Background:
Emicizumab was approved by the FDA in 2017 for routine prophylaxis in PwHA with inhibitors. HAVEN 1, a phase III study in adolescent and adult PwHA with inhibitors, demonstrated that emicizumab prophylaxis significantly reduced annualized treated bleed rate by 87% (P<0.001) vs no prophylaxis. In this retrospective, post-hoc analysis, we examined the use of BPAs to treat breakthrough bleeds before and after emicizumab initiation in HAVEN 1.
Methods:
HAVEN 1 patients were included from emicizumab-treated Arms A (previously treated with only episodic BPA) and C (previously treated with prophylactic BPA) and who had participated in the non-interventional study (NIS). In both studies, bleed and treatment data collection were comparable. In the study protocol, no guidance for the treatment of bleeds was provided; and hemostatic efficacy was not measured, thus optimal treatment of bleeds cannot be accurately assessed. Additionally, only data before October 7th, 2016 are included in this analysis to better represent treatment patterns before amended BPA guidance was provided. We describe the total number of patients and bleeds, number of infusions per bleed, and the cumulative dose/kg per bleed before and after emicizumab initiation.
Results:
This analysis (48 total patients) included 24 patients each from Arm A and Arm C who participated in the NIS prior to enrollment in the HAVEN 1 trial. On average, patients received numerically fewer activated prothrombin complex concentration (aPCC) infusions with lower cumulative doses while on emicizumab as compared to prior to emicizumab administration. In Arm A, 11 bleeds were treated with aPCC resulting in an average of 1.2 aPCC infusions/ bleed and an average cumulative aPCC dose/ bleed of 95.9 U/kg while on emicizumab as compared to 136 bleeds resulting in an average of 1.7 infusions/ bleed and cumulative dose 134 U/kg prior to emicizumab. Similar findings were seen in Arm C (bleeds, aPCC infusion/cumulative dose numbers: 14,2.3/166.6 U/kg on emicizumab compared to 205, 2.6/189 U/kg prior to emicizumab.) Fewer bleeds were treated with rFVIIa and no clear trend was seen regarding how rFVIIa was used to treat bleeds. In Arm A, 11 bleeds were treated with rFVIIa resulting in an average of 1.5 infusions/ bleed and cumulative dose 212.2 µg/kg on emicizumab, vs 97 bleeds, 1.4 infusions/ bleed and cumulative dose 181.6 µg/kg prior. In Arm C, 14 bleeds were treated with rFVIIa resulting in 4.4 infusions/ bleed and cumulative dose 555.6 µg/kg on emicizumab vs 58 bleeds, 8.6 infusions/ bleed and cumulative dose 1829 µg/kg prior.
Conclusions:
Treatment of bleeds with aPCC in HAVEN 1 resulted in numerically fewer infusions and lower cumulative doses of aPCC per bleed while on emicizumab when compared to bleeds treated prior to emicizumab initiation. Treatment of bleeds with rFVIIa showed no clear trend.