Teriflunomide Part 1
The results of a large study for an oral medication for MS, teriflunomide, were published this week in The New England Journal of Medicine. Results show that the medication is effective in diminishing relapses from MS. This is the second large study of this medication; the first trial, published in October 2010, showed that this medication was more effective than placebo in preventing relapses.
Teriflunomide works by inhibiting an important enzyme in the synthesis of DNA. This results in the disruption in the function of both T and B lymphocytes, each of which has been implicated in causing inflammation and tissue destruction in MS. It only affects the more rapidly dividing cells of the immune system and so has a limited effect on the immune system as a whole compared to chemotherapy, for example. The medication is taken once daily.
The study was very large, and involved 1,088 subjects. Subjects had to meet certain entry criteria, one of them being that they had an EDSS (Expanded Disability Status Scale) of less than 5.5. These subjects were randomly divided into three equal groups, those who received 7mg of teriflunomide, those who received 14mg of teriflunomide, and those who received placebo. The study was double-blinded so that neither subjects nor the study investigators knew which medication anyone was receiving until the conclusion of the trial. The duration of the trial was 108 weeks.
The primary endpoint in the study was the annualized relapse most commonly used in MS: the annual relapse rate. The study also investigated whether or not the medicine delayed the progression of disability, whether or not the medicine prevented new lesions on MRI, and whether the medication affected fatigue as reported by the subjects.
The results show that compared to placebo, teriflunomide reduced relapse rate by a statistically significant amount. Subjects who received either dose of teriflunomide had 0.37 relapses per year (or about one relapse every three years), while the subjects who received placebo had a rate of 0.54 relapse per year (or about one relapse every two years). Compared to placebo, more subjects who took teriflunomide were entirely without relapses. The medication also had a slight impact on diminishing the progression of disability in subjects, and the MRI in subjects who received teriflunomide had fewer new MRI lesions and fewer lesions that enhanced with contrast. The medication did not have a clear impact on fatigue.
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