Study finds fecal transplant improved immunotherapy response in melanoma patients

A clinical trial examining whether a fecal transplant could alter the gut microbiome of an advanced cancer patient to improve the patient’s response to cancer treatment has shown encouraging results.

The study showed that in 6 of 15 patients, a stool transplant changed the composition of a patient’s microbiome environment and helped turn the patient from being a “non-responder” to a “responder” to immunotherapy, said Stephanie Prescott, PhD, NNP-BC, RN, a University of South Florida College of Nursing researcher who worked on the study as a postdoctoral fellow at the National Cancer Institute (NCI).

The study was led by researchers from the UPMC Hillman Cancer Center and the NCI. The findings were published in Science in February.

A key element of the study is a person’s gut microbiota, which is comprised of a diverse mix of bacterial species and affects how patients respond to cancer treatments like immunotherapy. This study focused on patients with melanoma, an aggressive form of skin cancer, and the cancer treatment known as anti-PD-1 immunotherapy.

Researchers collected fecal samples from melanoma patients who responded positively to anti-PD-1 immunotherapy. After testing these donor samples to ensure they were free of pathogens, the stool samples were transplanted through colonoscopy to stage 4 melanoma patients who had previously failed to respond to anti-PD-1 immunotherapy.

The results showed that after the fecal transplant, most patients’ microbiota composition changed to be like the donors’.

Of the 15 melanoma cancer patients who received the transplant and were given the anti-PD-1 immunotherapy, six patients’ tumors were either reduced or the disease had stabilized for more than a year.

“We don’t think that the microbiome is the entire reason why somebody responds or doesn’t respond to immunotherapy. There can be other things that are going on. But we do think that a favorable microbiome can change a person’s immune response to therapy in a positive way,” Dr. Prescott said.

Stephanie Prescott is a nurse researcher at the University of South Florida College of Nursing.

Further analysis of the patients’ blood samples offers more insight into how the microbiome was helping.

“The fecal transplant changed the microbiota in the gut, which led to an immune response that then translated to the tumor microenvironment. Giving them a good microbiota initiates an immune response that can make the body more aware of the tumor. Basically, it helps to unblock the actions of immune cells that the tumor has been blocking,” she said.

Overall, the study shows what researchers had suspected— that the microbiota is playing a role in how a cancer patient responds to treatment, she said.

“All microbiome research is eventually trying to get to the point where we understand and communicate in the `language’ that the microbes speak to us, their host, influencing our health and behavior without instrumentation or untargeted interventions,” Dr. Prescott said.

Dr. Prescott said the results of the study are promising and she hopes to do a similar study in partnership with Moffitt Cancer Center in women who have breast cancer but are not responding to immunotherapy.

Story by Elizabeth L. Brown, USF College of Nursing