Minggao Shi

Edoxaban versus Warfarin in Patients with Atrial Fibrillation

BACKGROUND Edoxaban is a direct oral factor Xa inhibitor with proven antithrombotic effects. The long-term efficacy and safety of edoxaban as compared with warfarin in patients with atrial fibrillation is not known. METHODS We conducted a randomized, double-blind, double-dummy trial comparing two once-daily regimens of edoxaban with warfarin in 21,105 patients with moderate-to-high-risk atrial fibrillation (median follow-up, 2.8 years). The primary efficacy end point was stroke or systemic embolism. Each edoxaban regimen was tested for noninferiority to warfarin during the treatment period. The principal safety end point was major bleeding. RESULTS The annualized rate of the primary end point during treatment was 1.50% with warfarin (median time in the therapeutic range, 68.4%), as compared with 1.18% with high-dose edoxaban (hazard ratio, 0.79; 97.5% confidence interval [CI], 0.63 to 0.99; P<0.001 for noninferiority) and 1.61% with low-dose edoxaban (hazard ratio, 1.07; 97.5% CI, 0.87 to 1.31; P=0.005 for noninferiority). In the intention-to-treat analysis, there was a trend favoring high-dose edoxaban versus warfarin (hazard ratio, 0.87; 97.5% CI, 0.73 to 1.04; P=0.08) and an unfavorable trend with low-dose edoxaban versus warfarin (hazard ratio, 1.13; 97.5% CI, 0.96 to 1.34; P=0.10). The annualized rate of major bleeding was 3.43% with warfarin versus 2.75% with high-dose edoxaban (hazard ratio, 0.80; 95% CI, 0.71 to 0.91; P<0.001) and 1.61% with low-dose edoxaban (hazard ratio, 0.47; 95% CI, 0.41 to 0.55; P<0.001). The corresponding annualized rates of death from cardiovascular causes were 3.17% versus 2.74% (hazard ratio, 0.86; 95% CI, 0.77 to 0.97; P=0.01), and 2.71% (hazard ratio, 0.85; 95% CI, 0.76 to 0.96; P=0.008), and the corresponding rates of the key secondary end point (a composite of stroke, systemic embolism, or death from cardiovascular causes) were 4.43% versus 3.85% (hazard ratio, 0.87; 95% CI, 0.78 to 0.96; P=0.005), and 4.23% (hazard ratio, 0.95; 95% CI, 0.86 to 1.05; P=0.32). CONCLUSIONS Both once-daily regimens of edoxaban were noninferior to warfarin with respect to the prevention of stroke or systemic embolism and were associated with significantly lower rates of bleeding and death from cardiovascular causes. (Funded by Daiichi Sankyo Pharma Development; ENGAGE AF-TIMI 48 ClinicalTrials.gov number, NCT00781391.).

Edoxaban versus Warfarin for the Treatment of Symptomatic Venous Thromboembolism

BACKGROUND Whether the oral factor Xa inhibitor edoxaban can be an alternative to warfarin in patients with venous thromboembolism is unclear. METHODS In a randomized, double-blind, noninferiority study, we randomly assigned patients with acute venous thromboembolism, who had initially received heparin, to receive edoxaban at a dose of 60 mg once daily, or 30 mg once daily (e.g., in the case of patients with creatinine clearance of 30 to 50 ml per minute or a body weight below 60 kg), or to receive warfarin. Patients received the study drug for 3 to 12 months. The primary efficacy outcome was recurrent symptomatic venous thromboembolism. The principal safety outcome was major or clinically relevant nonmajor bleeding. RESULTS A total of 4921 patients presented with deep-vein thrombosis, and 3319 with a pulmonary embolism. Among patients receiving warfarin, the time in the therapeutic range was 63.5%. Edoxaban was noninferior to warfarin with respect to the primary efficacy outcome, which occurred in 130 patients in the edoxaban group (3.2%) and 146 patients in the warfarin group (3.5%) (hazard ratio, 0.89; 95% confidence interval [CI], 0.70 to 1.13; P<0.001 for noninferiority). The safety outcome occurred in 349 patients (8.5%) in the edoxaban group and 423 patients (10.3%) in the warfarin group (hazard ratio, 0.81; 95% CI, 0.71 to 0.94; P=0.004 for superiority). The rates of other adverse events were similar in the two groups. A total of 938 patients with pulmonary embolism had right ventricular dysfunction, as assessed by measurement of N-terminal pro-brain natriuretic peptide levels; the rate of recurrent venous thromboembolism in this subgroup was 3.3% in the edoxaban group and 6.2% in the warfarin group (hazard ratio, 0.52; 95% CI, 0.28 to 0.98). CONCLUSIONS Edoxaban administered once daily after initial treatment with heparin was noninferior to high-quality standard therapy and caused significantly less bleeding in a broad spectrum of patients with venous thromboembolism, including those with severe pulmonary embolism. (Funded by Daiichi-Sankyo; Hokusai-VTE ClinicalTrials.gov number, NCT00986154.).

