Disease-Modifying Therapies in Multiple Sclerosis

Several recently available medications offer preventive treatment in MS. The primary goal is to alter the natural course of the disease by reducing the frequency and severity of relapses and by preventing or slowing the progression of disability. Seven FDA-approved, disease-modifying medications are available in the United States at the time of writing this chapter: four injectable products, two intravenous medications, and one oral medication. Of note, the percentages quoted (i.e., relapse rate reduction by 60%) reflect group data. In other words, the treated group on average experienced 60% fewer relapses, but both treatment and control groups included both individuals who did very well or very poorly. Therefore, the group data do not apply to every individual case. Also of note, most clinical trials rely on MRI-proven disease activity as a secondary or even primary outcome. However, conventional, clinically derived MRI measures tend to correlate imperfectly with clinical outcome. Despite substantial progress in addressing the relapsing–remitting or highly inflammatory stages of MS, currently available treatment modalities fail to address the disabling progressive form of MS. Successful modification of the disease course is most likely to occur in three patient groups: those with clinically isolated syndromes, those with relapsing–remitting MS, and those with “highly inflammatory” forms of secondary or primary progressive MS, as discussed later.