The patients will continue their AVONEX® intramuscular injections of 30 micrograms (administered by patient or caregiver) on a weekly basis with scheduled intravenous high dose methotrexate at 2 Gm/m2 followed by intravenous and oral leucovorin rescue once every 2 months. The methotrexate infusions will be performed in our outpatient infusion center. The patient will be required to complete a patient diary during the course of the trial, participate in and keep all scheduled appointments, and to inform the research staff and physician of any change in concomitant medications or adverse events that they may experience.