Multicentre pharmacokinetic evaluation of rFVIII‐Fc (efmoroctocog alfa) in a real life and comparison with non‐extended half‐life FVIII concentrates

Abstract

The use of enhanced half‐life (EHL) FVIII has improved the quality of prophylaxis in haemophilia A, but with a benefit that may vary from one patient to another. We analysed the pharmacokinetic data obtained with efmoroctocog alfa (rFVIII‐Fc) in 114 patients and, in 47 cases, compared them to those previously measured with non‐EHL FVIII. The in vivo recovery (IVR) of rFVIII‐Fc measured with one stage clotting assay (OSA) and chromogenic assay (CSA) was 2.2 and 2.8 IU/mL per IU/kg, respectively. The median half‐life (T_1/2) of rFVIII‐Fc was 14.5 hours whatever the FVIII:C assay used, but variable and correlated with preinfusion VWF:Ag levels (r = .76). Both IVR and T_1/2 were lower in patients under 12 years old (2.4 IU/mL per IU/kg and 11.1 hours, respectively; CSA). PK study of rFVIII‐Fc vs non‐EHL FVIII showed a T_1/2 ratio of 1.4 in favour of rFVIII‐Fc, regardless of the patient's age. However the relative increase in T_1/2 with rFVIII‐Fc was lower than 30% in one‐third of patients evaluated, particularly when the previous FVIII administered was a BHK‐derived product. This study therefore suggests that analysis of individual PK profile in response to a specific FVIII concentrate is potentially useful before a switch in haemophilia A patients.