During the past 20 years, researchers have made major breakthroughs in MS treatment due to new knowledge about the immune system and the ability to use MRI to monitor MS in patients. As a result, a number of medical therapies have been found to reduce relapses in persons with relapsing-remitting MS. These drugs are called disease modulating drugs.
There is debate among doctors about whether to start disease modulating drugs at the first signs of MS or to wait until the course of the disease is better defined before beginning treatment. On one hand, U.S. Food and Drug Administration (FDA)-approved medications to treat MS work best early in the course of the disease and work poorly, if at all, later in the progressive phase of the illness. Clinical trials have shown convincingly that delaying treatment, even for the 1 to-2 years that it may take for patients with MS to develop a second clinical attack, may lead to an irreversible increase in disability. In addition, people who begin treatment after their first attack have fewer brain lesions and fewer relapses over time.
On the other hand, initiating treatment in patients with a single attack and no signs of previous MS lesions, before MS is diagnosed, poses risks because all FDA-approved medications to treat MS are associated with some side effects. Therefore, the best strategy is to have a thorough diagnostic work-up at the time of first attack of MS. The work-up should exclude all other diseases that can mimic MS so that the diagnosis can be determined with a high probability. The diagnostic tests may include an evaluation of the cerebrospinal fluid and repeated MRI examinations. If such a thorough work-up cannot confirm the diagnosis of MS with certainty, it may be prudent to wait before starting treatment. However, each patient should have a scheduled follow-up evaluation by his or her neurologist 6 to 12 months after the initial diagnostic evaluation, even in the absence of any new attacks of the disease. Ideally, this evaluation should include an MRI examination to see if any new MS lesions have developed without causing symptoms.
Until recently, it appeared that a minority of people with MS had very mild disease or “benign MS” and would never get worse or become disabled. This group makes up 10 to 20 percent of those with MS. Doctors were concerned about exposing such benign MS patients to the side effects of MS drugs. However, recent data from the long-term follow-up of these patients indicate that after 10 to 20 years, some of these patients become disabled. Therefore, current evidence supports discussing the start of therapy early with all people who have MS, as long as the MS diagnosis has been thoroughly investigated and confirmed. There is an additional small group of individuals (approximately 1 percent) whose course will progress so rapidly that they will require aggressive and perhaps even experimental treatment.
The current FDA-approved therapies for MS are designed to modulate or suppress the inflammatory reactions of the disease. They are most effective for relapsing-remitting MS at early stages of the disease. These treatments include injectable beta interferon drugs. Interferons are signaling molecules that regulate immune cells. Potential side effects of beta interferon drugs include flu-like symptoms, such as fever, chills, muscle aches, and fatigue, which usually fade with continued therapy. A few individuals will notice a decrease in the effectiveness of the drugs after 18 to 24 months of treatment due to the development of antibodies that neutralize the drugs' effectiveness. If the person has flare-ups or worsening symptoms, doctors may switch treatment to alternative drugs.
Glatiramer acetate is another injectable immune-modulating drug used for MS. Exactly how it works is not entirely clear, but research has shown that it changes the balance of immune cells in the body. Side effects with glatiramer acetate are usually mild, but it can cause skin reactions and allergic reactions. It is approved only for relapsing forms of MS.
The drug mitoxantrone, which is administered intravenously four times a year, has been approved for especially severe forms of relapsing-remitting and secondary progressive MS. This drug has been associated with development of certain types of blood cancers in up to one percent of patients, as well as with heart damage. Therefore, this drug should be used as a last resort to treat patients with a form of MS that leads to rapid loss of function and for whom other treatments did not stop the disease.
Natalizumab works by preventing cells of the immune system from entering the brain and spinal cord. It is administered intravenously once a month. It is a very effective drug for many people, but it is associated with an increased risk of a potentially fatal viral infection of the brain called progressive multifocal encephalopathy (PML). People who take natalizumab must be carefully monitored for symptoms of PML, which include changes in vision, speech, and balance that do not remit like an MS attack. Therefore, natalizumab is generally recommended only for individuals who have not responded well to the other approved MS therapies or who are unable to tolerate them. Other side effects of natalizumab treatment include allergic and hypersensitivity reactions.
In 2010, the FDA approved fingolimod, the first MS drug that can be taken orally as a pill, to treat relapsing forms of MS. The drug prevents white blood cells called lymphocytes from leaving the lymph nodes and entering the blood and the brain and spinal cord. The decreased number of lymphocytes in the blood can make people taking fingolimod more susceptible to infections. The drug may also cause problems with eyes and with blood pressure and heart rate. Because of this, the drug must be administered in a doctor’s office for the first time and the treating physician must evaluate the patient’s vision and blood pressure during an early follow-up examination. The exact frequency of rare side effects (such as severe infections) of fingolimod is unknown.
Other FDA-approved drugs to treat relapsing forms of MS in adults include dimethyl fumarate and teriflunomide, both taken orally.
Disease Modifying Drugs
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Reference: National Institute of Neurological Disorders and Stroke (NINDS)
Last Updated: May 26, 2016