RESUMEN
Although the earliest recorded description of multiple sclerosis (MS) dates back to the 14(th) century, it was not until the latter years of the 20(th) that treatments for this disabling condition were found. However, the "road to success" has not been without hurdles. Trials with both interferon alpha and gamma proved unsuccessful, as did treatment with oral myelin, cladribine, sulfasalazine and inhibitors of tumour necrosis factor. In 1993, interferon beta-1b (IFNbeta-1b) became the first therapy proven to be effective in altering the natural history of relapsing-remitting MS (RRMS). This was followed by successful trials with IFNbeta-1a and glatiramer acetate. In 1998, a European trial showed IFNbeta-1b to be also beneficial in the treatment of secondary progressive MS (SPMS). A similar trial in North America failed to reach its primary endpoint but was effective across secondary endpoints, highlighting how different methodology and patient populations can lead to inconsistent results and, thus, making comparisons across trials difficult. The trend for early intervention in MS with IFNbeta was recently supported by the CHAMPS (Controlled High-risk Avonex MultiPle Sclerosis) and ETOMS (Early Treatment of Multiple Sclerosis) studies using once-weekly IFNbeta-1a. Both trials demonstrated delayed conversion to clinically definite MS in patients with a clinically isolated syndrome and magnetic resonance imaging (MRI) findings suggestive of MS. Two directly comparative trials of high- (250 microg IFNbeta-1b or 44 microg IFNbeta-1a) and low-dose (30 microg IFNbeta-1a) IFNbeta (INCOMIN [INdependent COMparison of INterferons] and EVIDENCE [EVidence of Interferon Dose-response: European North American Comparative Efficacy]) support the superior efficacy of the higher dose and/or more frequent administration for treating RRMS. Since MS entered the treatment era in 1993, therapies for RRMS, SPMS and, more recently, progressive- relapsing MS have been developed. There is now a much better understanding of the pathogenesis of the disease, but new and improved therapeutic approaches are still needed.