Although Lemtrada (alemtuzumab) was found to be more effective in preventing MS relapses than the older drug – Rebif – it did not reduce disability in a late-stage clinical trial, the study’s second primary endpoint. In previous studies it had, makers Sanofi and its subsidiary Genzyme announced today.

The older drug, Rebif is marketed by Merck KGaA of Germany. Genzyme is developing alemtuzumab together with Bayer HealthCare.

The first of two randomized, Phase 3 trials are comparing investigational medication Lemtrada (alemtuzumab) with Rebif (high dose subcutaneous interferon beta-1a) in patients with multiple sclerosis, more specifically relapsing-remitting multiple sclerosis (RRMS).

Two annual cycles of Alemtuzumab treatment reduced relapses by 55% compared to Rebif over a 24 month period, in the CARE-MS I trial. This was the trial’s primary endpoint (main goal), meaning it was a success, Sanofi wrote.

Regarding its second primary endpoint, Sanofi wrote:

“Statistical significance was not achieved for the second primary endpoint, time to six month sustained accumulation of disability, as compared to Rebif®. At the two year time point, 8% of alemtuzumab treated patients had a sustained increase in their Expanded Disability Status Scale (EDSS) score (or worsening) as compared to 11% of those who received Rebif® (Hazard Ratio=0.70, p=0.22). The patients will have the option to be evaluated over the next 3 years as part of a separate protocol.

Professor Alastair Compston, Chair of the Steering Committee overseeing the conduct of the study said:

“The substantial effect of alemtuzumab on reduction of relapse rate over and above that seen with Rebif® confirms our experience gathered over many years and demonstrated in the Phase 2 stud. We treated patients in CARE-MS I at a very early stage in the course of their illness when the natural history may be relatively quiet, and both groups were remarkably stable over the two years of observation. Very few patients accumulated disability at the rate expected fromprevious clinical trials, including our Phase 2 experience. Whilst welcome from the clinicalperspective, this much reduced our ability to detect a significant treatment effect on the disabilityendpoint.”

Christopher A. Viehbacher, Chief Executive Officer, Sanofi.

“In this 2-year comparative study, the effect of alemtuzumab on reducing relapses versus Rebif, aleading drug for the treatment of Multiple Sclerosis, is impressive, and the safety profile is consistent with the Phase 2 clinical trial experience. We look forward to the results from CARE-MS II, which will provide clinical data in patients whose disease was not adequately controlled on other multiple sclerosis therapies. Today’s results are an important step forward in the development of alemtuzumab to address the substantial unmet needs for multiple sclerosis patients.”

In the CARE-MS I study, the most common side effects from alemtuzumab were headache, fever, nausea, hives, chills, flushing and rash. There were also cases of upper respiratory and urinary tract infections, as well as oral herpes. In most cases, infections were mild to moderate. There were no life-threatening infections. None of the trial participants had to abandon the trial because of an adverse event.

Sanofi informs that there is an ongoing CARE-MS II trial, comparing alemtuzumab with Rebif in relapsing-remitting MS patients who relapsed while on treatment. Topline trial results should be available during the last three months of this year.

Alemtuzumab has not been used in patients with multiple sclerosis outside a regulated clinical trial setting because it has not yet been approved for MS treatment. The FDA has granted Sanofi fast-track designation for alemtuzumab. Sanofi expects to file for approval in the European Union and the USA in early 2012.

Written by Christian Nordqvist