CardioSource World News

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1 20 January 2012

2 OVERWHELMED WITH OPTIONS: The (Mostly) Good News on Novel Oral Anticoagulants in AF I ndustry experts are excited, ready to embrace new oral anticoagulant options. Are you? In recent years, several novel oral anticoagulants have burst onto the treatment scene as alternatives to warfarin for stroke prevention in patients with atrial fibrillation. Two of these novel agents are approved in the United States, dabigatran and rivaroxaban, and one is still under FDA review, apixaban. Do you want the good news first, or the bad news? The good news is that physicians now have two soon possibly three novel oral anticoagulants that are as effective or more than industry standard warfarin at preventing embolic stroke and other thromboemboli in patients with atrial fibrillation (AF). The bad news is that physicians now have two soon possibly three novel oral anticoagulants that are as effective or more than industry standard warfarin at preventing embolic stroke and other thromboemboli in patients with atrial fibrillation. We now have potentially three different alternatives to warfarin for patients with AF, Deepak L. Bhatt, MD, FACC, Chief of Cardiology, VA Boston Healthcare System, and Director, Integrated Interventional Cardiovascular Program, Brigham and Women s Hospital & VA Boston Healthcare System, told CardioSource World News. It is slightly different how each one is better than warfarin: some are more efficacious, some are safer, some have both characteristics, but all three have advantages over warfarin. But the choice between warfarin, a drug in use for more than 50 years, and these new agents is not crystal Deepak L. Bhatt, clear, according to Dr. Bhatt. New MD, FACC drugs mean a lot more alternatives and more choices for the physician and the patient, Dr. Bhatt added, and several of his colleagues involved in the study of these new drugs agreed. Early adopters have taken up these drugs and the slow adopters are more hesitant, said Stuart J. Connolly, MD, Director, Division of Cardiology at McMaster University, Hamilton, Ontario, Canada, where some of these novel anticoagulants have been approved for a longer period of time (Dr. Connolly is first author of the AVERROES trial for apixaban). Like any new thing, some people will jump right in and others want to wait and see. Like everything in medicine you have to be careful when using new drugs. As the industry begins to learn about and use these new oral anticoagulants in day-to-day clinical practice, physicians continue to adjust to replacing a drug they have known for decades, grapple with issues of cost of PART OF THE CARDIOSOURCE.ORG NETWORK 21

3 the new drugs versus cheaper warfarin, and find the right risk-benefit balance for each of their patients. Option No. 1: Dabigatran Industry standard vitamin K antagonist warfarin is highly effective at preventing stroke and is cheap; however, for years physicians and patients have been asking for better alternatives to the drug. Warfarin has a narrow therapeutic range and a wide variety of food and drug interactions that necessitates frequent monitoring. In Europe, this wish was granted in early 2008 when the European Medicines Agency approved dabigatran (Pradaxa, Boehringer Ingelheim), a direct thrombin inhibitor, for the prevention of stroke in nonvalvular AF. Approval in Canada and the United States took about two more years, with dabigatran gaining regulatory approval in both countries in October Dabigatran was approved based on Phase III data from the RE-LY (The Randomized Evaluation of Long-Term Anticoagulation Therapy) trial. The trial randomly assigned 18,113 patients with nonvalvular AF at increased risk for stroke to dabigatran 110 mg, dabigatran 150 mg or openlabel warfarin. At two years of follow-up, data indicated that dabigatran 150 mg was superior to warfarin for stroke/systemic embolism prevention (RR=0.66; 95% CI, ) and dabigatran 110 mg was noninferior (RR=0.91; 95% CI, ). Both the 150 mg and 110 mg dosage of dabigatran reduced hemorrhagic stroke, but only 110 mg of dabigatran reduced the rate of major hemorrhage. The FDA approved dabigatran at 150 mg and 75 mg, a dose that was not studied in the RE-LY trial. The results show that there are clear advantages to the lower dose, which was that it was safer than the higher dose but not as effective against ischemic stroke, said Dr. Connolly, who was the lead author Stuart J. Connolly, MD on the RE-LY trial. The [FDA s] decision did not make a lot of sense to me. The lower dose is clearly as good as warfarin. Some physicians have voiced concerns about the use of the untested 75 mg dose in older adults with renal impairment. A July 2011 article describing two cases in France noted that renal impairment and low