Corvas International Inc. had expected the improved outcomes offered by its rNAPc2 would persuade physicians to use the agent instead of heparin in patients at risk for deep vein thrombosis (DVT) and pulmonary embolism (PE) despite the inconvenience of weight-adjusted dosing. But a change in the competitive landscape made CVAS rethink its dosing scheme, and the FDA balked at its plans.

rNAPc2 is a recombinant anticoagulant protein inhibitor of the Factor IX/Tissue Factor complex. CVAS changed the focus of its rNAPc2 development program to patients with acute coronary syndrome following discussions with the FDA regarding the company's intended Phase III protocol in DVT.