Long-term, single-arm, open-label, multicenter phase 2/4 study of glatiramer acetate by subcutaneous injection in Japanese patients with relapsing–remitting multiple sclerosis

Objective: Glatiramer acetate (GA) has been shown to be a well-tolerated and effective treatment for patients with multiple sclerosis (MS) with relapse. The present open-label study aimed to evaluate the efficacy and safety of long-term treatment with GA. Methods: Japanese patients with relapsing–remitting MS received up to 52-weeks’ treatment with GA 20 mg/mL once daily in the phase 2 study. In phase 4, patients continued to receive treatment after marketing approval in Japan until commercial availability. Key end-points were safety and tolerability of GA. Other analyses included numbers and volumes of gadolinium-enhancing and T2-weighted (T2) lesions. Results: Of 17 patients initially treated, 13 completed 52 weeks’ therapy and 10 completed the phase 4 extension (efficacy assessment: 104 weeks; maximum treatment period/long-term safety assessment: up to 5 years). No new safety signals were observed; most adverse events were mild or moderate, with injection site reactions being the most common. The number of T1 gadolinium-enhancing lesions declined from 2.9 (baseline) to 1.3 (week 104), and the number of T2 lesions increased from 1.7 to 6.7. T1 and T2 lesion volume changes were not clinically meaningful (changes of −0.090 and 0.088 mL, respectively, by week 104). The mean annualized relapse rate was 2.01 (baseline) and 1.78 (week 104); the mean Expanded Disability Status Scale scores indicated reduced levels of disability. Conclusions: These findings suggest the favorable tolerability and safety profile of GA in Japanese patients, and provide supportive evidence for the efficacy of GA in reducing MS recurrence and improving disability in Japanese MS patients.