IFN-β Products Seem Equivalent as Initial Treatment for MS

MIAMI BEACH — Four different interferon-β products and dosing schedules appear equally effective as initial therapy for relapsing/remitting multiple sclerosis, Volker Limmroth, M.D., reported in a poster session at the annual meeting of the American Academy of Neurology.

However, all IFN-β products were significantly less effective when used as follow-up therapy, said Dr. Limmroth, of the University of Essen (Germany), and his colleagues.

“These results suggest that patients do not gain further benefit when switching from one IFN-β product to another,” according to Dr. Limmroth.

Dr. Limmroth presented the results of the global Quality Assessment in Multiple Sclerosis Therapy (QUASIMS) study which examined long-term outcomes in more than 7,000 patients from 11 countries who took different IFN-β products and dosing regimens. The study broke results down among those who took IFN-β as initial therapy and those who took it as follow-up therapy.

The patients' mean age was 36 years; about 70% were female. Their mean disease duration was about 5 years. Their mean treatment duration was about 40 months and mean Expanded Disability Status Scale (EDSS) was 2.4–2.9.

The therapies examined were intramuscular IFN-β-1a, 30 mcg once weekly; subcutaneous IFN-β-1b, 8 mIU every other day; subcutaneous IFN-β-1a, 22 mcg three times weekly; and subcutaneous IFN-β-1a, 44 mcg three times weekly. Patients had to have been on at least 2 years' uninterrupted therapy (either initial or follow-up). Overall, there were no significant differences on EDSS between the therapies at 1 or 2 years' follow-up. Some differences emerged, however, when the drugs were stratified as either initial or follow-up therapy.

All drugs were more effective as initial therapy than as follow-up therapy. Intramuscular IFN-β-1a resulted in the highest percentage of progression-free patients at 2 years (66%). For the other therapies, the percentage of progression-free patients was 62.2% for subcutaneous IFN-β-1a 44 mcg; 61% for subcutaneous IFN-β-1a 22 mcg; and 52.7% for IFN-β-1b.

Intramuscular IFN-β-1a also resulted in the highest percentage of relapse-free patients over 2 years (50.2%). The percentages for the other therapies were 42% for IFN-β-1b; 37% for subcutaneous IFN-β-1a 22 mcg; and 33.8% for subcutaneous IFN-β-1a 44 mcg.

There were no significant differences in the drugs' effectiveness when they were used as follow-up therapy.

The percentage of progression-free patients ranged from 51.7% for IFN-β-1b to 62% for subcutaneous IFN-β-1a 44 mcg. The percentage of relapse-free patients over 2 years ranged from 33.8% for subcutaneous IFN-β-1a 44 mcg to 42% for IFN-β-1b.

During the study, 18% (1,309 patients) changed therapy. The most frequent reason was perceived lack of efficacy. Switch rates were intramuscular IFN-β-1a, 45%; IFN-β-1b, 31%; subcutaneous IFN-β-1a 22 mcg, 38%; subcutaneous IFN-β-1a 44 mcg, 40%.

Dr. Limmroth is a paid investigator for Biogen Idec Inc. which sponsored the study.