In Study 4, 468 patients who had recently (within 60 days) experienced an isolated demyelinating event, and who had lesions typical of multiple sclerosis on brain MRI were randomized to receive either 0.25 mg Betaseron (n=292) or placebo (n=176) subcutaneously every other day (ratio 5:3). The primary outcome measure was time to development of a second exacerbation with involvement of at least two distinct anatomical regions. Secondary outcomes were brain MRI measures, including the cumulative number of newly active lesions, and the absolute change in T2 lesion volume. Patients were followed for up to two years or until they fulfilled the primary endpoint.

Eight percent of subjects on Betaseron and 6% of subjects on placebo withdrew from the study for a reason other than the development of a second exacerbation. Time to development of a second exacerbation was significantly delayed in patients treated with Betaseron compared to placebo (p < 0.0001). The Kaplan-Meier estimates of the percentage of patients developing an exacerbation within 24 months were 45% in the placebo group and 28% of the Betaseron group (Figure 2). The risk for developing a second exacerbation in the Betaseron group was 53% of the risk in the placebo group (Hazard ratio= 0.53; 95% confidence interval 0.39 to 0.73).

Figure 2 - Onset of Second Exacerbation by Time on Study (Kaplan-Meier Methodology)

Patients treated with Betaseron demonstrated a lower number of newly active lesions during the course of the study. A significant difference between Betaseron and placebo was not seen in the absolute change in T2 lesion volume during the course of the study.

Safety and efficacy of treatment with Betaseron beyond three years are not known.

REFERENCES

¹ Poser CM, et al. Ann Neurol 1983; 13(3): 227-231

² Kurtzke JF. Neurology 1983; 33(11): 1444-1452

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