T. T. Yee

Factor VIII gene (F8) mutation and risk of inhibitor development in nonsevere hemophilia A

Neutralizing antibodies (inhibitors) toward factor VIII form a severe complication in nonsevere hemophilia A, profoundly aggravating the bleeding pattern. Identification of high-risk patients is hampered by lack of data that take exposure days to therapeutic factor VIII concentrates into account. In the INSIGHT study, we analyzed the association between F8 mutation and inhibitor development in patients with nonsevere hemophilia A (factor VIII 2-40 IU/dL). This analysis included 1112 nonsevere hemophilia A patients from 14 centers in Europe and Australia that had genotyped at least 70% of their patients. Inhibitor risk was calculated as Kaplan-Meier incidence with cumulative number of exposure days as the time variable. During 44 800 exposure days (median, 24 exposure days per patient; interquartile range [IQR], 7-90), 59 of the 1112 patients developed an inhibitor; cumulative incidence of 5.3% (95% confidence interval [CI], 4.0-6.6) after a median of 28 exposure days (IQR, 12-71). The inhibitor risk at 50 exposure days was 6.7% (95% CI, 4.5-8.9) and at 100 exposure days the risk further increased to 13.3% (95% CI, 9.6-17.0). Among a total of 214 different F8 missense mutations 19 were associated with inhibitor development. These results emphasize the importance of F8 genotyping in nonsevere hemophilia A.

Pharmacokinetics and safety of a novel recombinant human von Willebrand factor manufactured with a plasma-free method: a prospective clinical trial.

Safety and pharmacokinetics (PK) of recombinant von Willebrand factor (rVWF) combined at a fixed ratio with recombinant factor VIII (rFVIII) were investigated in 32 subjects with type 3 or severe type 1 von Willebrand disease (VWD) in a prospective phase 1, multicenter, randomized clinical trial. rVWF was well tolerated and no thrombotic events, inhibitors, or serious adverse events were observed. The PK of rVWF ristocetin cofactor activity, VWF antigen, and collagen-binding activity were similar to those of the comparator plasma-derived (pd) VWF-pdFVIII. In vivo cleavage of ultra-large molecular-weight rVWF multimers by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13; the endogenous VWF protease) and generation of characteristic satellite bands were demonstrated. In 2 subjects with specific nonneutralizing anti-VWF-binding antibodies already detectable before rVWF infusion, a reduction in VWF multimers and VWF activity was observed. Stabilization of endogenous FVIII was enhanced following post-rVWF-rFVIII infusion as shown by the difference in area under the plasma concentration curve compared with pdVWF-pdFVIII (AUC0-∞) (P < .01). These data support the concept of administering rVWF alone once a therapeutic level of endogenous FVIII is achieved.

Transmission of symptomatic parvovirus B19 infection by clotting factor concentrate

The risk of acquiring diseases from transfusion of blood and blood products is well recognized and the issue of parvovirus in haemophiliacs is not a new one. We report two patients with haemophilia acquiring iatrogenic parvovirus B19 infection, resulting in life‐threatening sepsis in one, an immunocompetent adult. Over the last 10 years there has been great progress in manufacturing safer products with regard to enveloped viruses such as HIV, hepatitis B and C. A recent outbreak across Europe of hepatitis A in haemophiliacs treated with plasma‐derived factor VIII concentrates has made haemophilic treaters concerned about the known (parvovirus B19 and hepatitis A) and the unknown non‐lipid enveloped viruses that may be contained in the clotting factor concentrates, because these are resistant to the existing viral inactivating techniques. The possibility of HIV itself mutating into a non‐lipid enveloped virus emphasizes the need to seek and use safer products.

Treatment related factors and inhibitor development in children with severe haemophilia A

