Efficacy and safety of linaclotide in patients with irritable bowel syndrome with constipation: Chinese sub-cohort analysis of a phase III, randomized, double-blind, placebo-controlled trial

Real-world safety of linaclotide in Chinese patients with irritable bowel syndrome with constipation: a multicenter, single-arm, prospective observational study

Background

Linaclotide, a guanylate cyclase-C agonist, is indicated for irritable bowel syndrome with constipation (IBS-C). However, real-world data on the safety and patient-reported outcomes (PROs) of linaclotide are scarce in Chinese patients with IBS-C.

Objectives

To assess the real-world safety and PROs of linaclotide in the Chinese IBS-C population.

Design

Multicenter, prospective observational study.

Methods

Adults with IBS-C who had taken or planned to take at least one dose of linaclotide 290 μg were enrolled and followed up for 3 months. Face-to-face visits were conducted at baseline (V1), Week 4 ± 7 days (V2), and Week 12 ± 7 days (V3). Primary endpoints included the incidences of adverse events (AEs), AEs by severity, adverse drug reactions (ADRs), serious AEs (SAEs), and AEs leading to treatment interruption, discontinuation, and death. Secondary endpoints included mean treatment satisfaction at V2 and V3, and mean overall Irritable Bowel Syndrome-Quality of Life (IBS-QoL) at V2.

Results

Out of 3000 enrolled patients, 2963 took at least one dose of linaclotide and were analyzed. Overall, 712 patients (24.0%) reported 1095 AEs, which were mostly mild (89.9%). Diarrhea, reported in 297 out of the 2963 patients analyzed (10.0%), was the most common AE. No severe diarrhea was reported. Totally, 319 patients (10.8%) reported ADRs. Forty-six patients (1.6%) reported 50 SAEs and two cases were considered related to linaclotide treatment. Fifty-one (1.7%) and 70 patients (2.4%) interrupted and discontinued treatment due to AEs, respectively. One patient died of hepatic cancer, which was considered unrelated to linaclotide treatment. During the follow-up, the mean (±SD) treatment satisfaction increased numerically and continuously (V1, 2.8 ± 1.3 (n = 1721); V2, 3.5 ± 1.1 (n = 1705); V3, 3.9 ± 1.0 (n = 833)). The mean (±SD) overall IBS-QoL increased numerically from 73.2 ± 16.6 (n = 1924) at V1 to 80.2 ± 15.5 (n = 1738) at V2.

Conclusion

In the Chinese real-world setting, linaclotide was safe and well tolerated in patients with IBS-C. Numerically, there are trends toward improvement in PROs with linaclotide treatment.

Efficacy and Safety of Transcutaneous Auricular Vagus Nerve Stimulation in Patients With Constipation-Predominant Irritable Bowel Syndrome: A Single-Center, Single-Blind, Randomized Controlled Trial

INTRODUCTION

Transcutaneous auricular vagus nerve stimulation (taVNS) is a promising therapy for irritable bowel syndrome (IBS). The aims of this clinical trial were to evaluate the influence of taVNS on autonomic functions, rectal sensation, and acetylcholine (Ach) levels and to explore potential mechanisms involving gut microbiota and metabolic profiles.

METHODS

This study was a single-center, single-blind, randomized controlled trial executed at the First Affiliated Hospital of USTC, Anhui, China. Individual patients' constipation-predominant IBS (IBS-C)-related symptoms and mental health were assessed and scored using questionnaires at baseline and at week 4. Levels of serum Ach and nitric oxide, anorectal manometry, and heart rate variability were assessed both before and after the therapy. Fecal samples from each group were assessed to compare the gut microbiota, short-chain fatty acids, and gut microbiota-derived tryptophan metabolites.

RESULTS

Between September 2023 and May 2024, 40 patients (n = 20 in both taVNS and sham-taVNS groups) completed the 4-week study by performing an intention-to-treat analysis. No differences in all parameters between taVNS and sham-taVNS groups at the baseline were found. The taVNS significantly improved the visual analog scale score ( P < 0.001), IBS Severity Scoring System score ( P < 0.001), weekly frequency of spontaneous bowel movements ( P < 0.001), weekly frequency of complete spontaneous bowel movements ( P = 0.004), Bristol Stool Form Scale score ( P < 0.001), Hamilton Anxiety Scale score ( P < 0.001), Hamilton Depression Scale score ( P < 0.001), and IBS Quality of Life score ( P < 0.001). Furthermore, taVNS improved rectal sensation in patients with IBS-C, including improvements in the threshold volume for initial sensation ( P = 0.033), urge to defecate ( P = 0.022), and rectoanal inhibitory reflex ( P = 0.002). Moreover, taVNS elevated serum levels of Ach ( P = 0.005) and reduced nitric oxide ( P = 0.016) while also enhancing vagal activity ( P < 0.001) as determined by spectral analysis of heart rate variability. Three patients in the taVNS group and 2 in the control group had adverse consequences, which were manageable. In addition, taVNS led to a significant rise in the level of the genus Bifidobacterium ( P = 0.038) and increased levels of acetic ( P = 0.003), butyric ( P = 0.011), and propionic ( P = 0.005) acids. It also decreased tryptophan metabolism content, including 3-hydroxyanthranilic acid ( P = 0.007), anthranilic acid ( P = 0.026), and L-tryptophan ( P = 0.002).

