Lilly starts Phase 2 trial of brenipatide in diarrhea-predominant IBS

Eli Lilly has started enrolling adults in a Phase 2 trial of brenipatide, an experimental drug also known as LY3537031, in people with irritable bowel syndrome with diarrhea, or IBS-D. The study is registered on ClinicalTrials.gov as NCT07545759, is described as RENEW-IBS-D, and is planned to include 531 participants ^[1].

IBS-D is a long-term digestive condition marked by recurring abdominal pain and loose, frequent stools. The registry lists the study as Phase 2, the stage of testing that generally follows small safety studies and comes before the large trials used to support an approval decision ^[1].

Lilly has not disclosed how brenipatide is thought to work, how it would be dosed, how long treatment would last, or whether participants would be compared with a placebo. The listing also does not name an approved drug as a comparator ^[1]. Whether brenipatide acts on the same gut-hormone pathways as Lilly's approved metabolic medicines has not been described in the trial record ^[1]. Brenipatide is not approved for any use ^[1].

The entry does not say whether brenipatide has been tested in people with IBS before, or whether Lilly plans other trials in digestive conditions ^[1].

What the registration does make clear is the size and the population: 531 adults with IBS-D, an enrollment target set out in the listing ^[1]. The listing also does not describe which symptoms the study will measure, such as stool frequency or abdominal pain, or how improvement will be judged ^[1].

Why it matters for patients

For someone living with IBS-D, this is a pipeline development rather than an available option. Phase 2 studies are designed mainly to see whether a drug shows signs of helping and whether it looks safe enough to test further; they do not settle whether a drug works ^[1].

People who want details on taking part can read the registry entry, which carries the study's inclusion and exclusion criteria along with contact information for enrollment ^[1]. Because it is not known whether the trial uses a placebo, it also is not known whether every participant would receive brenipatide ^[1].

Nothing about this study changes how IBS-D is treated today. No approval decision can happen before later-stage trials, and Lilly has not announced any ^[1].

What happens next

The trial's current step is enrollment, toward a target of 531 adults ^[1]. No completion date, results timeline, primary endpoint, dosing plan or list of study locations has been disclosed ^[1].

It also has not been reported whether other companies are running similar mid-stage trials of gut-hormone drugs in IBS-D, or whether Lilly intends to follow this study with a larger one ^[1].