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Additional Drug Reduces Lesions in Relapsing Multiple Sclerosis

An international team of researchers has found that adding a humanized monoclonal antibody called daclizumab to standard treatment reduces the number of new or enlarged brain lesions in patients with relapsing multiple sclerosis (MS). Daclizumab is specific for CD25, a protein that is expressed on activated T cells, and binding of daclizumab to CD25 results in selective inhibition of these activated T cells. Daclizumab treatment has been studied in patients with human autoimmune conditions, such as MS, that are characterized by abnormal T-cell responses. "Previous research has shown that treatment with daclizumab reduced multiple sclerosis disease activity," said Dr. John W. Rose, professor of neurology at the University of Utah School of Medicine, and senior author on the current article. "Our work in the CHOICE trial [a Phase 2, randomized, double-blinded, placebo-controlled clinical study] shows that daclizumab significantly reduces MS lesion formation in people with active relapsing disease." In addition to finding that add-on treatment with high-dose daclizumab resulted in a significantly lower number of new or enlarged MS lesions, the researchers found that patients treated with either high- or low-dose daclizumab had a seven to eight times higher number of immune cells called CD56bright natural killer cells (NK cells). Previous research has shown that untreated MS patients have lower numbers of these NK cells than healthy individuals. "Several lines of evidence point to a potential function for CD56bright natural killer cells in regulating the immune system," explained Dr. Rose. "This study provides confirmatory data that daclizumab treatment causes an expansion of CD56bright natural killer cells and adds support to the theory that this expansion might mediate some of the effects of daclizumab on reducing multiple sclerosis lesion activity." The author noted that further research is needed to clarify whether the risk-benefit of daclizumab is better when the drug is used alone or in combination with interferon beta, as well as to determine the optimum dose and length of treatment needed to see the full therapeutic effects of the drug.

"The CHOICE trial showed that treatment with daclizumab was associated with both a significant reduction in MS lesion formation and a robust increase in important cells that help to regulate the immune system," concluded Dr. Rose. "Combined with previous research, these two findings strongly support further study of daclizumab as a clinical treatment for multiple sclerosis."

MS is a debilitating disease in which the body's immune system attacks the fatty substance that surrounds and protects the nerve fibers in the brain and spinal cord. The resulting damage interferes with the transmission of nerve signals between the brain and spinal cord and other parts of the body, producing a variety of symptoms including problems with balance, coordination, vision, and even mental function. Approximately 85 percent of multiple sclerosis patients are initially diagnosed with relapsing MS, in which clearly-defined attacks of worsening neurologic function are followed by partial or complete recovery periods during which no disease progression occurs.

The photo shows famous American skiers Jimmy Heuga (r) and Billy Kidd. Kidd won the silver medal and Heuga the bronze in the men’s slalom event at the 1968 Olympics in Innsbruck, Austria. Heuga and Kidd were the first American men to ever win Olympic medals in alpine skiing. Heuga, who suffered from MS for many years after his skiing career, did much work in support of MS patients and MS research. He passed away on February 8, 2010, at the age of 66.

The new research report was published online on Feb. 16, 2010 in Lancet Neurology. [Press release] [Lancet Neurology abstract]