body weight could present a risk of over-dosage of dabigatran. An additional concern is that there is no tested antagonist available, although this is also the case for other anticoagulants. There have been calls for the FDA to reconsider approving the 110 mg dose; RE-LY investigators have been reported as supporting that dose for those older than 75. The investigators are undertaking an analysis of the RE-LY data by age group that may shed new light on the efficacy of the 110 mg dose in the elderly population. Keith A. A. Fox, MB, ChB, FACC Option No. 2: Rivaroxaban The final Phase III results for option No. 2, rivaroxaban (Xarelto, Bayer), a direct Factor Xa inhibitor, were published in the New England Journal of Medicine in August. The Phase III trial, ROCKET AF (Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation), randomly assigned 14,264 patients with nonvalvular AF at moderate-to-high risk for stroke to rivaroxaban 20 mg once daily or warfarin. This analysis was conservative, according to Keith A. A. Fox, MB, ChB, FACC, Professor of Cardiology at the University of Edinburgh and the Royal Infirmary of Edinburgh and co-chair of the ROCKET AF trial, because it included not only the time that patients were on the drug, but also a follow-up period where patients were off-drug, transitioning to warfarin, a period that was not included in the RE-LY trial. For this reason, results can be looked at as intention-to-treat or as on-treatment. At follow-up, the per-protocol, as-treated analysis found that rivaroxaban was noninferior to warfarin for composite stroke and systemic embolism (HR = 0.79; 95% CI, ). However, if you looked at data for the on-treatment analysis, rivaroxaban was found to be superior to warfarin (p = 0.015) for the primary endpoint. Although rates of major and nonmajor clinically relevant bleeding were similar for the two drugs, rivaroxaban significantly reduced intracranial hemorrhage (0.5% vs. 0.7%; p = 0.02) and fatal bleeding (0.2% vs. 0.5%; p = 0.003). Despite some concerns about safety, rivaroxaban was approved for the AF indication in Europe in September and by the FDA in November. The label was given a black box warning against discontinuation of the drug without consultation with a health care professional due concern about an excess of strokes. Option No. 3: Apixaban? The third possible option, apixaban (Eliquis, Pfizer/Bristol Myers Squibb), another Factor Xa inhibitor, gained priority review of its New Drug Application by the FDA in late November, with a final decision expected by March The FDA is reviewing results of the ARISTO- TLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) trial, which evaluated 18,201 patients with AF and at least one additional risk factor for stroke. Patients were randomly assigned to apixaban 5 mg twice ATLAS 2 Maps Path toward Possible ACS Indication for Rivaroxaban A2.5 mg dose of rivaroxaban in addition to antiplatelet therapy with aspirin and clopidogrel may present an effective strategy to reduce cardiovascular events in patients with recent acute coronary syndrome, despite an increased risk for major bleeding, according to the results of the ATLAS ACS 2-TIMI 51 trial presented late last year at the American Heart Association 2011 Scientific Sessions in Orlando. Adding an anticoagulant therapy to antiplatelet therapy in patients with ACS has been explored for decades with limited success. This trial randomly assigned patients to placebo (n=5,176), rivaroxaban 2.5 mg twice daily (n=5,174), or rivaroxaban 5.0 mg twice daily (n=5,176). All patients were taking aspirin and about 93% were also taking clopidogrel. Data from the ATLAS trial indicated that there was a reduced the risk for cardiovascular death, MI or stroke compared to placebo, the primary study endpoint, with rivaroxaban 2.5 mg (9.1% vs. 10.7%; p= 0.02) and 5 mg (8.8% vs. 10.7%; p= 0.002). In addition, the lower dose improved both all-cause death and cardiovascular death. However, rivaroxaban also resulted in an increased rate for major bleeding and intracranial hemorrhage, a result that the researchers said was expected given that the comparator was placebo. Neither dose significantly increased the rate of fatal bleeding, and the lower dose of rivaroxaban resulted in fewer fatal bleeding events than the 5 mg dose. This is a fascinating results and it shows why we need to do clinical trials, Dr. Granger. It shows how one can come up with very different results based on the dose of the drug that one studies and the population that one studies. Rivaroxaban s approval for AF was at a dose of 20 mg, a dose that was two- to fourfold higher than that tested in patients with ACS. Very low-dose rivaroxaban, when added to aspirin and clopidogrel in secondary prevention 22 January 2012

