Safety, pharmacokinetics and pharmacodynamics of idarucizumab, a specific dabigatran reversal agent in healthy Japanese volunteers: a randomized study

Is there a role for the laboratory monitoring in the management of specific antidotes of direct oral anticoagulants?

Given the growing number of patients receiving direct oral anticoagulant (DOAC), patients requiring rapid neutralization is also increasing in case of major bleedings or urgent surgery/procedures. Idarucizumab is commercialized as a specific antidote to dabigatran while andexanet alfa has gained the Food and Drug Administration and the European Medicines Agency approval as an oral anti-factor Xa inhibitors antidote. Other antidotes or hemostatic agents are still under preclinical or clinical development, the most advanced being ciraparantag. DOAC plasma levels measurement allows to appropriately select patient for antidote administration and may prevent unnecessary prescription of expensive molecules in some acute clinical settings. However, these tests might be inconclusive after some antidote administration, namely andexanet alfa and ciraparantag. The benefit of laboratory monitoring following DOAC reversal remains unclear. Here, we sought to provide an overview of the key studies evaluating the safety and efficacy of DOAC reversal using the most developed/commercialized specific antidotes, to discuss the potential role of the laboratory monitoring in the management of patients receiving DOAC specific antidotes and to highlight the areas that deserve further investigations in order to establish the exact role of laboratory monitoring in the appropriate management of DOAC specific antidotes.

Effectiveness and Safety of Dabigatran Reversal with Idarucizumab in the Taiwanese Population: A Comparison Based on Eligibility for Inclusion in Clinical Trials

Background and Objectives: The effectiveness and safety of idarucizumab for the reversal of the effects of dabigatran have been proven. However, there remains a paucity of literature comprehensively investigating outcomes in real-world patients. This is especially true when comparing patients who were eligible for inclusion in the RE-VERSE AD trial with patients who were ineligible. As the prescription of dabigatran has become increasingly popular, the generalizability of the results to real-world populations has come into question due to the broad variability of real-world patients receiving dabigatran. Our study aimed to identify all patients who were prescribed idarucizumab and examined how effectiveness and safety varied among those patients who were eligible and ineligible for the trial. Materials and Methods: This retrospective cohort study analyzed the largest medical database in Taiwan. We enrolled all patients who were prescribed and received idarucizumab from when it became available in Taiwan up until May 2021. A Total of 32 patients were included and analyzed, and they were further divided into subgroups based on their eligibility for inclusion in the RE-VERSE AD trial. Multiple outcomes were evaluated, including successful hemostasis rate, complete reversal efficacy of idarucizumab, 90-day thromboembolic events, intra-hospital mortality, and adverse event rate. Results: In our study, we found that 34.4% of real-world cases of idarucizumab use were ineligible for the RE-VERSE AD trials. The eligible group had higher successful hemostasis rates (95.2% vs. 80%) and anticoagulant effect reversal rates compared to the ineligible group (73.3% vs. 0%). The mortality rates were 9.5%, compared to 27.3% in the ineligible group. Few adverse effects (n = 3) and 90-day thromboembolic events (n = 1) were observed in either group. Among the ineligible cases, all acute ischemic stroke patients (n = 5) received definite, timely treatments without complications. Conclusions: Our study demonstrated the real-world effectiveness and safety of idarucizumab infusion for trial-eligible patients and all acute ischemic stroke patients. However, although it seems to be effective and safe, idarucizumab appears to be less effective in other trial-ineligible patients. Despite this result, our study provides further evidence for extending the applicability of idarucizumab in real-world scenarios. Our study suggests that idarucizumab can be a safe and effective option for reversing the anticoagulant effect of dabigatran, particularly for eligible patients.

Retrospective analysis of the effectiveness of a reduced dose of idarucizumab in dabigatran reversal

BACKGROUND

The recommended dose of idarucizumab, the specific reversal agent for dabigatran etexilate, is 5g. However, published data showed biochemical reversal after an initial 2.5g dose.

OBJECTIVES

This study aims to retrospectively compare the clinical effectiveness of 2.5g and 5g doses of idarucizumab used in dabigatran reversal in three hospitals in Auckland, New Zealand.

METHODS

All patients receiving idarucizumab for dabigatran reversal between 1st April 2016 and 31st December 2018 were included. The primary outcome was the likelihood of receiving a second dose of idarucizumab during the same admission. Secondary outcomes included normalisation of coagulation profiles; and 30-day thrombotic, bleeding and mortality rates.

RESULTS

Of 329 patients included, 206 received an upfront 2.5g dose and 123 received a 5g dose. The median age was 78 years and median creatinine clearance was 50mL/min. Most patients (62.6%) required idarucizumab for an urgent procedure, while 37.4% presented with bleeding. A 2.5g dose was not associated with an increased rate of receiving a second dose (OR 0.686, 95% CI 0.225-2.090). A similar proportion of patients in each group achieved a normal APTT (73.8% vs 80.0%, p=0.464) and dTCT (95.9% vs 91.4%, p=0.379) following idarucizumab infusion. There was no increase in the rate of death (OR 0.602, 95% CI 0.292-1.239), thrombosis (OR 0.386, 95% CI 0.107-1.396) or bleeding (OR 0.96, 95% CI 0.27-3.33) in the 2.5g dose group compared to the 5g dose group.

