Inclusion Criteria:
* Age \<12 years at the time of signing Informed Consent Form; or age ≥12 and \<18 years with body weight \<40 kg
* Diagnosis of severe (Factor VIII coagulation protein activity \[FVIII:C\] \<1 International Unit per decilitre \[IU/dL\]) or moderate (FVIII:C between ≥1 IU/dL and ≤5 IU/dL) congenital hemophilia A (HA) with or without inhibitors against factor VIII (FVIII)
* For potential participants with moderate HA without inhibitors, fulfillment of at least one of the following criteria: Current prophylaxis with long-term prophylaxis intention due to a severe bleed phenotype; For those not treated with prophylaxis: at least one traumatic joint or critical muscle bleed in the last 6 months or ≥2 spontaneous bleeds/year or 5 bleeds/year, including traumatic bleeds; Signs of joint degeneration compatible with hemophilic arthropathy (e.g., subchondral bone changes or the presence of synovitis) as assessed by any imaging assessment (e.g., ultrasound, MRI, radiograph); Bleeding at a critical site (e.g., intracranial).
* Diagnosis of mild (FVIII:C between \>5 IU/dL and \<40 IU/dL) congenital hemophilia A with chronic FVIII inhibitors, defined as documented FVIII inhibitor (≥0.6 BU/mL or ≥1.0 BU/mL only for laboratories with a historical sensitivity cutoff for inhibitor detection of 1.0 BU/mL) and chronic reduction of endogenous baseline FVIII:C to \<5 IU/dL for ≥12 months
* Documentation of the details of prophylactic and episodic FVIII treatment, bypassing agent (BPA) treatment, emicizumab prophylaxis treatment, and the number and type of bleeding episodes for at least the last 6 months prior to screening if appropriate
* For potential participants taking on-demand treatments prior to study entry: agreement to move to a prophylaxis treatment with NXT007
* Adequate renal, hepatic, and hematologic function, as defined in the protocol
Exclusion Criteria:
* Sensitivity to any of the study investigations, or components thereof, or drug or other allergy that, in the opinion of the investigator, contraindicates participation in the study
* Use of systemic immunomodulators (e.g., interferon or rituximab) at the time of enrollment or planned use during the study, except for antiretroviral therapy to treat HIV
* Refusal to accept plasma-derived and/or blood product transfusion support in an emergency scenario
* History or conditions, other than HA, which may indicate hypo- or hypercoagulopathy risk
* Planned surgery (excluding minor procedures, such as non-molar tooth extraction or incision and drainage) during the study
* History of ventricular dysrhythmias or risk factors for ventricular dysrhythmias such as structural heart disease (e.g., severe left ventricular systolic dysfunction, left ventricular hypertrophy)
* Any serious medical condition or abnormality in clinical laboratory tests that precludes an individual's safe participation in and completion of the study
