US-based Ironwood Pharmaceuticals has started a Phase IIb clinical trial of IW-3718 in patients with refractory gastroesophageal reflux disease (GERD), a chronic condition.

In refractory GERD, patients continue to suffer from symptoms such as heartburn and regurgitation despite receiving treatment with a proton pump inhibitor (PPI).

The company intends to report data from this Phase IIb clinical trial next year.

Ironwood research and development president and chief scientific officer Mark Currie said: "There is a significant unmet medical need among the estimated 10 million patients in the US with refractory GERD.

"There is a significant unmet medical need among the estimated 10 million patients in the US with refractory GERD."

"For these patients, PPIs are not enough to control their heartburn and regurgitation. They continue to suffer from frequent and bothersome symptoms, and there is a dearth of approved prescription medicines for this condition. For these reasons, the advancement of IW-3718 is a top priority for Ironwood."

Around 260 adult patients will be enrolled in the trial, which is designed to evaluate the safety, efficacy, and dose-response relationship of IW-3718.

Patients will have been diagnosed with GERD and report experiencing heartburn or regurgitation at least four days per week during the previous eight weeks, despite ongoing PPI treatment.

The trial will require eligible patients to continue taking their daily PPI therapy and to randomly receive additional treatment with placebo or one of three doses of IW-3718, twice-daily for eight weeks.

The primary efficacy endpoint of the trial is change in heartburn severity from baseline.

The company previously reported positive data from its Phase IIa trial of IW-3718 for refractory GERD.

This trial showed that IW-3718 reduced heartburn severity and was generally well-tolerated with the most common adverse event being constipation.

Ironwood used Acuform drug delivery technology licensed from Depomed to develop IW-3718, a new investigational gastric retentive formulation of a bile acid sequestrant.