Rebif® (interferon beta-1a)

FDA-Approved Medications: New Data

Company: EMD Serono

  • Subcutaneous injection; 22 mcg or 44 mcg three times per week
  • Approved in 2002 for RMS

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Between one-third and one-half of untreated people who have a clinically isolated syndrome (CIS) will convert to clinically definite multiple sclerosis (CDMS) within two years. Delaying, or potentially even avoiding that conversion has been a focus of considerable research. A study published last year indicated that one of the longest-established treatments for relapsing forms of MS, Rebif® (interferon beta-1a), can play an ongoing role in delaying that conversion.31

The REFLEXION trial enrolled 402 individuals who had experienced a clinically isolated syndrome and who had participated in an earlier trial of Rebif, called REFLEX. Participants who had received once-weekly or three-times-weekly Rebif over a two-year period in the REFLEX trial and who had not converted to CDMS continued to receive Rebif on their established schedules. These individuals made up the early treatment groups in REFLEXION. Meanwhile, people in the placebo arm of REFLEX who had not developed clinically definite MS began receiving Rebif three-times a week in the REFLEXION trial, and made up the delayed treatment group. This approach allowed researchers to compare the effects of early versus later interferon beta-1a therapy in CIS.

After five years, the cumulative probability of conversion to CDMS was 44.6 percent in the delayed treatment group versus 39.2 percent in those who had received three-times-weekly Rebif since the REFLEX study and 40.7 percent for individuals who had received weekly Rebif injections in the REFLEX and REFLEXION studies. It should be noted that these differences did not achieve statistical significance. MRI findings were also more favorable for the early treatment groups relative to the delayed treatment group. Researchers concluded that these findings supported the early use of Rebif in CIS.31

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