Diagnostic and prognostic value of factor VIII binding antibodies in acquired hemophilia A: data from the GTH-AH 01/2010 study.

UNLABELLED: Essentials Factor VIII (FVIII) binding IgG detected by ELISA could be an alternative to the Bethesda assay. We studied the performance of anti-FVIII IgG ELISA in patients with acquired hemophilia and controls. Anti-FVIII IgG > 99th percentile of controls was highly sensitive and specific. Patients with high anti-FVIII IgG have a lower chance of achieving remission. SUMMARY: Background Acquired hemophilia A is a severe bleeding disorder that requires fast and accurate diagnosis as it occurs often unexpectedly in previously healthy men and women of every age. The Nijmegen-modified Bethesda assay is the diagnostic reference standard for detecting neutralizing autoantibodies against factor VIII (FVIII), but is not widely available, not ideal for quantifying the complex type 2 inhibitors seen in acquired hemophilia, and suffers from high inter-laboratory variability. Objectives To assess the diagnostic and prognostic value of FVIII-binding antibodies as detected by ELISA compared with the Nijmegen Bethesda assay. Methods Samples from the time of first diagnosis and clinical data were available from 102 patients with acquired hemophilia enrolled in the prospective GTH-AH 01/2010 study. Controls (n = 102) were matched for gender and age. Diagnostic cut-offs were determined by receiver-operator curve analysis. The prognostic value was assessed in 92 of the 102 patients by Cox regression analysis of time to partial remission. Results Anti-FVIII IgG above the 99th percentile (> 15 arbitrary units per mL) revealed high sensitivity and specificity (both 0.99; 95% confidence interval, 0.95-1.0) for diagnosing acquired hemophilia. The likelihood of achieving partial remission was related to anti-FVIII IgG concentration (< 300 arbitrary units, 1.0; 300-1050, 0.65; > 1050, 0.39). The Bethesda titer was only associated with the likelihood of partial remission when analyzed in the central laboratory, but not when data from local GTH study sites were used. Conclusion Although the Nijmegen-modified Bethesda assay is the reference standard for demonstrating neutralizing antibodies, the detection of FVIII-binding antibodies by ELISA is similarly sensitive and specific for diagnosing acquired hemophilia. In addition, anti-FVIII IgG may provide prognostic information.

Safety and efficacy of healthy volunteer stem cell mobilization with filgrastim G-CSF and mobilized stem cell apheresis: results of a prospective longitudinal 5-year follow-up study.

BACKGROUND AND OBJECTIVES: G-CSF-mobilized peripheral blood stem cells have long replaced marrow as the major source for allogeneic transplants. Conclusive evidence questioning the long-term safety of G-CSF for donors has not been provided, but the cumulative number of followed donors remains insufficient to rule out rare adverse events. A long-term active follow-up study of G-CSF-mobilized healthy volunteer donors was therefore performed. PATIENTS AND METHODS: Two hundred and three successive donors were evaluated pre-apheresis, subjected to G-CSF-mobilization/apheresis, and actively followed for 5 years by the same physicians and laboratories. Follow-up laboratory work included standard biochemical/haematological tests and T-cell phenotyping. RESULTS: Donor epidemiology was typical for reported stem cell donor cohorts. Acute adverse effects of G-CSF and apheresis were mild and transient, consistent with the previous reports. Mean circulating CD34(+) cells after nine doses of G-CSF were 124 per µl. Other biochemical/haematological parameters were also altered, consistent with G-CSF treatment. Spleen enlargement was modest. At first follow-up, all clinical and laboratory parameters had normalized. Leucocyte/lymphocyte counts and CD4/CD8 ratios were the same as during premobilization work-up and remained unchanged throughout. A single severe but likely unrelated adverse event, a case of papillary thyroid carcinoma, was reported. CONCLUSION: The studies add an observation time of almost 500 donor years to the growing body of evidence of the long-term safety of G-CSF for allogeneic donor stem cell mobilization.

Clinical features and outcome of acquired haemophilia A. Interim analysis of the Düsseldorf study.

UNLABELLED: We have performed a monocenter study on 29 consecutive patients with acquired haemophilia A who were referred for diagnosis and treatment to the Düsseldorf Haemophilia Comprehensive Care Center between March 2001 and February 2010. PATIENTS, METHODS: 18 men (age: 44-86 years) and 11 women (age: 20-83 years). For laboratory evaluation, a standardized staged protocol of aPTT, FVIII:C activity and concentration, mixing studies with patient and normal plasma, and quantification of inhibitor titers (Bethesda assay) was used. Diagnostic work-up included elaborate examinations for any underlying disease. RESULTS: In 18 (62%) of the 29 patients with acquired haemophilia A, an underlying disorder was identified, including 9 patients with respiratory diseases (31%), 7 patients with autoimmune disorders (24%), one with malignancy, and one with postpartum state, while in 11 patients (38%) acquired haemophilia A remained idiopathic. Haemotherapy of bleeding, suppression or elimination of the inhibitor, and induction of immunotolerance to endogenous FVIII:C were performed according to a treatment algorithm. Predefined clinical endpoints were control of bleeding, eradication of the inhibitor, complete or partial remission (CR, PR), relapse, or early death (< or =30 days). Of the 29 patients in total, 22 individuals achieved CR (76%), three had PR, one relapsed, and three died within 30 days (one of acute myocardial infarction while on antihaemorrhagic treatment, one of sepsis while on immunosuppression due to active acquired haemophilia A, one of lung bleeding in association with pre-existing pulmonary sarcoidosis). CONCLUSION: This monocenter study demonstrates that control of life-threatening bleeding, eradication of the inhibitor, and induction of tolerance to endogenous FVIII have significantly improved the clinical outcome of acquired haemophilia A. Our data also suggest a shift in underlying disorders associated with acquired haemophilia A, whereby, in comparison to published studies, a relative increase in the proportion of patients with respiratory diseases is present.