4 daily or dose-adjusted warfarin. Results indicated that apixaban was superior to warfarin in the prevention of ischemic or hemorrhagic stroke or systemic embolism (p = 0.01), the rate of major bleeding (p < 0.001), death from any cause (p = 0.047), and hemorrhagic stroke (p < 0.001). We had four primary questions and we were successful in all four, said Christopher B. Granger, MD, FACC, Director, Cardiac Care Unit at Duke University Christopher B. Granger, MD, FACC Health System and co-principal investigator of the ARISTOTLE trial. It is easy to remember these results. There was an 11% reduction in mortality, a 21% reduction in stroke and a 31% reduction in major bleeding. Apixaban was better tolerated and there were fewer discontinuations than with warfarin. Other options on the horizon Additional Factor Xa inhibitors are under various stages of investigation as well. Edoxaban (NCT ; formerly DU-176b) is being studied in the Phase III ENGAGE-AF TIMI 48 trial, a double-blind, double-dummy trial that is comparing high-dose edoxaban to warfarin for AF and low-dose edoxaban to warfarin for embolism. The primary endpoint is composite of stroke and systemic embolism at 24 months. With enrollment of approximately 20,000 patients, ENGAGE-AF TIMI 48 is expected to be completed in March In Japan, edoxaban combined with LMWH is going up against warfarin/lmwh for the treatment of VTE in the Phase III Hokusai trial, and edoxaban has been filed for approval in Japan to prevent VTE. An agent with minimal renal excretion that is not expected to need adjustment in patients with New drugs mean a lot more alternatives and more choices for the physician and the patient. renal impairment, betrixaban was found to be safe and well tolerated at three different doses versus warfarin in the Phase II EXPLORE-Xa trial, reported in Funding was recently secured for a Phase III trial, which will likely look at the agent s potential in preventing pulmonary embolism both in-hospital and post-discharge in acute patients. Fate of warfarin Despite the buzz that exists around these new anticoagulants, warfarin is not going anywhere anytime soon. For starters, there are certain patients who are on warfarin for reasons outside of AF where these novel agents have not been tested. For example, patients who have a hypercoagulable state and patients with mechanical heart valves must still be treated with warfarin. However, Dr. Connolly did suggest that given time, clinicians may learn how to apply the novel drugs in these types of patients and the uses for warfarin may become fewer and fewer. Even for those patients with AF, I do not think that the three new drugs will completely overtake warfarin or make it irrelevant, Dr. Bhatt said. First, whenever there is an advance in medicine, change does not occur overnight. Physicians need time to adjust, to become familiar with new data, learn about side effects and become comfortable prescribing any new agent. Dr. Bhatt said that when discussing the use of dabigatran he has heard hesitation among physicians because they are unable to monitor if patients are compliant. The good thing about warfarin was that you could check an INR and ensure compliance, even if it was taxing, Dr. Bhatt noted. That is much trickier with these new agents. Drs. Fox and Granger agreed with this sentiment, calling patient compliance an enormous concern. But they added that compliance is a concern with any drug, and should be nothing new, challenge-wise, for cardiologists. Second, all three of the new oral anticoagulants are at least partially eliminated from the body through renal clearance. Although studies have indicated that rivaroxaban, dabigatran and apixaban do not cause a higher rate of bleeding in patients with chronic kidney disease, the drugs have not yet been tested in patients with an estimated glomerular filtration rate less than 30 ml/min. For these patients with extreme renal insufficiency, warfarin will likely remain the easier drug. Finally, warfarin will continue to be used, but of ACS patients, reduced mortality. However, the dose and dosing interval of rivaroxaban in ATLAS 2 were different than what were used in ROCKET AF, said Dr. Bhatt. Therefore, it still remains a major unresolved question what the optimal antithrombotic approach may be for patients with ACS and atrial fibrillation. The study results were published simultaneously in the New England Journal of Medicine. In an accompanying editorial, two independent authors wrote that ATLAS TIMI 51 heralds a new era in secondary prevention after an acute coronary syndrome. The results of ATLAS 2 were also enough for Xarelto manufacturer Janssen Research and Development, LLC, to file a late- December supplemental New Drug Application with the FDA for the prevention of thrombotic cardiovascular events in ACS patients, according to a press release. Final FDA approval for