Multiple Sclerosis : Treatment, Immunotherapy

by National Institute of Health

(Page 6 of 9)

Can MS be Treated?

There is as yet no cure for MS. Many patients do well with no therapy at all, especially since many medications have serious side effects and some carry significant risks. Naturally occurring or spontaneous remissions make it difficult to determine therapeutic effects of experimental treatments; however, the emerging evidence that MRIs can chart the development of lesions is already helping scientists evaluate new therapies.

In the past, the principal medications physicians used to treat MS were steroids possessing anti-inflammatory properties; these include adrenocorticotropic hormone (better known as ACTH), prednisone, prednisolone, methylprednisolone, betamethasone, and dexamethasone. Studies suggest that intravenous methylprednisolone may be superior to the more traditional intravenous ACTH for patients experiencing acute relapses; no strong evidence exists to support the use of these drugs to treat progressive forms of MS. Also, there is some indication that steroids may be more appropriate for people with movement, rather than sensory, symptoms.

While steroids do not affect the course of MS over time, they can reduce the duration and severity of attacks in some patients. The mechanism behind this effect is not known; one study suggests the medications work by restoring the effectiveness of the blood/brain barrier. Because steroids can produce numerous adverse side effects (acne, weight gain, seizures, psychosis), they are not recommended for long-term use.

One of the most promising MS research areas involves naturally occurring antiviral proteins known as interferons. Three forms of beta interferon (Avonex, Betaseron, and Rebif) have now been approved by the Food and Drug Administration for treatment of relapsing-remitting MS. Beta interferon has been shown to reduce the number of exacerbations and may slow the progression of physical disability. When attacks do occur, they tend to be shorter and less severe. In addition, MRI scans suggest that beta interferon can decrease myelin destruction.

Investigators speculate that the effects of beta interferon may be due to the drug's ability to correct an MS-related deficiency of certain white blood cells that suppress the immune system and/or its ability to inhibit gamma interferon, a substance believed to be involved in MS attacks. Alpha interferon is also being studied as a possible treatment for MS. Common side effects of interferons include fever, chills, sweating, muscle aches, fatigue, depression, and injection site reactions.

Scientists continue their extensive efforts to create new and better therapies for MS. Goals of therapy are threefold: to improve recovery from attacks, to prevent or lessen the number of relapses, and to halt disease progression. Some therapies currently under investigation are discussed below.

Immunotherapy

As evidence of immune system involvement in the development of MS has grown, trials of various new treatments to alter or suppress immune response are being conducted. Most of these therapies are, at this time, still considered experimental.

Results of recent clinical trials have shown that immunosuppressive agents and techniques can positively (if temporarily) affect the course of MS; however, toxic side effects often preclude their widespread use. In addition, generalized immunosuppression leaves the patient open to a variety of viral, bacterial, and fungal infections.

Over the years, MS investigators have studied a number of immunosuppressant treatments. One such treatment, Novantrone (mitoxantrone), was approved by the FDA for the treatment of advanced or chronic MS. Other therapies being studied are cyclosporine (Sandimmune), cyclophosphamide (Cytoxan), methotrexate, azathioprine (Imuran), and total lymphoid irradiation (a process whereby the MS patient's lymph nodes are irradiated with x-rays in small doses over a few weeks to destroy lymphoid tissue, which is actively involved in tissue destruction in autoimmune diseases). Inconclusive and/or contradictory results of these trials, combined with the therapies' potentially dangerous side effects, dictate that further research is necessary to determine what, if any, role they should play in the management of MS. Studies are also being conducted with the immune system modulating drug cladribine (Leustatin).

Another potential treatment for MS is monoclonal antibodies, which are identical, laboratory-produced antibodies that are highly specific for a single antigen. They are injected into the patient in the hope that they will alter the patient's immune response. One monoclonal antibody, natalizumab (Tysabri), was shown in clinical trials to significantly reduce the frequency of attacks in people with relapsing forms of MS and was approved for marketing by the U.S. Food and Drug Administration (FDA) in 2004. However, in 2005 the drug's manufacturer voluntarily suspended marketing of the drug after several reports of significant adverse events. In 2006, the FDA again approved sale of the drug for MS but under strict treatment guidelines involving infusion centers where patients can be monitored by specially trained physicians.

Another experimental treatment for MS is plasma exchange, or plasmapheresis. Plasmapheresis is a procedure in which blood is removed from the patient and the blood plasma is separated from other blood substances that may contain antibodies and other immunologically active products. These other blood substances are discarded and the plasma is then transfused back into the patient. Because its worth as a treatment for MS has not yet been proven, this experimental treatment remains at the stage of clinical testing.

Bone marrow transplantation (a procedure in which bone marrow from a healthy donor is infused into patients who have undergone drug or radiation therapy to suppress their immune system so they will not reject the donated marrow) and injections of venom from honey bees are also being studied. Each of these therapies carries the risk of potentially severe side effects.

About the Author

NIH is the nation's medical research agency - making important medical discoveries that improve health and save lives. The National Institutes of Health (NIH), a part of the U.S. Department of Health and Human Services, is the primary Federal agency for conducting and supporting medical research.