PB0554 - Real-world data on the use of emicizumab in pediatric patients in Baltic countries

Background: Real-world data on safety and efficacy of emicizumab prophylaxis among the pediatric hemophilia A (HA) patients is scarce.

Aims: To present real-world pediatric data from HA patients receiving emicizumab in Baltic countries.

Methods: A retrospective review of emicizumab treated patients with available emicizumab levels between January 2018 and December 2023. Emicizumab concentrations were tested in Estonian lab by modified one stage factor VIII assay (STA ImmunoDef VIII, STA-CK Prest, Diagnostica Stago, France) using emicizumab calibrator and controls (r2 Diagnostics, USA)(1). Additional parameters (aPTT, d-dimers and chromogenic FVIII assay with bovine reagents) were performed in local labs. All samples for emicizumab measurements were assessed during maintenance phase.

Results: In total 13 patients with HA with and without inhibitors, PTPs and PUPs were included into study (age from 10 months to 10 years). Therapy follow-up time ranged from 1 month to 3 years 7 months. None of the patients experienced spontaneous bleeding, none underwent surgery. Apart from local pain during injection of emicizumab no other adverse events were observed. No cessation of treatment was necessary. APTT decreased to the lower reference limit. Most patients had normal levels of d-dimers, except one (PUP), who demonstrated extreme episodic increase of d-dimers without clinical complications and consequent normalization of values in 4 months. Median plasma emicizumab concentration was 47.6 μg/mL. All patients and their families were highly satisfied with non-factor therapy and improved quality of life (QoL).

Conclusion(s): Emicizumab effectively prevents bleeding and improves QoL in HA patients with and without inhibitors. Although routine laboratory monitoring of emicizumab levels is not a common practice, we encourage the discussion regarding its potential benefits.