Emicizumab PUPs and Nuwiq ITI Study

This study prospectively investigates the safety, FVIII immunogenicity, and hemostatic efficacy of prophylactic HEMLIBRA® given with a concomitant low dose recombinant factor VIII (rFVIII) known as NUWIQ®, in HA infants and children \<3 years old who have had little to no previous exposure to FVIII. In addition, the study investigates the safety and efficacy of a novel FVIII ITI regimen in children \<21 with existing low and high titer inhibitors (LTI and HTI).

Hemophilia A (HA) is a congenital bleeding disorder caused by deficient or dysfunctional factor VIII (FVIII) which leads to bleeding correlated with severity. Management is focused on FVIII replacement in reaction to a bleed or preventive as prophylaxis. Effective treatment is complicated by the: (1) difficulty to administer standard replacement therapy via intravenous injection especially in infants and young children; and (2) development of inhibitors (FVIII neutralizing antibodies). Inhibitors can increase morbidity and mortality and exponentially raise the cost of health care. Although inherited and environmental risk factors for inhibitor formation have been identified, there is no effective strategy to prevent inhibitors from developing. Emicizumab (HEMLIBRA®) was recently approved by the Food and Drug Administration (FDA) in infants, children, and adults with congenital hemophilia A, with and without inhibitors, and offers hemostatic efficacy while reducing the burden of administration since it is given weekly, biweekly (every 2 weeks), or monthly via subcutaneous (SQ) route compared to the intravenous (IV) route of FVIII.

This study prospectively investigates the safety, FVIII immunogenicity, and hemostatic efficacy of prophylactic HEMLIBRA® given with a concomitant low dose recombinant factor VIII (rFVIII) known as NUWIQ®, in HA infants and children \<3 years old who have had little to no previous exposure to FVIII. In addition, the study investigates the safety and efficacy of a novel FVIII ITI regimen in children \<21 with existing low and high titer inhibitors (LTI and HTI).

Eligibility Criteria:
Inclusion Criteria - Part A:

* Moderately severe (≤2% FVIII) hemophilia A
* \<3 Years of age at the time of informed consent
* Caregiver (parent or legal guardian) has provided written informed consent
* ≤2 EDs to pdFVIII, rFVIII, or a single dose of FFP, Cryoprecipitate or PRBCs.
* Adequate hematologic function (HgB \>8 g/dL and platelet count \>100,000 µL)
* Adequate hepatic function (total bilirubin ≤1.5x ULN and both AST/ALT ≤3x ULN at screening (excluding known Gilbert's)
* Adequate renal function (≤2.5 x ULN and CrCl ≥30 mL/min)
* Negative test for inhibitor (\<0.6 BU/mL) with a 72-hour washout within 4 weeks of enrollment
* No documented FVIII inhibitor since birth \*Participants will be encouraged to co-enroll in the ATHN 8 Study

Inclusion Criteria - Part B

* Moderately severe (≤2% FVIII) hemophilia A
* \<21 Years of age at the time of informed consent
* Documented on 2 occasions a persistent low (\>0.6 BU/mL) titer inhibitor with a 72-hour washout within 24 weeks of enrollment or historical high titer inhibitor (\>5 BU/mL) and a single occasion of a low titer inhibitor (\>0.6 BU/mL) with a 72-hour washout within 24 weeks of enrollment after either the first time ITI or after single attempt of \<6 months of continuous 3x/week factor ITI
* Has completed loading doses of HEMLIBRA® (weekly for 4 weeks, dose 3 mg/kg, a total of 12 mg/kg/dose will also be allowed)
* Caregiver and/or participant provided written informed consent
* Adequate hematologic function (HgB \>8 g/dL and platelet count \>100,000 µL)
* Adequate hepatic function (total bilirubin ≤1.5x ULN and both AST/ALT ≤3x ULN at screening (excluding known Gilbert's)
* Adequate renal function (≤2.5 x ULN and CrCl ≥30 mL/min)

Exclusion Criteria - Part A and B

* Inherited or acquired bleeding disorder other than severe hemophilia A (participants with previous documentation of low von Willebrand factor (vWF) defined as vWF antigen and vWF ristocetin cofactor both between 40-50 will be permitted)
* Previous or current treatment for thromboembolic disease or signs of thromboembolic disease
* Conditions that may increase the risk of bleeding or thrombosis. Will not require or request a thrombophilia evaluation
* History of clinically significant hypersensitivity associated with monoclonal antibody therapies or components of the HEMLIBRA® injection (with the exception of rituximab)
* Known HIV infection with CD4 count \<200 cells/µL within 24 weeks prior to screening. Testing is not required if can demonstrate negative testing in the mother prior to pregnancy
* Use of systemic immunomodulators at enrollment or planned use during the study
* Participants who are at high risk for thrombotic microangiopathy (TMA) (for example, have a previous medical or family history of TMA), in the investigator's judgment
* Concurrent disease, treatment, or abnormality in clinical laboratory tests that could interfere with the conduct of the study, may pose an additional risk, or would, in the opinion of the investigator, preclude the participant's safe participation in and completion of the study
* Planned surgery (excluding minor procedures or central line placement) during the study
* Receipt of HEMLIBRA® as part of a prior investigational study; an investigational drug to treat or reduce the risk of hemophilic bleeds within 5 half-lives of the last drug administration; a non-hemophilia-related investigational drug concurrently, within the last 30 days or 5 half-lives, whichever is shorter