Challenges to the therapeutic pipeline for irritable bowel syndrome: end points and regulatory hurdles

Electro-acupuncture relieves visceral sensitivity and decreases hypothalamic corticotropin-releasing hormone levels in a rat model of irritable bowel syndrome

Previous studies into electro-acupuncture (EA) treatment of irritable bowel syndrome (IBS) have principally focused on the peripheral effects of EA in a rat model of IBS. It is not known whether EA exerts central effects in this rat model. We have examined the effects of EA on hypothalamic corticotropin-releasing hormone (CRH) levels in a rat model of IBS provoked by colorectal distension (CRD) and forelimb immobilization. EA was administered once daily to IBS model rats over a period of 7 d; untreated IBS rats and controls were also studied. The behavioral response to distension was rated according to the abdominal withdrawal reflex (AWR) score; hypothalamic CRH levels were measured by radioimmunoassay. We report that EA treatment significantly decreased visceral sensitivity to CRD in this rat model. In treated animals, EA also decreased hypothalamic CRH to control levels. Reduced hypothalamic CRH levels may mediate the beneficial effects of EA in this rat IBS model.

Editorial: is adequate relief fatally flawed or adequate as an end point in irritable bowel syndrome?

There is controversy on the validity of binary end points used in irritable bowel syndrome (IBS) clinical trials. In a usual-care observational study, baseline severity influenced the response measured as satisfactory relief. This editorial reviews the observations from a non-pharmacological study to assess the effect of baseline severity on the performance of binary end points in large drug trials. The pivotal finding is that once the patients who reported adequate relief at baseline were excluded from the analysis, baseline severity no longer affected the proportion of patients reporting adequate relief of IBS with treatment. As large drug trials enriched the study cohorts for at least moderate severity after a no-treatment, run-in period, it seems likely that the precaution of excluding mild disease de facto resolved the hypothetical weakness of the adequate relief end point. Given the high responsiveness and longitudinal construct validity demonstrated with adequate relief end point, it should be accepted as a trial end point.