Efficacy and safety of edoxaban for treatment of venous thromboembolism: a subanalysis of East Asian patients in the Hokusai-VTE trial

BACKGROUND

Direct oral anticoagulants have been evaluated for their efficacy and safety in the treatment of venous thromboembolism (VTE), which comprises deep vein thrombosis and pulmonary embolism. The randomized, double-blind Hokusai-VTE trial demonstrated that 60 mg of edoxaban once daily following initial heparin treatment is non-inferior to heparin overlapped with and followed by warfarin for the treatment of VTE, and is associated with significantly fewer bleeding events.

OBJECTIVES

To assess the efficacy and safety of edoxaban versus warfarin among East Asian patients enrolled in the Hokusai-VTE trial.

PATIENTS/METHODS

The Hokusai-VTE trial enrolled 8292 patients from 439 centers worldwide, including 1109 patients from Japan, China, Korea, and Taiwan. The primary efficacy and safety outcomes were symptomatic recurrent VTE and clinically relevant bleeding, respectively.

RESULTS

In the overall East Asian population, the primary efficacy outcome of symptomatic recurrent VTE occurred in 16 of 563 (2.8%) patients in the edoxaban group versus 24 of 538 (4.5%) patients in the warfarin group (hazard ratio [HR] 0.64; 95% confidence interval [CI] 0.34-1.19; P = 0.1601). The primary safety outcome of clinically relevant bleeding occurred in 56 of 563 (9.9%) patients in the edoxaban group versus 93 of 538 (17.3%) patients in the warfarin group (HR 0.56; 95% CI 0.40-0.78; P < 0.001).

CONCLUSIONS

Edoxaban is an effective and safer alternative to warfarin in East Asian patients with acute VTE who require anticoagulant therapy, consistent with overall study findings from the Hokusai-VTE trial.

Edoxaban for the long-term treatment of venous thromboembolism: rationale and design of the Hokusai-venous thromboembolism study--methodological implications for clinical trials

BACKGROUND

New oral anticoagulants may simplify long-term therapy by eliminating the need for laboratory monitoring. Edoxaban is an oral, direct inhibitor of factor Xa that is given in a fixed dose once daily.

OBJECTIVE AND METHODS

The Hokusai-VTE study is a randomized, double-blind trial to evaluate whether initial low molecular weight heparin (LMWH) followed by edoxaban (60 mg once daily) is non-inferior to LMWH followed by warfarin (International Normalized Ratio of 2.0-3.0) for the prevention of recurrent thromboembolism in patients with acute symptomatic venous thromboembolism (VTE). The primary efficacy outcome is symptomatic recurrent VTE during the 12-month study period. The principal safety outcome is clinically relevant bleeding (major or non-major) occurring during or within 3 days of stopping study treatment. A clinical events committee adjudicates all suspected outcome events. A unique study design feature is the flexible treatment duration of between 3 and 12 months to simulate usual clinical practice, and enabled by: (i) double-blinding to minimize bias that could occur if knowledge of the patient's treatment influenced the duration of therapy; and (ii) follow-up for 12 months of all patients and inclusion in the primary efficacy analysis, regardless of the duration of therapy received. A second innovative design feature is the strategy for achieving an appropriate time in therapeutic range in the warfarin group, with central tracking for each participating center and feedback to the investigators.

CONCLUSION

The standard methods combined with innovative design features should achieve study results that are both scientifically valid and relevant to clinical practice.

Treatment for intermittent claudication and the effects on walking distance and quality of life

The objective of the study was to provide an overview of the most common treatments for intermittent claudication and to determine the effectiveness in improving walking distance and quality of life based on a combination of direct and indirect evidence. We included trials that compared: angioplasty, surgery, exercise therapy or no treatment for intermittent claudication. Outcome measurements were walking distance (maximum, pain-free) and quality of life (physical, mental). We used a network meta-analysis model for the combination of direct and indirect evidence. We included 42 studies, presenting 3106 participants. The network meta-analysis showed that supervised exercise therapy (Δ = 1.62, P < 0.01), angioplasty (Δ = 1.89, P < 0.01) and surgery (Δ = 2.72, P = 0.02) increased walking distance significantly more than no treatment. Furthermore, supervised exercise therapy (Δ = 0.60, P < 0.01), angioplasty (Δ = 0.91, P = 0.01) and surgery (Δ = 1.07, P < 0.01) increased physical quality of life more than no treatment. However, in the sensitivity analysis, only supervised exercise therapy had additional value over no symptomatic treatment (Δ = 0.66, P < 0.01). In conclusion, this network meta-analysis indicates that supervised exercise therapy is more effective in both increasing walking distance and physical quality of life, compared with no treatment. Angioplasty and surgery also increase walking distance, compared with no treatment, but results for physical quality of life are less convincing.

