Abstract Number: PB0624
Meeting: ISTH 2021 Congress
Background: Emicizumab is an asymmetrical bispecific antibody that mimics the cofactor function of activated factor VIII (FVIIIa). In 2019, clinical usage of emicizamab was approved for hemophilia A regardless with or without inhibitor in Japan. Because most adult and adolescent patients have already received prophylactic treatment by factor concentrate, their bleeding episodes are suppressed enough. However, in case the switch from the conventional therapy to emicizumab administration in such patients, the bleed suppression efficacy has not been well-known.
Aims: Our objective is to clarify an efficacy of emicizumab in patients with hemophilia A(PWHAs) without inhibitor whose therapies switched from conventional prophylaxis.
Methods: We calculated respective annualized bleeding rates (ABR) and annualized joint bleeding rates (AJBR) by patient diaries of 11 PWHAs without inhibitor whose therapies switched from conventional prophylaxis to emicizumab administration. Then, the ABRs and the AJBRs were compared before and after switching to emicizumab. On the other hand, trough levels of factor VIII and factor VIII equivalent activities of patients’ plasma were respectively measured by chromogenic assay (CGA).
Results: Nine of 11 had severe hemophilia and the others had moderate. The observation periods of conventional prophylaxis and emicizumab administrations were 4.00 years and 1.08 years(median). The median ABR and AJBR during prophylaxis was 3.33 and 1.06. The median values of ABR and AJBR after switching emicizumab was 2.01 and 1.00. Most trough levels of Factor VIII activity at conventional prophylaxis were higher than respective baseline (median 3 IU/dL). However, their FVIII equivalent values at steady state by regulary emicizumab administrations were 15.7 IU/dL (median, min-max; 13.8-19.7).
Conclusions: Even when switching from conventional prophylaxis to emicizumab administration, their bleedings were still suppressed. Besides, their FVIII equivalent values seemed to be higher than their trough levels of FVIII activity at conventional prophylaxis.
To cite this abstract in AMA style:Fujii T, Yamasaki N, Inoue T, Fujii T. A Bleed Suppression Efficacy of Emicizumab in Patients with Hemophilia A whose Therapies Switched from Conventional Prophylaxis [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 1). https://abstracts.isth.org/abstract/a-bleed-suppression-efficacy-of-emicizumab-in-patients-with-hemophilia-a-whose-therapies-switched-from-conventional-prophylaxis/. Accessed July 26, 2021.
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