Long-term Effects of Fecal Transplants Questioned

Lara C. Pullen, PhD

October 21, 2015

Fecal transplants are increasingly being used to treat Clostridium difficile infection. The novel approach stands in marked contrast to standard of care, which is treatment with powerful antibiotics such as vancomycin and metronidazole. Yet not everyone is convinced that the approach is ready for regular clinical use.

In an editorial published online October 20 in the BMJ, Tim Spector, MD, from King's College in London, United Kingdom, and Rob Knight, PhD, from the University of California, San Diego, call for high-quality trials to provide more complete information on the long-term effects of fecal transplants.

"As well as refining faecal transplants to include most of the key beneficial microbes, we urgently need more expertise and centres, proper screening of donors, and good long term trials and monitoring procedures in order to provide sensible advice," they write. "Otherwise, especially given the ease of performing the procedure at home following instructions on the internet, patients with many chronic complaints may lose patience and take matters into their own hands with unpredictable consequences."

At this time, the US Food and Drug Administration (FDA) has granted fecal transplant a temporary exemption from its status as an investigational drug. The United States thus has 500 centers that now offer fecal transplants compared with seven in the United Kingdom.

Patients typically receive fecal transplants for C difficile infections, yet there are few studies to support its efficacy as a treatment for early and very resistant infections. Moreover, studies in support of the use of fecal transplants in other settings, such as for treatment for allergy and obesity, are even sparser.

Dr Spector and Dr Knight also point to the risks from the procedure, including infection and the possibility of weight gain, as highlighted by a few cases.

Elizabeth Louise Hohmann, MD, from Massachusetts General Hospital in Boston, performs fecal transplants using a capsule. "We certainly need a lot more information — follow-up, careful studies — particularly for other indications," explained Dr Hohmann in an interview with Medscape Medical News. "I think it is a fast-moving field," she added.

There are currently two companies on the front edge of delivering an FDA-approved microbiome treatment for C difficile: Rebiotix Inc's RBX2660 is a standardized "microbiota suspension" derived from fresh stool that is on the fast track for FDA approval, and in August, Seres Therapeutics Inc received FDA orphan drug designation for its capsule SER-109, used for the prevention of recurrent C difficile infection in adults.

"I think the FDA has taken a reasonable approach to this," added Dr Hohmann.

Some patients, however, are not willing to wait for FDA approval of a prepared microbiome treatment. According to Open Biome, more than 5000 patients have been treated with stool from its nonprofit stool bank. Open Biome was formed in 2012 and is dedicated to expanding safe access to fecal transplants as well as to catalyzing research into the human microbiome.

Dr Spector received fees for giving a talk on the microbiome to employees of Unilever and is the author of The Diet Myth. Dr Knight received fees for speaking at a symposium on nutrition and the human gut microbiome for Nestle and is author of Follow Your Gut. Dr Hohmann is a consultant and clinical investigator for Seres Therapeutics.

BMJ. 2015;351:h5149. Full text


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