Generic glatiramer acetate remains effective and safe over two years of treatment for patients with relapsing-remitting multiple sclerosis (MS), according to data published in the December 2017 issue of Multiple Sclerosis Journal. The data also indicate that switching from branded glatiramer acetate to a generic formulation is safe and well tolerated.
The European Medicines Agency required clinical trial data to support the authorization of generic glatiramer acetate. Krzysztof Selmaj, MD, a neurologist at the Neurology Center Lodz in Poland, and colleagues conducted a nine-month study to assess the equivalence of generic glatiramer acetate with that of Copaxone, a branded formulation of the drug. The double-blind, phase III GATE trial suggested that the drugs had equivalent efficacy, safety, and tolerability.
An Open-Label Extension
Patients who completed the nine-month trial were eligible to continue into a 15-month open-label extension on generic glatiramer acetate. The goals of the extension were to evaluate the effects of long-term exposure to the drug and to assess whether switching from branded to generic glatiramer acetate influenced drug safety and efficacy.
The researchers enrolled 796 patients from 17 countries into the double-blind study. Eligible patients were between ages 18 and 55, had relapsing-remitting MS, and had an Expanded Disability Status Scale (EDSS) score of 0 to 5.5. Patients were randomized to receive 20 mg/mL/day of generic glatiramer acetate, 20 mg/mL/day of branded glatiramer acetate, or matching placebo.
The investigators performed safety evaluations at months 12, 15, 18, 21, and 24. They conducted EDSS scoring and brain MRI scans at months 12, 18, and 24. To assess glatiramer acetate antidrug antibodies, the researchers collected serum samples at baseline and months 1, 3, 6, 9, 12, 18, and 24.
Branded and Generic Formulations Produced Similar Outcomes
In all, 735 participants completed the double-blind study. In addition, 728 patients entered the open-label extension, and 670 completed it.
The proportion of patients completing the trial was 93.8% among patients who received generic treatment throughout, 92.9% among patients who switched from branded to generic, and 81.5% among patients who switched from placebo to generic glatiramer acetate.
The mean number of gadolinium-enhancing lesions was similar at months 12, 18, and 24 for patients who had started the blinded study on generic glatiramer acetate and those who had started on branded glatiramer acetate. The changes in the other MRI outcomes were similar for these two groups.
The estimated annualized relapse rates in the extension study were 0.21 for patients who took generic glatiramer acetate throughout, 0.24 for patients who switched from branded to generic glatiramer acetate, and 0.23 for patients who switched from placebo to generic glatiramer acetate.
The rate of adverse events was similar for patients who took generic glatiramer acetate throughout (33.3%) and those who switched from branded to generic treatment (36.5%). The rate of adverse events was 43.2% among patients who switched from placebo to generic glatiramer acetate. Severe and serious adverse events were uncommon and occurred at similar rates among patients who started on generic treatment and those who started on branded treatment.
During the blinded phase, antidrug antibodies formed with comparable frequency among patients who received generic and branded glatiramer treatment. During the open-label extension, the antidrug antibody titers in the group switching from branded to generic glatiramer treatment remained similar to that of the group continuing on generic treatment.
“These data should help patients and prescribers to positively consider generic glatiramer acetate as an alternative to branded glatiramer acetate,” said Dr. Selmaj.
Selmaj K, Barkhof F, Belova AN, et al. Switching from branded to generic glatiramer acetate: 15-month GATE trial extension results. Mult Scler. 2017;23(14):1909-1917.