Recent Advances in Anticoagulant Treatment of Immune Thrombosis: A Focus on Direct Oral Anticoagulants in Heparin-Induced Thrombocytopenia and Anti-Phospholipid Syndrome

Complex management of pulmonary embolism in APLA syndrome: a case study of ECMO and bivalirudin utilization

We report a case of a 22-year-old female with antiphospholipid antibody (APLA) syndrome who presented with severe dyspnea. Diagnostic imaging confirmed pulmonary embolism (PE), and treatment comprised unfractionated heparin and apixaban. APLA syndrome was diagnosed based on clinical, serological, and radiological findings. During evaluation, the patient developed cardiogenic shock necessitating catheter-directed thrombolysis, followed by veno-arterial extracorporeal membrane oxygenation (VA-ECMO) due to deteriorating condition and suspected heparin-induced thrombocytopenia (HIT). Surgical embolectomy with bivalirudin use followed, and a hybrid veno-arterial-venous (VAV) ECMO setup was implemented. Postoperatively, the patient improved, transitioning to veno-venous (VV) ECMO and eventually ECMO withdrawal. ECMO is a valuable tool for managing complex cardiorespiratory cases like PE. In the context of HIT and APLA syndrome, prompt anticoagulant transition is vital, and bivalirudin is an effective heparin alternative. Our study highlights the challenges involved in managing patients needing ECMO support with immunothrombotic conditions like HIT and APLA syndrome.

Therapeutic strategies in FcγIIA receptor-dependent thrombosis and thromboinflammation as seen in heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombocytopenia and thrombosis (VITT)

INTRODUCTION

Fcγ-receptors (FcγR) are membrane receptors expressed on a variety of immune cells, specialized in recognition of the Fc part of immunoglobulin G (IgG) antibodies. FcγRIIA-dependent platelet activation in platelet factor 4 (PF4) antibody-related disorders have gained major attention, when these antibodies were identified as the cause of the adverse vaccination event termed vaccine-induced immune thrombocytopenia and thrombosis (VITT) during the COVID-19 vaccination campaign. With the recognition of anti-PF4 antibodies as cause for severe spontaneous and sometimes recurrent thromboses independent of vaccination, their clinical relevance extended far beyond heparin-induced thrombocytopenia (HIT) and VITT.

AREAS COVERED

Patients developing these disorders show life-threatening thromboses, and the outcome is highly dependent on effective treatment. This narrative literature review summarizes treatment options for HIT and VITT that are currently available for clinical application and provides the perspective toward new developments.

EXPERT OPINION

Nearly all these novel approaches are based on in vitro, preclinical observations, or case reports with only limited implementation in clinical practice. The therapeutic potential of these approaches still needs to be proven in larger cohort studies to ensure treatment efficacy and long-term patient safety.

Intraoperative argatroban vessel irrigation during microsurgical anastomosis in heparin-induced thrombocytopenia patients: About two cases

Patients with heparin-induced thrombocytopenia or confirmed allergies to heparin have a contraindication to heparin therapy, which poses a problem for intraoperative free flap irrigation in reconstruction. The use of argatroban as an alternative to heparin allowed us to perform a free flap for leg salvage and a deep inferior epigastric perforator flap for breast reconstruction without microvascular complication, with a 0.01 mg/mL solution. We reported two cases of using an alternative treatment to heparin in an emergency and planned surgeries for vessel irrigation during microsurgical anastomosis reconstruction without microvascular complications, suggesting the reliability and effectiveness of its use in case of contraindication to heparin.

[Thromboembolic diseases from a haemostaseologic point of view]

Venous thromboembolism is one of the most common vascular diseases. Increased thrombin formation together with reduced blood flow create a hypercoagulable environment that induces thrombus formation. Anticoagulants play a pivotal role in the treatment and secondary prophylaxis of venous thromboembolism because they effectively interrupt this hypercoagulability. A personalized assessment of the thrombotic risk is essential for planning the duration and intensity of secondary prophylaxis. The occurrence of thrombosis outside a typical risk situation, an atypical localization and a family history of thrombosis indicate a thrombophilic state. In these cases, thrombophilia diagnostics are useful for extended risk assessment. If anti-phospholipid antibodies are detected, the risk of recurrence is particularly increased.

