Elina Armstrong

Eculizumab in Pregnant Patients with Paroxysmal Nocturnal Hemoglobinuria

BACKGROUNDnEculizumab, a humanized monoclonal antibody against complement protein C5 that inhibits terminal complement activation, has been shown to prevent complications of paroxysmal nocturnal hemoglobinuria (PNH) and improve quality of life and overall survival, but data on the use of eculizumab in women during pregnancy are scarce.nnnMETHODSnWe designed a questionnaire to solicit data on pregnancies in women with PNH and sent it to the members of the International PNH Interest Group and to the physicians participating in the International PNH Registry. We assessed the safety and efficacy of eculizumab in pregnant patients with PNH by examining the birth and developmental records of the children born and adverse events in the mothers.nnnRESULTSnOf the 94 questionnaires that were sent out, 75 were returned, representing a response rate of 80%. Data on 75 pregnancies in 61 women with PNH were evaluated. There were no maternal deaths and three fetal deaths (4%). Six miscarriages (8%) occurred during the first trimester. Requirements for transfusion of red cells increased during pregnancy, from a mean of 0.14 units per month in the 6 months before pregnancy to 0.92 units per month during pregnancy. Platelet transfusions were given in 16 pregnancies. In 54% of pregnancies that progressed past the first trimester, the dose or the frequency of use of eculizumab had to be increased. Low-molecular-weight heparin was used in 88% of the pregnancies. Ten hemorrhagic events and 2 thrombotic events were documented; both thrombotic events occurred during the postpartum period. A total of 22 births (29%) were premature. Twenty cord-blood samples were examined for the presence of eculizumab; the drug was detected in 7 of the samples. A total of 25 babies were breast-fed, and in 10 of these cases, breast milk was examined for the presence of eculizumab; the drug was not detected in any of the 10 breast-milk samples.nnnCONCLUSIONSnEculizumab provided benefit for women with PNH during pregnancy, as evidenced by a high rate of fetal survival and a low rate of maternal complications. (ClinicalTrials.gov number, NCT01374360.).

Eculizumab treatment during pregnancy does not affect the complement system activity of the newborn

Eculizumab is a humanized IgG2/4 chimeric anti-complement C5 antibody used to treat patients with paroxysmal nocturnal hemoglobinuria (PNH) or atypical hemolytic uremic syndrome. The aim of this study was to evaluate whether or not the complement activity in newborns from pregnant women who receive eculizumab is impaired. A novel eculizumab-C5 complex (E-C5) specific assay was developed and revealed that two newborns carried only 6-7% of the E-C5 detected in their eculizumab-treated PNH mothers. Serum from the pregnant women completely lacked terminal complement pathway activity, whereas the complement activity in the serum of the newborns was completely normal. Data from the pregnant women and their newborns were compared with that of healthy age-matched female controls and healthy newborns, as well as a non-treated pregnant woman with PNH and her newborn. These all showed normal complement activity without detectable E-C5 complexes. Furthermore, absence of eculizumab or E-C5 in the newborn could not be explained by lack of eculizumab binding to the neonatal Fc receptor (FcRn), as eculizumab bound strongly to the receptor in vitro. In conclusion, despite binding to FcRn neither eculizumab nor E-C5 accumulates in fetal plasma, and eculizumab treatment during pregnancy does not impair the complement function in the newborn.

Active online assessment of patients using new oral anticoagulants: bleeding risk, compliance, and coagulation analysis.

Clinicians prescribing new oral anticoagulants (OACs; dabigatran, rivaroxaban, and apixaban) should be aware of the exclusion criteria related to bleeding risks defined in published clinical studies. At least a quarter of patients currently using warfarin have an exclusion criterion that may prevent easy transition to the new OACs. In the summary of product characteristics for dabigatran, as an example, the target populations appear generalized. Due to fixed dosing and predictable pharmacology, routine laboratory monitoring of new OACs is deemed unnecessary. Under special circumstances, however, understanding the extent of thrombin or factor (F) Xa inhibition may aid in evaluating compliance and handling emergency interventions, bleeding complications, or overdoses. Although commonly available global coagulation-time assessments (prothrombin time and activated partial thromboplastin time) are insensitive, they may assist clinical management by indicating a severe accumulation of OACs; moreover, a normal thrombin time (TT) excludes a thrombin-inhibitor effect. In particular circumstances, specific assays (diluted TT, Ecarin clotting time, anti-FIIa or anti-FXa activity) may quantify the anticoagulant effect, but therapeutic ranges for dose adjustment are not yet established. Laboratory results are also influenced by clinical situation: e.g. bleed (consumption of coagulation factors) versus postoperative state (activation of coagulation). Without specific antidotes and evidence-based treatment strategies, new OACs are clinically worrisome in patients with impaired renal or liver function. Postmarketing surveillance and recording of bleeding complications (ICD-10 D68.32) are therefore of major importance.

