Fibrinogen concentrates in hereditary fibrinogen disorders: Past,present and future

Hereditary fibrinogen disorders (HFD) are rare coagulation disorders. Even if the spectrum of symptoms is broad depending on the sub‐type, bleeding is the most common complication. Of the available sources of fibrinogen replacement, fibrinogen concentrate provides a safer and more effective option to treat and prevent bleeding. Recent clinical trials on established and new fibrinogen concentrates have increased our knowledge on the clinical pharmacology of these products, pointing out possible age and weight differences for dose adjustment. The efficacy of fibrinogen infusions has been demonstrated, especially for the management of acute bleeding with an excellent response based on investigator rating. The target fibrinogen levels in the setting of both minor and major surgeries have been better specified. The safety has been confirmed with a low number of adverse events but there still remains concern over possible thrombotic risks. Pharmacological, clinical aspects and future perspectives on the utilization of fibrinogen concentrates in the treatment and prevention of bleeding in patients with HFD are reviewed.     

Fibrinogen concentrates for bleeding trauma patients: what is the evidence?

Introduction A balanced transfusion of red blood cells, fresh frozen plasma and platelets are recommended for massively bleeding trauma patients. Fibrinogen concentrates could potentially lessen or replace the need for fresh frozen plasma and/or platelet transfusions. Objective To provide a review of the literature covering the application of fibrinogen concentrates in trauma care. Methods PubMed and Cochrane database search, ‘fibrinogen’ and (‘concentrate’ or ‘trauma’), not ‘congenital’, 10 years. Results Only four papers were identified. None were randomized controlled trials. The main conclusion of these papers was that administration of fibrinogen sometimes together with prothrombin complex concentrate might improve haemostasis in trauma patients resuscitated with synthetic colloids. Conclusion Evidence for the use of fibrinogen concentrate to trauma patients with massive bleeding is lacking. Well‐designed prospective, randomized, double‐blinded studies evaluating the effect of fibrinogen concentrate, as the only intervention, are urgently needed.     

Congenital afibrinogenemia

Congenital afibrinogenemia is a rare disorder with unusual clinical manifestations. The disease is inherited as an autosomal recessive trait and consanguinity is common among affected families. Clinical manifestations range from minimal bleeding to catastrophic hemorrhage. Congenitally afibrinogenemic patients seem to be peculiarly susceptible to spontaneous rupture of the spleen. Coagulation tests which depend on clot formation as an end point may be infinitely prolonged and abnormalities of platelet function are usually present. The diagnosis is established by demonstrating trace or no immunoreactive fibrinogen. The disease is caused by markedly reduced or absent synthesis of fibrinogen by liver cells, but the genetic defect remains unknown. Bleeding episodes can be effectively treated with cryoprecipitate. Purified virally inactivated fibrinogen concentrates have been used in Europe and may soon be widely available. © 1994 Wiley-Liss, Inc.     

Efficacy and tolerability of human fibrinogen concentrate administration to patients with acquired fibrinogen deficiency and active or in high-risk severe bleeding

Background and Objectives  Fibrinogen deficiency is a cause for massive haemorrhage whose management in emergency situations is the subject of debate. Plasma-derived fibrinogen concentrates are indicated for reversing the haemorrhagic diathesis found in congenital and acquired deficiencies.
Materials and Methods  We report on the results of an observational study that evaluated the effects of fibrinogen concentrates in patients suffering from various forms of acquired severe hypofibrinogenaemia with life-threatening consumptive thrombo-haemorrhagic disorders (surgery, trauma and digestive haemorrhage), or underlying disease states that limit fibrinogen synthesis (hepatic dysfunction, haematological malignancies).
Results  Sixty-nine patients were identified and included, in whom most of the processes (62%) corresponded to consumptive hypofibrinogenaemia. After a median dose of 4 g, a mean absolute increase of 1·09 g/l in plasma fibrinogen was measured and coagulation parameters were significantly improved ( P <  0·001). Mortality rates of 32·3% and 44·2% were reported after 24 h and 72 h, respectively.
Conclusion  We conclude that the administration of fibrinogen concentrates in unresponsive, life-threatening haemorrhage with acquired hypofibrinogenaemia improves laboratory measures of coagulation, and may also be life saving. Although observational in nature, our data indicate a direct relationship between plasma fibrinogen levels and survival in acquired fibrinogen deficiency. Further studies are warranted to ascertain a clear relationship between fibrinogen levels and survival.     