the indication is pending. At the AHA meeting, discussant Paul W. Armstrong, MD, pointed out an interesting and so far unexplainable difference in results seen for the two rivaroxaban doses studied. The very low-dose regimen yielded substantial benefit in cardiovascular and all-cause mortality. However, the 5 mg dose had no significant mortality benefit but it did significantly reduce the rate of MI. Overall, Dr. Armstrong said, the ATLAS trial results point to a new standard of antithrombotic therapy in ACS, built on the background of conventional antiplatelet therapy. Is it time to subtract aspirin from post-acs therapy as new agents, such as rivaroxaban, are introduced? Those studies still need to be done. Likewise, research is needed to determine whether similar results will be seen in higher risk patients. One other question remains: Will it be possible to better define the seam between safety and efficacy for oral anti Xa agents as a class? Gibson CM. LBCT 01. Presented at: 2011 AHA Scientific Sessions; Orlando. Mega JL, Braunwald E, Wiviott SD, et al. N Engl J Med. 2011;doi: NEJMa Roe MT, Ohman EM. N Engl J Med. 2011;doi: /NEJM PART OF THE CARDIOSOURCE.ORG NETWORK 23

5 it may end up playing a much more niche role, or limited role over time. However, the single biggest barrier to warfarin s demise in the United States will be the cost, said Dr. Granger. Elephant in the room Although these novel drugs have been found to be equivalent, if not superior to warfarin, it remains to be seen if the difference in stroke prevention warrants the increased price tag compared with the relatively inexpensive warfarin. These drugs are estimated to cost about $7 a day or more depending on the insurance plan or copay of the patient, Dr. Bhatt said. That could be very prohibitive to many patients. In fact, a study published in January 2011 in Annals of Internal Medicine analyzed data from RE- LY to estimate the quality-adjusted survival, costs and cost effectiveness of dabigatran compared with warfarin. The researchers based the drug price off of pricing from the United Kingdom, where it had been approved for a longer period of time. The study indicated that only in patients aged 65 years or older with nonvalvular AF at increased risk for stroke meaning a CHADS2 score of one or more was dabigatran a cost-effective alternative. Cost is clearly a challenge because warfarin is cheap, Fox said. But NICE, in the United Kingdom, recently determined that dabigatran is cost effective. In late 2011, the National Institute for Health and Clinical Excellence (NICE) in the United Kingdom issued a Final Appraisal Determination declaring that dabigatran is a cost-effective use of National Health Service resources when used within its licensed indication. An article published in BMJ, supported this determination, declaring that dabigatran had a positive benefit-to-harm ratio compared with warfarin, but came to a similar conclusion as the U.S. study: that high-dose dabigatran was only cost-effective for patients at increased risk for stroke. According to Fox, cost effectiveness is a difficult thing to measure. The cost of monitoring and analyses are not always taken into account in looking at warfarin, he said. In addition, the cost of stroke and the long-term effect of stroke complications are difficult to assess because they are not usually part of health budgets. A true analysis of warfarin has to take into account frequent return visits to physicians, and, if the new drugs do prevent more strokes, has to include the added cost of stroke and its complications. Ultimately, it may be too soon to draw conclusions on the cost effectiveness of these newer drugs. Advantages of novel agents Although experts acknowledged that cost will be a barrier to uptake, they were all clearly excited about some of the advantages of these new agents. The biggest benefit is really for patients who are not able to take warfarin, Connolly said. We know that less than half of people who can benefit from warfarin in Canada and the United States are actually receiving it on a chronic basis and even fewer of them are receiving it with good management. These new drugs are easier to take and safer to use. The biggest and most obvious advantage to these three drugs is the convenience. None of them require routine monitoring and each is at least as good as warfarin in preventing stroke. These drugs are estimated to cost about $ 7 a day or more depending on the insurance plan or co-pay of the patient On top of that, each agent has some additional advantages, Dr. Granger added. Dabigatran, at the higher dose, is more effective than warfarin at preventing ischemic stroke. Rivaroxaban is only once daily a huge advantage for ease of use and adherence and apixaban is more effective at preventing stroke and provides a 31% risk