Acquired haemophilia A (AHA) is a rare but potentially life-threatening bleeding disorder characterized by autoantibodies directed against coagulation factor VIII. These autoantibodies constitute the most common spontaneous inhibitor to any coagulation factor and may induce spontaneous bleeding in patients with no previous history of a bleeding disorder. [1]
Its incidence is approximately 1.5 cases/million/year. [2] The distribution is bimodal with a first period occurrence between 20 and 30 years old, which mainly corresponds to women who develop this disorder in the postpartum, and a second peak between 68 and 80 years old, corresponding to the majority of patients, with no sex difference. [3]
An underlying medical condition can be identified in up to 50% of patients, including cancer either solid or hematologic; autoimmune diseases such as rheumatoid arthritis, Sjögren syndrome, or bullous pemphigoid; administration of drugs and pregnancy. However, AHA can also emerge in elderly people without any risk factors. [4] [5] [6]
Overall mortality rate in AHA is varies from 20% to 70% depending on the series, attributed to the underlying disorder in about 50% of the cases, infections (5-15%) and major bleeding episodes (4%) [7] [8] [9]
The reason for this loss of tolerance to self-factors is still unclear. There may be different involved mechanisms, such as the presence of certain gene polymorphisms (e.g., HLA, CTLA4) and/or autoreactive CD4+ T lymphocytes. [10] [11]
Due to the variable bleeding phenotype of this disorder, the clinical picture ranges from life-threatening and traumatic bleeds to mild or no bleeding tendency. In some cases, it is first noted after a surgical procedure, however, most occur spontaneously without apparent provocation. As patients with AHA are often elderly, co-morbidities and co-medications such as anti-platelet agents may also influence the clinical profile and require an individualized therapeutic approach. Symptomatic patients often present with large hematomas, extensive ecchymosis or severe mucosal bleeding, including epistaxis, gastrointestinal bleeding, and haematuria. In contrast with what happens to patients with congenital haemophilia, spontaneous hemarthroses are unusual. [12] Women with postpartum factor VIII inhibitors usually present with abnormal vaginal bleeding. [13]
Any acute or recent onset of bleeding symptoms in a patient with no previous history of bleeding, especially in elderly or post-partum patients, and an unexplained isolated prolonged activated partial thromboplastin time (aPTT) suggest the diagnosis of AHA, and need further investigation. The differential diagnosis in prolonged aPPT with a normal prothrombin time (PT) includes factor deficiencies, lupus anticoagulant or heparin therapy. [14]
The first step to distinguish between factor deficiency and the presence of an inhibitory substance is to perform a mixing test, [15] in which patient plasma and normal plasma are mixed and aPTT measured; correction of prolonged aPTT suggests a factor deficiency while persistent prolongation indicates the presence of an inhibitor. Prolongation of the aPTT in a mixture of patient and normal plasma after a 1-2 h incubation compared to an immediate mix is typical of FVIII autoantibodies, as FVIII inhibitors are time and temperature-dependent.
The diagnosis is confirmed by the subsequent identification of reduced FVIII levels with evidence of FVIII neutralising activity (titrated using the Bethesda assay or the Nijmegen modification). [16]
Patients with acquired coagulation factor inhibitors should be treated jointly with haemophilia centres experienced in the management of inhibitors. Initial treatment consists of four steps: [17]
Anti-haemorrhagic treatment should be initiated in patients with AHA and active severe bleeding symptoms irrespective of inhibitor titre and residual FVIII activity. First-line treatment includes by-pass agents (activated prothrombin complex concentrates [aPCC] Factor Eight Inhibitor Bypassing Activity [FEIBA] and recombinant activated factor VII rFVIIa). Both treatments are effective and there is no evidence for the use of one product in preference to the other. Therapy should be continued until bleeding is controlled and management must generally rely on the clinical assessment as there are no validated laboratory tests to determine therapeutic levels. The main concern about the use of these agents is the appearance of thrombotic events. [18] Tranexamic acid is a useful adjunct therapy but concerns about its concomitant use with FEIBA exist.