Diagnosis,clinical features and molecular assessment of the dysfibrinogenaemias

Summary. Hereditary dysfibrinogenaemia is characterized by the presence of functionally abnormal plasma fibrinogen. Dysfibrinogenaemia is a heterogeneous disorder associated with different mutations throughout the three genes that code for the fibrinogen sub‐units, affecting many different aspects of fibrinogen/fibrin activity. Dysfibrinogenaemia may be discovered during the investigation of individuals who present with bleeding or thombosis, or may be found in individuals during routine coagulation screening. More specialized coagulation tests may confirm the diagnosis of dysfibrinogenaemia but do not reliably distinguish between the different fibrinogen variants and are not usually useful in predicting bleeding or thrombotic risk. Advances in molecular diagnostics have facilitated the investigation of the molecular causes of fibrinogen disorders. Several ‘hot spot’ areas have been identified where mutations causing a high proportion of cases of dysfibrinogenaemia are found (AαArg16 and γArg275). Molecular diagnostics have also shown that many fibrinogen variants share the same causative mutation. There is a discrepancy between the quality of the molecular and functional data available for each mutation and the clinical information on individuals and their family members. However, there are accumulating data that the ‘hot spot’ mutations accounting for 60–80% of cases of dysfibringenaemia are not associated with a significant bleeding or thrombosis in the absence of other risk factors. Rapid screening for these mutations may provide reassurance for patients in the presurgical setting.     

Spontaneous intracranial bleeding in two patients with congenital afibrinogenaemia and the role of replacement therapy.

Congenital afibrinogenaemia and hypofibrinogenaemia are rare disorders of haemostasis. In this case report the problems posed in the management of two patients with fibrinogen levels less than 0.1g L(-1) and who developed intracranial bleeding are considered. The value of fibrinogen concentrate and the role of prophylaxis is also discussed.     

Fibrinogen giessen I: a congenital homozygously expressed dysfibrinogenemia with A alpha 16 Arg----His substitution

Clinical reports are published for only two patients with homozygously expressed congenital dysfibrinogenemia. The patients, both of whom have a bleeding diathesis, have amino acid substitutions in the fibrinogen molecule at A alpha 16 Arg----Cys and A alpha 19 Arg----Ser, respectively. We report that a third patient with dysfibrinogenemia (fibrinogen Giessen I) is homozygous for A alpha 16 Arg----His. Although this patient has had excessive postpartum bleeding, she has had normal hemostasis throughout several minor surgical procedures and hysterectomy. Elucidation of the amino acid alterations in patients with dysfibrinogenemia may expand our understanding of structural determinants of fibrinogen that are critical to its function in vivo.     

Effect of epinephrine on fibrinogen receptor exposure by aspirin-treated platelets and platelets from concentrates in response to ADP and thrombin

Synergistic effects between agonists on platelet aggregation have long been appreciated. Recently epinephrine was reported to induce maximal aggregation of aspirin-treated platelets when combined with ADP or thrombin, and to increase fibrinogen binding of non-aspirin treated platelets stimulated with low doses of ADP. The present study extends these observations to correlate fibrinogen binding in response to various combinations of ADP, epinephrine, and thrombin with platelet aggregation and 14C-serotonin release using aspirin-treated platelets as well as platelets from stored concentrates. When fresh platelets were stimulated with epinephrine (5 microM) together with either ADP (10 microM) or thrombin (150 mU/ml), fibrinogen binding increased by 180% compared to binding observed in response to ADP or thrombin alone. This was accompanied by enhanced platelet aggregation, but no increase in 14C-serotonin release. While both ADP and epinephrine potentiated the aggregation and fibrinogen binding of stored platelets in response to high doses of thrombin (150 mU/ml), maximal aggregation was achieved only with thrombin (150 mU/ml) and epinephrine (5 microM) in combination. The data thus suggest that 1) epinephrine induces maximal aggregation of aspirin-treated platelets stimulated with thrombin or ADP by significantly enhancing fibrinogen receptor exposure independently of the cyclooxygenase-mediated release reaction; 2) epinephrine stimulates platelets by a mechanism different from that of thrombin or ADP; and 3) as demonstrated by others, the ability of platelets from stored concentrates to aggregate and to bind fibrinogen in response to ADP can be enhanced by epinephrine, and, in addition, these platelets can aggregate and bind fibrinogen maximally when stimulated with combinations of epinephrine and thrombin.     