reduction for major bleeding. However, the advantages of these drugs versus warfarin are infinitely clearer than their advantages compared with each other. These drugs are all different and have not yet been compared directly to each other, so any comparison we make is fairly indirect and not based on very good evidence, Dr. Connolly said. Although physicians can glean advantages of one novel anticoagulant compared to another from the Phase III clinical trial data, there is little else to go on at this time. Any true head-to-head comparison trial would be large and long and extremely expensive, with a high-risk/high-reward scenario for the three drug manufacturers, leaving little incentive to conduct such a study. It would be nice to have a head-to-head comparison comparing dabigatran to a Factor Xa inhibitor to see which is the best approach, biologically and clinically, Dr. Bhatt said. In the absence of that there may be a registry comparison down the road, which, for the purposes of drug evaluation, is often not the best way to evaluate the performance of a drug. Bhatt said he has little doubt that such a comparison will eventually be done and published, and it may lend some insight into how the drugs are faring in real-world practice, but that any results should be viewed with trepidation in the absence of a true randomized clinical trial. Don t worry, be happy Overall, all of the experts CardioSource World News spoke to declared that with the progress made with these novel anticoagulants and their current or pending approvals, it is an exciting time in medicine and the treatment of AF, despite any minor reservations that may exist. It is true that in hospitals with good INR control by doctors and good adherence by patients that warfarin is pretty good for stroke prevention, but I think we need to be honest and say that this combination of great health care systems, great doctors and great patients, for the purpose of warfarin control, does not always exist, Dr. Bhatt said. Warfarin is a tough drug and resources are finite. We have to admit that with two approved alternatives to warfarin, and potentially three approved down the road, that we can now do better than warfarin. From now on, physicians must seriously consider each patient with AF in need of an anticoagulant and decide if that patient would be better off on a novel anticoagulant, for any multitude of reasons. One of our most important goals is to assure that all eligible patients are being treated with some oral anticoagulation, and these drugs should help that goal, Dr. Granger said. Only about 45% of patients who have AF and should be on anticoagulation actually are, and that is partly because warfarin is such a nuisance and has limitations. These new agents provide an important opportunity to close this gap. by L. Lawrence References Connolly SJ, Eikelboom J, Joyner C, et al. N Engl J Med. 2011;364: Connolly SJ, Ezekowitz MD, Yusuf S, et al. N Engl J Med. 2009; 361: Eikelboom J, Wallentin L, Connolly S, et al. Circulation. 2011;123: Freeman JV, Zhu RP, Owens Dk et al. Ann Intern Med. 2011;154:1-11. Epub 2010 Nov 1. Fox KAA, Piccini JP, Wojdyla D, et al. Eur Heart J. doi: /eurheartj/ehr342. Granger CB, Alexander JH, McMurray JJ, et al. N Engl J Med. 2011; 365: Legrand M, Mateo J, Aribaud A, et al. Arch Intern Med. 2011;171: National Institute for Health and Clinical Excellence. Final appraisal determination: Dabigatran etexilate for the prevention of stroke and systemic embolism in atrial fibrillation. pdf Accessed December 3, National Institute for Health and Clinical Excellence. NICE asks for more information on new treatment for people with common heart condition. pressreleases/dabigatranforafconsultation.jsp Accessed December 3, Patel MR, Mahaffey KW, Garg J, et al. N Engl J Med. 2011; 365: Pink J, Lane S, Pirmohamed M, Hughes DA. BMJ. 2011;doi /bmj.d6333. Dr. Bhatt reports having a working relationship (i.e. consulting, research, and/or educational services) with Bristol Myers Squibb, Amarin, The Medicines Company, Astra Zeneca, Ethicon, Eisai, Medtronic, and Sanofi Aventis. Dr. Connolly reports having a working relationship (i.e. consulting, research, and/or educational services) with Boehringer Ingelheim, Sanofi-Aventis, Portola, and Merck. He also reports grant support on behalf of his institution, McMaster University, from Boehringer Ingelheim, Sanofi-Aventis, Portola, and Bristol-Myers Squibb. Dr. Fox reports no relevant financial disclosures. Dr. Granger reports having a working relationship (i.e. consulting, research, and/or educational services) with Astellas Pharma Inc., AstraZeneca, Boehringer Ingelheim, Bristol-Myers Squibb, GlaxoSmithKline, Hoffman LaRoche (Roche Holding), Medtronic Inc., Merck Sharpe & Dohme (Merck & Co, USA), Otsuka, Pfizer Inc., and Sanofi-Aventis. 24 January 2012