Fecal Microbiota Transplants Show Potential in Improving Melanoma Treatment

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Researchers have found that fecal microbiota transplants from healthy donors may be safe and show potential in improving response rates to immunotherapy in patients with advanced melanoma, according to a phase I study published by Routy et al in Nature Medicine.


While immunotherapy agents—designed to stimulate the immune system to attack and destroy cancer cells—can significantly improve survival outcomes in patients with melanoma, they are only effective in 40% to 50% of cases. Preliminary research has suggested that the human microbiome may play a role in treatment response.

“In this study, we aimed to improve patients’ responses to immunotherapy by [boosting] the health of their microbiome through fecal [microbiota] transplants,” explained co–study author John Lenehan, MD, Associate Professor of Oncology at the Western University Schulich School of Medicine & Dentistry as well as a medical oncologist at the London Regional Cancer Program and an associate scientist at the Lawson Health Research Institute at the London Health Sciences Centre.

A fecal microbiota transplant involves collecting stool from a healthy donor, screening and preparing it in a lab, and transplanting it to the patient. The goal of the procedure is to encourage healthy bacteria to proliferate in the patient’s gut.

“The connection between the microbiome, the immune system, and cancer treatment is a growing field in science,” highlighted senior study author Saman Maleki Vareki, MSc, PhD, Assistant Professor of Oncology, Pathology and Laboratory Medicine, and Medical Biophysics at the Western University Schulich School of Medicine & Dentistry as well as a scientist at the London Regional Cancer Program at the London Health Sciences Centre. “This study aimed to harness microbes to improve outcomes for patients with melanoma,” he added.

Study Methods and Results

In the new phase I trial, the researchers administered about 40 oral fecal microbiota transplant capsules during a single session 1 week prior to the initiation of immunotherapy to 20 patients with melanoma.

The researchers found that combining the fecal microbiota transplants with immunotherapy was potentially safe for the patients who participated in the study. They also discovered that 65% of the patients who retained the donors’ fecal microbiota had clinical responses to the combination treatment. However, 5 of them experienced adverse events sometimes associated with immunotherapy and had their treatment discontinued.

“We have reached a plateau in treating melanoma with immunotherapy, but the microbiome has the potential to be a paradigm shift,” emphasized lead study author Bertrand Routy, MD, PhD, Associate Clinical Professor of Hematology-Oncology in the Department of Medicine at the Université de Montréal and Director of the Laboratory of Immunotherapy/Oncomicrobiome at the Centre Hospitalier de l’Université de Montréal. “This study puts Canada at the forefront of microbiome research by showing we can safely improve patients’ response to immunotherapy through fecal transplants,” he proposed.


“These exciting results add to a rapidly growing list of publications suggesting that targeting the microbiome may provide a major advance in the use of immunotherapy for our patients with cancer,” underscored co–study author Wilson H. Miller Jr, MD, PhD, the James McGill Professor of Oncology and Medicine as well as Director of Developmental Therapeutics at McGill University and Associate Director of Clinical Research at the Lady Davis Institute for Medical Research at the Jewish General Hospital.

“Our group has been doing fecal [microbiota] transplants for 20 years, initially finding success treating Clostridioides difficile infections. This has enabled us to refine our methods and provide an exceptionally high rate of the donor microbes surviving in the recipient’s gut with just a single dose,” noted Michael Silverman, MD, FRCP, FACP, AAHIVMed, Chair of the Division of Infectious Diseases at the Western University Schulich School of Medicine & Dentistry, Chief of Infectious Diseases at St. Joseph’s Health Care London, and an associate scientist at the Lawson Health Research Institute at the London Health Sciences Centre. “Our data suggests at least some of the success we are seeing in patients [with melanoma] is related to the efficacy of the capsules," he indicated.

The researchers are currently conducting a larger phase II trial involving medical centers in Ontario and Quebec, and are also analyzing the potential of fecal microbiota transplants in the treatment of other cancer types—including renal cell carcinoma, pancreatic cancer, and lung cancer—as well as in patients with the human immunodeficiency virus and rheumatoid arthritis.

Disclosure: The research in this study was supported in part through donor funding from the London Health Sciences Foundation, Western University, the Lotte and John Hecht Memorial Foundation, the Jewish General Hospital Foundation, the Canadian Cancer Society’s Impact Grant program, and The Terry Fox Foundation. For full disclosures of the study authors, visit

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.