Extended half-life (EHL) factor VIII concentrates have served as successful alternatives for factor prophylaxis and in hemophilia A (HemA) and have the advantage of a more convenient dosing schedule for patients living with this disorder. Patients using EHL products have on average statistically significant lower annualized bleed rates (ABR) when compared to those on a short half-life (SHL) regimen. Head to head studies between EHL therapies are rare. Dr. Manuel Carcao and colleagues sought to compare the pharmacokinetic (PK) profiles of 2 EHL-FVIIIs concentrates and the correlation with other covariates in a group of Canadian boys (ages 12-18 years). The rationale for this comparison was the requirement in boy aged 12-18 in Canada to switch from one EHL product (rFVIII-Fc) to another (rAHF-FL-PEG).
Carcao and team sampled FVIII levels at 3, 24, 48 and 72 hours following prophylactic infusion of rFVIII-Fc and then, 1-3 months later, performed the same analysis for those who switched to rAHF-FL-PEG. Investigators found no significant differences between the 2 EHL-FVIIIs in half-life, drug clearance, area under the curve, volume of distribution at steady state or time taken for FVIII levels to drop to 5%, 3% and 1%. Additionally, the study showed a major impact of blood group on the PK of both products.
Carcao concluded that these 2 products, from a pharmacokinetic perspective, were virtually identical and that, when switching patients from one product to the other, no changes in treatment regimens are needed.