Evaluation of the novel factor Xa inhibitor edoxaban compared with warfarin in patients with atrial fibrillation: Design and rationale for the Effective aNticoaGulation with factor xA next GEneration in Atrial Fibrillation–Thrombolysis In Myocardial Infarction study 48 (ENGAGE AF–TIMI 48)

BACKGROUND Vitamin K antagonists have been the standard oral antithrombotic used for more than a half century for prevention and treatment of thromboembolism. Their limitations include multiple food and drug interactions and need for frequent monitoring and dose adjustments. Edoxaban is a selective and direct factor Xa inhibitor that may provide effective, safe, and more convenient anticoagulation. STUDY DESIGN ENGAGE AF-TIMI 48 is a phase 3, randomized, double-blind, double-dummy, multinational, noninferiority design megatrial comparing 2 exposure strategies of edoxaban to warfarin. Approximately 20,500 subjects will be randomized to edoxaban high exposure (60 mg daily, adjusted for drug clearance), edoxaban low exposure (30 mg daily, adjusted for drug clearance), or warfarin titrated to an international normalized ratio of 2.0 to 3.0. The edoxaban strategies provide for dynamic dose reductions in subjects with anticipated increased drug exposure. Blinded treatment is maintained through the use of sham international normalized ratios in patients receiving edoxaban. Eligibility criteria include electrical documentation of atrial fibrillation ≤12 months and a CHADS(2) score ≥2. Randomization is stratified by CHADS(2) score and anticipated drug exposure. The primary objective is to determine whether edoxaban is noninferior to warfarin for the prevention of stroke and systemic embolism. The primary safety end point is modified International Society on Thrombosis and Haemostasis major bleeding. Recruitment began in November 2008. The expected median follow-up is 24 months. CONCLUSIONS ENGAGE AF-TIMI 48 is a phase 3 comparison of the novel oral factor Xa inhibitor edoxaban to warfarin for the prevention of thromboembolism in patients with atrial fibrillation.

Association between edoxaban dose, concentration, anti-Factor Xa activity, and outcomes: an analysis of data from the randomised, double-blind ENGAGE AF-TIMI 48 trial.