DISCUSSION

The study manifested that noninvasive taVNS effectively improved constipation and abdominal pain symptoms in patients with IBS-C. The alleviation of IBS-C symptoms may be attributed to the integrative effects of taVNS on rectal functions, mediated through vagal, cholinergic, and multiomics mechanisms.

Nocebo effects and influencing factors in the randomized clinical trials of chronic constipation: A systematic review and meta-analysis

BACKGROUND

Nocebo effects are unavoidable in randomized clinical trials. We aimed to assess the magnitude of nocebo effects and explore the influencing factors in chronic constipation.

METHODS

We searched the PubMed, Embase, and Cochrane Library databases up to July 2022. Randomized, placebo-controlled trials investigating interventions in chronic constipation were included. We conducted a random effects meta-analysis of the proportion of adverse events (AEs) in placebo-treated participants and evaluated the effect of trial characteristics on nocebo effects.

KEY RESULTS

We identified 20,204 studies from the databases, of which 61 were included in the final analysis. The pooled placebo AE rate was 30.41%, and AE-related withdrawal rate was 1.53%. The most commonly reported AEs were headache (5.67%), diarrhea (4.45%), abdominal pain (3.98%), nasopharyngitis (3.39%), nausea (3.36%), and flatulence (2.95%). The placebo AE rate was lower in trials conducted in Asia compared to those in Europe, North America, and international trials. It was also lower in trials diagnosed by Rome III compared to clinician's opinion and Rome II. Additionally, the placebo AE rate was lower in single-center trials compared to multicenter trials, lower in 5-8 weeks therapy compared to 9-12 weeks therapy, lower in participants with FC compared to those with IBS-C and CC, lower in trials with 2 arms compared to 3 arms, and higher in trials with prokinetic drugs compared to secretagogues and laxatives.

CONCLUSIONS & INFERENCES

The placebo AE rate was 30.41% in patients with chronic constipation. Based on our findings, we recommend that researchers take the nocebo effects into consideration when designing and conducting clinical trials and adopt specific measures to mitigate the negative influence of nocebo effects.

Decoding signaling mechanisms: unraveling the targets of guanylate cyclase agonists in cardiovascular and digestive diseases

Soluble guanylate cyclase agonists and guanylate cyclase C agonists are two popular drugs for diseases of the cardiovascular system and digestive systems. The common denominator in these conditions is the potential therapeutic target of guanylate cyclase. Thanks to in-depth explorations of their underlying signaling mechanisms, the targets of these drugs are becoming clearer. This review explains the recent research progress regarding potential drugs in this class by introducing representative drugs and current findings on them.

Efficacy and safety of olorinab, a full agonist of the cannabinoid receptor 2, for the treatment of abdominal pain in patients with irritable bowel syndrome: Results from a phase 2b randomized placebo-controlled trial (CAPTIVATE)

BACKGROUND

Olorinab is a highly selective, peripherally acting, full agonist of cannabinoid receptor 2. This study assessed the efficacy and safety of olorinab to treat abdominal pain in patients with irritable bowel syndrome with diarrhea (IBS-D) and constipation (IBS-C).

METHODS

CAPTIVATE was a phase 2b, randomized, double-blind, placebo-controlled, parallel-group trial. Eligible participants aged 18-70 years with IBS-C and IBS-D diagnosed per Rome IV received olorinab 10 mg, 25 mg, or 50 mg three times daily (TID) or placebo TID for 12 weeks. The primary endpoint was the change in patient-reported average abdominal pain score (AAPS) from baseline to Week 12.

KEY RESULTS

A total of 273 participants were randomized to receive olorinab 10 mg (n = 67), olorinab 25 mg (n = 67), olorinab 50 mg (n = 69), or placebo (n = 70). Although a treatment response was observed across all groups, the weekly change in average AAPS from baseline to Week 12 was not significantly different between placebo and any olorinab dose. In a prespecified subgroup analysis of participants with a baseline AAPS ≥6.5, olorinab 50 mg (n = 35) significantly improved AAPS compared with placebo (n = 30) (p = 0.014). Adverse event rates were comparable between olorinab and placebo and there were no reported serious adverse events or deaths.

CONCLUSION AND INFERENCES

Although olorinab was well-tolerated and improved weekly AAPS, the primary endpoint was not met. However, in participants with moderate-to-severe pain at baseline (AAPS ≥6.5), olorinab 50 mg significantly improved weekly AAPS compared with placebo.

CLINICALTRIALS

gov: NCT04043455.

Update on treatment of abdominal pain in irritable bowel syndrome: A narrative review

The objectives of this narrative review are to update readers on the current state-of-the-art regarding diverse approaches for the treatment of pain, global symptoms, or adequate relief in irritable bowel syndrome (IBS). The article appraises medications, dietary interventions including low fermentable oligosaccharides, disaccharides, and monosaccharides and polyols (FODMAP) diet, fecal microbial transplantation (FMT), electrical approaches, and behavioral therapies including cognitive behavioral therapy (CBT), gut-directed hypnotherapy (GDH), mindfulness, and open-label placebo. Current evidence demonstrates only modest benefit in global IBS symptoms and pain relief. A future approach that identifies pathophysiological mechanisms of IBS through validated biomarkers has the potential to individualize treatment of patients rather than sequential therapeutic trial and error approaches.