Thromboprophylactic management in the neurosurgical patient with high risk for both thrombosis and intracranial bleeding.

Purpose of review Pharmacologic thromboprophylaxis is indicated in neurosurgery patients having high risk for venous or arterial thrombosis. The pharmacologic thromboprophylaxis, as well as temporary interruption of antithrombotic drugs because of surgery, and possible use of substitutive medication (‘bridging therapy’) are reviewed. Recent findings Pharmacologic thromboprophylaxis is used for most neurosurgical patients, but clinical practices vary a lot. There are only few reports of the management of neurosurgery patients having mechanical prosthetic heart valves, atrial fibrillation with comorbidities, history of deep venous thrombosis, thrombophilia, or coronary artery stent. These patients present a high risk for both thrombosis and bleeding as temporary interruption of antithrombotic medication as well as a substitutive medication would be indicated. Generally, the bridging therapy with low-molecular-weight heparin (LMWH) is a feasible approach in patients needing interruption of vitamin K antagonists. Experiences in neurosurgery patients emphasize carefully secured hemostasis and tailored dose as well as timing of LMWH. In patients with a recent coronary artery stent scheduled for neurosurgery, an individualized plan is needed. Bridging therapy for antiplatelet agents or novel oral anticoagulants is not yet settled. Summary Pharmacologic thromboprophylaxis, or bridging therapy, should be tailored according to the individual risks and the type of neurosurgery. The bleeding risk is likely minimized by allowing coagulation capacity to normalize preoperatively and by using reduced doses of LMWH starting relatively late after neurosurgery.

Platelets significantly modify procoagulant activities in haemophilia A

Summary.u2002 Haemophilia A replacement therapy is dosed according to patient’s weight and plasma FVIII activity (FVIII:C). The FVIII interacts with platelet membrane but limited data on the impact of platelet procoagulant activity (PCA) are available in haemophilia A. Our aim was to characterize individual PCA in vitro in 20 adult haemophilia A patients at various FVIII:C levels. We detected thrombin generation in platelet‐poor (PPP) and platelet‐rich plasma (PRP) using: (i) calibrated automated thrombography (CAT) triggered with tissue factor, (ii) adhesion‐induced PCA upon collagen and (iii) annexin V binding, expression of P‐selectin and active glycoprotein (GP) IIbIIIa on platelets after stimulation of GPVI with collagen‐related peptide. The FVIII:C levels varied between <1% and 37%. Thrombin generation was individual and strongly enforced by platelets and associated within the three methods. Range of thrombin generation was maximal (up to 30‐fold) at FVIII:C levels 1–5%, underlining the impact of platelets in the presence of traces of replacement therapy. At FVIII:Cu2003>u20035% platelet contribution in the variance faded. Platelet PCA and P‐selectin exposure lead to a fivefold variation. Intriguingly, at FVIII:Cu2003<u20031% thrombin generation in PPP associated negatively with platelet GPVI activation, suggestive of a regulatory interplay between plasma and platelets. In haemophilia A, the variability in thrombin generation is partially related to plasma FVIII:C, but mainly dependent on platelet procoagulant capacity. Annexin V binding and PCA in response to activation by collagen receptors contribute to this variability. In all, platelet PCA at least following collagen interaction significantly impacts thrombin generation in haemophilia A.

