Disease-modifying drugs reduce cortical lesion accumulation and atrophy progression in relapsing-remitting multiple sclerosis: results from a 48-month extension study.

Cortical lesions (CLs) and atrophy are pivotal in multiple sclerosis (MS) pathology. This study determined the effect of disease modifying drugs (DMDs) on CL development and cortical atrophy progression in patients with relapsing-remitting MS (RRMS) over 48 months. Patients (n = 165) were randomized to sc IFN β-1a 44 μg, im IFN β-1a 30 μg, or glatiramer acetate 20 mg. The reference population comprised 50 DMD-untreated patients with RRMS. After 24 months, 43 of the untreated patients switched to DMDs. The four groups of patients were followed up for an additional 24 months. At 48 months the mean standard deviation number of new CLs was significantly lower in patients treated with sc IFN β-1a (1.4 ± 1.0, range 0–5) compared with im IFN β-1a (2.3 ± 1.3, range 0–6, P = 0.004) and glatiramer acetate (2.2 ± 1.5, range 0–7, P = 0.03). Significant reductions in CL accumulation and new white matter and gadolinium-enhancing lesions were also observed in the 43 patients who switched to DMDs after 24 months, compared with the 24 months of no treatment. Concluding, this study confirms that DMDs significantly reduce CL development and cortical atrophy progression compared with no treatment.