BACKGROUND New oral anticoagulants for stroke prevention in atrial fibrillation were developed to be given in fixed doses without the need for the routine monitoring that has hindered usage and acceptance of vitamin K antagonists. A concern has emerged, however, that measurement of drug concentration or anticoagulant activity might be needed to prevent excess drug concentrations, which significantly increase bleeding risk. In the ENGAGE AF-TIMI 48 trial, higher-dose and lower-dose edoxaban were compared with warfarin in patients with atrial fibrillation. Each regimen incorporated a 50% dose reduction in patients with clinical features known to increase edoxaban drug exposure. We aim to assess whether adjustment of edoxaban dose in this trial prevented excess drug concentration and the risk of bleeding events. METHODS We analysed data from the randomised, double-blind ENGAGE AF-TIMI 48 trial. We correlated edoxaban dose, plasma concentration, and anti-Factor Xa (FXa) activity and compared efficacy and safety outcomes with warfarin stratified by dose reduction status. Patients with atrial fibrillation and at moderate to high risk of stroke were randomly assigned in a 1:1:1 ratio to receive warfarin, dose adjusted to an international normalised ratio of 2·0-3·0, higher-dose edoxaban (60 mg once daily), or lower-dose edoxaban (30 mg once daily). Randomisation was done with use of a central, 24 h, interactive, computerised response system. International normalised ratio was measured using an encrypted point-of-care device. To maintain masking, sham international normalised ratio values were generated for patients assigned to edoxaban. Edoxaban (or placebo-edoxaban in warfarin group) doses were halved at randomisation or during the trial if patients had creatinine clearance 30-50 mL/min, bodyweight 60 kg or less, or concomitant medication with potent P-glycoprotein interaction. Efficacy outcomes included the primary endpoint of all-cause stroke or systemic embolism, ischaemic stroke, and all-cause mortality. Safety outcomes included the primary safety endpoint of major bleeding, fatal bleeding, intracranial haemorrhage, and gastrointestinal bleeding. This trial is registered with ClinicalTrials.gov, number NCT00781391. FINDINGS Between Nov 19, 2008 and Nov 22, 2010, 21 105 patients were recruited. Patients who met clinical criteria for dose reduction at randomisation (n=5356) had higher rates of stroke, bleeding, and death compared with those who did not have a dose reduction (n=15 749). Edoxaban dose ranged from 15 mg to 60 mg, resulting in a two-fold to three fold gradient of mean trough drug exposure (16·0-48·5 ng/mL in 6780 patients with data available) and mean trough anti-FXa activity (0·35-0·85 IU/mL in 2865 patients). Dose reduction decreased mean exposure by 29% (from 48·5 ng/mL [SD 45·8] to 34·6 ng/mL [30·9]) and 35% (from 24·5 ng/mL [22·7] to 16·0 ng/mL [14·5]) and mean anti-FXa activity by 25% (from 0·85 IU/mL [0·76] to 0·64 IU/mL [0·54]) and 20% (from 0·44 IU/mL [0·37] to 0·35 IU/mL [0·28]) in the higher-dose and lower-dose regimens, respectively. Despite the lower anti-FXa activity, dose reduction preserved the efficacy of edoxaban compared with warfarin (stroke or systemic embolic event: higher dose pinteraction=0·85, lower dose pinteraction=0·99) and provided even greater safety (major bleeding: higher dose pinteraction 0·02, lower dose pinteraction=0·002). INTERPRETATION These findings validate the strategy that tailoring of the dose of edoxaban on the basis of clinical factors alone achieves the dual goal of preventing excess drug concentrations and helps to optimise an individual patients risk of ischaemic and bleeding events and show that the therapeutic window for edoxaban is narrower for major bleeding than thromboembolism. FUNDING Daiichi-Sankyo Pharma Development.

Oral direct factor Xa inhibition with edoxaban for thromboprophylaxis after elective total hip replacement. A randomised double-blind dose-response study.

Edoxaban is a new oral direct factor Xa inhibitor. The purpose of this study was to evaluate the efficacy and safety of different doses of edoxaban for the prevention of venous thromboembolism (VTE) in patients undergoing elective total hip replacement. A total of 903 patients were randomised to oral edoxaban 15, 30, 60 or 90 mg once daily or subcutaneous dalteparin once daily (initial dose 2,500 IU, subsequent doses 5,000 IU). Both drugs were begun 6-8 hours postoperatively and continued for 7-10 days, when bilateral venography was performed. The primary efficacy endpoint was the incidence of total VTE, which included proximal and/or distal deep-vein thrombosis (DVT) by venography or symptomatic, objectively confirmed DVT or pulmonary embolism during the treatment period. The primary safety outcome was the incidence of the composite of major and clinically relevant non-major bleeding. All venograms and bleeding events were reviewed by a central independent adjudication committee blinded as to treatment allocation. Of the 903 patients randomised, 776 were evaluable for the primary efficacy analysis. The incidences of VTE were 28.2%, 21.2%, 15.2%, and 10.6% in patients receiving edoxaban 15, 30, 60 and 90 mg, respectively, compared with 43.8% in the dalteparin group (p<0.005 ). There was a statistically significant (p<0.001) dose-response for efficacy across the edoxaban dose groups for total VTE and for major VTE. The incidence of clinically relevant bleeding was low and similar across the groups. Oral edoxaban once daily is effective for preventing VTE after total hip replacement.

