Administration of twice-monthly or monthly emicizumab appears safe and effective for children with severe hemophilia A without inhibitors, according to a small cohort study.
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After 24 weeks of treatment, only one moderate-intensity injection site reaction was reported, but no thrombotic microangiopathy or thromboembolic complications were observed.
The researchers evaluated the efficacy, safety, and pharmacokinetics of emicizumab in Japanese pediatric patients aged less than 12 years with severe hemophilia A without factor VIII inhibitors, wrote Midori Shima, MD, PhD, of Nara Medical University, Kashihara, Japan, and colleagues. The results were published in Haemophilia.
The open-label, nonrandomized study included 13 children who initially received weekly loading doses (3 mg/kg) of subcutaneous emicizumab for 4 weeks. Subsequently, patients received maintenance doses of 3 mg/kg every 2 weeks or 6 mg/kg every 4 weeks until week 24.
At baseline, the median age of patients in the 2- and 4-week dosing cohorts were 6.6 and 4.1 years, respectively. All participants had received factor VIII prophylaxis prior to starting emicizumab, with the exception of one patient.
Among six patients in the twice-monthly dosing cohort, two had no treated bleeding episodes, with an annualized bleeding rate for treated bleeding episodes of 1.3 (95% confidence interval, 0.6-2.9).
Among seven patients in the monthly dosing cohort, five had no treated bleeding episodes, with an annualized bleeding rate for treated bleeding episodes of 0.7 (95% CI, 0.2-2.6).
Caregivers completed a preference survey after the first 16 weeks of treatment, and “all reported a preference for emicizumab prophylaxis over the patient’s previous haemophilia treatment.” They cited the lower frequency of treatment and easier route of administration for favoring emicizumab.
With respect to pharmacokinetics, mean steady-state trough levels were within acceptable limits based on previous studies. No patients tested positive for anti-emicizumab antibodies.
The small sample size and nonrandomized design were key limitations of the study.
The results “confirm the appropriateness” of applying the every 2-week and every 4-week regimens of emicizumab in pediatric patients with hemophilia A without inhibitors, the researchers wrote.
The authors reported having financial affiliations with Chugai Pharmaceutical Co., which funded the study, and other companies.
SOURCE: Shima M et al. Haemophilia. 2019 Sep 12. doi: 10.1111/hae.13848.