GA Depot, a long-acting glatiramer acetate, vs placebo in patients with relapsing multiple sclerosis: A randomized phase 3 clinical trial

Background: GA Depot is a long-acting glatiramer acetate (GA)-based formulation designed to provide significantly extended dosing intervals compared to currently available GA formulations. Objective: To assess GA Depot efficacy, safety, and tolerability compared to placebo in patients with relapsing multiple sclerosis (RMS). Methods: A 52-week multi-center, double-blind, placebo-controlled phase 3 trial in RMS. Patients aged 18–55 with an Expanded Disability Status Scale (EDSS) score ⩽ 5.5 were enrolled and randomized (1:1) to intramuscular (IM) GA Depot 40 mg or matching placebo every 4 weeks. The primary endpoint was annualized relapse rate (ARR) at 52 weeks. Results: A total of 1016 patients were treated with GA Depot (n = 508) or placebo (n = 508). Adjusted ARR was lower in patients treated with GA Depot compared to placebo (0.18, 95% confidence interval [CI] = 0.14 to 0.3 vs 0.26, 95% CI = 0.21 to 0.32, 30.1% relative risk reduction, p = 0.0066). GA Depot significantly reduced the number of contrast-enhancing lesions (p = 0.0083). The most common adverse events were injection site reactions (46.1% with GA Depot vs 28.7% with placebo), primarily mild and self-limited. Conclusion: GA Depot effectively reduced clinical and radiological activity compared to placebo in RMS patients, recapitulating the favorable profile of subcutaneous GA products with significantly less frequent injections. Trial Registration: ClinicalTrials.gov Identifier: NCT04121221 (https://clinicaltrials.gov/study/NCT04121221).