PB0194 - Comparison of intraindividual bleeding outcomes pre- and post-emicizumab in Australian adults and children with haemophilia A with and without inhibitors: a nationwide real-world experience

Background: Emicizumab, a novel recombinant bispecific monoclonal antibody, became routinely available in Australia in November 2020 as regular prophylaxis for patients with severe or moderate haemophilia A (HA) with and without inhibitors.

Aims: To perform intraindividual comparison of bleeding outcomes in HA patients in the 12 months before, to the entirety of time after (minimum 6 months), commencement of emicizumab prophylaxis in this large-scale nationwide and multi-centre real-world setting.

Methods: Data were extracted from the Australian Bleeding Disorders Registry (ABDR) on all Australian patients currently on emicizumab regarding demographics, severity, treatment, inhibitors and number and type of intraindividual treated bleeds pre and post commencing emicizumab.

Results: As of April 2022, there are 463 HA patients on emicizumab in Australia: 86% (397/463) with severe disease, 12% (57/463) moderate and 2% (9/463) mild. 13% (59/463) have a current inhibitor. 49% (225/463) are adults > 18 years and 51% (238/463) < 18 years old. Median length of time on emicizumab was 81.1 weeks [interquartile range (IQR) 62.3-95.1 weeks]. 54% of patients had zero treated bleeding events prior to receiving emicizumab compared to 64% post-emicizumab, with a risk ratio (RR) of 1.25 (P < 0.01) (Figure 1). RR for zero treated bleeds post-emicizumab was significant in high-titre inhibitor (RR 1.46, P=0.03) and non-inhibitor patients (RR 1.24, P=0.02). Patients on on-demand or tolerisation therapy had the most significant improvement in zero bleed rates post emicizumab (RR 1.78, P< 0.01) within the various subpopulations. The bubble plot (Figure 2) illustrates the distribution of joint bleed numbers pre- and post-emicizumab, with the greatest proportion of those who had a bleeding event reducing from one bleed pre-emicizumab to zero bleeds post (46%, 42/91).

Conclusion(s): These large-scale favourable real-world results are consistent with trial results demonstrating a reduction in bleeding events with use of emicizumab prophylaxis in HA patients with and without inhibitors.