September 1, 2010

Drug Works Better Than Aspirin In Lowering Stroke Risk

Researchers said Tuesday that an experimental drug from Bristol-Myers Squibb and Pfizer reduces the risk of stroke by more than 50 percent compared to aspirin.

The findings boost expectations for apixaban, a new anticoagulant pill that aims to displace the old, problematic heart drug warfarin as a prevention for stroke in patients with atrial fibrillation (AF).

The race to find a drug that can replace warfarin, which was originally developed as a rat poison, could be worth billions of dollars annually, possibly as much as $20 billion, according to industry analysts.

Boehringer Ingelheim, German maker of Pradaxa, is leading the race, awaiting a review by US regulatory advisors on September 20.

But heart specialists meeting in Stockholm said a clear winner had yet to emerge. Stuart Connolly of McMaster University in Canada, who presented the findings on apixaban to the European Society of Cardiology, said the results with apixaban were "truly impressive."

An AVERROES study of 5,600 patients was halted in June after clear evidence showed that apixaban prevented stroke. Medical experts had been anticipating good results from the study.

Connolly said apixaban reduced the rate of strokes by 52 percent compared with aspirin in the patients studied, who were selected because they were unable to use warfarin treatments. The annual rate of strokes in patients on apixaban was 1.5 percent compared to 3.3 percent for those using aspirin.

Patients with AF have a higher risk of blood pooling in an upper chamber of the heart, which can cause clots and stroke.

Forty to fifty percent of AF patients are either intolerant to warfarin or refuse to take the drug, leaving them dependent only on aspirin, which is less-effective for stroke prevention.

The annual rate of major bleeding was close between patients on apixaban and aspirin, 1.4 percent for apixaban and 1.2 percent for aspirin, and there was no significant difference in clinically relevant non-major bleeding.

Bristol-Myers and Pfizer are also conducting a second trial, called ARISTOTLE, comparing apixaban head-to-head with warfarin. Results of the trial are due next year.

Connolly said it looked "highly likely" that the ARISTOTLE trial would also be positive.


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