CONCLUSIONS

An initial 2.5g dose of idarucizumab appears effective for dabigatran reversal in the real-world setting.

Effective Removal of Dabigatran by Idarucizumab or Hemodialysis: A Physiologically Based Pharmacokinetic Modeling Analysis

Background

Application of idarucizumab and hemodialysis are options to reverse the action of the oral anticoagulant dabigatran in emergency situations.

Objectives

The objectives of this study were to build and evaluate a mechanistic, whole-body physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) model of idarucizumab, including its effects on dabigatran plasma concentrations and blood coagulation, in healthy and renally impaired individuals, and to include the effect of hemodialysis on dabigatran exposure.

Methods

The idarucizumab model was built with the software packages PK-Sim® and MoBi® and evaluated using the full range of available clinical data. The default kidney structure in MoBi® was extended to mechanistically describe the renal reabsorption of idarucizumab and to correctly reproduce the reported fractions excreted into urine. To model the PD effects of idarucizumab on dabigatran plasma concentrations, and consequently also on blood coagulation, idarucizumab-dabigatran binding was implemented and a previously established PBPK model of dabigatran was expanded to a PBPK/PD model. The effect of hemodialysis on dabigatran was implemented by the addition of an extracorporeal dialyzer compartment with a clearance process governed by dialysate and blood flow rates.

Results

The established idarucizumab-dabigatran-hemodialysis PBPK/PD model shows a good descriptive and predictive performance. To capture the clinical data of patients with renal impairment, both glomerular filtration and tubular reabsorption were modeled as functions of the individual creatinine clearance.

Conclusions

A comprehensive and mechanistic PBPK/PD model to study dabigatran reversal has been established, which includes whole-body PBPK modeling of idarucizumab, the idarucizumab-dabigatran interaction, dabigatran hemodialysis, the pharmacodynamic effect of dabigatran on blood coagulation, and the impact of renal function in these different scenarios. The model was applied to explore different reversal scenarios for dabigatran therapy.

Electronic supplementary material

The online version of this article (10.1007/s40262-019-00857-y) contains supplementary material, which is available to authorized users.

Idarucizumab Reverses Dabigatran Anticoagulant Activity in Healthy Chinese Volunteers: A Pharmacokinetics, Pharmacodynamics, and Safety Study

INTRODUCTION

Idarucizumab is a humanized monoclonal antibody fragment that specifically binds to dabigatran with high affinity and reverses its anticoagulant effect. This study investigated the pharmacokinetics (PK) and pharmacodynamics (PD) of idarucizumab in healthy Chinese subjects at steady state of dabigatran and explored the effect of idarucizumab on PK and PD of dabigatran.

METHODS

Twelve subjects received dabigatran etexilate treatment alone (220 mg twice daily, b.i.d., oral). After a washout period, the 12 subjects again received dabigatran etexilate (220 mg b.i.d., oral) and idarucizumab (2.5 + 2.5 g, intravenous) 2 h after the last administration of dabigatran etexilate.

RESULTS

The geometric mean (gMean) values of area under the plasma concentration-time curve (AUC_0-∞) and maximum concentration (C_max) were 44,200 nmol h/L and 30,900 nmol/L, respectively. An amount of 35.3 μmol of idarucizumab, corresponding to 33.8% of the total dose, was excreted by urine over 72 h. The area under the effect (AUEC_above,2-12) in the presence and absence of idarucizumab was close to zero for all coagulation parameters, diluted thrombin time (dTT), ecarin clotting time (ECT), activated partial thromboplastin time (aPTT), and thrombin time (TT), which indicated the reversal of dabigatran anticoagulation by idarucizumab. There were no serious adverse events reported in this study. No subject tested positive for anti-idarucizumab antibodies.

CONCLUSION

Idarucizumab was well tolerated and no subject tested positive for anti-idarucizumab antibodies in this study. PK and PD of idarucizumab in healthy Chinese subjects at a steady state of dabigatran were comparable with those in Japanese and Caucasian subjects.

CLINICAL REGISTRATION

ClinicalTrials.gov Identifier No. NCT03086356.

Idarucizumab for Emergency Reversal of Anticoagulant Effects of Dabigatran: Interim Results of a Japanese Post-Marketing Surveillance Study

INTRODUCTION

Idarucizumab, a monoclonal antibody fragment, was developed to reverse the anticoagulant effect of dabigatran, and it was approved in Japan in September 2016. An all-case post-marketing surveillance is ongoing to collect data in Japanese patients treated with idarucizumab who had serious bleeding (Group A) or required an urgent procedure (Group B).

METHODS

The primary endpoint was the incidence of adverse drug reactions (ADRs). The secondary endpoint was the maximum extent of reversal of the anticoagulant effect of dabigatran based on activated partial thromboplastin time (aPTT) within 4 h after idarucizumab administration.

