A recent real-world analysis of pediatric patients with hemophilia A suggests that treatment with emicizumab was a safe and efficient treatment in the study population. Results of this study were reported in the journal BMC Pediatrics.

Emicizumab is a humanized bispecific antibody that has received approval from the US Food and Drug Administration as a prophylactic treatment in patients with hemophilia A, with or without inhibitors. However, real-world data on its usage in pediatric patients have been limited, particularly for primarily untreated or minimally treated patients.

In this retrospective chart review, the researchers evaluated emicizumab use in pediatric with hemophilia A that was severe or moderate. Annualized bleeding rates (ABRs) and other clinical data were analyzed from both prior to and after initiating emicizumab treatment.

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A total of 13 patients were included in the study, of whom 12 had severe hemophilia A. There were 2 primary untreated patients included, 1 of whom was 3 months old at the start of emicizumab treatment. Another patient was a minimally treated patient with fewer than 5 exposure days to treatment with factor VIII for acute bleeds.

Patients in this study had a median age of 5.3 years (range, 0.26-17.5) at the start of emicizumab treatment, and 3 patients were younger than 1 year of age when initiating this treatment. Patients had a median follow-up time on emicizumab of 23.8 months (range, 0.7-40).

Prior to receiving emicizumab, the median total ABR was 0.25 (range, 0-4). The median total ABR was 0 (range, 0-0.5) after transitioning to emicizumab (P =.009). The median spontaneous ABR was also significantly lower after emicizumab initiation (P =.018), as was the traumatic ABR (P =.018) and the median joint ABR (P =.027). Following emicizumab initiation, 92.3% of patients had no bleeds, and 1 patient experienced a traumatic bleed.

The safety profile of emicizumab was found to be favorable in this analysis. Local injection-site skin reactions were reported in 2 patients, 1 of whom had recurrent injection-site urticaria following each injection. The researchers reported that symptom improvement occurred in this patient with injecting more deeply within the subcutaneous tissue. Treatment discontinuation was not required for any patient as a result of side effects. Three patients successfully underwent surgery.

Patients had median trough levels of emicizumab of 43.2 mg/mL after receiving the first 3 doses of emicizumab and 51.9 mg/mL at first follow-up. Activated partial thromboplastin time dropped as emicizumab levels increased, and factor VIII activity levels were below 3.3% in all patients with emicizumab treatment.

The researchers who conducted the study concluded that emicizumab treatment was safe and efficient in patients of this cohort, including those who were primary untreated or minimally treated. “In the future, there might be patients in this cohort being treated with different dosing regimen (e.g. once every four weeks) and further studies with other dosing regimens may offer new insights,” the researchers wrote in their report.


Glonnegger H, Andresen F, Kapp F, Malvestiti S, Büchsel M, Zieger B. Emicizumab in children: bleeding episodes and outcome before and after transition to emicizumab. BMC Pediatr. 2022;22(1):487. doi:10.1186/s12887-022-03546-1