Bristol-Myers, Pfizer’s Apixaban Tops Warfarin In Anticoagulant Face-Off
Aug29

Bristol-Myers, Pfizer’s Apixaban Tops Warfarin In Anticoagulant Face-Off

Over the weekend Bristol-Myers Squibb and Pfizer announced that their blood-clot-preventing drug candidate, Eliquis (apixaban), bested the workhorse anticoagulant Coumadin (warfarin) in a large clinical trial. The results were announced at the European Society of Cardiology congress and simultaneously published in the New England Journal of Medicine. This is the first time that one of the cadre of anticoagulants seeking to replace warfarin has been shown to be superior to warfarin at preventing dangerous blood clots that can lead to strokes while also having a lower rate of bleeding compared to warfarin. In the 18,201 patient Phase III clinical trial, called ARISTOTLE, apixaban reduced the risk of stroke in patients with an abnormal heart rhythm called atrial fibrillation by 21 percent, major bleeding by 31 percent, and mortality by 11 percent. More statistics are available in the announcement, the journal article, and in this Forbes report, which plucks out these illustrative numbers: The investigators calculated that for every 1000 patients treated with apixaban instead of warfarin for 1.8 years •stroke would be avoided in 6 patients, •major bleeding would be avoided in 15 patients, and •death would be avoided in 8 patients. Analysts reacted positively to the data, with Leerink Swann analyst Seamus Fernandez raising his 2017 sales estimate for apixaban by $1.1 billion to $4.1 billion in a note to investors. We've previously explained how apixaban works-- briefly, it blocks Factor Xa, a protease enzyme near the end of the complex biochemical pathway that regulates blood clotting. Another Factor Xa inhibitor, rivaroxaban, has been approved in Europe but awaits FDA approval. Pradaxa (dabigatran), which blocks the enzyme thrombin, has been approved by FDA for reducing the risk of stroke associated with atrial fibrillation. So what's the secret of apixaban's success? In 2010, we spoke with Ruth R. Wexler, executive director of cardiovascular diseases chemistry at Bristol-Myers Squibb, who explained how apixaban was designed with pharmacokinetic properties (the properties that reflect how the body affects a drug's fate after administration) in order to reduce the risk of off-target effects. The extent to which an anticoagulant gets distributed through the body also matters, says Ruth R. Wexler, executive director of cardiovascular diseases chemistry at Bristol-Myers Squibb. “Coagulation factors are in the blood,” she says. So there’s no need for a drug candidate that blocks a coagulation factor, such as Factor Xa, to be distributed beyond the bloodstream and reach other tissues and organs. “Getting into other tissues and organs is frequently the reason why there are off-target safety issues,” she says. This was one of many concerns BMS had in mind as it developed its most advanced Factor Xa inhibitor,...

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Blood Thinner Blog Posts Worth Reading
Nov19

Blood Thinner Blog Posts Worth Reading

What you're looking at is an overview of the complex biochemical pathway behind blood clotting, and a smattering of the drugs researchers are developing to control clotting for preventing strokes and more. Over at Terra Sigillata, David Kroll has two back-to-back posts about some of these drugs that are worth reading. In the first post, Kroll discusses news out of the American Heart Association's annual meeting: Rivaroxaban (Xarelto), a blood clot preventing drug from Bayer and J&J, has been shown to be about as efficacious as the established medication warfarin (coumadin) and better with regard to spontanous bleeding complications. He also dishes on some of the fascinating historical context behind the drugs. In the second, he brings attention to Pfizer and BMS's announcement that they are halting a trial of apixaban, their investigational blood clot preventing medication. Eight other apixaban trials are ongoing. We covered some apixaban news last June, when a different apixaban clinical trial was stopped early because an independent analysis concluded that the drug candidate was more effective than aspirin at reducing strokes and blood clots in patients with a common abnormal heart rhythm. As we've written in C&EN, many factors will determine whether patients at risk of strokes or other dangerous blood clots will end up taking warfarin or will take one of the new drugs. Boehringer-Ingelheim's Pradaxa (dabigatran), which acts at a different target from apixaban and rivaroxaban, is already approved by FDA. Rivaroxaban and Pradaxa are already approved in a number of other countries for short-term use. Each drug is slightly different, from how many times a day it must be taken, to how much of it is cleared via the kidneys (a potential issue for patients on dialysis or other kidney conditions), and much more. And of course, a big question is what the difference in cost is going to be- warfarin pills are cheap but the quality of life costs- incessant testing and diet monitoring- can be steep. Image:...

