SAN DIEGO—Long-term treatment with Betaseron® (interferon beta-1b) appears to be safe and effective in patients with multiple sclerosis (MS), according to updated data from the ongoing Betaseron 16-Year Long-Term Follow-Up Study. When completed, the study will provide information about the long-term safety and efficacy of interferon beta-1b therapy in patients with MS who were enrolled in the Betaseron pivotal trial between 1988 and 1990 and will represent the longest follow-up assessment of any MS treatment carried out to date. George Ebers, MD, and colleagues presented their latest findings at the 130th Annual Meeting of the American Neurological Association.

The researchers reported that 331 of the 372 original participants (89%) from the pivotal trial had been identified. "This is important, because results from follow-up studies with retention rates higher than 80% can be viewed with greater confidence," said Dr. Ebers, Action Research Professor in the Department of Clinical Neurology at Oxford University, United Kingdom. The investigators noted that after the pivotal trial was completed, interferon beta-1b was made available to all patients in the study. They reported that 41% of the patients have been taking interferon beta-1b (250 μg every other day) for more than 80% of the time between the end of the pivotal trial and the 16-year follow-up assessment.

The updated data also showed that 51% of patients originally assigned to interferon beta-1b reported being able to walk with or without assistance, compared with 45% of those originally assigned to placebo. Ninety-five percent of those identified to have originally received the 250-μg dose of interferon beta-1b were still alive, compared with 82% of those identified who had originally received placebo.

In addition, the investigators have started to review 210 case report forms received thus far. A preliminary assessment of the forms revealed that half of the 210 patients have been taking 250 μg of interferon beta-1b for 10 years or longer (median, 14 years).

Patients in the pivotal trial initially received interferon beta-1b (50 or 250 μg) or placebo for a median of 45 months. Two years after randomization, significantly more patients receiving interferon beta-1b were relapse-free compared with patients receiving placebo, and the relapses that did occur were less severe. Also, hospitalizations for MS were reduced by nearly half for patients taking interferon beta-1b compared with those who took placebo.

The results of the pivotal trial led to the FDA's approval of Betaseron in 1993. In 2002, a formulation of the drug that is stable at room temperature was approved by the FDA.