Interferon beta-1a as adjunctive treatment for multifocal motor neuropathy: an open label trial.

Dear Editor, Infusions of intravenous immunoglobulins (IVIg) are the only established therapy for patients with multifocal motor neuropathy (MMN) (Umapathi et al., 2009), but the effects are transient and the infusions have to be repeated periodically (Van den Berg, 2007). As two pilot trials with interferon beta-1a (INFβ-1a) as a monotherapy have suggested some benefit (Martina et al., 1999; van den Berg-Vos et al., 2000), we conducted a pilot trial with INFβ-1a as adjunctive therapy to assess the effect on the IVIg dose requirement in patients with MMN who were responsive to IVIg but required chronic IVIg therapy. We recruited three MMN patients who had been treated with IVIg on an average of 6 years with IVIg therapy at one infusion every 2–6 weeks (Kuntzer et al., 2007). Prior attempts to wean the patients from IVIg by combining immunosuppressant agents (mofetil mycophenolate and intravenous cyclophosphamide) had failed. This study was a prospective, unblinded, uncontrolled, 6-month pilot study. INFβ-1a (Rebif®, sponsored by MerckSerono Inc., Switzerland) was administered at a 44 μg dose three times a week subcutaneously during 6 months whereas IVIg therapy was maintained. The patients could prolong INFβ-1a treatment by 3 months. Total IVIg dose was recorded in the 12 months prior, during, and 6 months after the introduction of INFβ-1a. We hypothesized that the addition of INFβ-1a would result in a reduction of IVIg dose or in prolonged intervals between IVIg. Secondary endpoints included: improvement of upper extremity INCAT score; improved strength in 15 muscles according to the Neurological Disability Scale; reduction of treatment costs; and improved quality of life by using the SF-36 questionnaire. Nerve conduction