External and internal validity of open label or double-blind trials in oral anticoagulation: better, worse or just different?

Currently, few topics in the field of anticoagulant therapy are as intensely discussed as the question: which is the best new oral anticoagulant? The most advanced substances in this field are the oral direct factor Xa-inhibitors rivaroxaban, apixaban and edoxaban and the oral direct thrombin inhibitor dabigatran. All of these substances are currently being tested in very similar phase III trials or are in the process of approval. In these trials, open-label or double-blind double-dummy designs are being used to evaluate the efficacy and safety in prevention and treatment of venous thromboembolism or stroke prevention in atrial fibrillation in several thousands of patients. As a consequence, an intense discussion of the advantages and disadvantages of open-label or double-blind trials is currently under way and interpretation of trial results is often focused on this matter. In general, a blinded trial is regarded as being less subject to bias than an open trial because it minimizes the impact of knowledge of treatment allocation on post-randomized treatment decisions and on reporting of outcomes. However, a blinded trial is not always feasible. Thus, in some respects, the two trial designs offer complementary strengths and weaknesses. This review addresses the risks of bias for internal and external validity of open-label and double-blind anticoagulation trials to help to objectify this debate.

Single intravenous administration of TB-402 for the prophylaxis of venous thromboembolism after total knee replacement: a dose-escalating, randomized, controlled trial

BACKGROUND

TB-402 is a novel anticoagulant monoclonal antibody with a prolonged antithrombotic effect resulting from its partial factor (F)VIII inhibition and long half-life. We evaluated the efficacy and safety of a single administration of TB-402 for the prevention of venous thromboembolism (VTE) after total knee replacement (TKR).

PATIENTS AND METHODS

This was a phase II, dose-escalating, randomized, enoxaparin-controlled, open-label study. Patients were post-operatively assigned to a single dose of TB-402 (0.3, 0.6 or 1.2 mg kg(-1)) or enoxaparin 40 mg for at least 10 days (n = 75 per group; 3:1 TB-402 to enoxaparin). The primary efficacy outcome was total VTE defined as asymptomatic deep vein thrombosis (DVT) detected by bilateral venography and symptomatic VTE by day 7 to 11. The principal safety outcome was the incidence of major bleeding and clinically relevant non-major bleeding.

RESULTS

Total VTE was lower in all TB-402 groups compared with enoxaparin: 16.7%(95% CI 9.8-26.9), 23.9%(95% CI 15.3-35.3), 24.1%(95% CI 16.0-34.5) and 39.0%(95% CI 28.8-50.1) for TB-402 0.3, 0.6, 1.2 mg kg(-1) and enoxaparin, respectively (P = 0.003 for TB-402 0.3 mg kg(-1) vs. enoxaparin). The incidence of total VTE in the pooled TB-402 groups was 21.6% (95%CI 16.6-27.5), an absolute risk reduction vs. enoxaparin of 17.4% (95% CI 5.2-29.6). Major or clinically relevant non-major bleeding was observed in 3/75(4.0%), 4/74(5.4%), 7/87(8.0%) and 3/79(3.8%) patients for TB-402 0.3, 0.6, 1.2 mg kg(-1) and enoxaparin, respectively.

CONCLUSIONS

TB-402, as a single post-operative administration, was associated with a lower rate of VTE in all doses tested, compared with enoxaparin. The incidence of major and clinically relevant non-major bleeding was similar to enoxaparin 40 mg for TB-402 0.3 and 0.6 mg kg(-1).

