A medication currently approved to treat some forms of cancer is now facing a clinical trial to see if it might be effective for people with a rare form of multiple sclerosis (MS). The drug is known as Rituxan (rituximab), a monoclonal antibody used as a therapy for a type of cancer known as non-Hodgkin's lymphoma. It's manufactured by Genentech Pharmaceuticals, and was first approved for this indication in 1997.
The medication works in combination with the body's immune system, targeting a type of white blood cell in non-Hodgkin's lymphoma. The result is the immune system attacks and destroys only this specific cell.1
Another Possible Target?
Now, doctors at the University of Texas are leading a multicenter clinical trial to see if the treatment might be safe and effective for people with primary progressive multiple sclerosis. This form of the disease affects about 10 percent of all people who've been diagnosed. It's characterized by a slow, but continuing worsening of MS, with no distinct relapses or remissions. However, the rate of progression tends to vary over time, sometimes plateaus, and even improves somewhat in certain instances.2
"There really hasn't been a lot of research or treatment options for patients with this form of MS," explained Kathleen Hawker, an assistant professor of Neurology at the University of Texas Southwestern Medical School in Dallas, who is heading the clinical investigation. "It's an exciting study and the patients are really enthusiastic about this," she said.
Few Therapy Options
People with primary-progressive MS don't respond to traditional medication as well as people with more common forms of the disease like relapsing-remitting MS, according to the study investigators. Because of this, many people with primary-progressive forms of the illness usually experience debilitating physical side effects more often. And many of them need walkers or wheelchairs to get around. Currently, most of the therapies available for MS, which target an immune system component known as T-cells, are more effective for people with the relapsing form of the illness.
Primary-progressive MS usually strikes people in their 40s and 50s, and men and women equally share the risk of contracting it, Hawker said. Less evidence of tissue damage in the brain can be seen on magnetic resonance imaging (MRI) tests, however. This makes it more difficult to diagnose this form of the disease.
How the Drug Under Review Works
"Rituxan works on a component of the immune system called B-cells," Hawker explained. "The drug depletes B-cells and has been used to treat other autoimmune diseases such as lupus."
Hawker told Priority Healthcare that it's believed primary-progressive MS is different immunologically from the relapsing form. Since it's thought that antibodies lead the strike against the central nervous system in primary-progressive MS, and since antibodies are made from a cell derived from B-cells, it's thought Rituxan might be effective in this case, she said.
Patient Recruitment
At UT Southwestern Medical School, Hawker and her colleagues are developing the trial's protocol, choosing other sites for testing, and overseeing the research.
Currently, 61 medical sites in the United States and nearly a dozen sites in Canada are taking part in the trial, planned to run two years, followed by 1 year of safety analysis. A total of 435 patients are expected to be enrolled for the study, with 15 of those at UT Southwestern. The enrollment phase is expected to conclude by early this summer, Hawker estimated.
People who meet specific criteria will be accepted. Those who participate in the trial, which will test the effects of Rituxan as compared to those of a placebo, will receive lab work, an electrocardiogram to check their heart function, MRI exam, spinal tap, and a physical and neurological exam prior to receiving the first dose.
Once medication is begun, patients will receive a day-long infusion. Hawker says a positive outcome would mark a treatment breakthrough for primary-progressive MS.
"This is the first trial, and at this time, the only trial in primary-progressive MS," Hawker said. "There was preclinical work done … that suggested that some patients responded to the drug."
1. Genentech Pharmaceuticals. A Breakthrough Treatment. Available at: http://www.rituxan.com/rituxan/patient/why/with-you/. Accessed May 6, 2005.
2. National Multiple Sclerosis Society. What is Multiple Sclerosis? Available at: http://www.nationalmssociety.org/What%20is%20MS.asp. Accessed May 6, 2005.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include coverage of health news for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