Current therapy for rare factor deficiencies

Haemophilia A and B and von Willebrand disease account for 80–85% of all inherited bleeding disorders. The other 15% are represented by deficiencies of fibrinogen, prothrombin, or factors V, VII, X, XI, or XIII. In addition, acquired factor deficiencies are seen in a variety of conditions ranging from malignancies to autoimmune disorders. The spectrum of symptoms in these conditions varies from severe and life-threatening haemorrhage to a mild bleeding diathesis. The diagnosis depends on demonstration of decreased activity of one of the clotting factors. Due to the rarity of each of the individual factor deficiencies, purified factor concentrates are not as readily available as they are for haemophilia A and B. Treatment of rare clotting factor deficiencies consists of the most purified blood product available that contains the missing factor. Depending on which factor is deficient, either purified concentrates, prothrombin complex concentrates, cryoprecipitate, or fresh frozen plasma can be used. In addition, recombinant factor VIIa is available for treating factor VII deficient patients.     

Fibrin sealant in preclinical and clinical studies.

Fibrin sealant, now commercially available in the United States, is a virally inactivated preparation of highly purified human fibrinogen and human thrombin that includes aprotinin to reduce fibrinolysis. Although the product is relatively expensive, cost can be justified when the sealant is used to produce localized hemostasis in surgery in which bleeding cannot be controlled by sutures. Fibrin sealant can also be justified as an alternative to factor concentrates in patients with coagulopathies who have a localized site of bleeding. Newer formulations of fibrinogen and thrombin in a freeze-dried form applied as a bandage may be useful in immediate, on-site treatment of trauma victims in either a civilian or military setting.     

Rate of fibrinogen breakdown related to coronary patency and bleeding complications in patients with thrombolysis in acute myocardial infarction--results from the PRIMI trial.

Four hundred and one patients with acute myocardial infarction of less than 4 h duration were randomized to receive intravenous thrombolytic treatment with either 80 mg of full length unglycosylated single-chain-urokinase plasminogen activator (INN saruplase) or 1.5 million IU of streptokinase delivered over a 60 min period. Angiographic patency rates were higher at 60 min in saruplase treated patients (71.8% vs 48%; P less than 0.001), but did not differ significantly at 90 min (71.2% vs 63.9%; P = 0.15). Fibrinogen levels dropped markedly in both groups, the decrease being delayed and less pronounced with saruplase. Total fibrin and fibrinogen degradation products and D-dimer values rose earlier and to higher peak values in streptokinase treated patients. In both groups marked plasminogen and alpha 2-antiplasmin consumption was observed. Lower fibrinogen levels, and in particular the faster rate of fibrinogen breakdown, were associated with higher patency rates at 90 min (P less than 0.05). Patients with bleeding complications had lower 'lowest points' and a more rapid decrease in fibrinogen (P less than 0.05). These findings were not related to the drug used. Increased heparin levels at 6 to 12 h were correlated to bleeding complications in streptokinase treated patients. It is concluded that the rate of fibrinogen breakdown during and following thrombolytic treatment for acute myocardial infarction is related to early vessel patency and bleeding complications.     

