Ironwood Launches Phase 3 Linaclotide Trial for Patients with IBS-C

Christopher Wright, MD, PhD

A new phase 3b clinical trial has been launched to evaluate the efficacy and safety of a set dosage of linaclotide (LINZESS) for the treatment of abdominal symptoms in patients with irritable bowel syndrome with constipation (IBS-C).

Researchers from biotech company Ironwood Pharmaceuticals have announced the initiation of a double-blind, placebo-controlled, parallel-group study that aims to observe linaclotide 290 mcg in 600 adult patients with IBS-C in the United States. The guanylate cyclase-C (GC-C) agonist locally binds to the GC-C receptor within the intestinal epithelium, and is indicated for the marketed treatment of IBS-C or chronic idiopathic constipation (CIC).

Christopher Wright, MD, PhD, senior vice president, global development and chief development officer at Ironwood, said more than two-thirds of the 13 million adult patients with IBS-C in the US suffer from abdominal bloating and discomfort at least once weekly.

“These symptoms are often a primary complaint and reason for patients seeking care," Wright said in a statement. "As IBS-C patients often describe their abdominal symptoms as bloating or discomfort, rather than pain, this can lead to under-treatment."

Eligible patients for the study will be randomized to linaclotide 290 mcg or placebo once daily for 12 weeks, followed by a randomized withdrawal period for 4 weeks. Researchers are gauging for a primary efficacy endpoint of change from baseline in abdominal score, based on patients’ daily assessments of bloating, discomfort, and pain at their worst. Scores will be measured on an 11-point numerical rating scale.

Researchers will also seek endpoints such as change from baseline in spontaneous bowel movement (SBM) frequency, complete spontaneous bowel movement (CSBM) frequency, stool consistency, and straining.

“If positive, we believe these data should further enable more effective communication between patients and physicians on both IBS-C and the role that linaclotide can play in treating the millions of appropriate patients suffering from IBS-C,” Wright said.

The trial is a joint product of Ironwood and Allergan, Ironwood's co-development and co-promotion partner for linaclotide in the United States.