A recombinant porcine FVIII molecule has recently been approved to treat bleeding episodes, with similar pharmacokinetics to human FVIII and the possibility of laboratory measurement and dose-adjustment. [19]
Alternative treatments if first-line treatment is unavailable or fails include human FVIII, DDAVP, intravenous immunoglobulin, immunoadsorption and plasmapheresis.
All patients diagnosed with AHA should receive immunosuppressive therapy immediately following diagnosis with prednisolone either alone or combined with cyclophosphamide, what has a complete remission rate of 70-80%.
If there is no response within 3–5 weeks, second-line therapies should be considered. The most common second-line treatment is with rituximab combined with other agents. Alternative options are calcineurin inhibitors, multiple immunosuppressive agents and immune tolerance protocols.
Most immunosuppressive drugs are associated with side effects, including neutropenia-related infections and sepsis.
The relapse rate after a first complete remission has been estimated at about 20% [20]
Haemophilia, or hemophilia, is a mostly inherited genetic disorder that impairs the body's ability to make blood clots, a process needed to stop bleeding. This results in people bleeding for a longer time after an injury, easy bruising, and an increased risk of bleeding inside joints or the brain. Those with a mild case of the disease may have symptoms only after an accident or during surgery. Bleeding into a joint can result in permanent damage while bleeding in the brain can result in long term headaches, seizures, or a decreased level of consciousness.
Haemophilia A is a genetic deficiency in clotting factor VIII, which causes increased bleeding and usually affects males. In the majority of cases it is inherited as an X-linked recessive trait, though there are cases which arise from spontaneous mutations.
Haemophilia B, also spelled hemophilia B, is a blood clotting disorder causing easy bruising and bleeding due to an inherited mutation of the gene for factor IX, and resulting in a deficiency of factor IX. It is less common than factor VIII deficiency.
Disseminated intravascular coagulation (DIC) is a condition in which blood clots form throughout the body, blocking small blood vessels. Symptoms may include chest pain, shortness of breath, leg pain, problems speaking, or problems moving parts of the body. As clotting factors and platelets are used up, bleeding may occur. This may include blood in the urine, blood in the stool, or bleeding into the skin. Complications may include organ failure.
Von Willebrand disease (VWD) is the most common hereditary blood-clotting disorder in humans. An acquired form can sometimes result from other medical conditions. It arises from a deficiency in the quality or quantity of von Willebrand factor (VWF), a multimeric protein that is required for platelet adhesion. It is known to affect several breeds of dogs as well as humans. The three forms of VWD are hereditary, acquired, and pseudo or platelet type. The three types of hereditary VWD are VWD type 1, VWD type 2, and VWD type 3. Type 2 contains various subtypes. Platelet type VWD is also an inherited condition.
Haemophilia C (also known as plasma thromboplastin antecedent deficiency or Rosenthal syndrome) is a mild form of haemophilia affecting both sexes, due to factor XI deficiency. It predominantly occurs in Ashkenazi Jews. It is the fourth most common coagulation disorder after von Willebrand's disease and haemophilia A and B. In the United States, it is thought to affect 1 in 100,000 of the adult population, making it 10% as common as haemophilia A.
In medicine (hematology), bleeding diathesis is an unusual susceptibility to bleed (hemorrhage) mostly due to hypocoagulability, in turn caused by a coagulopathy. Therefore, this may result in the reduction of platelets being produced and leads to excessive bleeding. Several types of coagulopathy are distinguished, ranging from mild to lethal. Coagulopathy can be caused by thinning of the skin, such that the skin is weakened and is bruised easily and frequently without any trauma or injury to the body. Also, coagulopathy can be contributed by impaired wound healing or impaired clot formation.
Coagulation factor VII is one of the proteins that causes blood to clot in the coagulation cascade, and in humans is coded for by the gene F7. It is an enzyme of the serine protease class. Once bound to tissue factor released from damaged tissues, it is converted to factor VIIa, which in turn activates factor IX and factor X.
Factor VII deficiency is a bleeding disorder characterized by a lack in the production of Factor VII (FVII) (proconvertin), a protein that causes blood to clot in the coagulation cascade. After a trauma factor VII initiates the process of coagulation in conjunction with tissue factor in the extrinsic pathway.
