Multiple sclerosis patients taking a new drug experienced fewer relapse rates but more side effects than patients receiving a standard MS therapy, new research indicates.
In a trial comparing two sets of more than 900 patients with relapsing-remitting multiple sclerosis, scientists found that those taking the drug daclizumab HYP had a 45 percent lower relapse rate than those taking interferon beta-1a.
But patients on the new drug, which has not yet been approved by the U.S. Food and Drug Administration, saw more side effects. Also, they did not experience significantly slower disease progression than those in the interferon beta-1a group over the first several months.
"This is one more drug for multiple sclerosis, which is of course very welcome, but it's just one in addition to the 11 or 12 drugs we already have," said Dr. Eugene Lai, a neurologist at Houston Methodist Hospital in Houston, who was not involved in the research.
"It does reduce the relapse rate, but it probably doesn't get to the real core of the MS disease process, and we still don't understand exactly how relapse rate and progression are related," Lai added. "It's still not the definitive treatment for MS yet that can stop it."
The study is published Oct. 8 in the New England Journal of Medicine.
More than 2 million people worldwide are affected by multiple sclerosis, a chronic, disabling condition affecting the brain, spinal cord and optic nerves, according to the National MS Society. Symptoms tend to progress over time and include loss of balance, fatigue, vision loss, paralysis, numbness and tingling in the limbs, and bowel and bladder problems.
In the new study, led by scientists at University Hospital Basel in Switzerland, more than 1,800 patients with relapsing-remitting MS -- a type in which symptoms wax and wane over time -- were randomly assigned to receive either daclizumab HYP or interferon beta-1a over a period averaging about two years.
Daclizumab is a so-called monoclonal antibody drug and is thought to work by binding to receptors on immune system cells linked to multiple sclerosis and other autoimmune disorders. Interferon beta-1a is a synthetic version of a natural substance produced in the body that fights infections and other threats.
While daclizumab recipients experienced much lower relapse rates than those on interferon beta-1a, disability progression 12 weeks after the study's start was similar in both groups -- 16 percent with daclizumab and 20 percent with interferon beta-1a.
But side effects, including serious infections and skin problems such as rash or eczema, were far more common among daclizumab recipients.
Johns Hopkins Hospital in Baltimore was one of the 244 study sites in 28 countries participating in the trial. Dr. Scott Newsome, director of neurology outpatient services at Hopkins, noted that daclizumab might be an easier regimen for MS patients because it's injected under the skin only once every four weeks. Interferon beta-1a requires a weekly infusion.
Another benefit, Newsome said, is that disease progression seemed to be slightly slower at the six-month mark and beyond in daclizumab patients.
"In my mind, that's the outcome measure to look at," he said. "MS is a marathon, not a 50-yard dash. As a group, we need to have better outcome measures in clinical trials that tell us long-term where a patient will be."
Lai and Newsome agreed that FDA approval for daclizumab seems likely, at which point a more complete idea of side effects will be available once the drug hits the market.
Newsome, also an assistant professor of neurology at Hopkins, said he wasn't sure how much daclizumab would cost if it becomes widely available, but it's likely its price would be far higher than for interferon beta-1a, which has been used for many years to treat MS.
"I think it's fantastic that we have a number of therapies to treat MS patients, because certainly throughout the years we're noticing an improvement in patients' overall quality of life and decreased disability over time," he said. "But it's becoming more complicated in terms of which medications we choose first or second, and some of what we decide is not driven by the doctor; often it's driven by the patient and insurer."
If daclizumab is FDA approved for use, Lai and Newsome said physicians should be vigilant for side effects.
"I myself will probably wait and let it be on the market for a while to make sure it's safe before I use it," Lai said. "We're encouraged to have so many effective medications for MS, but it's also kind of confusing to weigh the benefits versus the side effects and risks. It's important for patients to go to a doctor with more expertise in the treatment of MS to get the most benefit and select the right medication for them."
