Effects of treatment with eluxadoline on abdominal pain in patients with IBS‐D: Additional post hoc analyses of Phase 3 trials

Background Recurring abdominal pain is a characteristic and often unpredictable and debilitating symptom of irritable bowel syndrome with diarrhea (IBS‐D). Measuring the effects of IBS‐D treatments on abdominal pain remains a significant challenge in clinical trials. Here, we aimed to examine the effect of eluxadoline through various post hoc analyses. Methods Data from two eluxadoline Phase 3 trials were pooled over 26 weeks, comparing eluxadoline 100 mg twice daily to placebo. Worst abdominal pain (WAP) was measured daily on a 0‐10 scale. WAP responder criteria were prospectively defined as a ≥30% improvement in daily WAP score on ≥50% of days. Pairwise, two‐sided Cochran ‐ Mantel ‐ Haenszel tests assessed treatment effects. Cumulative distribution functions were used to plot WAP response rates using variations on the response criteria. Key results Of 1615 patients with IBS‐D (66% female, mean age 46 years), 806 received eluxadoline and 809 received placebo; 48.3% and 44.0% were WAP responders (≥30% improvement), respectively ( P value not significant). When the response threshold was increased to 50% daily WAP improvement from baseline, a significantly greater percentage of eluxadoline‐treated patients versus placebo‐treated patients were WAP responders (38.7% vs 32.5%, respectively; P  = .009). At Week 26, average WAP changes from baseline were −3.4 and −3.0 points, respectively ( P  = .002). Conclusions and Inferences Despite small effect sizes, eluxadoline demonstrated consistent and sustained improvement in WAP compared to placebo across a range of prospective and post hoc analyses. Assessing WAP response across a range of measures is important for fully understanding a treatment's efficacy.