Increased benefit of betrixaban among patients with a history of venous thromboembolism: a post-hoc analysis of the APEX trial

A clinical focus on the use of extended-duration thromboprophylaxis in medically ill patients

PURPOSE

This review describes and analyzes literature to provide recommendations for use of extended-duration thromboprophylaxis (EDT) in medically ill patients.

SUMMARY

Guidelines recommend pharmacologic thromboprophylaxis for patients at increased thrombosis risk during hospitalization and recommend against extending thromboprophylaxis beyond hospitalization. Despite these recommendations, observational data demonstrate that venous thromboembolism (VTE) risk persists following hospital discharge. A MEDLINE literature search was performed to identify original research evaluating the safety and efficacy of EDT. Eight meta-analyses and 5 randomized controlled trials-each varying in the agents studied (enoxaparin, rivaroxaban, apixaban, and betrixaban)-were selected for inclusion. Collectively, the evaluated data demonstrates that EDT reduces the incidence of VTE at the expense of increasing the risk of major bleeding and without providing mortality reduction. Variations in enrollment criteria, differences in EDT strategies, and uncertainty regarding proper patient selection limit the applicability of EDT in practice. Rivaroxaban and betrixaban gained Food and Drug Administration (FDA) approval on the basis of results of the APEX and MARINER trials and a post hoc analysis of the MAGELLEN trial results. Although a number of agents are FDA approved for use in EDT, clinicians must carefully weigh the risks vs benefits of EDT with these agents until studies demonstrate a more favorable risk-benefit profile.

CONCLUSION

Evidence to support EDT in medically ill patients is inconclusive and has highlighted the need for an individualized approach. The reviewed evidence supports guideline recommendations from both the American College of Chest Physicians and the American Society of Hematology that recommend against routine use of EDT in the majority of medically ill patients. Future studies are needed to optimize the risk-benefit profile of EDT and to ensure proper patient selection.

Current Opinion on the use of Direct Oral Anticoagulants for the Prophylaxis of Venous Thromboembolism among Medical Inpatients

Venous thromboembolism (VTE) is a known cause of morbidity and mortality, especially among acutely ill medical patients. Although VTE prophylaxis is part of post-discharge clinical care in surgical patients, there is controversy regarding its use in acutely ill medical patients and the current guideline statements suggest against its routine use. Recent clinical trials (APEX, MAGELLAN and MARINER) compared the safety and efficacy of direct oral anticoagulants (including betrixaban and rivaroxaban) with the standard of the care, enoxaparin, to identify the risk–benefit tradeoff. In this review, we summarized the key findings from these trials and substudies and recent updates in society guidelines regarding VTE prevention. In addition, we discussed the potential barriers, cost-effectiveness, and COVID-19 with respect to the implementation of extended-duration or post-discharge usage of direct oral anticoagulants.

Post-hospital discharge venous thromboembolism prophylaxis in medically ill patients

There is a widely expressed concern about an unmet need for post hospitalization venous thromboembolism (VTE) prophylaxis in medically ill patients, however, physicians and hospitals have been slow to implement this measure. Recommendations against extended VTE prophylaxis in medical patients from the American Society of Hematology (ASH) in 2018 and the withholding of approval of betrixiban by the European Medicines Agency also in 2018 may have been influential in this regard. Furthermore, rivaroxaban the other drug approved for this indication in the U.S has not yet been approved in Europe. In addition, hospital administrators, those monitoring expenses in the U.S, have been reluctant to support a treatment which will mostly involve outpatients. Internal medicine physicians, hospitalists and nursing home physicians have not shared the fervor for post hospital VTE prophylaxis, whether with anticoagulants or aspirin, that their orthopedic surgery colleagues have, particularly in hip and knee arthroplasty. This is despite an increased risk of post hospital discharge thrombosis in both groups of patients. Enter hospitalized patients with COVID-19, a potentially severe medical illness with high hospitalization related thrombosis risk, and questions arise as to whether these medical patients, who are clearly more hypercoagulable during hospitalization than those in previous studies, should warrant post hospital discharge prophylaxis.

