Sanofi has filed its multiple sclerosis drug Lemtrada with regulators in the USA and Europe.

The French drugmaker acquired Lemtrada (alemtuzumab) through its $20.1 billion takeover of Genzyme Corp last year. The submissions are based on two Phase III studies which demonstrated that the drug was superior to Merck KGaA's blockbuster Rebif (interferon beta-1a) on clinical and imaging endpoints, including a reduction in relapse rate.

In addition, data presented last month at the American Academy of Neurology meeting showed that some patients with preexisting disability treated with Lemtrada in the CARE-MS II trial were more than twice as likely to experience a sustained reduction in disability over two years than patients treated with Rebif.

In both CARE-MS I and CARE-MS II trials, which make up the bulk of the filings, alemtuzumab 12mg was given as an IV administration on five consecutive days, and the second course was administered on three days 12 months later. Rebif 44mcg was administered by subcutaneous injection three times per week, each week, throughout the two years of study.

David Meeker, Genzyme's chief executive, noted that "there remains a large unmet treatment need for patients living with active disease and we believe that Lemtrada, given its efficacy and unique dosing schedule, has the potential to transform the lives of patients with MS”. The drug, which is already approved as Campath for B-cell chronic lymphocytic leukaemia, was co-developed with Bayer, which retains an option to co-promote alemtuzumab in MS. The German firm could also pocket royalties up to a limit of $1.25 billion.

In addition to Lemtrada, Sanofi's MS portfolio includes the investigational once-daily pill Aubagio (teriflunomide), which is currently being reviewed by the US Food and Drug Administration and the European Medicines Agency.