The potent cancer drug Gleevec, used to combat leukemia and some gastrointestinal cancers, may be useful in treating rheumatoid arthritis, according to a team of researchers at the Stanford University School of Medicine. Their findings will be published in the October issue of the Journal of Clinical Investigation.
Although the study shows that Gleevec worked well in mice, the researchers cautioned against doctors using Gleevec for treating rheumatoid arthritis until clinical trials are completed demonstrating its effectiveness and safety for people with the disease.
Rheumatoid arthritis is a painful, chronic autoimmune disorder, characterized by inflammation of the lining of the joints. It affects more than 2 million Americans; up to half of those with the disease are disabled after 15 years due to disfigured joints. Standard therapy for rheumatoid arthritis now includes agents that suppress the immune system, but many patients do not benefit from such treatments. They do not get adequate reduction in the symptoms and signs of disease; they may also continue to have damage to their joints or develop side effects that make continued use of such therapies impossible. Thus, new approaches are needed.
Bill Robinson, MD, PhD, assistant professor of medicine and the study's senior author, led a team that set out to find drugs that might provide additional benefit to rheumatoid arthritis patients. They screened a range of drugs in mice that have a condition similar to human rheumatoid arthritis.
Ricardo Paniagua, an MD/PhD student and the study's first author, explained that they looked at every drug approved by the U.S. Food and Drug Administration, considering which ones might modulate the immune system and thus be effective in combating an autoimmune condition, regardless of the drug's FDA-approved use. Paniagua chose several drugs to test, including an antihistamine, a platelet modulator and other approved drugs with known effects on cells of the immune system.
"It was the combination of rational selection and serendipity that we found that Gleevec worked better than anything else," said Paniagua, who works in Robinson's laboratory at the Geriatric Research, Education and Clinical Center of the Palo Alto Veterans Affairs Health Care System.
In their study, Gleevec almost completely prevented the development of the rheumatoid arthritis-like disease in the mice. The drug also halted the progression of established disease, significantly reducing the amount of inflammation and bone destruction around the joints. The researchers also tested Gleevec on the cells of human rheumatoid arthritis patients and found that it reduced the processes associated with inflammation and abnormal growth in the joints.
Gleevec is the brand name of imatinib, a drug produced by the pharmaceutical company Novartis AG. It is part of a class of drugs called kinase inhibitors, which act by blocking communication signals between cells. These signals, when they go awry, are often at the root of diseases such as cancer and autoimmune conditions.
Gleevec targets kinase gene mutations seen in chronic myelogenous leukemia or CML (a bone marrow cancer) as well as certain types of stomach cancers. The same kinases turn out to play a critical role in rheumatoid arthritis.
Robinson said that the field of autoimmune disease research has been trying to develop kinase inhibitors for more than a decade. "We were very surprised that Gleevec worked as well as it did," said Robinson. "It just seemed too simple." The results are especially encouraging since the drug is already FDA-approved, and has relatively few side effects. None of the authors in the study has any affiliation with Novartis.
"We have taken a very potent kinase inhibitor and discovered that it works very well for an autoimmune disease," said Robinson. "The significance is twofold. First, it might provide insights into the mechanisms underlying rheumatoid arthritis by figuring out what Gleevec inhibits." Second, he added, it might represent a new therapeutic approach to rheumatoid arthritis and other autoimmune diseases. The kinases the drug inhibits likely play a role in other autoimmune diseases, such as scleroderma, psoriasis and inflammatory bowel disease.
Gleevec's potential in humans is buoyed by two published case studies of rheumatoid arthritis patients with CML; both experienced significant improvements in their arthritis symptoms after taking Gleevec to treat their cancer. In addition, there has been a published case study of Gleevec alleviating psoriasis in a cancer patient. Robinson said he hopes that in the near future, clinical trials will be conducted that look at the drug's effectiveness for a range of autoimmune diseases.
Others who contributed to the study are associate professors of medicine Mark Genovese, MD, and Paul Utz, MD; professor of orthopedic surgery Stuart Goodman, MD; assistant professor of pathology John Higgins, MD; professor of neurology and neurological sciences and of pediatrics Lawrence Steinman, MD; research associate Peggy Ho, PhD; research assistants Orr Sharpe, MS, and Beren Tomooka, MS; MD/PhD student Steven Chan; medical fellow Jason Song, MD; Stanford undergraduate Anna Chang, and visting undergraduate Fiona Thomas.
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