Linaclotide for irritable bowel syndrome with constipation: a 26-week, randomized, double-blind, placebo-controlled trial to evaluate efficacy and safety.

OBJECTIVES: Linaclotide is a minimally absorbed peptide guanylate cyclase-C agonist. The objective of this trial was to determine the efficacy and safety of linaclotide treatment in patients with irritable bowel syndrome with constipation (IBS-C) over 26 weeks. METHODS: This phase 3, double-blind, parallel-group, placebo-controlled trial randomized IBS-C patients to placebo or 290 µg of oral linaclotide once daily for a 26-week treatment period. The primary and the secondary efficacy assessments were evaluated over the first 12 weeks of treatment. Primary end points included the Food and Drug Administration's (FDA's) end point for IBS-C (responder: a patient who reported (i) improvement of ≥ 30 % from baseline in average daily worst abdominal pain score and (ii) increase of ≥ 1 complete spontaneous bowel movement (CSBM) from baseline, both in the same week for ≥ 6 / 12 weeks) and three other primary end points, based on improvements in abdominal pain and CSBMs for 9/12 weeks. Adverse events (AEs) were monitored. RESULTS: In all, 804 patients (mean age = 44 years, female = 90 % , white = 78 % ) were evaluated; 33.7 % of linaclotide-treated patients were FDA end point responders, vs. 13.9 % of placebo-treated patients ( P < 0.0001) (number needed to treat = 5.1, 95 % confidence interval (CI): 3.9, 7.1). The pain responder criterion of the FDA end point was met by 48.9 % of linaclotide-treated patients vs. 34.5 % of placebo-treated patients (number needed to treat = 7.0, 95 % CI: 4.7, 13.1), and the CSBM responder criterion was met by 47.6 % of linaclotide-treated patients, vs. 22.6 % of placebo patients (number needed to treat = 4.0, 95 % CI: 3.2, 5.4). Remaining primary end points ( P < 0.0001) and all secondary end points ( P < 0.001), including abdominal pain, abdominal bloating, and bowel symptoms (SBM and CSBM rates, Bristol Stool Form Scale (BSFS) score, and straining), were also statistically significantly improved with linaclotide vs. placebo. Statistically significant differences from placebo were observed for responder and continuous end points over 26 weeks of treatment. AE incidence was similar between treatment groups, except for diarrhea, which caused discontinuation in 4.5 % of linaclotide patients vs. 0.2 % of placebo patients. CONCLUSIONS: Linaclotide 290 µg once daily significantly improved abdominal and bowel symptoms associated with IBS-C over 26 weeks of treatment.

A 12-week, randomized, controlled trial with a 4-week randomized withdrawal period to evaluate the efficacy and safety of linaclotide in irritable bowel syndrome with constipation.

OBJECTIVES: Linaclotide is a minimally absorbed guanylate cyclase-C agonist. The objective of this trial was to determine the efficacy and safety of linaclotide in patients with irritable bowel syndrome with constipation (IBS-C). METHODS: This phase 3, double-blind, parallel-group, placebo-controlled trial randomized IBS-C patients to placebo or 290 µ g oral linaclotide once daily in a 12-week treatment period, followed by a 4-week randomized withdrawal (RW) period. There were four primary end points, the Food and Drug Administration ' s (FDA ' s) primary end point for IBS-C (responder: improvement of ≥ 30 % in average daily worst abdominal pain score and increase by ≥ 1 complete spontaneous bowel movement (CSBM) from baseline (same week) for at least 50 % of weeks assessed) and three other primary end points, based on improvements in abdominal pain and CSBMs for 9 / 12 weeks. Adverse events (AEs) were monitored. RESULTS: The trial evaluated 800 patients (mean age = 43.5 years, female = 90.5 % , white = 76.9 % ). The FDA end point was met by 136 / 405 linaclotide-treated patients (33.6 % ), compared with 83 / 395 placebo-treated patients (21.0 % ) ( P < 0.0001) (number needed to treat: 8.0, 95 % confidence interval: 5.4, 15.5). A greater percentage of linaclotide patients, compared with placebo patients, reported for at least 6 / 12 treatment period weeks, a reduction of ≥ 30 % in abdominal pain (50.1 vs. 37.5 % , P = 0.0003) and an increase of ≥ 1 CSBM from baseline (48.6 vs. 29.6 % , P < 0.0001). A greater percentage of linaclotide patients vs. placebo patients were also responders for the other three primary end points ( P < 0.05). Significantly greater improvements were seen in linaclotide vs. placebo patients for all secondary end points ( P < 0.001). During the RW period, patients remaining on linaclotide showed sustained improvement; patients re-randomized from linaclotide to placebo showed return of symptoms, but without worsening of symptoms relative to baseline. Diarrhea, the most common AE, resulted in discontinuation of 5.7 % of linaclotide and 0.3 % of placebo patients. CONCLUSIONS: Linaclotide significantly improved abdominal pain and bowel symptoms associated with IBS-C for at least 12 weeks; there was no worsening of symptoms compared with baseline following cessation of linaclotide during the RW period.

Two randomized trials of linaclotide for chronic constipation.

BACKGROUND: Linaclotide is a minimally absorbed peptide agonist of the guanylate cyclase C receptor. In two trials, we aimed to determine the efficacy and safety of linaclotide in patients with chronic constipation. METHODS: We conducted two randomized, 12-week, multicenter, double-blind, parallel-group, placebo-controlled, dual-dose trials (Trials 303 and 01) involving 1276 patients with chronic constipation. Patients received either placebo or linaclotide, 145 µg or 290 µg, once daily for 12 weeks. The primary efficacy end point was three or more complete spontaneous bowel movements (CSBMs) per week and an increase of one or more CSBMs from baseline during at least 9 of the 12 weeks. Adverse events were also monitored. RESULTS: For Trials 303 and 01, respectively, the primary end point was reached by 21.2% and 16.0% of the patients who received 145 µg of linaclotide and by 19.4% and 21.3% of the patients who received 290 µg of linaclotide, as compared with 3.3% and 6.0% of those who received placebo (P<0.01 for all comparisons of linaclotide with placebo). Improvements in all secondary end points were significantly greater in both linaclotide groups than in the placebo groups. The incidence of adverse events was similar among all study groups, with the exception of diarrhea, which led to discontinuation of treatment in 4.2% of patients in both linaclotide groups. CONCLUSIONS: In these two 12-week trials, linaclotide significantly reduced bowel and abdominal symptoms in patients with chronic constipation. Additional studies are needed to evaluate the potential long-term risks and benefits of linaclotide in chronic constipation. (Funded by Ironwood Pharmaceuticals and Forest Research Institute; ClinicalTrials.gov numbers, NCT00765882 and NCT00730015.).