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Bayer's Xarelto faces stepped-up reports of side effects, deaths

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The number of side-effect reports on Bayer's anticoagulant drug Xarelto appears to be increasing, and some doctors are growing wary of using the drug as a standard first-line treatment, the German newspaper Der Speigel reports. The increasing numbers follow broader use of the drug, with Xarelto sales up 240% for the first half of the year--and a new European indication in acute coronary syndrome could keep the growth coming.

Bayer CEO Marijn Dekkers

For the first 8 months of 2013, 968 side-effect reports were filed with Germany's drug regulators, including 72 deaths. During all of last year, the agency received 750 reports of adverse reactions, including 58 deaths, Der Spiegel says. The reports are voluntary, filed by doctors and patients, and don't prove that Xarelto was the cause. A Bayer spokesman told Reuters that Xarelto's benefits still outweigh its risks.

Xarelto is among a new generation of oral anticoagulants designed to replace the effective but difficult-to-administer standard treatment, warfarin. Its predecessor on the market, Boehringer Ingelheim's Pradaxa, has gathered up even more adverse-event numbers, but it is used in far more patients, too. The FDA last year reviewed safety data on Pradaxa and concluded that, despite thousands of adverse-event reports and almost 1,000 deaths, Pradaxa is at least as safe as warfarin, provided it's used properly.

Xarelto also is one of the linchpins of Bayer's growth strategy. CEO Marijn Dekkers has repeatedly predicted the drug would top €2 billion in sales. So far, so good; the drug brought in €322 million last year ($425 million), and it's on track to more than double this year. Sales for the first half of 2013 amounted to €374 million, or almost a half-billion dollars. Safety flags could put a damper on that growth, however, as Boehringer well knows. After growing twofold in 2012, Pradaxa is slowing down a bit, with sales up just 27% for the first half of the year, to €612 million, or about $800 million. Already, the FDA's concerns about bleeding risks have had an effect on Xarelto; the agency stiff-armed Johnson& Johnson's ($JNJ) bid for a new use in ACS.

As with all blood thinners, both Xarelto and Pradaxa come with a risk of serious bleeding. But unlike warfarin, they don't come with a quick-and-easy antidote in case of emergency. Bayer and its Xarelto partner, Johnson & Johnson, are working with Portola Pharmaceuticals to test one possibility, while Boehringer is scouting for an agent to help reverse Pradaxa's effects. Meanwhile, J&J and Bayer are studying Xarelto in a variety of other indications, including heart failure and coronary artery disease.

Meanwhile, Pfizer ($PFE) and Bristol-Myers Squibb's ($BMY) Eliquis, approved late last year, was supposed to snap up market share, partly because trial data suggest its bleeding risks aren't as severe. So far, however, the drug hasn't gained much momentum.

- see the Der Spiegel story (in German)
- get more from Reuters

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