Population pharmacokinetics of edoxaban in patients with symptomatic deep-vein thrombosis and/or pulmonary embolism--the Hokusai-VTE phase 3 study

Pharmacokinetics, Pharmacodynamics, and Safety of Edoxaban in Pediatric Subjects: A Phase I Single-Dose Study

This was an open-label, single-dose, phase I study to characterize the pharmacokinetics (PKs), pharmacodynamics (PDs), and safety of edoxaban in pediatric subjects from birth to 18 years at risk for venous thromboembolism (VTE). Children requiring anticoagulant therapy were enrolled into 5 age cohorts (0 to < 6 months (N = 12), 0.5 to < 2 years (N = 13), 2 to < 6 years (N = 13), 6 to < 12 years (N = 13), and 12 to < 18 years (N = 15)) receiving tablet or oral suspension of edoxaban at doses expected to be equivalent to 30 or 60 mg once daily (q.d.) in adult subjects with VTE. Sixty-six pediatric subjects were enrolled and completed the study. Edoxaban plasma concentration peaked between 1 and 3 hours and declined rapidly until 4-8 hours. The range of mean total apparent clearance across 5 age cohorts at low and high doses was 0.47 to 1.11 L/h/kg. The ranges of mean volume of central compartment and apparent peripheral volume were 2.31 to 3.59 L/kg and 1.92 to 4.14 L/kg, respectively. Across all age groups, the estimated median exposures were within the 0.5- to 1.5-fold of the median area under the plasma drug concentration-time curve (AUC) in adult subjects receiving corresponding doses (30 mg q.d. for low dose and 60 mg q.d. for high dose). In all age groups, PD parameters (prothrombin time, activated partial thromboplastin time, and anti-Factor Xa activity) showed a linear PK-PD relationship and were in line with previous adult data. The results support further evaluation of the pediatric doses in larger pivotal trials.

Challenges and Possible Solutions to Direct-Acting Oral Anticoagulants (DOACs) Dosing in Patients with Extreme Bodyweight and Renal Impairment

This article aims to highlight the dosing issues of direct oral anticoagulants (DOACs) in patients with renal impairment and/or obesity in an attempt to develop solutions employing advanced data-driven techniques. DOACs have become widely accepted by clinicians worldwide because of their superior clinical profiles, more predictable pharmacokinetics, and hence more convenient dosing relative to other anticoagulants. However, the optimal dosing of DOACs in extreme bodyweight  patients and patients with renal impairment is difficult to achieve using the conventional dosing approach. The standard dosing approach (fixed-dose) is based on limited data from clinical studies. The existing formulae (models) for determining the appropriate doses for these patient groups leads to suboptimal dosing. This problem of mis-dosing is worsened by the lack of standardized laboratory parameters for monitoring the exposure to DOACs in renal failure and extreme bodyweight patients. Model-informed precision dosing (MIPD) encompasses a range of techniques like machine learning and pharmacometrics modelling, which could uncover key variables and relationships as well as shed more light on the pharmacokinetics and pharmacodynamics of DOACs in patients with extreme bodyweight or renal impairment. Ultimately, this individualized approach-if implemented in clinical practice-could optimise dosing for the DOACs for better safety and efficacy.

Towards Personalized Antithrombotic Treatments: Focus on P2Y12 Inhibitors and Direct Oral Anticoagulants