The incidence and prognostic significance of elevated cardiac troponins in patients with submassive pulmonary embolism

Although the incidence and prognostic significance of elevated cardiac troponins are known in patients with massive pulmonary embolism (PE), few studies have addressed this issue in patients with hemodynamically stable, submassive PE, who comprise the majority of patients presenting with PE. This prospective cohort study was, therefore, designed to determine the incidence and prognostic significance of elevated cardiac troponins in patients with submassive PE. Consecutive patients with acute, symptomatic, submassive PE that was confirmed by objective diagnostic testing were studied. All patients received treatment with either unfractionated heparin or fondaparinux followed by a coumarin derivative and underwent clinical follow-up for 3 months. Cardiac troponin I (cTnI) levels were measured within 24 h of clinical presentation. An elevated cTnI was defined as > 0.5 microg L(-1) and indicated myocardial injury. Major myocardial injury, that is associated with myocardial infarction, was defined by a cTnI > 2.3 microg L(-1). The clinical outcomes were recurrent venous thromboembolism and all-cause death. In 458 patients with submassive PE, the incidence of cTnI > 0.5 microg L(-1) was 13.5%[95% confidence interval (CI): 10.4-16.7], and the incidence of cTnI > 2.3 microg L(-1) was 3.5% (95% CI: 2.0-5.6). An elevated cTnI > 0.5 microg L(-1) was associated with an increased risk of all-cause death [odds ratio (OR) = 3.5; 95% CI: 1.0-11.9], but did not appear to confer an increased risk of recurrent venous thromboembolism (OR = 1.1; 95% CI: 0.2-4.9). In patients who present with submassive PE, an elevated cTnI occurs in about one in seven patients and is associated with a 3.5-fold increased risk of all-cause death.

Dose-response study of recombinant factor VIIa/tissue factor inhibitor recombinant nematode anticoagulant protein c2 in prevention of postoperative venous thromboembolism in patients undergoing total knee replacement

BACKGROUND

With the best prophylactics now available, venous thromboembolism after total knee replacement remains substantial (25% to 27%). Recombinant nematode anticoagulant protein c2 (rNAPc2) is a potent inhibitor of factor VIIa/tissue factor complex that has the potential to reduce this risk. The present study was performed to determine an efficacious and safe dose of rNAPc2 for prevention of venous thromboembolism after elective, unilateral total knee replacement.

METHODS AND RESULTS

This open-label, sequential dose-ranging study was conducted in 11 centers in Canada, Europe, and the United States. Five regimens were tested. Injections were administered subcutaneously on the day of surgery (day 1) and days 3, 5, and optionally, day 7. Primary efficacy outcome was a composite of overall deep vein thrombosis based on mandatory unilateral venography (day 7+/-2) and confirmed symptomatic venous thromboembolism recorded </=48 hours after the last dose of rNAPc2. Primary safety outcome was major bleeding </=72 hours after the last dose. An independent, blinded Central Adjudication Committee assessed all outcome events. Of 293 patients studied, 251 (86%) could be evaluated for primary efficacy analysis. A dosage of 3.0 microgram/kg administered within 1 hour after surgery provided the best observed results, with an overall deep vein thrombosis rate of 12.2%, a proximal deep vein thrombosis rate of 1.3%, and a major bleeding rate of 2.3%.

CONCLUSIONS

A randomized, double-blind trial that compared rNAPc2 with current best prophylactics is warranted based on encouraging, first-reported clinical results for a factor VIIa/tissue factor inhibitor evaluated for thrombosis prophylaxis.

Is there a role for thrombolytic therapy in venous thromboembolism?

Theoretically, thrombolytic therapy would appear to offer benefits over standard heparin therapy in the treatment of venous thromboembolism based on the more rapid resolution of thrombus. In this paper, the results of clinical trials performed with thrombolytic agents in the initial treatment of both deep vein thrombosis (DVT) and pulmonary embolism (PE) are reviewed. Although there have been positive findings with surrogate markers, studies to date have failed to demonstrate that thrombolytic therapy is associated with an improved long-term clinical outcome in patients with DVT or PE. Recent reports have suggested that thrombolytic agents could be clinically useful in a subgroup who have right ventricular dysfunction on echocardiography. Randomized clinical trials, with clinically relevant endpoints, are required to determine the efficacy and safety of thrombolytic therapy in these patients.

Assessment of quality of life in the younger child: the use of an animated computer program

BACKGROUND

In the past, quality of life was primarily assessed using objective measurements of the condition of the patient. Today, most quality-of-life measurements include several aspects regarding the patient's opinions and feelings. There has been an extensive development of quality-of-life instruments particularly in adults, including those for people with inflammatory bowel disease (IBD). However, only a few instruments, mostly questionnaires, have been developed for the pediatric population. It has been noted, even in young patients with IBD, that there is reduced self-esteem and more anxiety and depression. Altogether, these are important aspects for early measurement of psychosocial functioning and possibly intervention during the treatment of children with IBD.

