"Alemtuzumab works by destroying lymphocytes, a type of white blood cell. By shutting down this part of the immune system, the drug seems to block the damage to brain tissue that occurs in MS.
But three per cent of those taking alemtuzumab in the trial developed a life-threatening autoimmune condition.
During the trial, 20 per cent of those treated with alemtuzumab developed an over- or under-active thyroid gland.
Three per cent of those in the alemtuzumab group developed a low platelet count that increases vulnerability to bleeding — a complication that can be easily treated if recognized early, the researchers said, but that led to one death during the study.
"The data convincingly demonstrate that intensive immunosuppression can dramatically reduce the accumulation of new inflammatory lesions and focal [neuron] scarring and the rate of clinical relapse in patients with recent-onset multiple sclerosis," neurologist Dr. Stephen Hauser wrote in an editorial accompanying the study.
The findings highlight the value of very aggressive therapy at the beginning of the disease and helps medical researchers address the relationship between the inflammatory and degenerative phases of the disease, Hauser added.