Multiple sclerosis (MS) is an autoimmune disease that has no known cause. White blood cells (lymphocytes) travel from lymph nodes to the brain and spinal cord, damaging the myelin sheath that surrounds and protects nerves. A reduction or blocking of messages between the brain and the body results. Symptoms vary greatly among individuals and include visual disturbances, muscle weakness, and problems with coordination and balance.
MS is highly unpredictable. Some patients exhibit a gradual but steady progression of the disease. More commonly, there are periods of remission lasting for months or years, alternating with relapses, or flare-ups, and a return of symptoms. Before the availability of Gilenya, cortisone-like steroids or interferon-beta (Avonex) relieved the MS symptoms and reduced the frequency or duration of relapses. However, these drugs failed to prevent the progression of MS and had many side effects.
In recent years, injectable drugs have appeared that decrease the frequency of MS relapses. These include Copaxone (glatiramer), approved in 1996, and Tysabri (natalizumad), a monoclonal antibody initially approved in 2004, withdrawn because of toxicity, and reintroduced in 2009. There is still no cure for MS.
BRAKING MS. Gilenya is a chemical modification of a natural immunosuppressant obtained from a fungus used as an eternal-youth product in traditional Chinese medicine. Between 2010 and 2011, Gilenya (fingolimod) was approved in North America, Europe, and Japan for the treatment of the relapsing form of MS. In clinical studies, Gilenya reduced the rate of relapses by one-half. The first oral drug to slow the progression of the disability associated with the disease and the frequency and severity of relapses, it is thought to act by preventing the release of lymphocytes.
Full assessment of the safety of Gilenya remains to be determined, but the drug is known to decrease heart rate, increase the susceptibility to infection, and cause swelling of the macula of the eye. The appearance of Gilenya has generated understandable enthusiasm among the 2.5 million MS patients worldwide. Time will tell whether it lives up to its potential.
SEE ALSO Cortisone (1949), Cyclosporine/Ciclosporin (1983).
In multiple sclerosis (MS), nerves lose patches of their myelin cover in a process called demyelinization. This photomicrograph shows a demyelinating MS lesion magnified tenfold.