BETHESDA, Md. _ The FDA's Cardiovascular and Renal DrugsAdvisory Committee on Friday restricted indications for CentocorInc.'s Myoscint, a monoclonal antibody radioassay, for use only inpatients with suspected myocardial infarction.
The Malvern, Pa.-based company had sought a broader indication touse the assay to detect myocardial necrosis in patients with hearttransplants and other conditions.
The committee voted 8-to-4, with two panel members voting byproxy, to recommend approval for the detection of myocardialinfarction but were split on whether the assay was useful in detectingthe location or characterizing the extent of the infarct.
Committee member Daniel Mark, professor of medicine at DukeUniversity, Durham, N.C., declared that the test had only"incremental value" that does not exceed the value of currentdiagnostics such as Thallium testing.
Several members of the panel were skeptical that Myoscint offeredany real benefit over existing diagnostic tools. Committeedeliberations broke down into often contentious disagreements aboutthe utility of Myoscint compared to the gold standard ofelectrocardiogram (EKG) and Thallium testing, a radio-pharmaceutical that has been used for many years to detectmyocardial infarcts.
The panel's discord led Jay Siegel, director, office of therapeuticsresearch and review in the FDA's Center for Biologics Evaluationand Research, to say that clinical utility of a new technologycompared to existing ones had been debated frequently in recentFDA advisory committee meetings. He promised a guidancedocument would be issued in the next few months to provide thecommittees with more structure on how to address this issue.
Centocor had sought to persuade the committee that its assay not onlyprovided more diagnostic information than existing tools but that theheart's uptake of the radio assay was a predictor of subsequentcardiac events. A Centocor-sponsored clinical trial involving 1,318patients showed that Myoscint had high sensitivity and specificityand correlated highly with current diagnostics tests for myocardialinfarcts. Centocor also pointed out that the test would replacebiopsies which involved more risks and complications than theradioassay.
But most of the panel members considered the test too limited andsaid it would be used only in restricted situations. "Myoscint wouldnot but used in the routine evaluation of myocardial infarction," saidBarry Massie, director of the coronary care unit at the Veteran'sAdministration Hospital, in San Francisco.
The company also was faulted for not having adequate data todemonstrate that the test identified necrosis of heart tissues.
FDA's Siegel had sought a definitive stand from the advisorycommittee on whether the radioassay could detect necrosis but mostpanel members agreed that they were not sure if the test identifiednecrosis or injury.
Centocor's stock (NASDAQ:CNTO) gained $1.88 Friday to close at$32.38 in trading of 3 million shares. n
-- Michele L. Robinson Washington Editor
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