Will gene-testing be a blood-thinner battleground?

Don't write off the latest blood-thinners just yet. Sure, the "gold standard" clotbuster Plavix may be going generic, making it much cheaper than recently approved--and upcoming--rivals. But new research could give the newer drugs a performance edge. At least Eli Lilly and AstraZeneca hopes it does.

Plavix works best for patients without particular genetic variations, to the point where FDA has advised doctors to either boost dosage or consider another drug in patients who don't respond to it. Genetic testing isn't mandated, but doctors have been debating whether to make it standard procedure for Plavix patients.

But new studies affirm that Lilly's new clot-fighter, Effient, and AZ's experimental alternative Brilinta, don't require genetic testing because they work despite genetic variations. So, as Reuters points out, there's a potential marketing opportunity for both these drugs over Plavix. Brilinta in particular, because the new study suggested that it may work even better than the old standby.

Meanwhile, however, Sanofi-Aventis and Bristol-Myers Squibb are fighting back with their own genetic research on Plavix. And newly released data showed that in one study, genetics didn't affect whether patients benefited from Plavix. Experts theorize that it's the sicker patients--the ones who need stents, for instance--whose genetic variations matter most. "We're left with a lot of uncertainty," one cardiologist told the Wall Street Journal. Indeed.

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