Oral anticoagulants and antiplatelet drugs are commonly prescribed to lower the risk of cardiovascular diseases, such as venous and arterial thrombosis, which represent the leading causes of mortality worldwide. A significant percentage of patients taking antithrombotics will nevertheless experience bleeding or recurrent ischemic events, and this represents a major public health issue. Cardiovascular medicine is now questioning the one-size-fits-all policy, and more personalized approaches are increasingly being considered. However, the available tools are currently limited and they are only moderately able to predict clinical events or have a significant impact on clinical outcomes. Predicting concentrations of antithrombotics in blood could be an effective means of personalization as they have been associated with bleeding and recurrent ischemia. Target concentration interventions could take advantage of physiologically based pharmacokinetic (PBPK) and population-based pharmacokinetic (POPPK) models, which are increasingly used in clinical settings and have attracted the interest of governmental regulatory agencies, to propose dosages adapted to specific population characteristics. These models have the benefit of combining parameters from different sources, such as experimental in vitro data and patients' demographic, genetic, and physiological in vivo data, to characterize the dose-concentration relationships of compounds of interest. As such, they can be used to predict individual drug exposure. In the near future, these models could therefore be a valuable means of predicting personalized antithrombotic blood concentrations and, hopefully, of preventing clinical non-response or bleeding in a given patient. Existing approaches for personalization of antithrombotic prescriptions will be reviewed using practical examples for P2Y₁₂ inhibitors and direct oral anticoagulants. The review will additionally focus on the existing PBPK and POPPK models for these two categories of drugs. Lastly, we address potential scenarios for their implementation in clinics, along with the main limitations and challenges.

Risk Factors for Major Bleeding and Clinically Relevant Non-major Bleeding in Japanese Patients Treated with Edoxaban

Edoxaban is used to prevent and treat stroke or systemic embolism such as venous thromboembolism. Although bleeding is the most common complication of anticoagulants, only a few studies have addressed the safety of direct oral anticoagulants in East Asian patients. In this study, we investigated the risk factors for bleeding in Japanese patients receiving edoxaban. A retrospective review of the records of 198 patients who received 30 mg/d edoxaban in our hospital between April 2015 and March 2017 was performed. Subsequently, these patients were followed up to 1 year. Seven (3.5%) and 22 (11.1%) patients developed major bleeding and clinically relevant bleeding, respectively. In the univariate Cox regression analyses, low baseline hemoglobin levels (p = 0.002) and low baseline creatinine clearance (p = 0.020) were significantly associated with major bleeding. Multivariate Cox regression analysis revealed that a low baseline hemoglobin level was a significant risk factor for major bleeding and clinically relevant bleeding [hazard ratio 1.67 per 1 g/dL decrease (95% confidence interval 1.14-2.56, p = 0.008) and hazard ratio 1.31 per 1 g/dL decrease (95% confidence interval 1.06-1.62, p = 0.013), respectively]. Baseline hemoglobin level in quartiles also showed a quartile-dependent decrease in major bleeding and clinically relevant bleeding event. These results suggest that low baseline hemoglobin level is a significant risk factor for both major bleeding and clinically relevant bleeding in Japanese patients receiving edoxaban. Thus, these patients should be carefully monitored.

Influence of Renal Function on the Pharmacokinetics, Pharmacodynamics, Efficacy, and Safety of Non-Vitamin K Antagonist Oral Anticoagulants

With the growing integration of non-vitamin K antagonist oral anticoagulants (NOACs) into clinical practice, questions have arisen regarding their use in special populations, including groups that may have been underrepresented in clinical trials. Patients with renal impairment, particularly in the lower echelons of renal function, are one such group. In an effort to elucidate the current evidence regarding the use of NOACs in patients with renal impairment, a systematic assessment of the literature was performed. The MEDLINE database was interrogated for studies and analyses evaluating the influence of renal function on the pharmacokinetics, pharmacodynamics, efficacy, and safety of NOACs published from January 1, 2000, through August 2, 2017. The 82 relevant publications retrieved highlight the diversity in the NOAC class regarding the impact of renal function on drug clearance, drug exposures, and clinical trial outcomes. In several large clinical trials, subgroup analyses revealed no significant differences when patients were stratified by creatinine clearance as a measure of renal function. Efficacy findings, in particular, were largely aligned with the overall population in the included studies. However, relative risks of bleeding were shown to vary, sometimes driven by changes in bleeding event rates in the comparator arm (eg, warfarin, enoxaparin). With few exceptions, minimal influence of mild renal impairment was observed on the relative efficacy and safety of NOACs. Taken together, the evidence suggests that the presence of renal impairment merits careful consideration of anticoagulant choice but should not deter physicians from appropriate use of NOACs.

