Still, "the fact that fingolimod is given orally is a huge advantage," said the lead author of the yearlong study, Dr. Jeffrey Cohen, director of experimental therapeutics at the Mellen MS Center at the Cleveland Clinic in Ohio. "It appears to be effective and is generally well-tolerated."
The third study, also a phase 3 study, looked at the oral medication cladribine in comparison to placebo. In this study, more than 1,300 people with relapsing-remitting MS were randomly assigned to receive a cladribine dose of either 3.5 mg or 5.25 mg per kilogram of body weight or a placebo. During the second year of the study, those on cladribine were all given the lower dose.
As in the fingolimod studies, annual relapse rates were less than 1 percent. However, those on cladribine had relapse rates that were up to 58 percent lower. Disease activity and disability scores were also lower in the treatment groups.
Although the drug appeared to be generally well-tolerated, there were some serious side effects with cladribine as well, including serious herpes zoster infections. Herpes zoster is the virus that causes shingles, and there is a vaccine available for this virus. Whether getting the vaccine prior to treatment would lessen the risk of infection isn't clear because it hasn't been studied, said Richert. Cladribine was also associated with a potentially increased risk of cancer.
Another question that remains to be answered for both medications is whether or not they will increase the risk of a very serious brain infection known as progressive multifocal leukoencephalopathy (PML). It wasn't discovered that the MS medication, natalizumab (Tysabri), caused a slight increase in the rate of these infections until the drug came to market. That's because it's such a rare side effect.
Learn more about the treatment options currently available for multiple sclerosis from the National Multiple Sclerosis Society.
SOURCES: Jeffrey Cohen, M.D., director, experimental therapeutics, Mellen MS Center, Cleveland Clinic, Ohio; John Richert, M.D., executive vice president, research and clinical programs, National Multiple Sclerosis Society, New York City; Jan. 20, 2010, New England Journal of Medicine, online