Once-weekly prophylactic injection of glycopegylated recombinant factor VIII (N8‐GP) for severe hemophilia A appears to be efficacious and safe, according to results from the pathfinder 2 extension phase.

The study, published in Haemophilia, included patients aged 12 years or older with severe hemophilia A who had experienced up to 2 bleeds during the pathfinder 2 study (ClinicalTrials.gov Identifier: NCT01480180), a multinational, open label, phase 3 trial evaluating N8-GP safety, efficacy, and pharmacokinetics. The efficacy and safety endpoints were annualized bleeding rate (ABR) and incidence of factor VIII inhibitors, respectively.

Related Articles

In total, 55 patients were randomly assigned to receive 50 IU/kg N8-GP every 4 days (17 patients) or 75 IU/kg N8-GP every 7 days (38 patients) for 24 weeks. The average ABR was 1.66 for the former cohort and 1.65 for the latter.

While receiving N8-GP prophylaxis, 52.9% (9/17) of patients in the 50 IU/kg cohort and 57.9% (22/38) of patients in the 75 IU/kg cohort experienced no bleeding episodes. Additionally, 92.3% (12/13) of bleeds in the 50 IU/kg cohort and 96.0% (24/25) of bleeds in the 75 IU/kg cohort were controlled with 2 or fewer injections.

No patients developed factor VIII inhibitors, and no anti-N8-GP antibodies were detected. Prior to the end of the study, 9 patients in the 75 IU/kg cohort requested to revert to 50 IU/kg prophylaxis.

There were 5 adverse events — rash, thrombocytopenia, increase in aspartate aminotransferase, and headache in the 75 IU/kg cohort; purpura in the 50 IU/kg cohort — that were considered to be related to N8-GP treatment.

The authors concluded that “weekly N8-GP may provide effective prophylaxis with a reduced treatment burden for a selected subset of low-bleeding patients with severe haemophilia A.”


1.     Curry N, Albayrak C, Escobar M, et al. Once-weekly prophylaxis with glycoPEGylated recombinant factor VIII (N8-GP) in severe haemophilia A: Safety and efficacy results from pathfinder 2 (randomized phase III trial) [published online February 28, 20190]. Haemophilia. doi: 10.1111/hae.13712