Inhibitor Development in Previously Untreated Patients with Severe Hemophilia a Treated with Nuwiq^®, a New Generation Recombinant FVIII of Human Origin

Background

Studies have shown that the incidence of inhibitor development varies between FVIII concentrates, with some suggesting that recombinant FVIII (rFVIII) concentrates produced in hamster cell lines pose a greater risk of inhibitor development than plasma-derived (pd) von Willebrand factor (VWF)-containing FVIII (pdFVIII/VWF) products. In the SIPPET study, the cumulative incidence of high-titer inhibitorswith hamster-cell derived rFVIII products was 28.4% vs 18.6% for pdFVIII/VWF (Peyvandi F et al. N Engl J Med 2016; 374:2054-2064).

These studies did not include new generation rFVIII products produced in human cell lines. Nuwiq^® (Human-cl rFVIII) is the first and only new-generation rFVIII produced in human cells without chemical modification or protein fusion. The pharmacokinetics, efficacy and safety of Nuwiq^® have been examined in previously treated patients (PTPs) with severe hemophilia A, and no inhibitors have been reported in 201 PTPs. The immunogenicity, efficacy and safety of Nuwiq^® in previously untreated patients (PUPs) with severe hemophilia A is currently being assessed in the ongoing NuProtect study.

Methods

The NuProtect study was initiated in 2013 and is being conducted in 17 countries and 38 centers worldwide. One hundred evaluable (110 enrolled) male PUPs of all ages and ethnicities are being studied for 100 exposure days (EDs) or a maximum study participation of 5 years. The patients were to have received no treatment with FVIII concentrates or other blood products containing FVIII prior to study entry. The primary objective of the NuProtect study is to assess the immunogenicity of Nuwiq^® by determining inhibitor activity (≥0.6 BU) using the Nijmegen modified Bethesda assay in a central laboratory. Intensive screening for inhibitors is scheduled every 3-4 EDs until 20 EDs, then every 10-12 EDs until 100 EDs, and every 3 months until study completion. Secondary endpoints include assessment of hemostatic efficacy in prophylaxis, in the treatment of bleeds and in surgical prophylaxis, as well as safety and tolerability. All patients undergo F8 gene mutation analysis.

Results

Data from 85 treated PUPs have been included in the first pre-planned interim analysis (May 2016) of which 66 PUPs had ≥20 EDs (by which time the majority of inhibitors are likely to have arisen). The median age at first treatment was 13 months (range: 3-135). Of the 59 patients with available F8 gene mutation analysis, 1 (1.7%) had no identifiable mutation, 44 (74.6%) had mutations conferring a high risk of inhibitor development and 47 (81.0%) had null mutations. Data analysis in May 2016 showed that only 8 of the 66 PUPs treated with Nuwiq^® for ≥20 EDs had developed a high-titer inhibitor after a median of 11.5 EDs (range 6-24). Five of the 66 PUPs developed a low-titer inhibitor, 4 (80%) of which were transient. Only 2 patients developed an inhibitor (1 high-titer) after 20 EDs. The cumulative incidence of high-titer inhibitors in PUPs treated with Nuwiq^® is 12.8% (95% CI: 4.49-21.15) (Figure 1). The cumulative incidence of low-titer inhibitors was 8.4% (95% CI: 1.28-15.59) and of all inhibitors was 20.8% (95% CI: 10.68-30.95). No patient developed an inhibitor after 25 EDs. The incidence has remained consistent since the start of the study in 2013. Twelve of 13 patients who developed inhibitors had the causative F8 gene mutation detected, all of which were null, and all but one were high-risk.

Conclusions

PUPs treated with Nuwiq^® for ≥20 EDs had 12.8% cumulative incidence of high-titer inhibitorsat the time of interim analysis (8 of 66 PUPs) despite the fact that 81% of patients had gene mutations known to be associated with increased inhibitor risk (e.g. null mutations). These interim data support the low rate of inhibitor development in PUPs treated with Nuwiq^® - a human-cell derived (not chemically modified or protein fused) recombinant FVIII. Final data from the NuProtect study are expected in 2018 and will provide further insights into the development of inhibitors in PUPs with severe hemophilia A.

Figure 1.

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Cumulative incidence of inhibitor development

Figure 1.

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Cumulative incidence of inhibitor development

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