Purpura fulminans is an acute, often fatal, thrombotic disorder which manifests as blood spots, bruising and discolouration of the skin resulting from coagulation in small blood vessels within the skin and rapidly leads to skin necrosis and disseminated intravascular coagulation.
Scott syndrome is a rare congenital bleeding disorder that is due to a defect in a platelet mechanism required for blood coagulation.
Thromboelastometry (TEM), previously named rotational thromboelastography (ROTEG) or rotational thromboelastometry (ROTEM), is an established viscoelastic method for hemostasis testing in whole blood. It is a modification of traditional thromboelastography (TEG). TEM investigates the interaction of coagulation factors, their inhibitors, anticoagulant drugs, blood cells, specifically platelets, during clotting and subsequent fibrinolysis. The rheological conditions mimic the sluggish flow of blood in veins. While traditional thromboelastography is a global assay for blood clotting disorders and drug effects, TEM is primarily used in combination with appropriate differential assays. They allow testing in the presence of therapeutic heparin concentrations and provide differential diagnostic information to support decisions in therapy. In numerous publications the validity of the method is shown. Application of TEM at the point of care (POC) or in emergency laboratories is getting more and more popular. TEM detects both hypo- and hyperfunctional stages of the clotting process and is probably the only reliable rapid test for the diagnosis of hyperfibrinolysis. In contrast to standard clotting tests, the fibrin stabilizing effect of factor XIII contributes to the result. The rapid availability of results helps to discriminate surgical bleeding from a true haemostasis disorder and improves the therapy with blood products, factor concentrates, anticoagulants and protamine, hemostyptic and antifibrinolytic drugs. Several reports confirm that application of TEM is cost effective by reducing the consumption of blood products.
Octapharma AG, founded in 1983, is a family-owned pharmaceutical company, and bills itself as "one of the largest human protein manufacturers in the world, developing and producing human proteins from human plasma and human cell lines[3]."
Moroctocog alfa is a recombinant antihemophilic factor genetically engineered from Chinese hamster ovary (CHO) cell line. Chemically it is a glycoprotein. It is manufactured by Genetics Institute, Inc. and used to control and prevent hemorrhagic bleeding and prophylaxis associated with surgery or to reduce the number of spontaneous bleeding episodes in patients with hemophilia A. It is partially a recombinant coagulation factor VIII since it has an amino acid sequence which compares to the 90 + 80 kDa form of factor VIII (BDDrFVIII). It also has posttranslational modifications which are similar to those of the plasma-derived molecule. It can not prevent hemorrhagic bleeding associated with von Willebrand's disease since it is not a von Willebrand factor.
Recombinant factor VIIa also known as eptacog alfa (INN), and sold under the brand name NovoSeven among others, is a form of blood factor VII that has been manufactured via recombinant technology. It is administered intravenously (IV).
Thrombodynamics test is a method for blood coagulation monitoring and anticoagulant control. This test is based on imitation of coagulation processes occurring in vivo, is sensitive both to pro- and anticoagulant changes in the hemostatic balance. Highly sensitive to thrombosis.
Jeanne Marie Lusher, M.D. was an American physician, pediatric hematologist/oncologist, and a researcher in the field of bleeding disorders of childhood, and has served as the director of Hemostasis Program at the Children's Hospital of Michigan until her retirement on June 28, 2013.
Turoctocog alfa is a recombinant antihemophilic factor VIII used for the treatment of and prophylaxis of bleeding patients with haemophilia A. It is marketed by Novo Nordisk. It was approved in the United States, the European Union, and Japan in 2013.
Factor XII deficiency is a deficiency in the production of factor XII (FXII), a plasma glycoprotein and clotting factor that participates in the coagulation cascade and activates factor XI. FXII appears to be not essential for blood clotting, as individuals with this condition are usually asymptomatic and form blood clots in vivo. FXII deficiency tends to be identified during presurgical laboratory screening for bleeding disorders.
Valoctocogene roxaparvovec, sold under the brand name Roctavian, is a gene therapy for the treatment of hemophilia A. It was developed by BioMarin Pharmaceutical.