Modelling and simulation of edoxaban exposure and response relationships in patients with atrial fibrillation

Edoxaban is a novel, orally available, highly specific direct inhibitor of factor Xa and is currently being developed for the treatment and prevention of venous thromboembolism and prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation (NVAF). The objectives of the present analyses were to characterise edoxaban population pharmacokinetics (PPK) and identify potential intrinsic and extrinsic factors affecting variability in edoxaban exposure, determine if there are relationships between edoxaban pharmacokinetics or biomarkers and the risk of bleeding in patients with NVAF using an exposure-response model, and to use the PPK and exposure-response model to support dose selection for a phase III trial of edoxaban in patients with NVAF. PPK analysis of data from 1,281 edoxaban-dosed subjects with intrinsic factors such as renal impairment or NVAF and extrinsic factors such as concomitant medications revealed significant effects of renal impairment and concomitant strong P-glycoprotein (P-gp) inhibitors on the pharmacokinetics of edoxaban. Exposure-response analysis found that in patients with NVAF, the incidence of bleeding events increased significantly with increasing edoxaban exposure, with steady-state minimum concentration (Cmin,ss) showing the strongest association. Clinical trial simulations of bleeding incidence were used to select 30 mg and 60 mg once-daily edoxaban with 50% dose reductions for patients with moderate renal impairment or receiving concomitant strong P-gp inhibitors as the treatment regimens in the ENGAGE AF-TIMI 48 (NCT00781391) trial.

Edoxaban for the Treatment of Cancer-Associated Venous Thromboembolism

Background Low‐molecular‐weight heparin is the standard treatment for cancer‐associated venous thromboembolism. The role of treatment with direct oral anticoagulant agents is unclear. Methods In this open‐label, noninferiority trial, we randomly assigned patients with cancer who had acute symptomatic or incidental venous thromboembolism to receive either low‐molecular‐weight heparin for at least 5 days followed by oral edoxaban at a dose of 60 mg once daily (edoxaban group) or subcutaneous dalteparin at a dose of 200 IU per kilogram of body weight once daily for 1 month followed by dalteparin at a dose of 150 IU per kilogram once daily (dalteparin group). Treatment was given for at least 6 months and up to 12 months. The primary outcome was a composite of recurrent venous thromboembolism or major bleeding during the 12 months after randomization, regardless of treatment duration. Results Of the 1050 patients who underwent randomization, 1046 were included in the modified intention‐to‐treat analysis. A primary‐outcome event occurred in 67 of the 522 patients (12.8%) in the edoxaban group as compared with 71 of the 524 patients (13.5%) in the dalteparin group (hazard ratio, 0.97; 95% confidence interval [CI], 0.70 to 1.36; P=0.006 for noninferiority; P=0.87 for superiority). Recurrent venous thromboembolism occurred in 41 patients (7.9%) in the edoxaban group and in 59 patients (11.3%) in the dalteparin group (difference in risk, ‐3.4 percentage points; 95% CI, ‐7.0 to 0.2). Major bleeding occurred in 36 patients (6.9%) in the edoxaban group and in 21 patients (4.0%) in the dalteparin group (difference in risk, 2.9 percentage points; 95% CI, 0.1 to 5.6). Conclusions Oral edoxaban was noninferior to subcutaneous dalteparin with respect to the composite outcome of recurrent venous thromboembolism or major bleeding. The rate of recurrent venous thromboembolism was lower but the rate of major bleeding was higher with edoxaban than with dalteparin. (Funded by Daiichi Sankyo; Hokusai VTE Cancer ClinicalTrials.gov number, NCT02073682.)

Left atrial structure and function in atrial fibrillation: ENGAGE AF-TIMI 48.

AIMS The complex relationship between left atrial (LA) structure and function, electrical burden of atrial fibrillation (AF) and stroke risk is not well understood. We aimed to describe LA structure and function in AF. METHODS AND RESULTS Left atrial structure and function was assessed in 971 subjects enrolled in the echocardiographic substudy of ENGAGE AF-TIMI 48. Left atrial size, emptying fraction (LAEF), and contractile function were compared across AF types (paroxysmal, persistent, or permanent) and CHADS2 scores as an estimate of stroke risk. The majority of AF patients (55%) had both LA enlargement and reduced LAEF, with an inverse relationship between LA size and LAEF (R = -0.57, P < 0.001). With an increasing electrical burden of AF and higher CHADS2 scores, LA size increased and LAEF declined. Moreover, 19% of AF subjects had impaired LAEF despite normal LA size, and LA contractile dysfunction was present even among the subset of AF subjects in sinus rhythm at the time of echocardiography. CONCLUSIONS In a contemporary AF population, LA structure and function were increasingly abnormal with a greater electrical burden of AF and higher stroke risk estimated by the CHADS2 score. Moreover, LA dysfunction was present despite normal LA size and sinus rhythm, suggesting that the assessment of LA function may add important incremental information in the evaluation of AF patients. CLINICAL TRIAL REGISTRATION http://www.clinicaltrials.gov; ID = NCT00781391.

