Wolfgang Miesbach

The course of ADAMTS‐13 activity and inhibitor titre in the treatment of thrombotic thrombocytopenic purpura with plasma exchange and vincristine

The therapeutic efficacy of plasma exchange (PE) in thrombotic thrombocytopenic purpura (TTP) is attributed to the restoration in ADAMTS‐13 (a disintegrin and metalloproteinase with thrombospondin motif‐13) activity by substitution of the enzyme and removal of ADAMTS‐13‐neutralizing autoantibodies. We explored this rationale by analysing ADAMTS‐13 activity and corresponding inhibitor levels during PE‐treatment in 27 episodes from 23 adults with TTP. All patients with an initial episode of TTP (n = 14) and nine of 11 patients with a relapse showed severe ADAMTS‐13 deficiency. ADAMTS‐13 inhibitors were detected in 81% of these patients. Twenty‐one patients responded to PE‐therapy and two patients died. For patients with severe ADAMTS‐13 deficiency, 15 patients (71%) showed a PE‐induced recovery in ADAMTS‐13 activity and six patients (29%) had persistent severe ADAMTS‐13 deficiency despite clinical response. Three patients with recurrent TTP demonstrated a permanent increase in inhibitor titre during therapy. Six patients (43%) with an initial episode of TTP displayed a transient increase in inhibitor titre during PE‐therapy, which was associated with deterioration in clinical and haematological symptoms of TTP. Treatment with vincristine induced an immediate increase in platelet count and ADAMTS‐13 activity in seven of eight patients. We conclude that ADAMTS‐13 activity and inhibitor levels, as measured using current methodology, do not solely determine the clinical course of TTP.

New direct oral anticoagulants – current therapeutic options and treatment recommendations for bleeding complications

To date, clinical studies show that the incidence of spontaneous bleeding with new direct oral anticoagulants (DOAs) is comparable to that of established anticoagulants. However, unlike vitamin K antagonists, there are currently no clinically available antidotes or approved reversal agents for new DOAs. Restoring normal coagulation is important in many cases, such as emergency surgeries, serious bleedings, or anticoagulant overdosing. Attempts have been made to restore normal coagulation after treatment with new DOAs using compounds such as recombinant activated factor VII (rFVIIa), prothrombin complex concentrate (PCC), or FEIBA (factor eight inhibitor bypassing activity). Limited pre-clinical data and even less clinical evidence are available on the usefulness of these methods in restoring normal coagulation for the emergency management of critical bleeding episodes. Evaluating the utility of DOAs is further complicated by the fact that it is unknown how predictive established test systems are of the bleeding risks. Clinical practice requires further evaluation of the emergency management options for the new DOAs to define the agents and the doses that are most useful. Furthermore, patients receiving long-term treatment with a DOA are likely to undergo elective surgery at some point, and there is lack of evidence regarding perioperative treatment regimens under such conditions. This review summarises potential bleeding management options and available data on the new DOAs.

Molecular basis of antithrombin deficiency

Antithrombin (AT) is the most important physiological inhibitor of coagulation proteases. It is activated by glycosaminoglycans such as heparin. Hereditary antithrombin deficiency is a rare disease that is mainly associated with venous thromboembolism. So far, more than 200 different mutations in the antithrombin gene (SERPINC1) have been described. The aim of our study was to characterise the molecular background in a large cohort of patients with AT deficiency. Mutation analysis was performed by direct sequencing of SERPINC1 in 272 AT-deficient patients. Large deletions were identified by multiplex PCR coupled with liquid chromatography or multiplex ligation-dependent probe amplification (MLPA) analysis. To predict the effect of SERPINC1 sequence variations on the pathogenesis of AT deficiency, in silico assessments, multiple sequence alignment, and molecular graphic imaging were performed. The mutation profile consisted of 59% missense, 10% nonsense, 8% splice site mutations, 15% small deletions/insertions/duplications, and 8% large deletions. Altogether 87 different mutations, including 42 novel mutations (22 missense and 20 null mutations), were identified. Of the novel missense mutations, nine are suspected to impair the conformational changes that are needed for AT activation, two to affect the central reactive loop or the heparin binding site, and six to impair the structural integrity of the molecule. Despite the heterogeneous background of AT deficiency, 10 AT variants occurred in multiple index patients. Characterisation of the SERPINC1 mutation profile in large cohorts of patients may help to further elucidate the pathogenesis of AT deficiency and to establish genotype-phenotype associations.

