Clinical trials of multiple sclerosis therapies: improvements to demonstrate long-term patient benefit

BACKGROUND: The therapeutic goal for multiple sclerosis (MS) is to achieve a better long-term outcome. However, since available data come from short-term studies, it is important to review the evidence that current therapies provide long-term benefit. METHOD AND RESULTS: Long-term data from both registry studies and long-term follow-up studies, and efficacy treatment data were reviewed. Registry data show that the course of MS is predictable after a certain level of disability is reached, indicating that short-term efficacy data from randomized, controlled trials provide evidence of long-term benefit. Long-term studies of patients originally enrolled in pivotal randomized, controlled trials consistently show that delayed or discontinued treatment provides less benefit than continuous therapy. The 16-Year Long-Term Follow-Up Study of interferon beta-1b (IFNbeta-1b; Betaferon/Betaseron) therapy had the highest ascertainment of long-term follow-up efforts of the pivotal trials, which led to the currently approved therapies. Disability scores at the start of treatment were predictive of their current disability scores. In addition, this 16-year study showed an excellent safety profile with no unexpected side effects to IFNbeta-1b and a lower mortality rate after 16 years compared with those receiving placebo treatment during the pivotal study (6 deaths vs 20 deaths). CONCLUSION: This article reviews the key data and provides recommendations for optimizing clinical studies in MS to demonstrate long-term patient benefit.