Summary.  With the advent of modern factor replacement therapy the most important remaining obstacle to successful treatment in haemophilia A is the development of inhibitory antibodies against Facto VIII (FVIII). This retrospective case control study examined genetic variables and early treatment patterns in severe haemophilia A patients who subsequently developed clinically significant inhibitors to FVIII compared with matched controls who did not. Seventy eight inhibitor patients were identified from 13 UK centers over 25 years (1982‐2007). For each case an age matched control was selected. Data on potential genetic and treatment related risk factors were collected for cases and controls. Treatment related data was collected for the first 50 exposure days (EDs) for controls or up to inhibitor development for cases. Risk factors were compared for significance by univariate and multivariate analysis. Of the genetic risk factors, major defects in the FVIII gene and non‐caucasian ethnicity were each responsible for approximately 5‐fold increases in inhibitor risk. When treatment related variables are considered, high intensity treatment increased inhibitor risk around 2.5 fold whether represented by the presence of peak treatment moments or by high overall treatment frequency. This finding was significant regardless of the timing of the high intensity treatment. Periods of intense treatment associated with surgery for porta‐cath insertion were however not found to be associated with increased inhibitor risk. No association was shown between inhibitor development and age at first FVIII exposure, type of FVIII product, or the use of regular prophylaxis. This study confirms treatment‐related factors as important risks for inhibitor development in Haemophilia A.

Early and prolonged antiretroviral therapy is associated with an HIV-1-specific T-cell profile comparable to that of long-term non-progressors.

Background Intervention with antiretroviral treatment (ART) and control of viral replication at the time of HIV-1 seroconversion may curtail cumulative immunological damage. We have therefore hypothesized that ART maintenance over a very prolonged period in HIV-1 seroconverters could induce an immuno-virological status similar to that of HIV-1 long-term non-progressors (LTNPs). Methodology/Principal Findings We have investigated a cohort of 20 HIV-1 seroconverters on long-term ART (LTTS) and compared it to one of 15 LTNPs. Residual viral replication and reservoirs in peripheral blood, as measured by cell-associated HIV-1 RNA and DNA, respectively, were demonstrated to be similarly low in both cohorts. These two virologically matched cohorts were then comprehensively analysed by polychromatic flow cytometry for HIV-1-specific CD4+ and CD8+ T-cell functional profile in terms of cytokine production and cytotoxic capacity using IFN-γ, IL-2, TNF-α production and perforin expression, respectively. Comparable levels of highly polyfunctional HIV-1-specific CD4+ and CD8+ T-cells were found in LTTS and LTNPs, with low perforin expression on HIV-1-specific CD8+ T-cells, consistent with a polyfunctional/non-cytotoxic profile in a context of low viral burden. Conclusions Our results indicate that prolonged ART initiated at the time of HIV-1 seroconversion is associated with immuno-virological features which resemble those of LTNPs, strengthening the recent emphasis on the positive impact of early treatment initiation and paving the way for further interventions to promote virological control after treatment interruption.

Antiviral therapy for chronic hepatitis C in patients with inherited bleeding disorders: an international, multicenter cohort study

Summary.  Background: Hepatitis C is a major co‐morbidity in patients with hemophilia. However, there is little information on the efficacy of antiviral therapy and long‐term follow‐up after treatment.Objectives: To assess the effect of interferon‐based (IFN‐based) therapy on hepatitis C virus (HCV) eradication, to identify determinants associated with treatment response, and to assess the occurrence of end‐stage liver disease (ESLD) after completing antiviral therapy.Patients and methods: In a multicenter cohort study, 295 treatment‐naïve hemophilia patients chronically infected with HCV were included. The effect of therapy was expressed as sustained virological response (SVR). Determinants associated with treatment response were expressed as odds ratios (ORs). Cumulative incidence of ESLD was assessed using a Kaplan–Meier survival table.Results: Among human immunodeficiency virus (HIV) negative patients (n = 235), SVR was 29% (29/101) for IFN monotherapy, 44% (32/72) for IFN with ribavirin, and 63% (39/62) for pegylated IFN (PegIFN) with ribavirin. In patients co‐infected with HIV (n = 60), IFN monotherapy, IFN with ribavirin, and PegIFN with ribavirin eradicated HCV in 7/35 (20%), 1/2 (50%), and 11/23 (48%), respectively. SVR increased with genotype 2 and 3 [OR 11.0, 95% CI: 5.8–20.5], and combination therapy (IFN and ribavirin OR 3.7, 95% CI: 1.7–8.4), PegIFN and ribavirin (OR 4.2, 95% CI: 1.8–9.5). Up to 15 years after antiviral treatment, none of the patients with a SVR relapsed and none developed ESLD. In contrast, among unsuccessfully treated patients the cumulative incidence of ESLD after 15 years was 13.0%.Conclusions: Successful antiviral therapy appears to have a durable effect and reduces the risk of ESLD considerably.

Factor VIII inhibitors in haemophiliacs: a single-centre experience over 34 years, 1964-97.