Concomitant Use of Single Antiplatelet Therapy With Edoxaban or Warfarin in Patients With Atrial Fibrillation: Analysis From the ENGAGE AF‐TIMI48 Trial

Background We studied the concomitant use of single antiplatelet therapy (SAPT) on the efficacy and safety of the anti‐Xa agent edoxaban in patients with atrial fibrillation (AF). Methods and Results ENGAGE AF‐TIMI 48 was a randomized trial that compared 2 dose regimens of edoxaban with warfarin. We studied both the approved high‐dose edoxaban regimen (HDER; 60 mg daily reduced by one half in patients with anticipated increased drug exposure), as well as a lower‐dose edoxaban regimen (LDER; 30 mg daily, also reduced by one half in patients with anticipated increased drug regimen). SAPT (aspirin in 92.5%) was administered at the discretion of the treating physician. Cox proportional hazard regressions stratified by SAPT at 3 months with treatment as a covariate were performed. The 4912 patients who received SAPT were more frequently male, with histories of coronary artery disease and diabetes, and had higher CHADS 2Vasc and HAS BLED scores than did the 14 977 patients not receiving SAPT. When compared to patients not receiving SAPT, those receiving SAPT had a higher incidence of major bleeding; (adjusted hazard ratio [HR adj]=1.46; 95% CI, 1.27–1.67, P<0.001). SAPT did not alter the relative efficacy of edoxaban compared to warfarin in preventing stroke or systemic embolic events (SEEs): edoxaban versus warfarin without SAPT, hazard ratio (HR adj for HDER)=0.94; (95% CI: 0.77–1.15) with SAPT, HR adj=0.70 (95% CI: 0.50–0.98), P interaction (P int)=0.14. (HR adj for LDER versus warfarin without SAPT=1.19 (95% CI 0.99–1.43) With SAPT, 1.03 (95% CI, 0.76–1.39) P int=0.42. Major bleeding was lower with edoxaban than warfarin both without SAPT, HR adj for HDER=0.80 (95% CI, 0.68–0.95), and with SAPT, HR adj=0.82 (95% CI, 0.65–1.03; P int=0.91). For LDER without SAPT (HR adj=0.56 [95% CI 0.46–0.67]) and with SAPT (HR adj=0.51 [95% CI 0.39–0.66]). Conclusions Patients with AF who were selected by their physicians to receive SAPT in addition to an anticoagulant had a similar risk of stroke/SEE and higher rates of bleeding than those not receiving SAPT. Edoxaban exhibited similar relative efficacy and reduced bleeding compared to warfarin, with or without concomitant SAPT. Clinical Trial Registration URL: http://www.clinicaltrials.gov/. Unique identifier: NCT00781391.

The effects of the antiplatelet agents, aspirin and naproxen, on pharmacokinetics and pharmacodynamics of the anticoagulant edoxaban, a direct factor Xa inhibitor.

Abstract: Edoxaban is an oral factor Xa (FXa) inhibitor in clinical development for stroke prevention in patients with atrial fibrillation, an elderly population that frequently receives aspirin (ASA) and/or nonsteroidal anti-inflammatory drugs for concurrent illnesses. Three studies were conducted to evaluate the pharmacokinetic and pharmacodynamic interactions of edoxaban 60 mg coadministered with low-dose (100 mg) ASA, high-dose (325 mg) ASA, or naproxen (500 mg) in healthy subjects (n = 126). Template bleeding times (BT) were measured. Mean baseline (predose) BT for the 3 studies ranged from 4.72 to 6.13 minutes. Edoxaban administered alone increased BT by 21%–35% (4 hours post dose) from baseline. Concomitant administration of edoxaban with high-dose ASA, low-dose ASA, or naproxen increased BT approximately 2-fold showing an additive effect greater than either agent administered alone. Edoxaban pharmacokinetics were not affected by concomitant low-dose ASA or naproxen, but high-dose ASA increased systemic exposure of edoxaban by approximately 30%. The effects of edoxaban on prothrombin time, activated partial thromboplastin time, international normalized ratio, anti-FXa, and intrinsic FXa activity were not influenced by administration with ASA or naproxen. Inhibition of platelet aggregation by high-dose ASA, low-dose ASA, or naproxen was not affected by edoxaban. Concomitant administration of edoxaban and ASA or naproxen was well tolerated.