How Effective Is Natalizumab for Multiple Sclerosis?

Many medical studies have been performed to evaluate the use of natalizumab for multiple sclerosis (MS). Most of these studies have concluded that natalizumab typically is effective in reducing the rate of relapse as well as morbidity in rapidly evolving severe relapsing-remitting multiple sclerosis. Despite its effectiveness, the potential risks of natalizumab can be serious and include allergic reactions, fatigue and a slightly increased occurrence of progressive multifocal leukoencephalopathy.

Multiple sclerosis is a progressive neurological disorder in which the myelin that surrounds nerve cells in the brain and spinal cord is damaged by the patient’s immune system. Multiple areas of inflammation or lesions — which are clearly visible on brain and spinal cord imagining studies — are characteristic of the disease. There are several types of multiple sclerosis, and symptoms vary greatly between patients. MS can develop throughout one’s life. Women are slightly more prone than men.

Certain immune system components typically are dysfunctional in multiple sclerosis. Integrins are a family of immune system molecules. They are important in determining whether inflammatory cells can cross the blood-brain barrier and enter the brain. When defective, integrins allow an excess of inflammatory cells through the blood-brain barrier, and this leads to inflammation and relapses in MS patients. Natalizumab is a monoclonal antibody that blocks the effects of alpha 4 integrin, decreasing the frequency of exacerbations and the formation of new brain and spinal cord lesions.

An intravenous infusion is used to administer natalizumab. The typical dosage of natalizumab for multiple sclerosis is 300 milligrams every 28 days. The drug acts as an immunosuppressant, so possible side effects include an increased risk of opportunistic infections and a slightly higher incidence of progressive multifocal leukoencephalopathy. Patients who are undergoing treatment with natalizumab should not use other immunosuppressant medications, such as beta interferon, immunoglobulins or cyclophosphamide, because of potential drug interactions.

There are many types of multiple sclerosis, and the disorder can have various degrees of severity. Natalizumab typically is used as a standalone therapy for rapidly evolving severe relapsing-remitting multiple sclerosis, a form of MS that involves a minimum of two severe relapses a year and the presence of multiple lesions on imaging studies. Uses of natalizumab sometimes include other types of multiple sclerosis for patients experiencing frequent, severe exacerbations that cannot be controlled with other medications and Crohn’s disease. Scientific studies into the effects of natalizumab for multiple sclerosis indicate the drug is more effective than other treatments or lack of treatment at reducing the relapse rate in patients who have severe disease.