Integrated Population Pharmacokinetic Analysis of Rivaroxaban Across Multiple Patient Populations

The population pharmacokinetics (PK) of rivaroxaban have been evaluated in several population‐specific models. We developed an integrated population PK model using pooled data from 4,918 patients in 7 clinical trials across all approved indications. Effects of gender, age, and weight on apparent clearance (CL/F) and apparent volume of distribution (V/F), renal function, and comedication on CL/F, and relative bioavailability as a function of dose (F) were analyzed. Virtual subpopulations for exposure simulations were defined by age, creatinine clearance (CrCL) and body mass index (BMI). Rivaroxaban PK were adequately described by a one‐compartment disposition model with a first‐order absorption rate constant. Significant effects of CrCL, use of comedications, and study population on CL/F, age, weight, and gender on V/F, and dose on F were identified. CrCL had a modest influence on exposure, whereas age and BMI had a minor influence. The model was suitable to predict rivaroxaban exposure in patient subgroups of special interest.

Dose reduction of edoxaban preserves efficacy and safety for the treatment of venous thromboembolism

Direct oral anticoagulants simplify venous thromboembolism (VTE) treatment by obviating the need for coagulation monitoring. Nonetheless, renal function, body weight and P-glycoprotein inhibitors influence drug levels. The objective of this analysis was to determine whether reduction in edoxaban dose based on clinical criteria avoids excess drug exposure and preserves efficacy and safety in the Hokusai-VTE study. After initial heparin, patients received edoxaban or warfarin for 3-12 months. Edoxaban was given once daily at a dose of 60 mg, which was reduced to 30 mg in patients with a creatinine clearance of 30–50 ml/minute, body weight ≤60 kg or receiving certain P-glycoprotein inhibitors. The primary efficacy outcome was recurrent VTE and the principal safety outcome was major or clinically relevant non-major bleeding. A total of 8292 patients with acute VTE were randomised, 733 and 719 patients in the edoxaban and warfarin groups met the criteria for dose reduction. These patients were older, more often female or Asian and had more extensive VTE. Edoxaban levels were lower in the 30 mg edoxaban group. Rates of recurrent VTE and bleeding with the 30 mg and 60 mg edoxaban dose were comparable: VTE rates were 3.0 % and 3.2 % and clinically relevant bleeding rates were 7.9 % and 8.6 %, respectively. Rates of recurrent VTE and bleeding in the warfarin-treated patients meeting the criteria for dose reduction were 4.2 % and 12.8 %, respectively. The reduced dose edoxaban regimen maintained efficacy and safety compared with the 60 mg dose but was safer than warfarin in patients meeting the criteria for dose reduction.

Supplementary Material to this article is available online at www.thrombosis-online.com.

Population Pharmacokinetics of Edoxaban in Patients with Non-Valvular Atrial Fibrillation in the ENGAGE AF-TIMI 48 Study, a Phase III Clinical Trial

INTRODUCTION

Edoxaban is a novel factor Xa inhibitor. This study characterizes the population pharmacokinetics of edoxaban in patients with non-valvular atrial fibrillation (NVAF) included in the phase III ENGAGE AF-TIMI 48 study, evaluates covariates for the dose-exposure relationship in this population, and assesses the impact of protocol-specified dose reductions on exposure using simulations.

METHODS

Model development was performed using NONMEM(®) and based on sparse data from the ENGAGE AF-TIMI 48 study augmented with dense data from 13 phase I studies to inform and stabilize the model. The influence of body weight (WT), creatinine clearance (CLCR), concomitant P-glycoprotein (P-gp) inhibitors, age, sex, race, and NVAF on pharmacokinetic parameters was evaluated based on statistical significance and clinical relevance.

RESULTS

A two-compartment model with first-order elimination and first-order absorption after an absorption lag-time best described the data. Apparent volume and clearance terms increased with increasing WT. Apparent renal clearance increased with increasing CLCR. Apparent non-renal, renal, and inter-compartmental clearance terms differed between phase I volunteers and NVAF patients. Asian patients were found to have increased apparent central volume of distribution, bioavailability, and total apparent clearance. Concomitant P-gp inhibitors increased the bioavailability statistically significantly, but this did not reach clinical relevance.

