FDA APPROVES DIAGNOSTIC TEST FOR LUPUS

The U.S. Food and Drug Administration has cleared for market a new screening test for lupus developed by researchers at the Fred Hutchinson Cancer Research Center. According to a spokesperson from the Center, the new test should be available to doctors sometime in early 2004.

The test is expected to pick up the 20 percent of SLE cases that previously fell through the cracks because they could not be detected by the most widely used, standard screening test. Because symptoms range from skin rash and mild fatigue to organ failure, diagnosis can be difficult.

While the majority of lupus patients produce antibodies to their own tissue that can be detected with a blood test that’s been available since the early 1960s, about one-fifth of patients – those who do not make such antibodies – often go undiagnosed.

The new test, developed by Mark Roth, Ph.D., a member of Fred Hutchinson’s Basic Sciences Division, promises to bridge that diagnostic gap.“This test will improve the ability for doctors to make correct decisions when diagnosing SLE, and we also have evidence that this test is of value in determining where in the body the disease will present itself,” said Roth, also an affiliate associate professor of biochemistry at the University of Washington School of Medicine.

Two years ago, in the August 2000 issue of Arthritis and Rheumatism, Roth and colleagues at Fred Hutchinson and the University of Washington, in collaboration with New York Medical College rheumatologist Robert G. Lahita, M.D., Ph.D., first reported the discovery that molecules called SR proteins are particularly useful biomarkers for lupus because the majority of patients produce antibodies to them.

This discovery spawned the development of a color-coded test to detect the presence of telltale SR proteins in the serum, the clear-fluid portion of the blood. The test, called the “Anti-SR protein antibody assay,” involves adding sera to tiny wells in a plastic plate that has been coated with human SR proteins. A colored molecular tag detects antibodies in the sera that stick to the SR proteins. Sera from people with lupus turns purple, while sera from non-affected individuals remains clear. This test can identify 50 percent to 70 percent of lupus patients who react positively to SR proteins.

“It is often difficult to predict who will flare from lupus or when. This test makes it easier to make such predictions,” said Lahita, professor of medicine at NYMC and chief of rheumatology at St. Vincent’s Hospital and Medical Center, who has authored several textbooks and publications about immune diseases and lupus and is the editor of Systemic Lupus Erythematosus.

The initial idea behind the test arose from a scientific experiment more than a decade ago, when Roth and colleagues injected mice with extracts of frog nuclei. Antibodies produced by these mice led to the discovery of the SR proteins used in this new screening test.

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Research Results

Over 15 Years of Ground Breaking Findings

of Dr. Ramsey-Goldman

The Lupus Program at Northwestern University Medical School