A retrospective study of the natural history of factor VIII inhibitors in haemophilia A patients experienced in a single comprehensive haemophilia centre over three decades is reported. 431 haemophilia A patients of all severities have been followed‐up for a total of 5626 patient‐years. The frequency of inhibitors was 10% in the severe haemophilia A patients and 37% occurred in children <10 years. The majority of the patients received several products before developing the inhibitors. 59% of patients had <50 exposure days and 48% were high responders (>5 BU). An 8‐year (1987–95) inhibitor‐free period was seen during which all previously untreated patients were treated with an intermediate‐purity factor VIII concentrate. A moderate haemophiliac with a misense mutation that has not been described in association with inhibitor is reported. Six HIV‐positive patients preserved their antibody response to factor VIII even at the advanced stage of their disease.

Phase I, randomized, double-blind, placebo-controlled, single-dose escalation study of the recombinant factor VIIa variant BAY 86-6150 in hemophilia

Summary.  Background:  BAY 86‐6150 is a new human recombinant factor VIIa variant developed for high procoagulant activity and longer action in people with hemophilia with inhibitors.

Experience of four UK comprehensive care centres using FEIBA® for surgeries in patients with inhibitors

Summary.  Increasing evidence indicates that factor VIII (FVIII) inhibitor bypassing agents (FEIBA® and NovoSeven®) can provide effective peri‐operative haemostasis in haemophilia patients with high‐responding inhibitors. We report the collected experience of all major and minor surgeries, conducted between December 1998 and September 2008, at four UK haemophilia Comprehensive Care Centres with FEIBA® as the first‐line bypassing agent in patients with inhibitors. A total of 26 surgical procedures were performed in 18 patients of ages 34–83 years including five patients with acquired FVIII inhibitors. A single pre‐operative infusion of FEIBA was followed by 6–12 h interval dosing for major surgeries at the discretion of the physician to approximate a maximum of 200 U kg−1 day−1, with tapering when postoperative haemostasis and wound healing permitted. Haemostatic outcomes were retrospectively reviewed against European consensus thresholds for blood loss and duration of treatment compared with expectations for equivalent procedures in non‐inhibitor patients. Peri‐operative haemostatic outcome with FEIBA was rated excellent or good in 78% of 18 major surgeries in 12 patients, including 11 major orthopaedic procedures. Haemostatic outcome was rated excellent in all seven procedures in five patients with acquired FVIII inhibitors and in all eight minor surgical procedures in six patients. FEIBA was well tolerated with no intra‐operative haemostatic complications. A single, transient postoperative thrombotic adverse event occurred in a patient with cerebrovascular disease. This case series adds significantly to existing evidence that FEIBA can provide adequate, well‐tolerated, peri‐operative haemostatic cover for a wide variety of major and minor surgical procedures.

A genome-wide association study of resistance to HIV infection in highly exposed uninfected individuals with hemophilia A

Human genetic variation contributes to differences in susceptibility to HIV-1 infection. To search for novel host resistance factors, we performed a genome-wide association study (GWAS) in hemophilia patients highly exposed to potentially contaminated factor VIII infusions. Individuals with hemophilia A and a documented history of factor VIII infusions before the introduction of viral inactivation procedures (1979-1984) were recruited from 36 hemophilia treatment centers (HTCs), and their genome-wide genetic variants were compared with those from matched HIV-infected individuals. Homozygous carriers of known CCR5 resistance mutations were excluded. Single nucleotide polymorphisms (SNPs) and inferred copy number variants (CNVs) were tested using logistic regression. In addition, we performed a pathway enrichment analysis, a heritability analysis, and a search for epistatic interactions with CCR5 Δ32 heterozygosity. A total of 560 HIV-uninfected cases were recruited: 36 (6.4%) were homozygous for CCR5 Δ32 or m303. After quality control and SNP imputation, we tested 1 081 435 SNPs and 3686 CNVs for association with HIV-1 serostatus in 431 cases and 765 HIV-infected controls. No SNP or CNV reached genome-wide significance. The additional analyses did not reveal any strong genetic effect. Highly exposed, yet uninfected hemophiliacs form an ideal study group to investigate host resistance factors. Using a genome-wide approach, we did not detect any significant associations between SNPs and HIV-1 susceptibility, indicating that common genetic variants of major effect are unlikely to explain the observed resistance phenotype in this population.