Abstract

BACKGROUND The development of neutralizing antibodies (inhibitors) against factor VIII (FVIII) is the most severe complication in the early phases of treatment of severe haemophilia A. Recently a randomized trial, the Survey of Inhibitors in Plasma-Product Exposed Toddlers (SIPPET) demonstrated a two-fold higher risk of inhibitors development in children treated with recombinant FVIII (rFVIII) products than with plasma-derived FVIII (pdFVIII) during the first 50 exposure days (EDs). OBJECTIVE/METHODS In this post-hoc SIPPET analysis we evaluated the rate of inhibitor incidence over time by every 5 EDs (from 0 to 50 EDs) in patients treated with different classes of FVIII product, made possible by a frequent testing regime. RESULTS The highest rate of inhibitor development occurred in the first 10 EDs with a large contrast between rFVIII and pdFVIII during the first 5 ED: hazard ratio 3.14 (CI95% 1.01-9.74) for all inhibitors and 4.19 (CI95% 1.18-14.8) for high-titre inhibitors. For patients treated with pdFVIII, the peak of inhibitor development occurred later (6-10 EDs) and lasted shorter. CONCLUSION These results emphasize the high immunologic vulnerability of patients during the earliest exposure to FVIII concentrates with the strongest response to recombinant FVIII products. This article is protected by copyright. All rights reserved.

Abstract

BACKGROUND The development of neutralizing anti-factor VIII alloantibodies (inhibitors) in patients with severe hemophilia A may depend on the concentrate used for replacement therapy. METHODS We conducted a randomized trial to assess the incidence of factor VIII inhibitors among patients treated with plasma-derived factor VIII containing von Willebrand factor or recombinant factor VIII. Patients who met the eligibility criteria (male sex, age <6 years, severe hemophilia A, and no previous treatment with any factor VIII concentrate or only minimal treatment with blood components) were included from 42 sites. RESULTS Of 303 patients screened, 264 underwent randomization and 251 were analyzed. Inhibitors developed in 76 patients, 50 of whom had high-titer inhibitors (≥5 Bethesda units). Inhibitors developed in 29 of the 125 patients treated with plasma-derived factor VIII (20 patients had high-titer inhibitors) and in 47 of the 126 patients treated with recombinant factor VIII (30 patients had high-titer inhibitors). The cumulative incidence of all inhibitors was 26.8% (95% confidence interval [CI], 18.4 to 35.2) with plasma-derived factor VIII and 44.5% (95% CI, 34.7 to 54.3) with recombinant factor VIII; the cumulative incidence of high-titer inhibitors was 18.6% (95% CI, 11.2 to 26.0) and 28.4% (95% CI, 19.6 to 37.2), respectively. In Cox regression models for the primary end point of all inhibitors, recombinant factor VIII was associated with an 87% higher incidence than plasma-derived factor VIII (hazard ratio, 1.87; 95% CI, 1.17 to 2.96). This association did not change in multivariable analysis. For high-titer inhibitors, the hazard ratio was 1.69 (95% CI, 0.96 to 2.98). When the analysis was restricted to recombinant factor VIII products other than second-generation full-length recombinant factor VIII, effect estimates remained similar for all inhibitors (hazard ratio, 1.98; 95% CI, 0.99 to 3.97) and high-titer inhibitors (hazard ratio, 2.59; 95% CI, 1.11 to 6.00). CONCLUSIONS Patients treated with plasma-derived factor VIII containing von Willebrand factor had a lower incidence of inhibitors than those treated with recombinant factor VIII. (Funded by the Angelo Bianchi Bonomi Foundation and others; ClinicalTrials.gov number, NCT01064284; EudraCT number, 2009-011186-88.).

Abstract

BACKGROUND The development of neutralizing alloantibodies (inhibitors) is the most serious complication of factor VIII (FVIII) replacement therapy in patients with hemophilia A. Unlike previously untreated patients, no definite risk factors for inhibitor development are known for previously treated patients (PTPs). The investigation of the development of inhibitors in PTPs is hindered by several methodological limitations in the available literature. We conducted a systematic review to account for these limitations. METHODS We considered the studies reporting on PTPs that were included in the Wight and Paisley meta-analysis and a systematic search of MEDLINE, EMBASE, and The Cochrane Library was conducted to identify studies published after 2003. Studies that investigated the development of inhibitors in hemophilia A PTPs who were treated with any type of FVIII concentrate and that included at least 25 patients with follow-up were included in the analysis. RESULTS Thirty-three independent cohorts of PTPs with 4323 subjects and 43 incident de novo inhibitors were found and analyzed. The pooled incidence rate of inhibitor development for the 25 studies providing data on follow-up was 3 (95% confidence interval 1-4) per 1000 person-years. A significant association was not found between putative risk factors and inhibitor development in PTPs at meta-regression analysis and subgroup analysis, but the model was sensitive enough to the inclusion of the reports on the Belgian-Dutch experience with a highly immunogenic factor VIII. CONCLUSION We confirmed a low overall rate of de novo inhibitors in PTPs, without any significant effect of putative predictors, including the type of factor VIII concentrate. 2013 International Society on Thrombosis and Haemostasis.