Thrombotic manifestations of the antiphospholipid syndrome in patients with malignancies

The presence of antiphospholipid antibodies has been reported in a large variety of patients with malignancies. Many case reports and reviews have appeared indicating that the presence of the antiphospholipid antibodies is related to thrombotic associations with the antiphospholipid syndrome (APS) in a proportion of these patients. We investigated the frequency of the thrombotic manifestations in 58 patients demonstrating antiphospholipid antibodies and with a history of neoplasia, including haematologic and lymphoproliferative malignancies. Antiphospholipid antibodies were detected by clotting assay [lupus anticoagulant (LAC)] or by enzyme-linked immunosorbent assay [anticardiolipin antibodies (aCL)] according to the Sapporo criteria. Patients, 39/58, suffered from solid tumours and 19/58 patients from malignant haematologic or lymphoproliferative diseases. One patient was suffering simultaneously from two solid tumours and a malignant lymphoma. Among the patients with solid tumours, 18/39 (46%) patients had thromboembolic complications of the antiphospholipid syndrome. Among the patients with haematologic and lymphoproliferative malignancies, only 6/19 (32%) suffered from thromboembolic complications. There was, however, no relation between the titres of aCL antibodies and the clinical manifestations. The presence, but not the titres, of antiphospholipid antibodies may identify a subset of cancer patients with a high risk of developing thrombotic complications. The frequency of thrombosis, however, is lower in aPL-positive patients with lymphoproliferative and haematological malignancies.

Comorbidities and bleeding pattern in elderly haemophilia A patients

Summary.  The increasing numbers of comorbidities related to higher age and their treatment constitute a challenge in the treatment of haemophiliacs. Comparing prevalences of morbidities in the elderly haemophilia A population (n = 29) and the general elderly population of Germany reveals some differences. HCV infections are more frequent in the elderly haemophilia population (69% vs. 0.6%). Prevalence of cancer was five times higher than in the age matched general population (28% vs. 5.2%). Cardiac diseases seem to be less frequent although the prevalences of cardiovascular risk factors like hypertension, diabetes, and body mass index (BMI) >25 do not differ in comparison to the general population. A reduction of bleeding symptoms or dosage of FVIII could not be observed. There is a tendency of increasing bleeding symptoms with increasing age of the patients due to more frequent spontaneous joint bleedings, malignancies or treatment with phenprocoumon or ASA. In consequence, FVIII dosage had to be increased in eight patients (28%). Our patient population at the age >60 years is very small and no statistical evidence can be shown, therefore appropriate treatment of elderly haemophiliacs needs further evaluation in multicentre studies with sufficient patient numbers.

Prognostic factors for remission of and survival in acquired hemophilia A (AHA): results from the GTH-AH 01/2010 study

Acquired hemophilia A (AHA) is caused by autoantibodies against factor VIII (FVIII). Immunosuppressive treatment (IST) results in remission of disease in 60% to 80% of patients over a period of days to months. IST is associated with frequent adverse events, including infections as a leading cause of death. Predictors of time to remission could help guide IST intensity but have not been established. We analyzed prognostic factors in 102 prospectively enrolled patients treated with a uniform IST protocol. Partial remission (PR; defined as no active bleeding, FVIII restored >50 IU/dL, hemostatic treatment stopped >24 hours) was achieved by 83% of patients after a median of 31 days (range 7-362). Patients with baseline FVIII <1 IU/dL achieved PR less often and later (77%, 43 days) than patients with ≥1 IU/dL (89%, 24 days). After adjustment for other baseline characteristics, low FVIII remained associated with a lower rate of PR (hazard ratio 0.52, 95% confidence interval 0.33-0.81, P < .01). In contrast, PR achieved on steroids alone within ≤21 days was more common in patients with FVIII ≥1 IU/dL and inhibitor concentration <20 BU/mL (odds ratio 11.2, P < .0001). Low FVIII was also associated with a lower rate of complete remission and decreased survival. In conclusion, presenting FVIII and inhibitor concentration are potentially useful to tailor IST in AHA.

von Willebrand's disease: a report from a meeting in the Åland islands

von Willebrands disease (VWD) is probably the most common bleeding disorder, with some studies indicating that up to 1% of the population may have the condition. Over recent years interest in VWD has fallen compared to that of haemophilia, partly the result of focus on blood‐borne diseases such as HIV and hepatitis. Now the time has come to revisit VWD, and in view of this some 60 international physicians with clinical and scientific interest in VWD met over 4 days in 2010 in the Åland islands to discuss state‐of‐the‐art issues in the disease. The Åland islands are where Erik von Willebrand had first observed a bleeding disorder in a number of members of a family from Föglö, and 2010 was also the 140th anniversary of his birth. This report summarizes the main papers presented at the symposium; topics ranged from genetics and biochemistry through to classification of VWD, pharmacokinetics and laboratory assays used in the diagnosis of the disease, inhibitors, treatment guidelines in different age groups including the elderly who often have comorbid conditions that present challenges, and prophylaxis. Other topics included managing surgeries in patients with VWD and the role of FVIII in VWF replacement, a controversial subject.

