Real-world data shows that emicizumab (Hemlibra®) reduces bleeding rates in young pediatric patients with hemophilia A, including previously untreated patients (PUPs) and minimally treated patients (MTPs) as well as patients with inhibitors.

The study, published in BMC Pediatrics, showed that the median annualized bleed rate (ABR) of the patients prior to emicizumab treatment was 0.25 (range, 0-4) and it dropped to 0 (range, 0-0.5, P =.009) during the follow-up period (median, 23.8 months; range, 0.7-40 months). After the transition to emicizumab, significant reductions were also observed in median spontaneous ABR (P =.018), traumatic ABR (P =.018), and joint ABR (P =.027).

No correlation was found between age and ABR in the small patient cohort. There was a slightly higher spontaneous ABR in patients with inhibitors prior to treatment onset, however this did not reach significance (P =.104).

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Of the 13 patients enrolled in the study, 12 (92.3%) experienced no bleeds during follow-up after transitioning to emicizumab. A traumatic bleed did occur in 1 of the patients while taking emicizumab.

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“This current study provides additional evidence on efficacy and safety of emicizumab in 5 children [under] the age of 3 years, [2 previously untreated patients] and [1 minimally treated patient]. Our data show that the ABR significantly reduced under emicizumab, regardless of age and inhibitor status,” the study’s authors said.

The 2 previously untreated patients and 1 minimally treated patient had no adverse reactions to treatment with emicizumab and none of the 3 developed inhibitors.

Minor surgery to remove central venous lines occurred in 3 patients with inhibitors during the study. One of the patients additionally had surgery for the removal of keloid scarring. All 3 patients received a preoperative dose of recombinant factor VIIa (rFVIIa) and they also received between 2 and 6 postoperative doses. No perisurgical or postsurgical bleeds were observed.

Local skin reactions at the injection site were observed in 2 patients after their first emicizumab dose. Recurrent urticaria was observed at each additional dose in 1 of the patients. Skin prick testing was negative for allergic reactions to emicizumab or other contents of the medication. No cessation of treatment was needed in any of the patients due to side effects.

Hemophilia A patients with confirmed mutations in the FVIII producing gene (F8) were recruited for the study. The median age at emicizumab initiation was 5.3 years (range, 0.26-17.5 years) while 3 of the patients were less than a year old. Inhibitors were present in 4 of the patients.


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