The Janus face of thromboprophylaxis in patients with high risk for both thrombosis and bleeding during intracranial surgery: report of five exemplary cases

BackgroundThe antithrombotic agents are usually interrupted in fear of bleeding complications before neurosurgery. However, the optimal schematic regimen of substitutive medication to prevent thromboembolic events after surgery is unsettled.MethodsWe report five complex neurosurgical cases with high risk for thromboembolism requiring thromboprophylaxis during craniotomy.Clinical featureIn one patient with coronary bare metal stent and antiplatelet therapy, acetylsalicylic acid and clopidogrel was discontinued 5 and 11xa0days prior to surgery, respectively. Four other patients were on regular warfarin therapy due to previous deep venous thrombosis, pulmonary embolism, or mechanical aortic valve. Adjusted bridging therapy with low-molecular-weight heparin was applied in all cases. The patient with the coronary stent who was managed with reduced-dose dalteparin developed postoperative intracranial hemorrhage despite having platelet and fresh-frozen plasma transfusions, and the patient did not survive. Another patient with a history of lower-extremity deep venous thrombosis developed a postoperative intracranial hematoma but also a recurrence of left lower extremity deep venous thrombosis and had a delayed recovery. The other two patients with history of pulmonary embolism, and one patient having mechanical aortic valve and atrial fibrillation, recovered uneventfully when reduced doses of low molecular weight heparin bridging therapy were administered.ConclusionOur observations confirm the complexity of balancing the risks of bleeding and thrombosis in neurosurgical patients on antithrombotic medication. In these patients, the individual bleeding risk is likely minimized by the administration of reduced doses of LMWH relatively late after craniotomy and by delaying the start of warfarin after surgery.

Assay discrepancy in mild haemophilia A.

There are three main methods used to assay factor VIII (FVIII) activity: the one‐stage and two‐stage clotting assays and the two‐stage chromogenic method. The most commonly used assay for the diagnosis of haemophilia A is the automated one‐stage FVIII assay. The classical two‐stage FVIII assays are less frequently used. The chromogenic FVIII:C assay is a variant of the two‐stage assay. It is easier to use and therefore used more commonly. Recently significant assay discrepancy has been recognised in the FVIII:C measurements in approximately one‐third of mild haemophilia A patients. This so‐called discrepant mild haemophilia A is characterised by a high ratio of one‐stage/two‐stage assay with one‐stage FVIII levels that are typically more than double those of the two‐stage coagulation assay. There are several mutations that destabilise the FVIIIa structure that can explain this result of a more pronounced decrease of the chromogenic FVIII:C activity compared with the one‐stage activity. These mutations are clustered at the interfaces of the A1, A2 and A3 domains of the FVIII protein. The inverse discrepancy, where the one‐stage assay gives lower FVIII:C results than the chromogenic assay, seems to be associated with mutations found close to important sites for thrombin cleavage or FIX binding. We are carrying out a study of mild haemophilia A samples from the Malmö Haemophilia Centre of families with a unique F8 genotype. The activity of FVIII will be measured using a chromogenic assay and two different one‐stage assays. We hope to estimate the true size of assay discrepancy.

Phenotypic and genotypic characterization of 10 Finnish patients with von Willebrand disease type 3: discovery of two main mutations.

Severe von Willebrands disease (VWD) type 3 is a rare autosomal‐recessively inherited bleeding disorder, showing considerable genotypic heterogeneity. We investigated the phenotype in correlation with the genotype in Finnish type 3 VWD patients. Ten patients previously diagnosed with VWD type 3 treated at the Coagulation Disorder Unit in Helsinki University Hospital were re‐evaluated for bleeding tendency and treatment. Phenotypic characterization included coagulation and platelet function testing confirming the diagnosis. The genotype was assessed by initial screening for the common c.2435delC mutation and subsequently if needed, by analysing all 51 coding exons of the von Willebrand factor gene. Our result confirmed the diagnosis of type 3 VWD for all 10 patients. We discovered two common mutations: nine of the 20 alleles (45%) were found to carry the c.2435delC frameshift mutation, previously described to be frequent in countries surrounding the Baltic Sea. The nonsense mutation c.4975C>T (p.R1659X) was found on 8/20 (40%) of the alleles. In addition, three novel mutations, a potential splice site mutation (c.874+2T>C) and two frameshift mutations (c.1668delC and c.2072delCCinsG) were found. Seven patients were homozygous and three compound heterozygous for the reported mutations. This study indicates that mainly two mutations (c.2435delC and p.R1659X) cause the majority of type 3 VWD in Finland. This result sets future standards for the genetic testing among the Finnish type 3 VWD population.

