Alemtuzumab, the anti-CD52 monoclonal antibody has shown its ability to reduce relapse rates in patients with multiple sclerosis (MS). Used in the treatment of leukaemia, this drug is now commonly prescribed off-label for MS. According to two phase III trials published in The Lancet on 1 November 2012, the antibody was tested as a first and second-line treatment for relapsing-remitting multiple sclerosis and showed greater efficacy than interferon beta-1a.

The first study used 525 individuals with relapsing-remitting MS who hadn’t received any former treatment. Patients were allocated to receive intravenous alemtuzumab or interferon beta-1a. Those who were given alemtuzumab had a relapse rate of just 22% compared to the interferon beta-1a group which had a relapse rate of 40% – a difference that altogether means a 54.9% improvement. After two years, 79% of the alemtuzumab patients were relapse free, as opposed to 59% of those treated with interferon beta-1a.

The second study looked at 667 patients with relapsing-remitting MS who had at least one relapse whilst being treated with interferon beta-1a or glatiramer. The results were again similar as patients in the alemtuzumab group had relapse rates averaging 35% while the interferon beta-1a group had 51%. Again, two years later 65% of alemtuzumab patients were free as opposed to just 47% of individuals given interferon beta-1a.

Both studies demonstrated similar levels of side effects associated with alemtuzumab as 9/10 had reactions to the infusions and nearly 3/4 suffered from mild infections. However the results of the trials are very encouraging and it will not be very long before several disease modifying drugs, including alemtuzumab will have regulatory approval.