Initially, all participants will receive 4 loading doses of 3 milligrams per kilogram (mg/kg) emicizumab subcutaneously (SC) once every week (QW) for 4 weeks followed by the maintenance dosing regimen 3 mg/kg emicizumab SC once every 2 weeks (Q2W) for a total of 52 weeks. Starting from Week 17 of treatment, individual participants may have their dose up-titrated to 3 mg/kg SC QW if they experience suboptimal bleeding control.
At the Week 53 clinic visit following consultation with the treating physician, parents/caregivers may elect for their child to continue with the maintenance 3-mg/kg SC Q2W dosing regimen or to switch to the maintenance 1.5-mg/kg SC QW or 6-mg/kg SC once every 4 weeks (Q4W) dosing regimen for the subsequent 7-year long-term follow-up period.
During the study, participants will be treated with emicizumab until unacceptable toxicity, discontinuation from the study due to any cause, or other criteria specified in the protocol, whichever occurs first.