A novel fibrinogen variant--Praha I: hypofibrinogenemia associated with gamma Gly351Ser substitution

OBJECTIVES: A 25-yr-old man from Prague had abnormal bleeding after several surgical operations with low fibrinogen level and hypofibrinogenemia was suspected. PATIENTS AND METHODS: The patient, 25 yr-old male had a low fibrinogen concentration as determined by the thrombin time and immunoturbidimetrical method. His 48-yr-old mother presented with normal coagulation tests, normal fibrinogen level and reported no history of bleeding. To identify the genetic mutation responsible for this hypofibrinogen, genomic DNA extracted from the blood was analyzed. Fibrin polymerization measurement, kinetics of fibrinopeptide release, fibrinogen clottability measurement, mass spectroscopy, and scanning electron microscopy were performed. RESULTS: DNA sequencing showed heterogeneous fibrinogen gammaG351S mutation in the propositus. The mutant chain was found not to be expressed to the circulation by matrix-assisted laser desorption/ionization time of flight mass spectrometry. Scanning electron micrographs of the patient's fibrin clot as well as kinetics of fibrinopeptide release and fibrin polymerization were found to be normal. CONCLUSION: A case of hypofibrinogenemia gammaG351S was found by routine coagulation testing and was genetically identified.     

Diagnostic utility of bleeding assessment tools in congenital fibrinogen deficiencies

Background

The assessment of clinical history is crucial before referring a patient for further laboratory testing. Bleeding assessment tools (BAT) are developed to standardize clinical evaluation. A small number of patients with congenital fibrinogen deficiencies (CFDs) have been evaluated with these tools without definitive results.

Aims

We compared the adequacy of the ISTH-BAT and the European network of rare bleeding disorders bleeding score system (EN-RBD-BSS) to identify patients with CFDs. The correlation between the two BATs and fibrinogen levels and patient clinical grade severity was further analyzed.

Methods

We included 100 Iranian patients with CFDs. Routine coagulation and fibrinogen-specific tests (fibrinogen antigen [Fg:Ag] and activity [Fg:C]) were performed. The ISTH-BAT and EN-RBD-BSS were used to assess the bleeding score (BS) of all patients.

Results

The ISTH-BAT and EN-RBD-BSS median (range) were 4 (0–16) and 2.21 (−1.49 to 6.71), with a statistically significant moderate correlation between the two systems (r = .597, P < .001). In patients with quantitative deficiencies (afibrinogenemia and hypofibrinogenemia), the correlation between Fg:C and the ISTH-BAT was moderately negative (r = −.4, P < .001), while the correlation between Fg:C and the EN-RBD-BSS was weakly negative (r = −.38, P < .001). Overall, 70% and 72% of patients with fibrinogen deficiencies were correctly identified by both the ISTH-BAT and EN-RBD-BSS, respectively.

Conclusion

These results suggest that in addition to the ISTH-BAT, the EN-RBD-BSS may also be useful in identifying CFD patients. We found a significant level of sensitivity for detecting fibrinogen deficiency in the two BATs, and bleeding severity classification correctly identified severity grades in almost two-thirds of patients.     

Fibrinogen levels are associated with bleeding in patients with primary immune thrombocytopenia

Abstract

Bleeding is the most common clinical symptom and the leading cause of death in patients with primary immune thrombocytopenia (ITP). Our research intends to verify the role of fibrinogen levels as independent determinants of bleeding. We retrospectively analyzed the relationship between fibrinogen levels and bleeding events in 463 patients. Additionally, we confirmed the impact of fibrinogen level on clot firmness in 25 patients via thrombelastography (TEG). Fibrinogen levels (median and inter-quartile range, IQR) were significantly different (p < .001) between bleeding and non-bleeding patients [258(207–314) mg/dL vs. 315(262–407) mg/dL, respectively]. Further analyzes in three subgroups based on platelet (PLT) count showed that non-bleeding patients still had higher fibrinogen levels than bleeding patients. The optimal discriminant threshold of fibrinogen in bleeding was 288.5 mg/dL according to receiver operating characteristic (ROC) curves. Patients were divided into low (LF, 230[193–258] mg/dL) and high (HF, 349[313–424] mg/dL) fibrinogen groups based on this threshold. Bleeding event rates were significantly different (LF: 84.6% vs. HF: 60.4%, P < .001) between the two groups. Multivariable analyses further confirmed these differences. Moreover, TEG parameters showed elevated clot firmness in the HF group. Our data suggest that high fibrinogen levels are associated with reduced bleeding events.     

