Andexanet alfa for the treatment of hemorrhage

Effect of PCC on Thrombin Generation among Patients on Factor Xa Inhibitors with Major Bleeding or Needing Urgent Surgery (GAUGE): Design and Rationale

Background  Direct factor Xa inhibitors (FXaIs) account for most oral anticoagulant use and FXaI-associated bleeding events are common. Clinicians have variable national and regional access to specific FXaI reversal agents such as andexanet alfa. Many centers have adopted the use of prothrombin complex concentrates (PCCs) as hemostatic therapy for FXaI-associated major bleeding events. PCC does not impact circulating FXaI levels and its mechanism of action to achieve hemostasis in FXaI-associated bleeding is uncertain. While PCC increases quantitative thrombin generation assay (TGA) parameters, it does not correct FXaI-altered thrombin generation kinetics, nor does it normalize thrombin generation. Clinical data supporting the use of PCC are based on cohort studies reporting clinical hemostatic efficacy, which is difficult to measure. The benefits of PCC for FXaI-associated bleeding beyond supportive care are uncertain. Objective  GAUGE is a prospective observational study designed to measure the effects of four-factor PCC administration (Octaplex) on TGA parameters among patients with FXaI-associated bleeding or needing urgent surgery. Methods  Laboratory outcomes will include the mean paired change in TGA parameters from pre- to post-PCC administration and the proportion of participants whose post-PCC TGA values fall within a defined reference range. Clinical outcomes will include hemostatic efficacy, thromboembolic complications, and all-cause death at 30 days post-PCC. Conclusion  Development of a viable and universally accessible FXaI bleed management strategy is crucial. GAUGE will provide in vivo data on the effects of PCC among patients with FXaI-associated bleeding.

Andexanet Alfa to Reverse the Effect of Factor Xa Inhibitors in Intracranial Hemorrhage

Andexanet alfa (AA) is a recombinant factor Xa competing for binding with factor Xa inhibitors, thereby reversing their anticoagulation effects. Since 2019, it has been approved for individuals under apixaban or rivaroxaban therapy suffering from life-threatening or uncontrolled bleeding. Apart from the pivotal trial, real-world data on the use of AA in daily clinics are scarce. We reviewed the current literature on patients with intracranial hemorrhage (ICH) and summarized the available evidence regarding several outcome parameters. On the basis of this evidence, we provide a standard operating procedure (SOP) for routine AA application. We searched PubMed and additional databases through 18 January 2023 for case reports, case series, studies, reviews, and guidelines. Data on hemostatic efficacy, in-hospital mortality, and thrombotic events were pooled and compared with the pivotal trial data. While hemostatic efficacy in world-wide clinical routine seems to be comparable to the pivotal trial, thrombotic events and in-hospital mortality appear to be substantially higher. Various confounding factors responsible for this finding such as exclusion and inclusion criteria resulting in a highly selected patient cohort within the controlled clinical trial have to be considered. The SOP provided should support physicians in patient selection for AA treatment as well as facilitate routine use and dosing. This review underlines the urgent need for more data from randomized trials to appreciate the benefit and safety profile of AA. Meanwhile, this SOP should help to improve frequency and quality of AA use in patients suffering from ICH while on apixaban or rivaroxaban treatment.

DOAC-associated bleeding, hemostatic strategies, and thrombin generation assays - a review of the literature

Direct oral anticoagulants (DOACs) account for most oral anticoagulant use. DOAC-associated bleeding events are commonly encountered in clinical practice and are associated with substantial morbidity and mortality. Both specific reversal agents and nonspecific hemostatic therapies, such as prothrombin complex concentrates, are used in the management of DOAC-associated bleeding. Measuring hemostatic efficacy and demonstrating a clinical impact from these therapies among studies of bleeding patients is challenging. Thrombin generation assays provide information on the total hemostatic potential of plasma, and have emerged as a promising modality to both measure the impact of DOACs on coagulation and to evaluate the effects of hemostatic therapies among patients with DOAC-associated bleeding. The mechanisms by which nonspecific hemostatic agents impact coagulation and thrombin generation in the context of DOAC therapy are unclear. As a result, we undertook a review of the literature using a systematic search strategy with the goal of summarizing the effects of DOACs on thrombin generation and the effects of both specific reversal agents and nonspecific hemostatic therapies on DOAC-altered thrombin generation parameters. We sought to identify clinical studies focusing on whether altered thrombin generation is associated with clinical bleeding and whether correction of altered thrombin generation parameters predicts improvements in clinical hemostasis. Lastly, we sought to outline future directions for the application of thrombin generation assays toward anticoagulation therapies and the question of anticoagulation reversal.

Andexanet alfa for reversal of factor Xa inhibitors: a critical review of the evidence

Direct oral anticoagulants are associated with lower rates of bleeding than vitamin K antagonists, but life-threatening bleeding still occurs. Andexanet alfa is a catalytically inactive recombinant modified human factor Xa molecule that reverses the anticoagulant effect of direct and indirect acting factor Xa inhibitors. In the ANNEXA-4 study, treatment with andexanet was associated with a 92% reduction in median anti-Xa activity levels and excellent or good hemostasis in 82% of patients presenting with serious bleeding while receiving apixaban or rivaroxaban. In this review, we discuss the burden of bleeding in anticoagulated patients and the need for reversal agents, review the mechanism of action of andexanet and critically evaluate the evidence for its efficacy and safety.