Merck Serono’s multiple sclerosis drug Rebif (interferon beta-1a) has failed to show superiority over rival Teva’s Copaxone (glatiramer acetate) in patients with the relapsing remitting form of the disease, according to media reports this morning.

Although the results from the REGARD study found in favour of Rebif, overall it failed to meet the primary endpoint - the time to first relapse. Full data from the 96-week, 800-patient study will be presented at the forthcoming European Committee for Treatment and Research in Multiple Sclerosis meeting.

From the analysts’ viewpoint, there will be little if no negative impact on Copaxone as it is already viewed as being less effective than the interferon class of drugs. Indeed there could be a significant upside for Teva, but whether the news will hit sales of Rebif remains to be seen.

Merck acquired Rebif through its merger with Serono and had hoped to improve the drug’s market share by demonstrating superiority over Copaxone; sales of Rebif in the first quarter of this year alone rose 3.5% to 283 million euros.

But positive news from new Rebif formulation

Meanwhile, Merck Serono also says its new formulation of Rebif three times weekly offers a three-fold improvement in injection tolerability and immunogenicity reactions compared to the previous formulation.

According to data from the two-year, Phase IIIb EVIDENCE study involving 260 patients with relapsing MS, “the new formulation of Rebif offers the treatment benefits of a high-dose high-frequency interferon beta-1a coupled with improvements in the overall safety and immunogenicity profiles when compared with historical data for the previous formulation.” The new formulation of Rebif was recently approved in the European Union and Canada, with launches starting in September, and is currently under review at the US Food and Drug Administration.

Multiple sclerosis is a chronic, inflammatory condition of the nervous system and is the most common, non-traumatic, neurological disease in young adults. The World Health Organisation estimates that up to 2.5 million people suffer from MS worldwide.

Although Merck Serono's share price has declined of late, this is on concerns over the future of its liquid crystals business. It announced yesterday that the division’s chief Paul Breddels is to leave the company for personal reasons, and will be replaced by Walter Galinat, who is currently head of the performance and life science chemicals division.