Management of acute myocardial infarction in a patient with factor XIII deficiency using prophylactic factor replacement therapy

Congenital factor XIII deficiency is a rare autosomal recessive coagulation disorder characterized by severe bleeding tendency. Some patients, however, experience only mild bleeding problems. The clinical features include impaired wound healing, easy bruising, muscle and joint bleeds, recurrent miscarriages in women and intracranial haemorrhage encountered by 30% of patients without prophylactic treatment [1,2]. The routine laboratory coagulation assays are normal, and the diagnosis of FXIII deficiency is initially established through a standard clot solubility test in 5 m urea [1]. Further estimation of FXIII activity and concentrations of the A and B subunits in plasma are required for proper diagnosis and classification of FXIII deficiency. Prophylactic factor replacement therapy has been successful in FXIII deficiency because of the long in vivo half-life of the protein after infusion, and also because even low plasma levels of FXIII (<5%) are sufficient to control bleeding [1]. Thrombosis is rare in patients with FXIII deficiency. In fact, there has been only one case report of deep vein thrombosis so far [3]. Subsequent to an acute myocardial infarction (AMI) in an experimental model, infarct expansion, heart failure and cardiac rupture have been observed in FXIII-deficient mice because of inadequate healing of the myocardial tissue [4]. This suggests that low values of FXIII levels may impair healing and lead to complications in patients with AMI. Here, we report a case of AMI and its management in a Finnish patient with congenital severe FXIII deficiency on prophylactic factor replacement therapy. The patient, a 69-year-old man was diagnosed with FXIII deficiency in 1990. The clinical and laboratory features of his bleeding disorder have been reported earlier [2,5]. His bleeding history included umbilical cord bleeding, easy bruising, subcutaneous tissue, muscle and joint bleeds, and a severe episode of pleural bleeding. Impaired wound healing and haematuria had also been recorded [2]. Initial laboratory examination revealed an abnormal urea clot lysis test, undetectable FXIII activity (<1%), undetectable FXIII A-subunit (<1%) and reduced B-subunit [5]. Compound heterozygosity for the Met242Thr mutation and the Arg661 stop mutation was found [2]. The pedigree of his family is illustrated in Fig. 1. Coinciding diseases in the family members are also indicated. Before the 1990s the patient had received whole blood transfusions approximately six to eight times per year for severe bleeds. From 1990 onwards he was treated with cryoprecipitate for bleeding episodes as an inpatient. For the last 6 years the patient has been on regular prophylaxis, using plasmaderived FXIII concentrate (Fibrogammin P; CSL Behring AB, Danderyd, Sweden), at a dose of 1250 U (15 U kg) once in every 3 weeks. His risk factors for coronary artery disease (CAD) included a positive family history, moderate midwaist obesity, hypertension since 2001 and mild hyperlipidaemia. In July 2004, he had an episode of unstable angina without evidence of MI. Coronary angiography revealed a 70% stenosis of the left circumflex coronary artery (LCX), which was treated by percutaneous transluminal coronary angioplasty (PTCA). He received clopidogrel (75 mg) for the following 3 months with his prior medical regimen of simvastatin and candesartan (16 mg) combined with thiazide. Notably, while taking clopidogrel, the patient had no bleeding problems. He was These authors contributed equally to this study.

Interaction between clinic and laboratory

Clinicians order laboratory tests to diagnose, monitor, and screen for diseases, to evaluate or confirm previously abnormal results and to develop prognoses. The rigorous quality assurance programs, large automated processes and economic constraints may induce direct challenges to tailored diagnosis. Clinicians will have to gain an understanding of the underlying principles of laboratory technologies without losing their ability to practice the art of medicine at their primary focus - the patient. Specialized laboratory services and expertise play especially important roles in coagulation hematology. Assays are technically demanding and often based on functional properties of proteins, producing results that are far more than plain numbers. Interpretation of laboratory data poses many challenges, such as pre-analytical and patient-dependent factors, of which the laboratory is often not well informed, but which the clinicians are required to take into account. The laboratory scientist needs to understand the multiple clinical circumstances causing variance or interference in the laboratory results. Direct interaction between clinic and laboratory is needed. When laboratory-specific issues are uncertain to the clinician, the laboratory scientist should become the clinicians primary consultant. The better the education and knowledge of both directions, the better the outcome. Regular multidisciplinary rounds by the clinicians and the laboratory scientists are of great benefit. This interaction at its best fosters research and development by identifying new mechanisms and tools.