By Steven Reinberg
Monday, June 9, 2008 12:00 AM
SUNDAY, June 8 (HealthDay News) -- A drug used to treat multiple myeloma, a cancer of the white blood cells, may also be a treatment for the chronic autoimmune disease lupus, German researchers report.
The drug, Velcade (bortezomib), which is a proteasome inhibitor, worked against the disease and prolonged survival in mice with lupus. The finding could one day offer treatment options for other antibody-associated diseases, too, the researchers said.
"Autoantibody-mediated diseases such as autoimmune hemolytic anemia, immune thrombocytopenia, myasthenia gravis and systemic lupus erythematosus are often difficult to treat," said lead researcher Dr. Reinhard Voll, of the University of Erlangen-Nuremberg.
A big problem is that plasma cells, which are the predominant producers of the disease-causing autoantibodies, can't be efficiently attacked with current treatments, Voll said.
Lupus is a so-called autoimmune disease in which the immune system attacks healthy cells and tissues by mistake, leading to damage to joints, skin, blood vessels and organs. There are many kinds of lupus, with the most common type being systemic lupus erythematosus, which affects many parts of the body. There's no one test to diagnose lupus, and it may take months or years to make the diagnosis. There's also no cure, but medicines and lifestyle changes can help control the disease, according to the U.S. National Institutes of Health
For the new study, Voll's team found that bortezomib efficiently eliminated the plasma cells in the mice, leading to a drastic decrease in autoantibodies and prolonged survival. And, the drug had no effect on other cells, he said.
"Proteasome inhibitors may be beneficial in refractory human diseases caused predominantly by autoantibodies," Voll said. "Proteasome inhibitors can selectively deplete plasma cells, which are resistant to current treatments."
Outside experts were divided on the findings, published in the June 8 online edition ofNature Medicine.
"This is a very exciting study that explores a novel mechanism for treating lupus erythematosus," said Dr. Jennifer Grossman, an assistant professor of medicine at the University of California, Los Angeles.
"The fact that antibodies almost completely disappeared is encouraging. I look forward to hearing more about this treatment in the future," she said.
But, another expert expressed concern that the treatment could adversely affect other cells in the human body.
"I think they're onto something important, it looks as if it has a remarkable therapeutic effect," said Dr. Noel Rose, director of the Autoimmune Disease Research Center at Johns Hopkins University. "The downside is that this is a proteasome inhibitor, and there is no reason to think that it would be specific for plasma cells. It does affect other rapidly proliferating cells."
Rose noted that many drugs may appear safe during an initial trial. "I'm still really suspicious that if this is used clinically, there are going to be side effects like effects on intestinal or other rapidly dividing cells," he said. "The question is, are the side effects going to be severe enough to prevent the use of this drug?"
To learn more about lupus, the U.S. National Library of Medicine.
SOURCES: Reinhard Voll, M.D., University of Erlangen-Nuremberg, Erlangen, Germany; Jennifer Grossman, M.D., assistant professor of medicine, University of California, Los Angeles; Noel Rose, M.D., director, Autoimmune Disease Research Center, Johns Hopkins University, Baltimore; June 8, 2008,Nature Medicine, online