Abstract Number: PB1049
Meeting: ISTH 2020 Congress
Background: Although surveillance in previously treated patients (PTPs) with hemophilia A switching factor products suggests no increased inhibitor development risk, real-world data on the incidence of inhibitor development following a switch to a new factor product is imperative. Rurioctocog alfa pegol (TAK-660, SHP660, BAX 855), an extended half-life factor VIII concentrate, received initial FDA approval in 2015.
Aims: The ATHN 2: Factor Switching Study provides the opportunity to longitudinally observe a cohort of PTPs switching to TAK-660 to determine the incidence of inhibitor development.
Methods: This longitudinal cohort study is being conducted in ATHN-affiliated sites in the United States (NCT02546622). The ATHN 2 protocol was approved by institutional review boards and participants signed informed consent. Inclusion criteria included moderate or severe hemophilia A on any FVIII concentrate prior to switching. Inhibitor titers were measured at baseline, after 10 and 50 exposure days (EDs). Participants with a history of an inhibitor were eligible.
Results: Fifty-two participants switching to TAK-660 were enrolled. Thirty-seven were in the prospective arm. The median enrollment age was 27 years of age (IQR 14-36). All participants were male. Thirty-two participants were Caucasian, 11 were African American, 3 were Asian, 3 were other races and 3 were unknown (race information). Forty-three participants had severe and 4 had moderate hemophilia A. Eight of the participants had a prior history of inhibitors, three transient and five successfully tolerized. The baseline inhibitor titer for all participants was negative. No participant developed an inhibitor within one year of switch or 50 EDs.
Conclusions: No new inhibitors were noted amongst 52 hemophilia A participants over 50 EDs or 12 months, providing real-world evidence of the rarity of inhibitor development after product switch. Further data reporting participant satisfaction with TAK-660 and the results of other Patient Reported Outcomes (PROs) will be reported as data matures.
To cite this abstract in AMA style:Journeycake J, Caicedo J, Cheng D, Denne M, Guelcher C, Lattimore S, Ragni M, Recht M, Sidonio R, Takemoto C, Tarantino M, Watson C, Neufeld E. Lack of Inhibitor Development after Switching to Rurioctocog Alfa Pegol in the American Thrombosis and Hemostasis Network (ATHN) 2: Factor Switching Study [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/lack-of-inhibitor-development-after-switching-to-rurioctocog-alfa-pegol-in-the-american-thrombosis-and-hemostasis-network-athn-2-factor-switching-study/. Accessed September 26, 2022.
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