Therapy with either recombinant beta-1a or beta-1b interferons ( IFNs ) is approved for relapsing remitting multiple sclerosis ( RRMS ). A major unanswered question is whether this treatment is able to safely reverse or retard the progressive phase of the disease.
The main objective of a study was to verify whether interferons treatment in secondary progressive multiple sclerosis ( SPMS ) is more effective than placebo in reducing the number of patients who experience disability progression.
The analysis included all randomised, double or single blind, placebo-controlled trials ( RCTs ) evaluating the efficacy of interferons versus placebo in SPMS patients.
Five RCTs met the inclusion criteria, from which 3122 ( 1829 Interferon and 1293 placebo ) treated patients contributed to the analysis. Included population was heterogeneous in terms of baseline clinical characteristics of the disease, in particular the percentage of patients affected by secondary progression with superimposed relapse ranging from 72% to 44%.
Interferon beta 1a and 1b did not decrease the risk of progression sustained at 6 months ( RR=0.98 ) after three years of treatment. A significant decrease of the risk of progression sustained at 3 months ( RR=0.88 ) and of the risk of developing new relapses at three years ( RR=0.91 ) were found.
The risk of developing new active brain lesions decreased over time but this data was obtained from single studies on magnetic resonance imaging ( MRI ), performed in subgroups of patients; in spite of no effect on progression, the radiological data supported an effect on MRI parameters. The safety profile reflects what is commonly reported in MS IFN-treated patients.
In conclusion, recombinant Interferon-beta does not prevent the development of permanent physical disability in secondary progressive multiple sclerosis. Researchers were unable to verify the effect on cognitive function for the lack of comparable data. This treatment significantly reduces the risk of relapse and of short -term relapse-related disability.
Overall, these results has shown that IFNs' anti-inflammatory effect is unable to retard progression, when established. In the future, no new RCTs for interferons versus placebo in secondary progressive multiple sclerosis will probably be undertaken, because research is now focusing on innovative drugs. Researchers believe that this review gives conclusive evidence on the clinical efficacy of IFNs versus placebo in secondary progressive multiple sclerosis.
Source: The Cochrane Library, 2012