CONCLUSION

Edoxaban disposition and the variability in this disposition, including influence of covariates, after oral administration were adequately characterized in patients with NVAF. The 50 % dose reduction in patients with low WT (≤60 kg), moderate renal impairment (CLCR ≤50 mL/min), or concomitant P-gp inhibitors led to 30 % lower exposure than in the other patients.

Population Pharmacokinetics of Edoxaban in Japanese Atrial Fibrillation Patients With Severe Renal Impairment

This is a population pharmacokinetic (PopPK) analysis to predict PK of edoxaban, a direct-acting oral anticoagulant, in nonvalvular atrial fibrillation (NVAF) patients with severe renal impairment (SRI; creatinine clearance [CL_cr ] <30 mL/min). Data from a phase 3 study recently conducted in Japanese NVAF patients (n = 90), including patients with SRI, were used to update the ENGAGE PopPK model that had been developed based on pooled data from the phase 3 ENGAGE AF-TIMI 48 study and 13 phase 1 PK studies, which included few patients with SRI. The final model indicated that the ENGAGE PopPK model was applicable to Japanese patients in that the model-simulated and study-observed concentration-time profiles were in agreement. Estimated model parameters after the addition of Japanese SRI data were consistent with those derived from the original ENGAGE PopPK data set. The model-predicted exposure in NVAF patients with SRI who received edoxaban at a 15-mg, once-daily dose was similar to that in patients with normal renal function or with mild renal impairment receiving a 30-mg dose. This suggests that efficacy and safety data from the ENGAGE AF study can be used to support dose setting for NVAF patients with SRI.

Direct oral anticoagulant considerations in solid organ transplantation: A review

For more than 60 years, warfarin was the only oral anticoagulation agent available for use in the United States. In many recent clinical trials, several direct oral anticoagulants (DOACs) demonstrated similar efficacy with an equal or superior safety profile, with some other notable benefits. The DOACs have lower inter- and intrapatient variability, much shorter half-lives, and less known drug-drug and drug-food interactions as compared to warfarin. Despite these demonstrated benefits, the use of DOACs has not gained uniform acceptance because of lack of supportive data in special patient populations, including recipients of solid organ transplants maintained on immunosuppression. This review describes the properties of several novel DOACs including their pharmacology and mechanisms of action as they relate to use among solid organ transplant recipients. We have particularly focused on (i) dosing in patients with impaired renal and hepatic function; (ii) considerations for drug-drug interactions with immunosuppressive medications; and (iii) management of the anticoagulated patients at the time of unplanned surgery. The risks and benefits of the use of DOACs in solid organ transplant recipients should be carefully evaluated prior to the introduction of these agents in this highly distinct patient population.

The factor xa inhibitor edoxaban for the prevention of stroke and systemic embolism in patients with atrial fibrillation

INTRODUCTION

With the rising prevalence of nonvalvular atrial fibrillation (NVAF) in the general population, the development of new drugs for prevention of thromboembolic events is essential. Non-vitamin K antagonist oral anticoagulants (NOACs) have been shown to present a number of advantages over conventionally used agents, such as predictable pharmacokinetics and no requirement for continuous anticoagulant monitoring. The most recently approved NOAC for the NVAF indication is edoxaban. Several subgroup analyses from the edoxaban phase III ENGAGE AF-TIMI 48 trial have now been published, alongside meta-analysis data comparing the four currently approved NOACs. Consequently, an updated review of the literature is merited. Areas covered: A PubMed search using the terms 'edoxaban', 'non-vitamin K antagonist oral anticoagulant', 'ENGAGE AF-TIMI 48', and 'atrial fibrillation' was performed and results screened for the most relevant English language publications. The market position, pharmacological profile, clinical efficacy, safety and tolerability of edoxaban are presented and discussed. Expert commentary: Edoxaban has been shown to have an efficacy similar or superior to that of warfarin, with a potentially lower risk of major bleeding and predictable, dose-dependent pharmacology. In order to clarify its position within the NOAC market, head-to-head comparative studies are required.