Fibrinogen Denver: a dysfibrinogenemia associated with an abnormal Reptilase time and significant bleeding

This paper reports a new dysfibrinogenemia with an unusual pattern of laboratory assays. The patient, a 51-year-old female with a lifelong moderate bleeding history, was initially diagnosed with von Willebrand disease based on routine coagulation assays and the clinical bleeding presentation. During recent testing as part of a preoperative screen and without any current history of treatment, levels of von Willebrand factor (VWF) antigen, VWF activity, and factor VIII activity were all significantly elevated, which was unexpected given her previous diagnosis. Additional testing was performed looking for other heritable causes for her considerable bleeding tendency. Interestingly, the patient had a significantly prolonged Reptilase time, minimally short thrombin time, and an abnormal fibrinogen-crossed immunoelectrophoresis pattern. Clearly, this patient had a fibrinogen abnormality that had been missed when only routine coagulation screening assays were performed. A brief review of the fibrinogen literature revealed no other dysfibrinogenemias reported with a similar pattern of test results, and thus this defect was designated fibrinogen Denver.     

Three New Cases of an Inborn Qualitative Fibrinogen Defect (Fibrinogen Oslo II)

An autosomally inherited, qualitative fibrinogen defect is presented. It is associated with prolonged thrombin clotting time, low plasma fibrinogen when assayed by a fibrin polymerization test and large amounts of fibrinogen antigen determinants in the supernatant after clotting. The plasma fibrinogen level was normal when assayed by an immunological technique or by quantitation of insoluble fibrin under conditions in which fibrin polymerization is enhanced. As judged from N-terminal amino acid analyses, fibrinopeptides were split off at normal speed, and the subunit chains of the fibrinogen appeared normal when examined on polyacrylamide gels. The abnormality was not associated with bleeding tendency, and other routine coagulation tests gave normal results. The findings are in accordance with the concept of defective fibrin polymerization.     

Rare inherited disorders of fibrinogen

Summary. Fibrinogen, a hexameric glycoprotein encoded by three genes –FGA, FGB, FGG– clustered on chromosome 4q is involved in the final steps of coagulation as a precursor of fibrin monomers required for the formation of the haemostatic plug. Inherited disorders of fibrinogen abnormalities are rare and not as well clinically characterized as some other inherited bleeding disorders. To characterize the clinical manifestations, molecular defects and treatment modalities of these rare disorders, a Medline search from January 1966 to September 2007 for these disorders reported in large studies and registries was undertaken. Inherited fibrinogen disorders can manifest as quantitative defects (afibrinogenemia and hypofibrinogenemia) or qualitative defects (dysfibrinogenemia). Quantitative fibrinogen deficiencies may result from mutations affecting fibrinogen synthesis, or processing while qualitative defects are caused by mutations causing abnormal polymerization, defective cross‐linking or defective assembly of the fibrinolytic system. Clinical manifestations vary from being asymptomatic to developing catastrophic life‐threatening bleeds or thromboembolic events. Management of bleeds includes use of purified plasma‐derived concentrates, cryoprecipitate or fresh frozen plasma. Use of some of these products carries risks of viral transmission, antibody development and thromboembolic events. Establishment of registries in Iran, Italy and North America has fostered a better understanding of these disorders with an attempt to explore molecular defects. Rare Bleeding Disorder Registries developed through the United States and international efforts hopefully will encourage development and licensure of safer, effective products.     

State of the Art – How I manage coagulopathy in cardiac surgery patients

Over 35 000 cardiac operations using cardiopulmonary bypass are performed annually in the UK. Post‐operative bleeding is a common cause of morbidity. Although there have been improvements in surgical techniques, recent publications still show post‐operative blood loss to be significant, with allogeneic blood product usage as high as 50%. Despite greater understanding of the mechanisms of the coagulopathy encountered during cardiac surgery the development of treatment options has been slow. There has been a realization of the inadequacy of fresh frozen plasma to correct the coagulopathy in this setting, leading to greater off‐label use of specific factor concentrates to stop bleeding, e.g., prothrombin complex concentrates and fibrinogen concentrates. Recent trials using factor XIII and IX concentrates have not been successful. This article will review preventative measures to reduce post‐operative bleeding and the current management of bleeding with such factor concentrates and, in most cases, the limited evidence supporting their widespread use.     

