Several recent studies of drugs used to treat and prevent strokes appear to favor AstraZeneca's (AZN) Brilinta and Eli-Lilly's (LLY) Effient over Plavix. Plavix, co-marketed by Bristol-Myers Squibb (BMY) and Sanofi-Aventis (SNY), is the second best-selling drug in the world.
Plavix reduces the risk of heart attack and stroke in patients with cardiovascular disease by making platelets less likely to form blood clots. But in 2009, researchers at the University of Maryland showed the drug can be less effective in people who have a genetic variation. Those people who are Plavix-resistant cannot metabolize the drug to convert it to its active form and therefore need a higher dose or a different medication. This gene variation can be discovered through genetic testing.
The Food and Drug Administration then added a black-box warning -- its toughest safety advisory -- to the Plavix label, indicating that doctors can increase the dose or switch to a different treatment for patients who don't respond adequately to the drug. Since then, doctors have been debating whether to make genetic testing standard procedure for Plavix patients.
But now new studies show that Lilly's already marketed anti-clot Effient and AZ's experimental alternative Brilinta, work just as well, despite genetic variations and therefore don't require genetic testing.
Brilinta was compared to Plavix in a head-to-head study involving over 18,000 patients. The study showed Brilinta reduced risk of heart attack and stroke compared to Plavix, without increasing the risk of bleeding. The genetic substudy, which was published Sunday in The Lancet, involved over 10,000 patients. Researchers found that platelet levels were maintained regardless of genetic differences in patients taking Brilinta. And if it worked equally well regardless of genetic variations, patients don't need genetic testing to take Brilinta.
However, Gooznews points out that while the 30-day data may have shown significance, the one-year data didn't, and the differences could be purely due to chance. Brilinta is already under FDA review and last month an advisory panel voted in favor of approval.
Meanwhile, Lilly and Daiichi Sankyo's Effient also wasn't affected by the genetic variations that reduced Plavix's effectiveness, another study published in The Lancet Sunday showed. However, previous studies showed Effient may increase the risk of bleeding.
Sanofi-Aventis and Bristol-Myers Squibb, though, have their own research on Plavix. And new data released in the New England Journal of Medicine showed that genetic variations didn't affect whether patients benefited from Plavix. Still, researchers said the study did not focus on the use of drug-coated stents, which may make a difference.
Plavix, which generated $9.8 billion in global sales last year, is expected to face generic competition in 2012. While the recent studies may give the new drugs an edge over the cheap generic form, AZ, Lilly and others may have to show more benefit to justify the increased cost. Although gene testing has costs of its own, which are not always covered by insurance companies.
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