Abstract Number: PB0521
Meeting: ISTH 2021 Congress
Background: Emicizumab replaces the function of missing activated FVIII in PwHA, thereby restoring hemostasis.
Aims: Report the final analysis from STASEY (NCT03191799), a phase III trial assessing the safety of emicizumab prophylaxis in PwHA with FVIII inhibitors.
Methods: Informed consent and ethics committee approval were acquired. PwHA age ≥12 years with FVIII inhibitors received subcutaneous emicizumab 3 mg/kg once weekly (QW) for 4 weeks, followed by 1.5 mg/kg QW for up to 2 years. The primary objective was to evaluate the safety of emicizumab (adverse events [AEs]; including thromboembolic events [TEs], thrombotic microangiopathies [TMAs], and hypersensitivity reactions). Secondary objectives included assessing the efficacy of emicizumab (annualized bleed rates [ABRs]), and anti-drug antibody (ADA) development.
Results: At date of last participant’s last visit (19-November-2020), 193 PwHA (median age [range]: 28.0 [12–80] years) had received ≥1 dose of emicizumab, thus forming the safety-evaluable population. Median (range) treatment duration was 103.1 (1.1–108.3) weeks. Emicizumab was well-tolerated (Table 1). The most common AEs were arthralgia (n=33, 17.1%), nasopharyngitis (n=30, 15.5%), and headache (n=29, 15.0%). No new TEs were reported since the two in the interim analyses (myocardial infarction; hypertrophic clot). Emicizumab-related AEs were reported in 35 (18.1%) participants; most frequently, injection-site reactions (n=19, 9.8%). Further to the fatality reported at the first interim analysis, one death was reported (abdominal compartment syndrome; deemed unrelated to emicizumab). Five PwHA received activated prothrombin complex concentrate, with no associated TMAs or TEs. Ten (5.2%) participants developed ADAs, five (2.6%) were neutralizing in vitro. Mean ABR for treated bleeds was 0.5, with 82.6% of participants having zero treated bleeds (Table 2).
Conclusions: The safety profile of emicizumab demonstrated in the HAVEN clinical trials was confirmed in a large, diverse population of PwHA with FVIII inhibitors, with no new safety signals and the majority of PwHA having zero treated bleeds.
To cite this abstract in AMA style:Jiménez-Yuste V, Peyvandi F, Klamroth R, Castaman G, Shanmukhaiah C, Rangarajan S, García Chavez J, Martinez R, Kenet G, Alzahrani H, Robson S, Schmitt C, Kiialainen A, Meier O, Ozelo M. Final Analysis of the STASEY Trial: A Single-arm, Multicenter, Open-label, Phase III Clinical Trial Evaluating the Safety and Tolerability of Emicizumab Prophylaxis in Persons with Hemophilia A (PwHA) with Factor (F)VIII Inhibitors [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 1). https://abstracts.isth.org/abstract/final-analysis-of-the-stasey-trial-a-single-arm-multicenter-open-label-phase-iii-clinical-trial-evaluating-the-safety-and-tolerability-of-emicizumab-prophylaxis-in-persons-with-hemophilia-a-pwha/. Accessed July 27, 2021.
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