Patients with relapsing-remitting multiple sclerosis (RRMS) who were on placebo and then treated with Rebif in the PRISMS study showed substantial clinical benefits with a 54 per cent relative reduction in relapse rate, announced by Serono at the 20th congress of the European Committee for Treatment and Research In Multiple Sclerosis (ECTRIMS) meeting in Vienna, Austria.

The data also showed a significant improvement in MRI results for patients treated with Rebif 44 mcg. There was a highly, statistically significant relative reduction in the mean number of brain lesions1 of 67 per cent. In addition, 76 per cent of patients treated with Rebif 44 mcg remained free of disease progression.

This data is based on a prospective pre-planned analysis of the progress of patients who received two years of placebo therapy followed by two years of Rebif in the PRISMS study. The four year PRISMS study demonstrated significant improvements in the three key efficacy measures of MS: reductions in MRI lesion area and activity2, reduced frequency of relapses, and delayed disability progression. Rebif is the only disease-modifying drug with proven efficacy in all three measures, release from Serono said here.

The two-year results from the PRISMS study showed that both doses of interferon beta-1a significantly reduced MRI activity and area, relapse rates, as well as reduced progression of Expanded Disability Status Scale (EDSS) scores. Dose-blinded extension data to four years demonstrated sustained treatment benefit over time, with increasing evidence of a dose-effect that favoured Rebif 44 mcg. The Long-Term Follow Up (LTFU) assessment was then performed on the seventh or eighth anniversary of patients' enrolment in the original PRISMS study, and these data provided a comprehensive long-term clinical and MRI assessment of cohort of MS patients on therapy with interferon. The LTFU results support the long-term effectiveness of Rebif 44 mcg in the treatment of RRMS.

"Our results show the immediate and long-term benefits of treatment with Rebif in controlling MS," said Dr Paul Lammers, head of Neurology Product Development at Serono. "This is important news for patients with MS, as these data further demonstrate that treatment with high-dose, high-frequency interferon beta-1a can slow disease progression and enable people with relapsing MS to have an active life longer," he added.

Rebif (interferon beta-1a) is a disease-modifying drug used to treat relapsing forms of multiple sclerosis and is similar to the interferon beta protein produced by the human body. Interferon helps modulate the body's immune system, fight disease and reduce inflammation.

Rebif, which was approved in Europe in 1998 and in the US in 2002, is registered in more than 80 countries worldwide. In the United States, Rebif is co-marketed by Serono, Inc and Pfizer Inc.