Link of the mechanisms of action of glatiramer acetate to its long-term clinical data.

A consequence of the long-term nature of progression in multiple sclerosis is that treatment needs to be provided over the long term. Gathering evidence for long term clinical efficacy, safety and patient acceptance of immunomodulatory therapies is thus a critically important issue. However, pivotal trials, which generally last no more than two years, cannot address this issue. Glatiramer acetate is the only immunomodulatory treatment for which prospective data is available covering a treatment period of over a decade. In the long-term extension of the pivotal trial of glatiramer acetate, 108 patients have been followed for a mean treatment duration of 10.1 years. At the end of the treatment period, patients were experiencing a relapse only once every five years and 92% remained ambulatory throughout. Similar findings have been made in observational studies in the long-term follow-up of patients with relapsing remitting multiple sclerosis treated with glatiramer acetate under a compassionate use programme in France and in a patient registry in Argentina. Such data strongly suggest that a reduced risk of relapse represents a real long-term treatment effect. The cumulative evidence for the long-term clinical efficacy of glatiramer acetate is consistent with its dual mechanism of action, reassures the physician that glatiramer acetate can really help improve patient care over the long term, and may contribute to a more positive view of prognosis for patients with multiple sclerosis.