapy.

In research led by Lawson Research Institute (Ontario, Canada), in collaboration with London Health Sciences Centre Research Institute (LHSCRI, Ontario, Canada) and clinical partners, scientists have developed advanced oral fecal microbiota transplant capsules, known as LND101, created from healthy donor stool and designed to restore a balanced gut microbiome safely. The capsules are standardized, scalable, and easy to administer, making them suitable for use alongside cancer immunotherapy in clinical settings.

In a Phase I clinical trial, researchers evaluated whether FMT could be safely combined with immunotherapy in patients with advanced kidney cancer. The study involved 20 patients treated at a specialized cancer center and focused on reducing immune-related side effects that often limit therapy. The findings, published in Nature Medicine, showed that customized FMT could significantly reduce gastrointestinal toxicity without compromising cancer treatment.

Separate Phase II trials examined the effect of FMT on immunotherapy response in lung cancer and melanoma. In lung cancer patients, 80 percent responded to immunotherapy after receiving FMT, compared with the typical 39–45 percent response rate seen with immunotherapy alone. In melanoma, 75 percent of patients responded following FMT, compared with about 50–58 percent in standard treatment, demonstrating a marked improvement across both cancer types.

Together, the studies suggest that fecal microbiota transplantation can both enhance immunotherapy effectiveness and reduce harmful side effects, addressing two major limitations of current cancer treatments. By reshaping the gut microbiome, FMT appears to remove harmful bacteria and promote immune responses that better target tumors. Researchers are now expanding this approach through larger randomized trials, including pan-Canadian studies, and exploring its potential in other cancers such as pancreatic and triple-negative breast cancer.

“Our clinical trials show that fecal microbiota transplantation can both reduce immunotherapy toxicity and significantly improve treatment response,” said Dr. Arielle Elkrief, Physician Scientist and Co-Principal Investigator, who was involved in the lung cancer and melanoma studies. “These results open a new path toward personalized microbiome-based therapies in oncology.”

Related Links:
Lawson Research Institute
LHSCRI