LAUSR

Background:Prophylactic treatment with standard half-life coagulation factors (SHL) requires 3-4 weekly periodic infusions. Extended half-life (EHL) factor VIII (FVIII) provides improvements in half-life (t1/2) and area under the curve (AUC) of 1.3 and 1.25 times compared to standard half-life (SHL) products. Rurioctocog alfa pegol is an extended half-life (EHL) rFVIII (rFVIII-EHL) treatment that could be a more convenient and cost-effective therapeutic alternative than SHL, since it would reduce the number of weekly infusions (NWI). Aims:The aim of this study is to analyze pharmacokinetic (PK) parameters and compare NWI and bleeding rates after switching from SHL to this EHL in hemophilia A (HA) patients. Methods:In a prospective study, the number of weekly infusions (NWI), annualized bleeding rate (ABR), annualized joint bleeding rate (AJBR), and PK parameters were compared between previous treatment with FVIII-SHL vs rFVIII-EHL (Rurioctocog alfa pegol). The assessment of the PK parameters: volume of distribution (Vd (dL/kg)), clearance (Cl (dL/h/kg)) and half-life time (t½ (h)) was performed by using the pharmacokinetic poblacional software online myPKFiT®. Results:Nineteen patients from 2 Spanish hospitals (n=12 Vall d'Hebron Hospital, n=7 Hospital Regional Universitario de Málaga) were recruited. Median age was 30 years (range, 12-54), with five pediatric patients, and 18 had severe HA (one moderate HA). Sixteen patients were under prophylactic treatment with Advate® and 1 with Kovaltry®. Two patients were switched from on-demand treatment to prophylaxis. The median use of rFVIII-EHL was 15.63 month. The PK parameters after the switch to the rFVIII-EHL in entire cohort and pediatric cohort are shown in Table 1. The t ½ of rFVIII-EHL was positively correlated to preinfusion plasma levels of von Willebrand factor antigen (vWF:Ag) (Figure 1). ABR and AJBR were reduced, as well as weekly infusion frequency (33.3%, IQR:0-50%) (Table 2). Of note, 57.9% of patients presented zero joint bleeding events after switchingtorFVIII-EHL. Conclusions:In this prospective analysis rFVIII- EHL presents as a therapeutic alternative that allows reducing ABR and AJBR as well as weekly infusion frequency according to PK patient parameters. Bosch: Roche:Honoraria;Celgene:Honoraria;Jansen:Honoraria;Abbvie:Honoraria;Novartis:Honoraria;Astra Zeneca:Honoraria;Takeda:Honoraria.Gironella Mesa:Bristol Myers Squibb:Honoraria, Speakers Bureau;Janssen:Consultancy, Honoraria.