No abstract

Turoctocog alfa pegol (N8-GP) is a novel glycoPEGylated extended half-life recombinant factor VIII (FVIII) product developed for prophylaxis and treatment of bleeds in patients with haemophilia A, to enable higher activity levels with less frequent injections compared with standard FVIII products. This phase III (NCT01480180), multinational, open-label, non-randomised trial evaluated the safety and clinical efficacy of N8-GP when administered for treatment of bleeds and for prophylaxis, in previously treated patients aged ≥12 years with severe haemophilia A. Patients were allocated to receive N8-GP for prophylaxis or on-demand treatment for up to 1.8 years. Patients on prophylaxis were administered one dose of 50 IU/kg of N8-GP every fourth day. Bleeds were treated with doses of 20-75 IU/kg. Total exposure to N8-GP in the trial was 14,114 exposure days (159 patient-years). For the prophylaxis arm (n=175), the median annualised bleeding rate (ABR) was 1.33 (interquartile range, 0.00-4.61), the mean ABR was 3.70 (95 % confidence interval 2.94-4.66) and 70 (40 %) patients had no bleeds during the trial. Across treatment arms, 83.6 % of bleeds resolved with one injection and 95.5 % with up to two injections. N8-GP had a favourable safety profile and was well tolerated. The frequency and types of adverse events reported were as expected in this population. One patient developed inhibitory antibodies against FVIII (≥0.6 Bethesda units [BU]) after 93 N8-GP exposure days. No clinically significant safety concerns were identified and N8-GP was effective for prophylaxis and treatment of bleeds in previously treated patients.

Turoctocog alfa pegol (N8-GP, Novo Nordisk, Bagsværd, Denmark), an extended half-life glycoPEGylated recombinant factor VIII (rFVIII), is being developed for prophylaxis and treatment of bleeds in haemophilia A patients. pathfinder™5 is a multinational, open-label, single-arm trial to assess safety, efficacy and pharmacokinetics of N8-GP in paediatric (<12 years), previously treated patients. Boys with severe haemophilia A (<1 % FVIII), no history of inhibitors and previously treated with FVIII products (>50 exposure days [ED] for patients aged 0-5 years [younger cohort]; >150 ED for patients aged 6-11 years [older cohort]) were included. For prophylaxis, N8-GP was dosed at 50-75 IU/kg twice weekly; bleeds were treated with 20-75 IU/kg. Half-life was estimated for the patients' previous FVIII product and for N8-GP. Sixty-eight patients received N8-GP; none developed inhibitors and no other concerns were identified. Median annualised bleeding rate was 1.95 (1.94 and 1.97 in the younger and older cohorts, respectively). Twenty-nine patients (42.6 %; 15 younger and 14 older children, respectively) did not report any bleeding while on N8-GP prophylaxis; 39 patients (57.4 %; 19 younger and 20 older children, respectively) reported 70 bleeds (all mild/moderate). N8-GP treatment was successful for 78.6 % of bleeds in all patients, 80.0 % in younger and 77.5 % in older patients. Most bleeds (80.0 %) were treated with ≤2 injections. Half-life ratio between N8-GP and the patients' previous FVIII product was 1.85. N8-GP was well tolerated and provided effective prophylaxis and treatment of bleeds in paediatric patients with severe haemophilia A.

We report our clinical experience in the immune tolerance (IT) therapy of 21 paediatric haemophiliacs with FVIII inhibitor: high responders (16HR) received initially FVIII twice daily at a dosage of 50-300 U/kg/day, 11/16 received a concomitant treatment with activated prothrombin complex concentrate (100-200 U/kg/day). Low responders (five LR) received 20-100 FVIII U/kg every second or third day. Inhibitor elimination was achieved in 19/21 patients in a median time of 4 months in HR and 1.5 months in LR. The outcome and length of time needed to induce IT was significantly correlated with FVIII exposure between the first inhibitor detection and onset of IT therapy and to interruption of IT therapy. For a rapid elimination of FVIII inhibitors it is important to start continuous administration of high-dose FVIII (≥ 100 FVIII U/kg/day) before repeated exposure to FVIII, in order to prevent rebooster effects, prolongation of elimination time, and to reduce expense.