Long-term experience with emicizumab in people with hemophilia A in the Canadian Bleeding Disorders Registry

Abstract: Emicizumab prophylaxis has been approved in Canada for the prevention or reduction of bleeding episodes in people with congenital hemophilia A (PwHA). Using routinely collected health data from the Canadian Bleeding Disorders Registry (CBDR), this observational cohort study aimed to evaluate the long-term safety and effectiveness of emicizumab in PwHA. Deidentified data from the CBDR were collected for PwHA who had received ≥1 dose of emicizumab from 2018 up to 31 December 2023. Intrapatient comparisons of annualized bleeding rates (ABRs) for all reported bleeds before and after emicizumab were performed using a negative binomial regression model. Overall, 710 PwHA received ≥1 emicizumab dose, and 539 (75.9%) had >1 year of emicizumab exposure. During the observational period, the safety profile was in keeping with previous reports; 34 adverse events were observed, including 2 thrombotic events (1 unlikely related to emicizumab; 1 probably related to previous use of eptacog alfa and/or possibly related to previous emicizumab, and associated with a central venous access device). Over a median (first to third quartiles) follow-up time of 549 (374-690) days, 439 (61.8%) PwHA had no recorded bleeds. Mean ABR decreased from 1.00 (95% confidence interval [CI], 0.87-1.14) before emicizumab to 0.47 (95% CI, 0.40-0.55) after emicizumab (rate ratio, 0.47 [95% CI, 0.41-0.55]; P < .001). A notable decrease in bleeds and sustained bleed control were observed in this population for up to a 5-year follow-up period. Continued follow-up will allow for greater quantification of this impact over time, providing valuable information to health care practitioners and regulatory authorities.