Emicizumab in Severe Hemophilia A: Clinical and Patient Determinants of Transition Within a Standardized Program

Emicizumab (Hemlibra) became more accessible for Canadians in 2021, when Canadian Blood Services approved it under formulary for prophylaxis in patients with severe hemophilia A (PWHA) without inhibitors. This offered an alternative to factor VIII (FVIII) prophylaxis. Starting in November 2021, a coordinated effort to offer and support the transition to emicizumab was initiated for all eligible adult PWHA living in British Columbia (BC) and Yukon Territory. Of the 69 PWHA who transitioned to emicizumab, it was observed that some were early adopters whereas others demonstrated more caution and transitioned later. Our aim was to better understand patient and clinical practice factors associated with the early and late transition to emicizumab.

Retrospective data were assessed from clinical records, transition documents and available pre-transition patient-reported surveys for both patient and clinical factors.

Of the 83 patients with PWHA eligible for transition, 69 transitioned to emicizumab between November 2021 and December 2023. Median time to emicizumab transition was 10 months. Younger PWHA and those with fewer cumulative comorbidities tended to delay transition to emicizumab. Geographic distance from Vancouver was not significantly associated with transition timing. In multivariable analysis, younger age remained independently associated with longer time to transition (P = 0.0008), while having five or more joints affected by hemophilic arthropathy was associated with later transition (P = 0.007).

Using a standardized transition program offered an opportunity to gain a deeper understanding of patient and clinical factors associated with transition to a novel agent. This analysis highlights that certain clinical factors may influence uptake of new therapies within hemophilia care and the importance of early identification of barriers to facilitate treatment uptake.