The importance of maintaining effective therapy in multiple sclerosis.

ABSTRACT

The INCOMIN study (INdependent COMparison of INterferons) lends further support to the growing body of evidence that both dose and frequency of interferon beta (IFNbeta) administration are important in the treatment of multiple sclerosis (MS). High-dose, high-frequency IFNbeta (IFNbeta-1b 250 microg eod sc and IFNbeta-1a 44 microg sc) treatment offers greater therapeutic benefit, in terms of clinical and magnetic resonance imaging (MRI) outcome measures, compared with low-dose, once-weekly administration of IFNbeta. The importance of maintaining the most effective treatment regimen has been shown in another study. The data from this study suggested that patients who have 'stable' disease (i. e. no evidence of clinical or MRI disease activity) during long-term treatment with IFNbeta-1b 250 microg, who are subsequently treated with low-dose, once-weekly IFNbeta-1a 30 microg, are more likely to experience relapses, disease progression or MRI activity compared with those remaining on IFNbeta-1b 250 microg. These data clearly indicate that frequently administered therapy must be maintained to achieve the optimal therapeutic benefit for patients. Those patients who had their IFNbeta-1b 250 microg therapy reduced to low-dose, once-weekly IFNbeta-1a and experienced a resumption of disease activity were returned to their previous regimen. However, after 1 year of additional follow-up, many of these patients still had clinical or MRI signs of disease activity, highlighting further the risks associated with the reduction of IFNbeta dose and frequency of administration. Taking into consideration the evidence supporting the greater efficacy of IFNbeta-1b 250 microg or IFNbeta-1a 44 microg in MS it is of considerable interest to examine whether it is useful to increase the dose of IFNbeta-1b in patients who do not respond satisfactorily to the approved standard dose. This is the rationale for the recently completed OPTIMS (OPTimization of Interferon for MS) study, in which partially responding patients were randomised to IFNbeta-1b 250 or 375 microg every other day. An interim safety analysis of OPTIMS patients has not raised any safety or tolerability concerns. In summary, there is consistent evidence to support the importance of maintaining frequently administered IFNbeta (IFNbeta-1b 250 microg or IFNbeta-1a 44 microg) for the treatment of MS.