Identification of simultaneous mutation of fibrinogen alpha chain and protein C genes in a Japanese kindred

Afibrinogenaemia usually induces a bleeding tendency during infancy, whereas protein C deficiency increases susceptibility to thrombosis in children or adolescence. Mutations of these genes have been, therefore, established as independent risk factors for coagulation disorders. We describe the homozygous mutation of the fibrinogen alpha chain gene and additional heterozygous mutation of the protein C gene in a male infant who showed prolonged umbilical bleeding after birth. On examination, the plasma fibrinogen was undetectable, and the activity and antigen level of protein C were reduced. The patient showed no fibrinogen Aalpha chain as well as Bbeta and gamma chains by Western blotting. The sequencing analysis showed the homozygous deletion of 1238 bases from intron 3 at position 2008 to intron 4 at position 3245 in the fibrinogen alpha chain gene. Both parents were heterozygous carriers of this mutation. In this patient, an additional mutation was also detected in the protein C gene: the heterozygous deletion of exon 7 at position 6161-6163 or 6164-6166, resulting the deletion of one amino acid (Lys150 or 151). His mother was also a carrier of this mutation. As the simultaneous mutation of the fibrinogen alpha chain and protein C genes has not been previously reported, the influence of the interaction between these two mutations on the clinical manifestations of this patient should be carefully monitored for a long period.     

Clinical significance of plasma fibrinogen level as a predictive marker for postoperative recurrence of esophageal squamous cell carcinoma in patients receiving neoadjuvant treatment

Among multidisciplinary therapies developed for advanced esophageal cancer, neoadjuvant chemotherapy and chemoradiotherapy have been established as standard treatments. To deliver cautious follow up and intense treatment for high‐risk patients, a simple and instructive biomarker for the postoperative recurrence needs to be identified. Fibrinogen, a common component of hemostasis, has been suggested to not only play an important role in cancer metastasis, but also correlate with tumor recurrence. We aim to clarify the validity of plasma fibrinogen as a marker for predicting the postoperative recurrence of esophageal squamous cell carcinoma patients who received neoadjuvant treatment. We reviewed 72 consecutive patients with esophageal squamous cell carcinoma who received neoadjuvant chemotherapy or chemoradiotherapy, followed by esophagectomy at the Keio University Hospital from 2001 to 2010. Of them, we retrospectively examined 68 patients who underwent plasma fibrinogen examination before and after neoadjuvant treatment and underwent transthoracic radical esophagectomy. We investigated patient characteristics, clinicopathological factors, neoadjuvant treatment effects, postoperative course, and plasma fibrinogen levels. We investigated pretreatment and preoperative (postneoadjuvant treatment) plasma fibrinogen levels, as well as changes in fibrinogen levels before and after neoadjuvant treatment. Patients with preoperative hyperfibrinogenemia (>350 mg/dL) and patients with increased plasma fibrinogen levels during neoadjuvant treatment showed significantly shorter postoperative disease‐free survival (DFS) (P = 0.002 and P = 0.037, respectively). Moreover, we classified these patients into three classes on the basis of their preoperative fibrinogen levels and changes in fibrinogen levels during neoadjuvant treatment. Patients who had both high preoperative plasma fibrinogen and increased fibrinogen levels showed significantly shorter DFS than others. In contrast, patients who had normal preoperative plasma fibrinogen and decreased fibrinogen levels showed significantly longer DFS. Based on this fibrinogen classification, we could differentiate between significantly favorable and poor prognosis patients group. Overall, this classification (hazard ratio = 1.812, P = 0.013) and the response to neoadjuvant treatment (hazard ratio = 0.350, P = 0.007) were found to be significant determining factors for postoperative DFS. With the validity of preoperative plasma fibrinogen levels and changes in fibrinogen levels during neoadjuvant treatment, the plasma fibrinogen level was found to be a possible biomarker for postoperative recurrence in advanced esophageal cancer patients who received neoadjuvant treatment. Moreover, plasma fibrinogen classification could be a simple and valuable predictive marker for postoperative follow up.