The Race to Replace Warfarin

The company’s experimental anticoagulant drug apixaban worked better than aspirin in preventing stroke and systemic blood clots for patients who have a heart rhythm disorder called atrial fibrillation, according to new study data presented on Tuesday morning at a cardiology conference in Stockholm.

Investment bank analysts have estimated that a new category of stroke prevention drugs like apixaban, if approved by the Food and Drug Administration, could generate $10 billion or more in annual global sales. (See related article.)

Patients taking apixaban had a rate of stroke or systemic blood clots of 1.7 percent per year while those on aspirin had a rate of 3.9 per year, according to an interim analysis of the new data. The rate of major hemorrhage was 1.6 percent per year for the apixaban group and 1.4 percent on aspirin, researchers reported.

Atrial fibrillation affects about 2.2 million people in the United States, and that number is expected to double in the next 10 years, according to the National Heart, Lung and Blood Institute.

Bristol-Myers discovered apixaban and is developing the drug jointly with Pfizer. The study involved 5,600 patients who were unsuited for the standard treatment for atrial fibrillation, warfarin.

In a note to investors on Tuesday morning, Chris Schott, an analyst at J.P. Morgan, wrote that positive responses to the study data among leading cardiologists “suggest that apixaban will likely capture a disproportionate share,” by some estimates up to 50 percent, of warfarin-intolerant patients.

The companies are also conducting a head-to-head trial of apixaban and warfarin in more than 18,000 patients with atrial fibrillation. The companies expect to report data from that study next year, a spokeswoman for Bristol-Myers Squibb said.

Indeed, apixaban is one of several drugs that pharmaceutical companies are developing in an effort to replace warfarin, a decades-old drug for atrial fibrillation that is effective but comes with drawbacks. Prescription drugs like antibiotics, as well as foods rich in vitamin K, can affect the effectiveness of warfarin. Also, patients on warfarin need regular tests to evaluate their blood clotting rate.

Other warfarin alternatives in the pharmaceutical pipeline include rivaroxaban, originally discovered by Bayer Healthcare and now under development jointly with Johnson & Johnson and dabigatran from Boeheringer Ingelheim.

According to a new study presented Tuesday at the cardiology conference in Stockholm, rivaroxaban worked about as well as standard treatments at preventing recurrent blood clots in the veins for people with deep vein thrombosis. The rate of risky blood clots in the veins or lungs was 2.1 percent for the rivaroxaban group and 3 percent for the standard treatment group, according to a press statement Tuesday from Johnson & Johnson. The rate of bleeding, a side effect, was about 8 percent in each group, the release said.

Johnson & Johnson has submitted an application to the Food and Drug Administration for rivaroxaban as a treatment to reduce the risk of dangerous blood clots in people undergoing knee or hip replacement surgery. Rivaroxaban is already marketed for that purpose in 75 countries outside of the United States, including Canada.

Meanwhile, Boehringer Ingelheim, the German drug maker has developed dabigatran, a drug to prevent stroke and systemic blood clots in patients with atrial fibrillation. The drug is already approved for use in Canada. An F.D.A. panel is scheduled to review the drug on September 20th.

The share price of Bristol-Myers was up more than 1 percent, to $26.15 in morning trading.