Copaxone (glatiramer acetate injection) is a disease-modifying therapy that the U.S. Food and Drug Administration (FDA) approved for the treatment of relapsing forms of multiple sclerosis (MS). This includes clinically isolated syndrome (CIS), relapsing-remitting multiple sclerosis (RRMS), and active secondary progressive multiple sclerosis (SPMS). Teva Pharmaceuticals is marketing the treatment.
How does Copaxone work?
MS is a progressive neurodegenerative disorder in which the immune system mistakenly targets the myelin protein. Myelin is the main component of the protective sheath that insulates nerve fibers. This triggers inflammation and causes damage to the brain and spinal cord, leading to a wide range of symptoms.
Copaxone is a small synthetic protein that mimics a fragment of myelin. It consists of four amino acids, the building blocks of proteins, that make up myelin.
The exact mechanism of how Copaxone reduces the frequency of relapses is not known. However, researchers think that the medication modifies the immune attack against myelin. For example, Copaxone may act to increase the immune system’s tolerance to myelin through repeated exposure, in a similar way to a vaccine.
Another mechanism could be that Copaxone may alter which immune cells are active. For example, it may be able to induce a type of immune cells called suppressor T-cells that secrete anti-inflammatory proteins and prevent damage. Copaxone may also act to prevent the activation of T-cells that target and attack myelin.
Copaxone can reduce the rate of relapses and slow the progression of MS. However, it cannot reverse the damage that MS already caused or cure the disease.
Copaxone in clinical trials
Researchers studied Copaxone in several clinical trials.
The key clinical trial that led to Copaxone’s approval for marketing was the so-called the Copolymer 1 multiple sclerosis study, carried out in the 1990s. The randomized, double-blind, placebo-controlled Phase 3 trial enrolled 251 patients with RRMS. During the trial, participants received either Copaxone or a placebo daily for two years.
The initial results, published in the journal Neurology, demonstrated that patients receiving Copaxone had a 29% reduction in their relapse rate compared to those who received placebo. Researchers also assessed patients in terms of their change on the expanded disability status scale, after two years of treatment compared to the start of the trial. On average, patients taking Copaxone had an improved score after two years. In contrast, the score of patients in the placebo group had worsened. Patients tolerated the treatment well. The most common side effect was a reaction at the injection site.
Following the end of the trial, researchers gave patients the chance to continue treatment in an optional extension study. The results of this extension study showed that after one to 11 months of follow-up treatment, the benefits of Copaxone were maintained. There were also no long-term complications.
Of the original 251 participants, 208 opted to participate in this open-label extension study in which all of them received Copaxone. A final report of the trial and the extension, which spanned a total of about six years, appeared in the journal Multiple Sclerosis. Copaxone continued to provide a sustained reduction in relapse rate and slowed worsening disability.
More recently, researchers assessed the effectiveness of a higher dose of Copaxone (40 mg three times weekly instead of 20 mg daily) in a randomized placebo-controlled Phase 3 trial (NCT01067521) called GALA. The trial recruited 1,404 participants with RRMS worldwide to receive Copaxone or a placebo for one year. An open-label extension study followed this trial.
The results appeared in the Annals of Neurology. They confirmed that Copaxone reduced the number of relapses compared to placebo, by about 34%. Researchers also assessed the patients by magnetic resonance imaging (MRI) to check for lesions, or areas of damage, in the brain. Copaxone was associated with a significant reduction in the number of lesions compared to the placebo.
Copaxone is administered as an injection under the skin. Common side effects include reactions at the injection site (such as itching, swelling, redness, pain, or bruising), anxiety, chest pain, shortness of breath, palpitations (pounding or irregular heartbeat), flushing, hives, and swollen lymph nodes.
The FDA approved the therapy to treat RRMS in 1996. It later expanded its use to include CIS and active SPMS. The agency approved Copaxone at a dose of 40 mg, three times a week in 2014 following the results of the GALA trial.
Generic versions of Copaxone also are now available.
Last updated: May 22, 2020
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