Engineered factor IX variants bypass FVIII and correct hemophilia A phenotype in mice

The complex of the serine protease factor IX (FIX) and its cofactor, factor VIII (FVIII), is crucial for propagation of the intrinsic coagulation cascade. Absence of either factor leads to hemophilia, a disabling disorder marked by excessive hemorrhage after minor trauma. FVIII is the more commonly affected protein, either by X-chromosomal gene mutations or in autoimmune-mediated acquired hemophilia. Whereas substitution of FVIII is the mainstay of hemophilia A therapy, treatment of patients with inhibitory Abs remains challenging. In the present study, we report the development of FIX variants that can propagate the intrinsic coagulation cascade in the absence of FVIII. FIX variants were expressed in FVIII-knockout (FVIII-KO) mice using a nonviral gene-transfer system. Expression of the variants shortened clotting times, reduced blood loss after tail-clip assay, and reinstalled clot formation, as tested by in vivo imaging of laser-induced vessel injury. In addition, we confirmed the therapeutic efficacy of FIX variants in mice with inhibitory Abs against FVIII. Further, mice tolerant to wild-type human FIX did not develop immune responses against the protein variants. Our results therefore indicate the feasibility of using variants of FIX to bypass FVIII as a novel treatment approach in hemophilia with and without neutralizing FVIII Abs.

Identification of Thrombin Antibodies in Patients with Antiphospholipid Syndrome

Abstract: Venous or arterial thrombosis, abortion, and the presence of antiphospholipid antibodies (aPL) define the criteria for the antiphospholipid syndrome (APS). A heterogeneous group of antibodies against phospholipids and plasma proteins may influence several coagulation pathways and lead to thrombophilia. We investigated the presence of antibodies to thrombin (Thr) in patients with aPL and reviewed their clinical manifestations. IgG and IgM titers of aPL were measured by ELISA (Aesku.Diagnostics, Wendelsheim, Germany). Lupus anticoagulants (LA) were measured according to the criteria of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis. One hundred twenty patients were identified with LA or anticardiolipin (aCL). Of the 120 patients, 98 (82%) had primary APS and 22 (18%) had secondary APS. Further, 76/120 (63%) were suffering from thromboembolic manifestations, mostly venous thrombosis. Anti‐thrombin‐IgG was detected in 20%, and anti‐thrombin‐IgM was detected in 23% of the patients. The presence of anti‐thrombin antibodies was closely related to the presence of anti‐β2‐glycoprotein‐I (β2‐GP‐I) (96%), aCL (97%), and LA (87%), and less well to the presence of anti‐phosphatidylserine/prothrombin /Ser/Pro) antibodies (71%) or anti‐prothrombin antibodies (Pro) (50%). Sixty‐seven percent of the patients with anti‐Thr‐IgG suffered from thromboembolic complications, mostly arterial thrombosis. The rate of thrombosis was higher for these patients than for patients with anti‐β2‐GP‐I antibodies (37/60, 62%), LA (50/79, 63%), or anti‐Ser/Pro antibodies (18/28, 64%). Anti‐thrombin antibodies were found in 20% of patients with aPL; 67% of these patients were admitted with thrombotic manifestations of APS. The presence of anti‐thrombin antibodies was closely associated with the presence of aCL and anti‐β2‐GP‐I antibodies. The sensitivity of the test for anti‐thrombin antibodies for the diagnosis of APS was higher than the sensitivity of the anti‐prothrombin assay and similar to the sensitivity of the anti‐Ser/Pro assay.

Association between phenotype and genotype in carriers of haemophilia A

Summary.  Female carriers of haemophilia might suffer from increased bleeding tendency therefore the assessment of the bleeding risk is very important for improving care. This single‐centre study documents the occurrence of bleedings in 46 carriers of haemophilia A including bleeding after tooth extraction (77%), easy bruising (67%), postsurgical bleeding (61%), menorrhagia (50%) or prolonged postpartum bleeding (43%). The F8 gene mutation of all 46 carriers (median age: 36.5 years, 15–80 years; mean FVIII:C activity: 59 ± 24.45%; normal range: 64–167%) was determined, and family history of haemophilia was recorded. For analysis, the bleeding tendency of the carriers was differentiated by severity into three groups. There was no statistically significant difference of FVIII:C between these groups. However, a correlation was found between the severity of bleeding tendency and the type of F8 gene mutation (P < 0.05) as well as the severity of haemophilia in affected male relatives (P < 0.0005). Results show that even carriers with a FVIII:C activity as high as 50–60% are at increased risk of bleeding. Incidence and intensity of bleeding symptoms of haemophilia A carriers are high and correlated with the phenotype of the male haemophilic relative and the underlying F8 gene mutation.