Evaluating Fecal Microbiota Transplant in IBS

Mark Pimentel, MD: I’ve got to say that this area confuses doctors who aren’t experts and patients. Because on the 1 hand, and we’ll get to antibiotics, we say antibiotics. On the other hand, some people say probiotics, which is the opposite of antibiotics. And then some say prebiotics, to try to nurture particular organisms. And then we’re giving diets to reduce bacteria, or fermentation. And then, FMT [fecal microbiota transplantation]. I know it’s not part of diet, but Ali, do you want to comment on FMT? You had a poster at this meeting, and there have been a lot of descriptions about FMT here.

Anthony J. Lembo, MD: As you said, IBS [irritable bowel syndrome] and the microbiome are a hot topic. One idea is that, what happens if I take somebody’s healthy microbiome and put it in somebody who’s sick to see if the symptoms improve? That worked really well in recurrent Clostridium difficile infection. It was almost a miraculous therapy for that. But unfortunately, that hasn’t really panned out for irritable bowel syndrome. Multiple trials coming out are showing that FMT is even inferior to a placebo because…

Mark Pimentel, MD: I want to stop you there. When something is inferior to placebo, another way of saying that is, “It’s hurting people and making the difference.” So what is it? Is it that the placebo is working and FMT is not? Or is the FMT making people worse?

Anthony J. Lembo, MD: It’s probably the latter that you mention. The bottom line is that in irritable bowel syndrome, the rule of microbiome is extremely complex. It’s not about putting somebody else’s microbiome into you, and then you feel better. It’s the fact that the microbiome changes because of the underlying dysmotility and the gut, and now the microbiome is different. So changing that microbiome is not going to fix the whole thing. In fact, it may make it worse because now you have the microbiome of 2 individuals, which is not working well. Obviously, that’s putting it in a simple way, but I think that is where the problem is. So we have to go the route that Brennan mentioned, with precision medicine, toward a specific target in the microbiome rather than using a very holistic approach like FMT.

Mark Pimentel, MD: Not to start a war, but you just did a study. I’m not saying you’re a believer, but you’re trying to get evidence-based medicine on giving FMT. Now by capsules, I think, right?

Anthony J. Lembo, MD: I agree with what Ali has said. I think the jury is still out on FMT in IBS. It clearly has worked in other conditions, and there’s some evidence in inflammatory bowel disease. As you said, it’s not for every patient. We need to do more precision medicine, and we probably can identify patients who have alterations. There is evidence that there are abnormalities in people with IBS, and some suggest that may be more of a proinflammatory, and the diversity is a little different in some patients with IBS. So we can do better.

There are several studies. We just completed a pill-based study. That’s the third one that’s been published. All 3 are negative, so I think we can say that pills are probably not the way to go. But there is the colonoscopy, and another one where they gave it through an NG [nasogastric] tube. There is some evidence that it may be effective there. So we’re still learning about FMT, and I think more studies will clearly need to be done.

Mark Pimentel, MD: I’m not going to take a show of hands on if any of us would use FMT for our IBS-D [IBS with diarrhea] patients because I have a feeling I know the answer right now. Because of the lack of evidence, not because we don’t like the idea. Is that fair? All right, I won’t do that.

Transcript edited for clarity.