PB1219 - Real-world Utilization of Extended Half-life Factor VIIIs in the Treatment of Hemophilia A: A Retrospective Single Center Study in Korea

Background: The treatment options for hemophilia A patients are gradually diversifying. In Korea, Rurioctoco alfa pegol has been actively used since 2018, Efmoroctocog alfa since 2020. Additionally, emicizumab was introduced in 2020.

Aims: In this context, we aim to examine how extended half-life(EHL) factor agents are being prescribed to patients visiting tertiary hemophilia center.

Methods: We investigated patients who were prescribed EHL FVIIIs at Severance Hospital, Seoul, Korea, from 2018 to 2023. Their data was retrospectively analyzed. Among 48 patients who used EHL factor, 38 suitable patients were analyzed.

Results: Rurioctocog alfa pegol was used in 16(42.1%), Efmoroctocog alfa in 22 patients(57.9%). 25 patients(65.8%) were under 19 years old at the time of EHL use. Two patients started each drug as an additional choice to control bleeding, combined with emicizumab or another clinical trial drug. The remaining 36 patients(94.7%) used EHLs prophylactic treatment. Most patients switched from standard half-life(SHL) FVIIIs to EHLs, except for 6 previously untreated patients(PUPs). During a median of 24.9 months of EHLs usage, none of the patients who changed drugs developed an inhibitor; however, two PUPs developed inhibitor after 9 and 12 exposure days, respectively. The reasons for changing to EHLs included decreased dosing frequency with better efficacy(n=18), frequent bleeding with SHLs(n=10), and a low half-life of SHL observed in a pharmacokinetic study(n=3). The median annualized bleeding rate(ABR) with EHLs was 0.55, which was lower than previous drugs(ABR=2.0). However, among the 36 patients, 8 patients(2 with inhibitors, 6 without inhibitors) switched to emicizumab, and 6 patients enrolled in clinical trials, necessitating the discontinuation of EHLs. Only 22 out of the 36 patients who initially started EHLs prophylaxis continued to use EHLs.

Conclusion(s): While there is a limitation in the retrospective nature of this study, it has provided insights into the dynamic nature of actual EHLs usage among hemophilia patients.