Anticoagulation in Venous Thromboembolism Prophylaxis in Medically Ill Patients: Potential Impact of NOACs

While substantial evidence supports the use of standard-duration injectable anticoagulants for venous thromboembolism (VTE) prophylaxis, consensus is mixed about which agents may be preferred in acutely ill patients with ongoing need of VTE prophylaxis past the first 10-day duration of hospital stay and post-discharge. Non-vitamin K antagonist oral anticoagulants (NOACs) provide Factor Xa inhibition to prevent the thrombin generation essential in thromboembolism development, but evidence for the efficacy and safety of most NOACs is conflicting regarding extended-duration prophylaxis. Enoxaparin, a preferred injectable anticoagulant in standard-duration VTE prophylaxis, has shown an increased risk of major bleeding events when used in extended-duration prophylaxis, which outweighs its benefit. Rivaroxaban has demonstrated efficacy in extended-duration prophylaxis, but both rivaroxaban and apixaban have shown increased risks of major bleeding. Betrixaban remains the only NOAC approved in the USA for extended-duration VTE prophylaxis, and it demonstrates efficacy, with fewer adverse effects than other NOACs. This review evaluates the appropriateness of different NOAC agents compared with current therapies for the extended-duration VTE prophylaxis setting in medically ill populations.

Venous thromboembolism: A clinician update

Venous thromboembolism (VTE) is a common vascular condition. New medications are available to prevent hospital-associated VTE. Strategies are being studied to increase appropriate diagnostic testing utilization. Management of deep vein thrombosis (DVT) and pulmonary embolism (PE) has evolved with the advent of new anticoagulant options and catheter-directed intervention. In light of this, providers are commonly challenged with the decision regarding inpatient versus outpatient management. Which patients require long-term (> 3 months) anticoagulation is challenging and multiple clinical prediction models may be used to help determine the risk-benefit ratio in each patient. The management of VTE is an ongoing area of research and is rapidly evolving.

Evaluation of unmet clinical needs in prophylaxis and treatment of venous thromboembolism in high-risk patient groups: cancer and critically ill

Background

Clinical practice shows that venous thromboembolism (VTE) presents a substantial burden in medical patients, and awareness and advocacy for its primary and secondary prevention remains inadequate. Specific patient populations, such as those with cancer and the critically ill, show elevated risk for VTE, bleeding or both, and significant gaps in VTE prophylaxis and treatment exist in these groups.

Objective

To present novel insights and consolidated evidence collected from experts, clinical practice guidelines and original studies on the unmet needs in thromboprophylaxis, and on the treatment of VTE in two high-risk patient groups: patients with cancer and the critically ill.

Methodology

To identify specific unmet needs in the management of VTE, a methodology was designed and implemented that assessed gaps in prophylaxis and treatment of VTE through interviews with 44 experts in the field of thrombosis and haemostasis, and through a review of current guidelines and seminal studies to substantiate the insights provided by the experts. The research findings were then analysed, discussed and consolidated by a multidisciplinary group of experts.

Results

The gap analysis methodology identified shortcomings in the VTE risk assessment tools, patient stratification approaches for prophylaxis, and the suboptimal use of anticoagulants for primary prophylaxis and treatment.

Conclusions

Specifically, patients with cancer need better VTE risk assessment tools to tailor primary thromboprophylaxis to tumour types and disease stages, and the potential for drug–drug interactions needs to be considered. In critically ill patients, unfractionated heparin is not advised as a first-line treatment option, and the strength of evidence is increasing for direct oral anticoagulants as a treatment option over low-molecular-weight heparins.

Electronic supplementary material

The online version of this article (10.1186/s12959-019-0196-6) contains supplementary material, which is available to authorized users.

