How do we optimally utilize factor concentrates in persons with hemophilia?

Nonacog beta pegol prophylaxis in children with hemophilia B: safety, efficacy, and neurodevelopmental outcomes for up to 8 years

Background

Nonacog beta pegol (N9-GP) is an extended half-life PEGylated factor (F)IX product with established efficacy and short-term safety in persons with hemophilia B (HB). Long-term safety has been evaluated for polyethylene glycol exposure but not N9-GP.

Objectives

To assess safety, neurodevelopmental, and efficacy outcomes of children with HB receiving N9-GP prophylaxis across 2 open-label, single-arm, phase 3 studies: paradigm5 (previously treated patients [PTPs]) and paradigm6 (previously untreated patients [PUPs]) in this interim analysis.

Methods

PTPs (aged ≤12 years) and PUPs (aged <6 years) with severe/moderate (≤2% FIX level) HB were recruited to N9-GP prophylaxis (40 IU/kg once weekly) in paradigm5 and paradigm6, respectively. Safety assessments included FIX inhibitor incidence, adverse events, neurocognitive and neurologic outcomes, polyethylene glycol concentration in plasma, and medical events of special interest. Efficacy endpoints included bleeds, N9-GP hemostatic effect, and FIX consumption.

Results

Overall, 25 patients in paradigm5 and 50 patients in paradigm6 received N9-GP and were followed for up to 8 and 6 years, respectively. No inhibitory antibodies were reported in PTPs; 4 of the 50 PUPs developed inhibitors. Extensive evaluation revealed no neurocognitive or neurologic concerns with N9-GP use in children during the study period. Across both studies, few adverse events were reported as possibly related to N9-GP. High hemostatic response rate, high treatment adherence, low annualized bleeding rates, and no new target joints were reported.

Conclusion

These data provide the longest follow-up for an extended half-life FIX and confirm the long-term efficacy of N9-GP prophylaxis in children with HB with no observed neurocognitive or neurologic safety concerns.

Joint Dysfunction as a Cause of Spontaneous Subclinical Bleeding in Infants with Hemophilia

Hemophilia is an inherited hemorrhagic disorder; its main clinical manifestations being bleeding in muscles and joints. Ankles, knees, and elbows are the most frequently affected joints, followed by shoulders and hips. The clinical signs of joint involvement are reduced mobility, swelling and walking difficulties. Bleeding episodes in patients with hemophilia are usually divided into traumatic and spontaneous, but we believe that the latter are not truly spontaneous but rather the result of joint stresses owing to motion actions that create dysfunctions starting from infancy. Pharmacological prophylaxis with factor replacement therapies or non-replacement drugs markedly reduces musculoskeletal hemorrhages. However, the onset of subclinical joint stress can be reduced only by associating this therapeutic approach with the accurate observation of the child motion patterns and restoring them if dysfunctional, thereby primarily preventing subclinical bleeding and ultimately the onset or progression of hemophilic arthropathy.

Harmonizing factor assay-related testing performed in a large laboratory network

Coagulation factor testing is commonly performed within haemostasis laboratories, either to assess for bleeding disorders, such as haemophilia, or to investigate unexplained prolongation in routine coagulation assays. The aim of this evaluation was to harmonize procedures and normal reference ranges (NRRs) for investigation of coagulation factors on the ACL TOP 50 family of instruments in a large laboratory network. We employed comparative evaluations using newly installed ACL TOPs 550 and 750 and HemosIL reagents vs. existing 'reference' instrumentation and reagents, predominantly Stago and Siemens, as well as assessment of factor sensitivity in routine coagulation assays, prothrombin time (PT) and activated partial thromboplastin time (APTT). Also, establishment of coagulation factor NRRs using normal plasma samples. HemosIL factor assays showed good comparability with the existing reference methods (R > 0.9). Factor sensitivity for PT and APTT assays were acceptable at around 30 U/dl. NRRs were established and harmonized across the laboratory network. This evaluation of factor testing on ACL TOP 50 Family instruments identified overall acceptable performance using Werfen reagents and enabled harmonization of coagulation factor testing in our large network.