RESULTS

This interim analysis included 262 patients who received idarucizumab. Eighteen patients (6.9%) experienced ADRs within 4 weeks. The reversal effect of idarucizumab based on aPTT within 4 h after idarucizumab administration was assessed in 30 patients and the median maximum percentage reversal was 100%. In Group A, the median time to bleeding cessation in patients without intracranial bleeding was 3.3 h. In Group B, normal intraoperative hemostasis was reported in 63 patients (72.4%).

CONCLUSIONS

The results of this interim analysis suggest that idarucizumab is safe and effective for the reversal of dabigatran in Japanese patients in a real-world setting, and support the continued use of idarucizumab.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT02946931.

Direct-Acting Oral Anticoagulants and Their Reversal Agents-An Update

Background: Over the last ten years, a new class of drugs, known as the direct-acting oral anticoagulants (DOACs), have emerged at the forefront of anticoagulation therapy. Like the older generation anticoagulants, DOACs require specific reversal agents in cases of life-threatening bleeding or the need for high-risk surgery. Methods: Published literature was searched, and information extracted to provide an update on DOACS and their reversal agents. Results: The DOACs include the direct thrombin inhibitor—dabigatran, and the factor Xa inhibitors—rivaroxaban, apixaban, edoxaban, and betrixaban. These DOACs all have a rapid onset of action and each has a predictable therapeutic response requiring no monitoring, unlike the older anticoagulants, such as warfarin. Two reversal agents have been approved within the last five years: idarucizumab for the reversal of dabigatran, and andexanet alfa for the reversal of rivaroxaban and apixaban. Additionally, ciraparantag, a potential “universal” reversal agent, is currently under clinical development. Conclusions: A new generation of anticoagulants, the DOACs, and their reversal agents, are gaining prominence in clinical practice, having demonstrated superior efficacy and safety profiles. They are poised to replace traditional anticoagulants including warfarin.

Pharmacokinetics of idarucizumab and its target dabigatran in patients requiring urgent reversal of the anticoagulant effect of dabigatran

BACKGROUND

Idarucizumab is a monoclonal antibody fragment that reverses dabigatran anticoagulation. Pharmacokinetics (PK) of idarucizumab have been described in healthy, elderly, or renally impaired (RI) volunteers, but PK data in patients are lacking.

OBJECTIVES

This analysis describes the PK of idarucizumab and its target dabigatran in bleeding/surgical patients.

PATIENTS AND METHODS

Results from the Reversal Effects of Idarucizumab on Active Dabigatran study, a prospective, multicenter, single-arm study demonstrated the reversal of dabigatran anticoagulation by idarucizumab in patients with uncontrollable bleeding (group A) or who needed urgent surgery (group B). Idarucizumab and unbound dabigatran concentrations, immunogenicity, and pharmacodynamics were assessed.

RESULTS

Total and unbound dabigatran levels at baseline were 165 ng/mL vs 110 ng/mL and 103 ng/mL vs 69.5 ng/mL in group A and B patients, respectively. Maximum plasma concentrations and area under the curves (AUC0-24 ) of idarucizumab in group A vs B, respectively, were 24 900 nmol/L vs 25 000 nmol/L and 76 600 nmol/h/L vs 68 000 nmol/h/L. Idarucizumab AUC0-24 increased by 38% in mild, 90% in moderate, and 146% in severe RI patients vs normal renal function. Hepatic impairment or geographical region had no relevant effect on idarucizumab PK. Idarucizumab immediately decreased unbound dabigatran concentration (<20 ng/mL). A linear correlation was observed between unbound dabigatran and diluted thrombin time and ecarin clotting time. Antidrug antibody titers were low (1-64 at day 30; 0-16 at day 90) and had no impact on idarucizumab PK and pharmacodynamics.

CONCLUSION

Idarucizumab PK in target patients was consistent with phase I data. Patient characteristics had no impact on PK, whereas RI increased the exposure of idarucizumab and dabigatran.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT02104947.

Novel reversal agents and laboratory evaluation for direct-acting oral anticoagulants (DOAC): An update

Novel oral anticoagulants (NOACs) are no longer "novel" but their reversal agents definitely are. Although NOACs enjoy high clinical efficacy, monitoring and reversal of their effect is a challenge which this review attempts to surmount. Ideally, for NOAC activity measurement, specific anti-Factor IIa levels and anti -Factor Xa levels should be monitored (chromogenic assays), but such tests are not readily available. Modifications of the existing coagulation tests catering to this unmet need for quantification of DOAC activity have been reviewed. The available United States Food and Drug Administration (FDA) approved reversal agents, idarucizumab for dabigatrin and andexanet alfa for anti-Xa direct acting oral anticoagulants have given promising results but are prohibitively priced. Medline, Embase, and Scopus databases were thoroughly searched for clinical trials on laboratory investigations and specific as well as non-specific reversal-agents for DOACs.