In the last few years, several new drugs have been developed for relapsing remitting MS. One of these is alemtuzumab, also known as Lemtrada, which has been approved in Europe, Canada, Australia, and Latin America.

In particular, earlier this year the UK’s National Institute of Heath and Care Excellence (NICE) published guidance recommending alemtuzumab as an option for the treatment of relapsing-remitting MS.

Alemtuzumab belongs to the family of monoclonal antibodies, which can stop certain types of blood cells from entering the brain and attacking myelin, which is the cause of damage in MS.

Alemtuzumab is taken as an intravenous infusion on five consecutive days, with a second course given on three consecutive days 12 months later.

Alemtuzumab infusions are few due to its ability to permanently change the body’s immune system.

The efficacy, tolerability, and safety of alemtuzumab have been tested on patients with relapsing-remitting MS in three main clinical trials between 2002 and 2009 (CAMMS223, CARE-MS I, CARE-MS II).

These three big trials involved nearly 1,800 people with relapsing-remitting MS. A sample of these patients was treated with alemtuzumab and another sample with interferon.

Overall, alemtuzumab was significantly more effective than interferon in reducing the number of relapses and the risk of disability.

Despite the very good results in terms of efficacy, in one of the trials three patients developed a severe blood disease, immune-mediated thrombocytopenic purpura.

Moreover, several patients on alemtuzumab presented with other autoimmune diseases, like thyroiditis and nephropathy.

As it works by decreasing the number of immune cells in circulation, alemtuzumab also leads to an increased risk of infection. Several cases of herpes virus infections and other minor types of infection, were observed during the trials.

Because alemtuzumab is effective and because the way it is administered has a low impact on patients’ daily life, it seems a promising alternative to other MS drugs, like interferon or glatiramer acetate.

Unfortunately, its safety has not been completely assessed yet and its long-term effects on the immune system are unpredictable. In addition, due to the severity of the potential side effects, patients might need to have their blood and urine tested monthly for several years after treatment with alemtuzumab, to prevent the onset of severe autoimmune or infectious diseases.

These factors should be taken into account when prescribing alemtuzumab.