Other neurologists also indicated that they would most likely use the test when faced with patients who have relapsed -- but not routinely during the first 2 years of treatment. For example, Steven Cavalier, MD, a neurologist in Baton Rouge, Louisiana, said that perhaps he would perform the test when a patient wasn't doing well. Asked what would he do with a positive finding, he said that he might give some consideration to switching to glatiramer acetate.
Although Goodin opposed using the test, he had this to say: "I could imagine a scenario where I might use the drug. If you have a patient on Avonex and the patient is not doing well, you might test for antibodies. If they have high titers, it would make no sense to move them up to Betaseron or Rebif. I'd probably move them to Copaxone." Goodin disagreed strongly with discontinuing therapy in patients with persistently high titers who were doing well. However, he took exception to the Danish guidelines that call for taking all patients off the drug no matter how they are doing. "If you pull a drug for a test, patients are going to go nuts. If I got worse after they pulled the drug, I would sue."
CLINICAL PRACTICE GUIDELINES
At present, many health plans won't cover the test; patients who want it must pay at least $500. How long will it be before the test is adopted or is discarded as another assay of limited value? Both proponents and naysayers say that evidence to back or question its use is now on their side.
Ransohoff would like to see the American Academy of Neurology and the National Multiple Sclerosis Society endorse new clinical practice guidelines that integrate the assay into practice for patients treated with IFN. So far, the National Multiple Sclerosis Society has posted a link on its Web site that discusses the latest findings (www.nationalmssociety.org/Clinup-Antibodies.asp), but it has not given recommendations for or against using the test or guidance about situations in which testing might be helpful.
According to John Richert, MD, vice president of research and clinical programs at the Multiple Sclerosis Society, the issues are complex. "Some variables to consider are how elevated a titer is it, is it reproducible at 3 months, how is the person clinically, and how long has the patient been on the drug," he said. "What the presence or absence of antibodies dictates is not straightforward." That said, Richert acknowledged that the studies in the July issue of Neurology "helped cement the perspective that persistently high titers are associated with adverse effects."
Yet neurologists want guidance now. "The bigger question is, do you start a medicine that is least likely to produce antibodies?" Goodin asked, "or do you weigh reported evidence of improved outcomes with given therapies and use them?"
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