Implications of edoxaban in the prevention and treatment of thromboembolic complications in clinical practice

Edoxaban is a once-daily oral inhibitor of factor Xa, currently indicated to reduce the risk of stroke or systemic embolism in nonvalvular atrial fibrillation patients and for the treatment and prevention of venous thromboembolism (EMA, FDA and Japan). The ENGAGE AF-TIMI 48 and the Hokusai-VTE trials demonstrated that edoxaban was at least as effective as warfarin for the prevention of stroke or systemic embolism in nonvalvular atrial fibrillation patients, as well as for the prevention and treatment of venous thromboembolism, but with a lesser risk of bleeding in both cases. In addition, it seems a cost-effective strategy for the management of this population. In this review, the implications of the most recent available evidence about edoxaban in clinical practice will be updated.

Edoxaban Exposure-Response Analysis and Clinical Utility Index Assessment in Patients With Symptomatic Deep-Vein Thrombosis or Pulmonary Embolism

Edoxaban exposure-response relationships from the phase III study evaluating edoxaban for prevention and treatment of venous thromboembolism (VTE) in patients with acute deep vein thrombosis (DVT) and/or pulmonary embolism (PE) were assessed by parametric time-to-event analysis. Statistical significant exposure-response relationships were recurrent VTE with hazard ratio (HR) based on average edoxaban concentration at steady state (Cav) (HRCav) = 0.98 (i.e., change in the HR with every 1 ng/mL increase of Cav); the composite of recurrent DVT and nonfatal PE with HRCav = 0.99; and the composite of recurrent DVT, nonfatal PE, and all-cause mortality HRCav = 0.98, and all death using maximal edoxaban concentration (Cmax) with HR (Cmax) = 0.99. No statistical significant exposure-response relationships were found for clinically relevant bleeding or major adverse cardiovascular event. Results support the recommendation of once-daily edoxaban 60 mg, and a reduced 30 mg dose in patients with moderate renal impairment, body weight ≤60 kg, or use of P-glycoprotein inhibitors verapamil or quinidine.

Population pharmacokinetics of edoxaban in patients with symptomatic deep-vein thrombosis and/or pulmonary embolism--the Hokusai-VTE phase 3 study

AIMS

This study characterized the population pharmacokinetics of edoxaban in patients with symptomatic deep-vein thrombosis and/or pulmonary embolism in the Hokusai-VTE phase 3 study. The impact of the protocol-specified 50% dose reductions applied to patients with body weight ≤ 60 kg, creatinine clearance (CL(cr)) of 30 to 50 ml min(-1) or concomitant P-glycoprotein inhibitor on edoxaban exposure was assessed using simulations.

METHODS

The sparse data from Hokusai-VTE, 9531 concentrations collected from 3707 patients, were pooled with data from 13 phase 1 studies. In the analysis, the covariate relationships used for dose reductions were estimated and differences between healthy subjects and patients as well as additional covariate effects of age, race and gender were explored based on statistical and clinical significance.

RESULTS

A linear two-compartment model with first order absorption preceded by a lag time best described the data. Allometrically scaled body weight was included on disposition parameters. Apparent clearance was parameterized as non-renal and renal. The latter increased non-linearly with increasing CL(cr). Compared with healthy volunteers, inter-compartmental clearance and the CL(cr) covariate effect were different in patients (+64.6% and +274%). Asian patients had a 22.6% increased apparent central volume of distribution. The effect of co-administration of P-glycoprotein inhibitors seen in phase 1 could not be confirmed in the phase 3 data. Model-based simulations revealed lower exposure in dose-reduced compared with non-dose-reduced patients.

CONCLUSIONS

The adopted dose-reduction strategy resulted in reduced exposure compared with non-dose-reduced, thereby overcompensating for covariate effects. The clinical impact of these differences on safety and efficacy remains to be evaluated.