WASHINGTON -- A simple lab test can predict most of the patients at risk for progression of ankylosing spondylitis and should be part of clinical practice, a researcher said here.
WASHINGTON, Nov. 15 -- A simple lab test can predict most of the patients at risk for progression of ankylosing spondylitis and should be part of clinical practice, a Canadian researcher said here.
Serum matrix metalloproteinase-3 (MMP-3) -- a biomarker associated with damage to joint matrix -- is elevated in two-thirds of ankylosing spondylitis patients who go on to the more severe forms of the disease, according to Walter Maksymowych, M.D., of the University of Alberta in Edmonton.
Testing for MMP-3 is cheap and readily available," Dr. Maksymowych told a press conference at the American College of Rheumatology meeting.
"This is a test that should be done in patients with ankylosing spondylitis," he said. "It is essentially our only predictor."
The finding emerged from a continuing study of ankylosing spondylitis patients at four centers on Europe. Researchers analyzed blood samples from 100 patients for a panel of eight biomarkers associated with other forms of inflammatory disease, including rheumatoid arthritis.
Of the eight, only MMP-3 was significantly associated (P=0.004) with two-year radiological progression in ankylosing spondylitis, as measured by the modified Stoke Ankylosing Spondylitis Spinal Score, Dr. Maksymowych said.
He said the finding may make it easier for physicians to decide which patients should get new biologic treatments for the disease, which are both more toxic and more expensive than standard anti-inflammatory medications.
Also, he said, the result may help improve the design of clinical trials.
Physicians now have "highly effective" treatments for the disease, he said, but resource constraints in many countries mean that the medications aren't easily available. Being able to target the drugs to specific patients at high risk may break down such barriers, Dr. Maksymowych said.
That's not a serious concern in the U.S., said Eric Ruderman, M.D., of Northwestern University in Chicago, who was not involved in the study. By and large, he said, U.S. payers are covering biologics for ankylosing spondylitis if physicians make a case for the drugs on the basis of on clinical signs and symptoms.
He said the "missing piece of the puzzle" is evidence that early treatment of patients with high levels of MMP-3, using biologics such as Remicade (infliximab), would prevent future damage. Currently, a patient with minimal clinical symptoms probably would not be offered the drugs because of the expense and toxicity.
On the other hand, "if I knew that I could give a patient something that is going to prevent damage, even in the absence of clinical signs right now, I would encourage that," he said. "And that's where this is going."