Abstract

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.

Abstract

IB1001 trenacog alfa is an investigational recombinant factor IX (FIX) for the treatment and prevention of bleeding in individuals with haemophilia B. To compare the pharmacokinetics (PK) of IB1001 with nonacog alfa in individuals with haemophilia B and to assess the relationship between sialylation and PK of IB1001 (NCT00768287). A randomized, double-blind, non-inferiority, cross-over study conducted in participants aged >= 12 years weighing >= 40 kg, with severe or moderately severe haemophilia B (FIX activity <= 2 IU dL (-1) ). PK parameters were derived using observed FIX concentration levels and actual PK sampling times, and repeated in a subset of participants who had received IB1001 prophylaxis for 4-18 months. A retrospective analysis was conducted in subgroups according to the sialylation levels of IB1001 (50.8, 57.8-59.0%, or 71.7%). In the 32 adolescent and adult males evaluated, there were no clinically meaningful differences in PK parameters between those receiving IB1001 75 IU kg (-1) or nonacog alfa. The lower limit of the one-sided 95% confidence interval for the ratio of AUC (0-t) and AUC (0-) (IB1001/nonacog alfa) was 0.90, establishing non-inferiority. Terminal phase half-lives were similar (29.7 +/- 18.2 h for IB1001 and 33.4 +/- 21.2 h for nonacog alfa). The PK results were stable for up to 18 months of IB1001 exposure; the impact of sialylation levels was not clinically meaningful. There were no clinically meaningful PK differences between IB1001 and nonacog alfa. IB1001 was well tolerated and without safety concerns. The non-inferiority of IB1001 to nonacog alfa supports IB1001 becoming a useful alternative recombinant agent for the management of haemophilia B. 2012 Blackwell Publishing Ltd.

Abstract

In the last three decades there have been dramatic improvements in the availability and quality of treatment for people with inherited coagulation disorders. Indeed, the improvement of methods of purification and viral inactivation for plasma-derived coagulation factor concentrates first and then the development of products utilizing recombinant DNA technology have greatly improved the life expectancy of hemophiliacs, which has progressively become similar to that of males in the general population. Nowadays, the most frequent complication of factor replacement therapy for hemophilia is the development of inhibitors. However, no studies so far have systematically analysed the type and incidence of other adverse reactions following the administration of coagulation factor concentrates. The aim of this systematic review was to screen the published literature data to evaluate the types and frequencies of non-thrombotic-, non-inhibitor-associated adverse reactions to coagulation factor concentrates in patients with hemophilia A, hemophilia B and von Willebrand's disease. On behalf the European Haemophilia Safety Surveillance System (EUHASS), a systematic review of the prospective studies published in the last 20 years was performed using electronic databases and article references. Both severe and mild adverse events following infusion of coagulation factor concentrates are relatively rare in patients with inherited coagulation disorders; the most common events are of an allergic type. There are no differences in the rate of adverse events caused by plasma-derived or recombinant products. On the whole, these data confirm the high degree of safety of the products currently used for replacement therapy. Copyright 2012 Blackwell Publishing Ltd.

Abstract

Thrombotic adverse events (AEs) after clotting factor concentrate administration are rare but the actual rate is unknown. A systematic review of prospective studies (1990-2011) reporting safety data of factor concentrates in patients with haemophilia A (HA), haemophilia B (HB) and von Willebrand disease (VWD) was conducted to identify the incidence and type of thrombotic AEs. In 71 studies (45 in HA, 15 HB, 11 VWD) enrolling 5528 patients treated with 27 different concentrates (20 plasma-derived, 7 recombinant), 20 thrombotic AEs (2 HA, 11 HB, 7 VWD) were reported, including two major venous thromboembolic episodes (both in VWD patients on prolonged replacement for surgery). The remaining thrombotic AEs were superficial thrombophlebitis, mostly occurring at infusion sites in surgical patients and/or during concentrate continuous infusion. The overall prevalence was 3.6 per 10(3) patients (3.6 per 10(4) for severe AEs) and 1.13 per 10(5) infusions, with higher figures in VWD than in haemophilia. Thrombotic AEs accounted for 1.9% of non-inhibitor-related AEs. Thrombosis-related complications occurred in 10.8% of patients with central venous access devices (CVADs) reported in six studies, the risk increasing with time of CVAD use. Data from prospective studies over the last 20 years suggest that the risk of thrombotic AEs from factor concentrate administration is small and mainly represented by superficial thrombophlebitis. These findings support the high degree of safety of products currently used for replacement treatment. Copyright 2012 Blackwell Publishing Ltd.