WEDNESDAY, Jan. 20 (HealthDay News) -- Two new drugs -- both oral, rather than injected -- may soon be available to combat multiple sclerosis.
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Three studies, all being published early online Jan. 20 in the New England Journal of Medicine, find that the new drugs -- fingolimod and cladribine -- reduce relapse rates in people with relapsing-remitting multiple sclerosis (MS). Both drugs work by altering the immune system response.
However, as is often the case with immune-suppressing medications, there are concerns about side effects, including an increased risk of serious infections and possibly, cancer.
"Oral drugs are what people with MS have been wishing for a long time. This is wonderful news for people with MS," said Dr. John Richert, executive vice president of research and clinical programs for the National Multiple Sclerosis Society (NMSS). "The drugs appear to be quite effective, and at the moment, appear to have a reasonable risk-benefit ratio. However, it will be very important for people with MS and their physicians to remain vigilant and be on the lookout for side effects."
All three studies were funded by the drug's manufacturers -- Novartis for fingolimod and Merck Serono for cladribine. Both manufacturers are currently pursuing U.S. Food and Drug Administration approval for their medications.
Multiple sclerosis is a chronic, potentially disabling illness that's believed to be an autoimmune disorder. In MS, the body's natural defense system mistakenly attacks the fatty substance that protects the nerves (myelin). About 400,000 Americans have multiple sclerosis, according to the NMSS.
The current treatments for MS are all injectable medications, which Richert said is sometimes a barrier for people to start early treatment. He said that treatments may be more successful if they're started early in the course of the disease, so he's hoping that having oral medications will help people start treatment sooner.
Two of the new studies focused on the oral medication called fingolimod. Both were phase 3 studies. One study included more than 1,000 people with relapsing-remitting MS. The study participants were randomly selected to receive a daily dose of 0.5 milligrams (mg), 1.25 mg or a placebo.
Annual relapse rates were less than 1% each year, but were 54% less for the lower dose of fingolimod and 60% for the higher dose. The study also found slower disease activity and progression.
In the second study on fingolimod, 1,153 people with relapsing-remitting MS were randomly assigned to receive a daily dose of 0.5 mg or 1.25 mg of fingolimod or a weekly dose of 30 micrograms of interferon beta-1a (Avonex) for one year. The annual relapse rate on either drug was less than 1% in this study as well. However, the people on fingolimod had up to a 52% lower relapse rate. This study found no significant differences in disease progression between the two treatments.
Both studies found that the lower dose of the drug was better tolerated. A small number of serious infections occurred, including two deaths from herpes infections in these studies. And, there appeared to be a higher incidence of cancer in people taking fingolimod.
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%. However, those on cladribine had relapse rates that were up to 58% 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.
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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