A proof-of-concept study evaluating the effect of ADX10059, a metabotropic glutamate receptor-5 negative allosteric modulator, on acid exposure and symptoms in gastro-oesophageal reflux disease

Background: In preclinical models, antagonism of metabotropic glutamate receptor 5 (mGluR5) reduces transient lower oesophageal sphincter relaxations (TLOSRs) and increases LOS pressure. This study evaluated the effect of ADX10059, a potent, selective, negative allosteric modulator of mGluR5, on oesophageal pH-metry and clinical symptoms in GORD. Methods: Two groups of patients with GORD (n=12 per group) underwent 24-h oesophageal pH-metry on two sequential treatment days. The patients received oral placebo three times daily (tds) 30 min before a high-fat meal on Day 1 and oral ADX10059 50 mg (Group 1) or 250 mg (Group 2) tds 30 min before a high-fat meal on Day 2. The primary variable was acid exposure (%time pH, 4). Secondary variables included number and duration of reflux episodes, number and duration of symptomatic episodes and symptoms recorded in diaries. Comparisons were made for Day 2 (active) versus Day 1 (placebo) treatment and for Group 1 versus Group 2. Results: ADX10059 250 mg tds significantly decreased the percentage of time with pH, 4 from 7.2% to 3.6% (p=0.01). ADX10059 250 mg tds reduced pH-metry-measured oesophageal acid exposure, throughout the 24 h period, nocturnally and postprandially, and significantly reduced the number and duration of symptomatic reflux episodes (p=0.03). ADX10059 50 mg tds was not significantly superior to placebo. ADX10059 was generally well tolerated. Conclusion: The mGluR5 negative allosteric modulator ADX10059 reduced acid reflux which was associated with improvement in clinical symptoms in patients with GORD. ADX10059 appears to have a potential role in the clinical management of GORD.