Clinical trials indicate that natalizumab’s benefits may outweigh its risks. Several studies published in 2006 in the New England Journal of Medicine showed that natalizumab, alone or in combination with IFN1a (Avonex) can help prevent disability in patients with multiple sclerosis. Another study suggested that the risk of PML is very low if patients use natalizumab for less than 18 months.
Other MAbs under investigation for MS include daclizumab and alemtuzumab. Results from a 2005 phase II trial for alemtuzumab (Campath) indicated that the drug helped prevent relapse but also caused serious side effects. Patients who took the drug had a high risk for developing a serious bleeding disorder caused by a low blood platelet count.
Intravenous Immunoglobulin
Intravenous immunoglobulin treatments are monthly infusions of natural antibodies. They appear to have some modest benefits for relapsing-remitting MS. Studies suggests that intravenous immunoglobulin reduces relapse rates and occurrences of new lesions and slows disease progression in relapsing-remitting MS. It does not appear to reduce disability. It is extremely expensive and does not appear to have any benefits for patients with secondary progressive MS.
Immunosuppressants for Chronic Progressive MS
Many drugs being investigated for chronic progressive multiple sclerosis are immunosuppressants, which block certain factors in the immune system that contribute to the inflammatory process. Each of these drugs can produce serious side effects, including susceptibility to infection. Evidence on benefits is uncertain, mainly because of high toxicity or study limitations. Still, some may help some patients with severe MS. Among immunosuppressant drugs or procedures that have been investigated with little or no obvious benefits or unacceptably high side effects are total lymphoid irradiation, sulfasalazine, cyclosporine, acyclovir, and oral bovine myelin.
Mitoxantrone. Mitoxantrone (Novantrone) was the first drug approved specifically for secondary progressive MS. Two studies suggested that it may be of some help in reducing progression and relapse rates. Cumulative doses can have toxic effects on the heart, however, so the drug is only used for a limited period.
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