Betrixaban for Extended Venous Thromboembolism Prophylaxis in High-Risk Hospitalized Patients: Putting the APEX Results into Practice

Acutely ill hospitalized medical patients remain at high thromboembolic risk for several weeks after discharge. Previous trials with extended-duration thromboprophylaxis using enoxaparin, apixaban, and rivaroxaban failed to achieve acceptable net clinical benefit, largely due to excess of major bleeding. Betrixaban is a novel factor Xa inhibitor with unique pharmacokinetic properties, including low renal clearance, long half-life, and low peak-to-trough ratio. The phase III APEX trial (N = 7513) compared a betrixaban 160 mg loading dose followed by 80 mg once daily for 35-42 days, with enoxaparin 40 mg once daily for 6-14 days; the betrixaban dose was reduced for renal impairment or a concomitant strong P-glycoprotein (P-gp) inhibitor. The primary efficacy endpoint of composite thrombotic events was not different between treatment arms in cohort 1 (D-dimer ≥ 2 × upper limit of normal). Subsequent exploratory analyses showed a statistically significant difference favoring betrixaban for symptomatic venous thromboembolism and net clinical benefit in the overall population. For the primary safety outcome, betrixaban did not significantly increase major bleeding compared with enoxaparin. Based on available data from the APEX trial and subanalyses, the use of betrixaban in patients similar to those enrolled in the APEX trial can reduce the risk of thromboembolic events without increasing the risk of major bleeding. Patients who may benefit more from betrixaban therapy include those with elevated D-dimer, history of venous thromboembolism, hospitalized for ischemic stroke, hospitalized for heart failure with N-terminal pro-B-type natriuretic peptide ≥ 1975 ng/L, or two or more VTE risk factors. Reduced-dose betrixaban does not appear to provide the same clinical utility as full-dose betrixaban.

Betrixaban in the prevention of venous thromboembolism in medically ill patients

Despite significant advances in strategies and compliance with venous thromboembolism (VTE) prophylaxis, hospital-acquired VTE remains a leading cause of preventable deaths in acute medically ill patients. A majority of venous thromboembolic events occur posthospital discharge when risk factors persist and pharmacoprophylactic regimens have been completed. Until recently, there has been an unmet need for safe and effective extended-duration VTE prevention. Three major trials evaluated this concept, but excess bleeding outweighed the benefit of reduced thromboembolic events. Betrixaban is an oral direct factor Xa inhibitor recently approved for extended-duration VTE prophylaxis in acute medically ill patients at risk for thromboembolism based on results from the Phase III APEX study. This article reviews the pharmacology and supporting data for betrixaban.

Betrixaban for first-line venous thromboembolism prevention in acute medically ill patients with risk factors for venous thromboembolism

INTRODUCTION

Compared to other direct oral anticoagulants, betrixaban has a longer half-life, smaller peak-trough variance, minimal renal clearance, and minimal hepatic Cytochrome P (CYP) metabolism. The Acute Medically Ill VTE Prevention with Extended Duration Betrixaban (APEX) trial evaluated the efficacy and safety of extended duration betrixaban compared to standard duration enoxaparin in acutely ill hospitalized patients. Areas covered: This article describes the role of betrixaban in the prevention of venous thromboembolism (VTE) in acutely ill medical patients. This article provides a consolidated summary of the primary APEX study findings as well as prespecified and exploratory substudies. This article also provides a review of the results of studies in which other direct factor Xa inhibitors have been evaluated in an extended duration regimen in this patient population. Expert commentary: While previous agents have demonstrated that extended duration VTE prophylaxis can be efficacious, betrixaban is the first agent to demonstrate efficacy without an increase in major bleeding. The totality of the data from the APEX trial supports extended duration betrixaban for VTE prophylaxis in the acute medically ill patient population. As such, betrixaban has been approved in the USA for extended VTE prophylaxis in at-risk acute medically ill patients.