Hematology
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Vitamin K antagonists (VKAs) are commonly used for the prevention and treatment of thrombotic disorders. The response to VKAs is highly variable due to their specific interaction with the vitamin K cycle, and hence interference with hepatic synthesis of vitamin K-dependent coagulation factors. Monitoring the anticoagulant effect of VKAs by assessing the patient's international normalized ratio (INR) is essential because complications are closely related to the intensity of anticoagulation. ⋯ Reversal of VKAs is required in case of bleeding or a supratherapeutic INR, but also prior to high-risk surgery or interventions. Choice of methods to reverse VKAs depends on whether or not the patient is bleeding or is in need of an urgent procedure, and has to be based on the pharmacokinetic and pharmacodynamic properties of the VKA. Reversal strategies include withholding the VKA, administration of vitamin K1, and substitution of vitamin K-dependent procoagulant factors, and need to be combined with measures according to general bleeding management.
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Rare bleeding disorders (RBDs) are a heterogeneous group of coagulation disorders characterized by fibrinogen, prothrombin, factors V, VII, X, XI, or XIII (FV, FVII, FX, FXI, or FXIII, respectively), and the combined factor V + VIII and vitamin K-dependent proteins deficiencies, representing roughly 5% of all bleeding disorders. They are usually transmitted as autosomal, recessive disorders, and the prevalence of the severe forms could range from 1 case in 500 000 for FVII up to 1 in 2-3 million for FXIII in the general population. Patients affected with RBDs may present a wide range of clinical symptoms, varying from mucocutaneous bleeding, common to all types of RBDs to the most life-threatening symptoms such as central nervous system and gastrointestinal bleeding. ⋯ Minor bleedings could be managed using antifibrinolytic agents. Recently, 2 novel drugs, recombinant FXIIIA and a plasma-derived FX, have been added to the list of available specific hemostatic factors; only prothrombin and FV deficiencies still remain without a specific product. Novel no-replacement therapies, such as monoclonal antibody anti-tissue factor pathway inhibitor, RNA interference, and a bispecific antibody that is an FVIIIa mimetic, enhancing thrombin generation through different mechanisms, were developed for patients with hemophilia and may in the future be a good therapeutic option also in RBDs.
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The use of proteasome inhibitors and immunomodulatory agents in the treatment of myeloma have resulted in significant improvements in patient outcomes over the last decade. Although these agents now form the backbone of current myeloma treatment regimens both in the frontline and in a relapsed setting, drug resistance remains an inevitable challenge that most patients will encounter during their disease course. ⋯ Hoping to build on these advances, a number of other mAbs are in various stages of clinical development, including those targeting myeloma cell surface antigens, the bone marrow microenvironment, and immune effector T cells such as anti-programmed cell death protein 1 antibodies. In this review, the current landscape and practical use of mAb-based therapy in myeloma will be discussed.
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Although the direct oral anticoagulants (DOACs) do not require routine monitoring and reduce bleeding compared with warfarin, there are special circumstances in which laboratory measurement or reversal of their anticoagulant effect may be indicated. The dilute thrombin time and ecarin-based assays are able to quantify dabigatran across a broad range of concentrations, but are not widely available. A normal thrombin time excludes clinically relevant levels and a normal activated partial thromboplastin time probably excludes excess levels of dabigatran. ⋯ Patients with minor and moderate DOAC-associated bleeding can be treated with supportive care and general hemostatic measures. Nonspecific reversal agents (eg, prothrombin complex concentrate, activated prothrombin complex concentrate) are of unproven benefit, carry a risk of thrombosis, and should be reserved for severe bleeding. Specific reversal agents, such as idarucizumab (a monoclonal antibody fragment that binds dabigatran) and andexanet alfa (a recombinant factor Xa variant that binds factor Xa inhibitors but lacks coagulant activity), are in clinical development.
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Randomized clinical trials (RCTs) have determined, in surgical and critically ill patients, relatively safe hemoglobin (Hb) thresholds of 7-8 g/dL to guide restrictive transfusion of red blood cells (RBCs). However, in patients with various hematologic disorders, strong evidence in support of such an approach is sparse and the optimal transfusion practice is yet to be defined. This review focuses on RBC transfusion practice in three hematologic diseases and a treatment strategy, including autoimmune hemolytic anemia, thalassemia, myelodysplastic syndrome, and hematopoietic stem cell transplantation. ⋯ Thus the nuances in the indications of RBC transfusion and the goals to achieve in these specific situations may have been underappreciated. The limited data available highlight the importance of titrating RBC transfusion based on the clinical context and patient characteristics. Future RCTs are necessary to firmly establish the Hb thresholds associated with improved outcomes relevant to these specific patient populations, which will facilitate the personalized decision-making in RBC transfusion.