Interferon-α2a reduces MRI disease activity in relapsing-remitting multiple sclerosis

Objective: To evaluate the efficacy and safety of interferon-alpha 2a (IFN-alpha 2a) in relapsing-remitting MS (RRMS). Background: Several immune-modulating therapy regimens of IFN-alpha have shown varying results in MS. A recent pilot study suggested benefits from IFN-alpha 2a. Methods: Ninety-seven patients were randomized to receive subcutaneous injections of placebo (33 patients) or 4.5 million international units (mIU) (32 patients) or 9.0 mIU (32 patients) of IFN-alpha 2a three times weekly for 6 months, with a further 6 months of follow-up. Monthly gadodiamide-enhanced MRI was the primary method of evaluating efficacy. Results: IFN-alpha 2a treatment resulted in fewer new MRI lesions during the treatment period (p < 0.003). The probability of no new lesions during treatment was >2.5 times higher with 9.0 mIU IFN-alpha 2a than with placebo (p < 0.005). The median number of lesions at the end of treatment was lower with IFN-alpha 2a treatment than with placebo (p = 0.0004), but the difference disappeared during follow-up. The total number of lesions (mean) increased by 4.78 with placebo, 0.86 with 4.5 mIU IFN-alpha 2a, and 0.28 with 9.0 mIU IFN-alpha 2a during treatment (p = 0.030). No treatment effect on exacerbation rate, progression of disability, or quality of life was detected. Nine patients discontinued treatment, five because of adverse events. Conclusions: IFN-alpha 2a treatment significantly reduced disease activity as measured by MRI, but the efficacy disappeared within 6 months after discontinuation of treatment. A long-term study of more patients using disability as a primary outcome measure is needed to evaluate the clinical impact.