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Blood Thinner Marketing, Soap Opera-Style
Sep22

Blood Thinner Marketing, Soap Opera-Style

Let's say your blood thinner got a unanimous thumbs-up from an FDA panel. And now, in anticipation of the drug's possible approval, you'd like to raise awareness about atrial fibrillation, one of the conditions your drug candidate will treat. Why not send out some well-respected cardiologists or researchers to spread the word to the people? Not sexy enough, you say? OK, then, how about a soap opera star? Yes, this internal monologue may sound implausible, but it pretty much describes the latest news on the blood thinner Pradaxa's front. Boehringer-Ingelheim, the maker of Pradaxa, has announced it is sponsoring a press conference in Rockefeller Center this Thursday, and the featured speaker is none other than longtime "All My Children" star Susan Lucci. Her husband, Helmut Huber (love that name!) has atrial fibrillation, an abnormal heart rhythm that increases the risk of stroke, so the two of them will be on hand to tell their story while the company trots out a study about atrial fibrillation and stroke. Here's how atrial fibrillation can lead to stroke. The heart muscles in the atria normally coordinate their contraction to pump blood efficiently. But if you have atrial fibrillation, those muscles flutter around in an uncoordinated fashion instead. That leads to less efficient pumping, and what can happen is that blood will pool around in the atria. If that blood clots, and the clots end up traveling to the brain, then bam- you get a stroke. So using a blood thinner, which prevents clots, might reduce that stroke risk. I wish I could be on hand to see this event for myself. But I guess I'll have to do with seeing Lucci on YouTube instead. Below is a video of Lucci finally winning a Lead Actress Emmy Award. She was snubbed at the Emmys 18 times before finally winning in 1999. I suppose we'll see whether Lucci's track record at marketing blood thinners turns out to be better than her track record at awards ceremonies. And thanks to Cardiobrief for pointing me to this event. I agree with Cardiobrief's assessment- if Pradaxa is approved it's a guarantee that it will be more expensive than warfarin (coumadin), the drug that it would be replacing. So Boehringer needs to convince folks Pradaxa is worth plunking down the extra...

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Boehringer’s Blood Thinner Dabigatran (Pradaxa) Unanimously Endorsed
Sep22

Boehringer’s Blood Thinner Dabigatran (Pradaxa) Unanimously Endorsed

After last week's Meridia and Lorqess drama, I could've really used some good news from an FDA panel. And on Monday, I got it- in the form of a unanimous endorsement for a new blood thinner. The drug getting the love is dabigatran etexilate, which was developed by family-owned Boehringer Ingelheim and will be marketed as Pradaxa if approved. It's one of a cadre of drugs trying to replace warfarin (also known as coumadin), a medication that has been on the market for over 50 years and is among the most difficult to manage. Warfarin prevents formation of blood clots and can reduce ongoing clots. Doctors prescribe it to prevent painful leg clots in patients getting hip or knee replacements, to prevent stroke in patients with an abnormal heart rhythm called atrial fibrillation, and more. We recently wrote about how warfarin is a dirt cheap and effective medication, but it interacts with a plethora of foods, herbal supplements, and other drugs. Pradaxa is already approved in several countries outside the U.S. for short-term use, preventing leg clots in patients getting hip or knee replacements. The drug blocks thrombin, a protease enzyme that sits near the end of the complex biochemical pathway known as the coagulation cascade. Just about all of the drugs being developed to replace warfarin, at least the ones toward the end of the pipeline, target either thrombin or Factor Xa, the protein immediately before thrombin in the pathway. FDA's cardiovascular and renal drugs advisory committee voted 9-0 in favor of approving Pradaxa for preventing stroke in patients with atrial fibrillation. (Boehringer-Ingelheim press release) This will be a longer-term stint on Pradaxa than post-hip or knee surgery patients typically experience. So the most important part of the panel's discussion, to me, was their assessment of the drug's effects on the liver. That's because in 2006, another thrombin blocker called ximelagatran, developed by AstraZeneca, was pulled from the market because of liver toxicity. When you dig into the briefing documents that FDA provided to the panel, you find this blurb on page 103: Based on these data, the risk of severe drug induced liver injury from dabigatran appears to be low. Because the perceived risk is low and frequent liver monitoring may not prevent serious cases from occurring (even if an association did exist), regular monitoring of liver tests is not recommended. So it seems that ximelagatran's liver issues may not be a class-wide problem. Still to be determined is what doses of the drug might be approved- read this post by Pharmalot for an assessment of why doses matter. FDA is expected to make its call on...

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