Glatiramer acetate is a mixture of synthetic polypeptides that interacts with the T cells and B cells of the adaptive immune system and the antigen-presenting cells of the innate immune system.
The efficacy of glatiramer acetate 40mg three times weekly, in terms of annualised relapse rate, is consistent with that of glatiramer acetate 20mg given as a once-daily dose.
Reduced relapse rate
Glatiramer acetate 40mg three times weekly was assessed for efficacy and safety in a randomised, placebo-controlled, parallel-group, double-blind phase III study (GALA) in 1,404 patients with relapsing-remitting MS and at least one documented relapse in the 12 months before screening or at least two documented relapses in the 24 months before screening.
Participants were randomised 2:1 to receive either subcutaneous glatiramer acetate 40mg or placebo three times weekly for 12 months.
Patients receiving glatiramer acetate 40mg three times weekly showed a 34% relative reduction in the risk of confirmed relapse compared with placebo (mean annualised relapse rate 0.331 vs 0.505, absolute risk reduction 0.174, p<0.0001). The time to first relapse (an exploratory endpoint) was significantly longer in the group taking glatiramer acetate 40mg three times weekly than in the placebo group (393 vs 377 days, p<0.0001).
Compared with patients receiving placebo, those receiving glatiramer acetate 40mg three times weekly experienced a 45% relative reduction in the cumulative number of gadolinium-enhancing T1 lesions (absolute reduction 0.734) and a 35% relative reduction in the cumulative number of new or newly enlarging T2 lesions at months 6 and 12 (absolute reduction 1.942; both p<0.0001).
The safety profile of glatiramer acetate 40mg administered three times weekly is consistent with that of the 20mg daily dose.
Patients using glatiramer acetate 40mg/ml three times weekly receive 57% fewer injections per year than if they were using the existing daily Copaxone 20mg/ml presentation. Injection site reactions, including erythema, pain and pruritus, were the most commonly observed adverse reactions with glatiramer acetate 40mg three times weekly in the GALA study, but were half as frequent as previously reported with the 20mg daily injection (35.5% vs 70%) and 99.9% were mild to moderate in severity.