Background: Emicizumab use as prophylaxis in pediatric hemophilia A (HA) is increasing due to improved ease of administration and less frequent dosing schedule compared to factor VIII or bypassing agent infusions. Data on the pediatric experience with emicizumab outside of clinical trials, however, is limited.

Aims: To determine the safety and efficacy of emicizumab prophylaxis in pediatric HA within our institution.

Methods: Retrospective review on patients under 21 years of age with HA who have been treated with emicizumab as prophylaxis at Texas Children’s Hospital.

Results: A total of 28 patients received emicizumab, 96.4% (n=27) of which had severe HA. Emicizumab initiation occurred at a median age of 6.7 years (range 0.2-20.4) with all receiving an every-other-week maintenance dosing schedule. The median length of time patients were on emicizumab at the time of data collection was 18.5 months (range 2-26). A history of inhibitors was present in 46.4% (n=13), 38.5% (n=5) of which had undergone immune tolerance prior to initiating emicizumab. The mean annualized bleeding rate (ABR) declined from 3.61 (range 0-15) over the 12-24 months prior to initiating emicizumab to 0.44 (range 0-4) after (p=0.0002; paired t-test). Seven patients underwent a surgical procedure (5 port removals, one lower extremity orthopedic procedure, and one arteriovenous fistula takedown). All were treated with continuation of emicizumab and peri-operative factor replacement with one minor post-operative bleeding event (hematoma at the site of a port removal). 14.3% (n=4) patients experienced mild injection site side effects. One patient with a history of multiple deep venous thromboses experienced a symptomatic cephalic vein thrombosis following arteriovenous fistula takedown, there were no other thrombotic complications. All patients but one opted to remain on emicizumab.

Conclusions: The experience at our center demonstrates that emicizumab is a safe and effective prophylactic option for patients with HA both with and without inhibitors.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/emicizumab-in-pediatric-hemophilia-a-single-center-retrospective-study/