Development of new anticoagulant in 2023: Prime time for anti-factor XI and XIa inhibitors

Thrombosis remains one of the leading causes of death in the world. The history of anticoagulation has evolved considerably from non-specific drugs (i.e., heparins and vitamin K antagonists, VKA) to agents that directly target specific coagulation factors (i.e., argatroban, fondaparinux and direct oral anticoagulants, DOAC). Since the last decade, DOAC are widely used in clinical practice because of their ease to use with favorable pharmacological profile and not requiring monitoring, particularly for venous thromboembolism treatment and prevention and stroke prevention in atrial fibrillation. However, despite having a better safety profile than VKA, their bleeding risk is not negligible. Therefore, research is underway to develop new anticoagulant therapies with a better safety profile. One of these news approaches to reduce the risk of bleeding is to target the coagulation in the intrinsic pathway, in particular the contact activation, with the ultimate goal of preventing thrombosis without impairing hemostasis. Based on epidemiological data with patients with inherited factor XI (FXI) deficiency and preclinical studies, FXI emerged as the most promising candidate target separating hemostasis from thrombosis. This review summaries the role of FXI and FXIa in hemostasis, provides evidence of initial success with FXI pathway inhibitors in clinical trials (such as IONIS-FXI_Rx, fesomersen, osocimab, abelacimab, milvexian, asundexian or xisomab 3G3) and highlights the opportunities and challenges for this next generation of anticoagulants.

Direct oral anticoagulants (DOACs): From the laboratory point of view

Direct oral anticoagulants (DOACs) represent a new generation of drugs that have been increasingly used in the prevention and treatment of thromboembolic states. According to the mechanism of anticoagulant action, DOACs are divided into two groups: direct inhibitors of thrombin (dabigatran) and direct inhibitors of activated factor X (FXa) (rivaroxaban, apixaban, edoxaban, betrixaban). Compared to the vitamin K antagonists, DOACs are superior in terms of onset of action, pharmacokinetic and pharmacodynamics properties and fixed daily dose without the need for routine coagulation monitoring. Despite these advantages, there are clinical conditions in which laboratory measurement of DOACs should be performed. Although DOACs have an impact on screening haemostasis assays (prothrombin time, PT; activated partial thromboplastin time, aPTT; and thrombin time, TT), these tests are not appropriate for quantifying drug levels. Therefore, specific quantitative methods (LC-MS/MS as a gold standard method for all DOACs, coagulometric and chromogenic assays for dabigatran, and chromogenic anti-Xa assays with drug-specific calibrators for inhibitors of FXa) should only be used for determination of DOACs concentration. The aim of this review is to present all aspects of laboratory assessment of DOACs, including pre-analytical, analytical and post-analytical factors in the overall testing process with a special accent on the available specific quantitative methods for measurement of DOACs in circulation.

A Review of the Past, Present and Future of Cancer-associated Thrombosis Management

Venous thromboembolism (VTE) can have a significant impact on the management, quality of life and mortality of patients with cancer. VTE occurs in 5-20% of patients with cancer, and malignancy is associated with up to 25% of all VTE. It is the second leading cause of death in ambulatory patients with cancer who are receiving chemotherapy. Increased rates of cancer-associated thrombosis are attributed to improved patient survival, increased awareness, surgery, antineoplastic treatments and the use of central venous access devices. Many factors influence cancer-associated thrombosis risk and are broadly categorized into patient-related, cancer-related and treatment-related risks. Direct-acting oral anticoagulants have shown themselves to be at least as effective in preventing recurrent VTE in patients with cancer with symptomatic and incidental VTE. This has led to a change in treatment paradigms so that direct-acting oral anticoagulants are now considered first-line agents in appropriately selected patients. In this article, we review the prior and recent landmark studies that have directed the treatment of cancer-associated thrombosis, and discuss specific factors that affect management as well as future treatment considerations.

[Contribution of antiphosphatidylserine/prothrombin (anti-PS/PT) antibody detection in the diagnosis and management of antiphospholipid syndrome (APS)]

Antiphospholipid syndrome (APS) is an autoimmune disease and one of the most common causes of acquired thrombophilia. It is characterised by the occurrence of thrombotic or obstetric events associated with the presence of persistent antiphospholipid antibodies. The diagnosis can be challenging, particularly because some biological tests can be disturbed by anticoagulant treatment or inflammation. In the recent years, new antiphospholipid antibodies, including anti-phosphatidylserine/prothrombin antibodies (anti-PS/PT), have emerged but their clinical significance and causality remain uncertain. Biologically, several studies have found a strong correlation between the presence of lupus anticoagulant (LA) and anti-PS/PT antibodies. Clinically, the presence of anti-PS/PT antibodies is associated with an increased risk of thrombosis and obstetric complications. There is also an association with thrombocytopenia, suggesting that the presence of anti-PS/PT antibodies may be associated with more severe clinical APS. Among seronegative APS patients, 6-17% of patients are positive for anti-PS/PT antibodies. This might influence the therapeutic management of patients. This article aims to provide an update on contribution of anti-PS/PT antibodies detection for the diagnosis and management of APS.