METHODS

For the current study, an instrument was developed for young children aged 5 years or more in which a computer-based animated program was used to measure quality of life in children with inflammatory bowel disease. The instrument was designed to be similar for boys and girls with no reference to racial identity. In addition, it was culturally acceptable for all Dutch children. The program was in the form of a story of a bear and a clown playing in an attic of an old house where they come across many objects with which they play and where many adventures occur. All 35 questions were interwoven in this story.

RESULTS

The animated computer program was well accepted and easily used by 16 children between the ages of 5 and 12 in a small pilot study. In those older than 11 years, another approach is probably necessary, using an age-appropriate animated program.

CONCLUSIONS

The computer program can easily be used in an outpatient setting and thus ensures that quality-of-life measurement will become a routine part of a medical visit.

Association of idiopathic venous thromboembolism with single point-mutation at Arg506 of factor V

Abnormal coagulation factor V may underlie the thrombotic events associated with resistance to activated protein C (APC). We analysed 27 consecutive patients with documented idiopathic (recurrent) thromboembolism for the occurrence of point mutations within the APC sensitive regions of blood coagulation factor V. In 10 patients we observed a single basepair mutation resulting in a substitution of Arg506 to Gln. This mutation was significantly linked to in-vitro resistance to APC in these subjects. This mutation at Arg506 of factor V may form the molecular basis for the thrombotic events associated with APC resistance.

Biologic effects of recombinant hirudin (CGP 39393) in human volunteers. European Hirudin in Thrombosis Group

OBJECTIVES

The purpose of this study was to investigate the biologic efficacy and pharmacokinetics of different doses of recombinant hirudin administered in single or repeated subcutaneous injections in healthy volunteers.

BACKGROUND

Hirudin is a highly specific inhibitor of thrombin, the pivotal enzyme in thrombosis. Differences between hirudin and heparin in experimental animals indicate that hirudin may be a superior antithrombotic drug in humans.

METHODS

The biologic effect of recombinant desulfato-hirudin (CGP 39393) administered as single or repeated (every 8 h for 3 days or every 12 h for 6 days) subcutaneous injections was studied in 231 healthy human volunteers.

RESULTS

Single subcutaneous doses of 0.1, 0.2, 0.3, 0.4, 0.5 and 0.75 mg/kg body weight in 195, 8, 12, 8, 4 and 4 volunteers, respectively, prolonged the activated partial thromboplastin time in a dose-proportional fashion within the 1st 30 min, with a near-maximal effect for 3 to 4 h after the dose. The mean activated partial thromboplastin time increased to 1.48 and 1.93 times baseline values 30 min after single subcutaneous injections of 0.2 and 0.4 mg/kg of CGP 39393, respectively. There was a linear relation over a wide range between the activated partial thromboplastin time prolongation and plasma concentrations of CGP 39393. Plasma clearance was between 1.5 and 1.7 ml/min per kg. The subcutaneous administration of 0.3 and 0.5 mg recombinant hirudin three times a day for 3 days or two times a day for 6 days prolonged the activated partial thromboplastin time by 1.71 to 1.69 and 1.78 to 1.92 times baseline levels, respectively, with the preinjection values maintained in the hypocoagulable range. No prolongation of bleeding time was measured at peak plasma hirudin levels. Because thrombin and prothrombin times are not able to reflect high or low CGP 39393 concentrations, respectively, neither test is suitable for monitoring administration of this drug.

CONCLUSIONS

CGP 39393 appears to be well tolerated in volunteers, even after repeated doses. The activated partial thromboplastin time test seems to be well suited to monitor the anticoagulant effect of recombinant hirudin because the dose effect is linear up to 0.5 mg/kg of subcutaneous CGP 39393. The prolongation of activated partial thromboplastin time after subcutaneous injection of CGP 39393 shows a plateau lasting for 3 h. Further studies are now required to determine the dose that will provide the best antithrombotic effect and the lowest bleeding tendency in arterial or venous thrombosis indications.

Vitamin-K status beyond the neonatal period. A prospective study in normal breast-fed and formula-fed infants

Vitamin K-dependent clotting factors (FII, FVII, FX) and PT and TT were studied prospectively in 113 healthy newborns during the first 6 weeks of life. No vitamin K prophylaxis was given. Infants were divided into three groups: breast fed, formula fed or combination. The method of nutrition could not be found to influence the coagulation status.