February 7th, 2012

Bleeding Problems Continue to Bedevil Merck’s Novel Antiplatelet Agent Vorapaxar

In the large TRA-2P study of more than 26,000 patients with  MI, ischemic stroke, or documented peripheral vascular disease, the novel antiplatelet agent vorapaxar significantly reduced the primary endpoint of CV death, MI, stroke, or urgent coronary revascularization. But treatment resulted in a significant increase in bleeding, including intracranial hemorrhage.

The fate of vorapaxar now appears to be uncertain, as the company said it will review data from the drug’s two large clinical trials with the investigators of the trials and external experts to inform the company’s next steps.

The full results of the TRA-2P (Thrombin Receptor Antagonist in Secondary Prevention of atherothrombotic ischemic events) trial are scheduled to be presented in March at the American College of Cardiology meeting. Merck today released the top-line results in a press release.

TRACER, the large ACS trial with vorapaxar, was terminated early last year due to similar safety concerns. As reported here last year, at the same time TRACER was stopped, the TRA-2P trial was modified. TRA-2P investigator Eugene Braunwald said that vorapaxar would be discontinued in patients who experienced a stroke prior to entry or during the trial because of an increase in intracranial hemorrhage in these patients.

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