A Study to Evaluate the Efficacy, Safety, and Pharmacokinetics of Prophylactic Emicizumab Versus no Prophylaxis in Hemophilia A Participants With Inhibitors

Study Overview
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Brief Summary
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This multicenter, open-label study will evaluate the safety, efficacy and pharmacokinetics of prophylactic emicizumab treatment in participants previously treated with episodic or prophylactic bypassing agents. Episodic bypassing agent participants will be randomized in a 2:1 fashion to receive emicizumab prophylaxis (Arm A) versus no prophylaxis (Arm B) and will be stratified across Arms A and B according to the number of bleeds they experienced over the last 24 weeks prior to study entry (less than [<] 9 or greater than or equal to [>/=] 9 bleeds); Arm B participants will have the opportunity to switch to emicizumab prophylaxis after at least 24 weeks on-study. Prophylactic bypassing agent participants will switch to emicizumab prophylaxis (Arm C) from the start of the trial; enrollment will be extended for 24 weeks after the last participant has enrolled in Arms A or B or until approximately 50 participants have enrolled in Arm C, whichever occurs first. Episodic bypassing agent participants who previously participated in the non-interventional study BH29768 (NCT02476942) who were unable to enroll in Arms A or B, or participants on prophylactic bypassing agents who were unable to enroll in Arm C, prior to their closure will have the opportunity to enroll in Arm D. Like participants in Arms A and C, Arm D participants will receive emicizumab prophylaxis from the start of the trial. All participants will continue to receive episodic bypassing agent therapy to treat breakthrough bleeds, preferably with recombinant activated factor VII (rFVIIa).

Official Title
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A Randomized, Multicenter, Open-Label, Phase III Clinical Trial to Evaluate the Efficacy, Safety, and Pharmacokinetics of Prophylactic Emicizumab Versus no Prophylaxis in Hemophilia A Patients With Inhibitors

Conditions
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Hemophilia A

Intervention / Treatment
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* Drug: Emicizumab
* Drug: rFVIIa
* Drug: aPCC


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Body weight >/= 40 kilograms (kg) at the time of screening Diagnosis of congenital hemophilia A of any severity and documented history of high-titer inhibitor ( that is [i.e.], >/= 5 Bethesda Units [BU]) Documentation of treatment with episodic or prophylactic bypassing agents for at least the last 24 weeks >/= 6 bleeds in the last 24 weeks prior to screening (if on an episodic bypassing agent regimen) or >/=2 bleeds in the last 24 weeks prior to screening (if on a prophylactic bypassing agent regimen) Adequate hematologic, hepatic and renal function For women who are not postmenopausal or surgically sterile: agreement to remain abstinent or use single or combined highly effective contraceptive methods Exclusion Criteria: Participants with inherited or acquired bleeding disorder other than hemophilia A Participants with ongoing (or plan to receive during the study) immune tolerance induction therapy or prophylaxis with Factor VIII (FVIII), with the exception of participants who have received a treatment regimen of FVIII prophylaxis with concurrent bypassing agent prophylaxis Previous (in the past 12 months) or current treatment for thromboembolic disease (with the exception of previous catheter-associated thrombosis for which antithrombotic treatment is not currently ongoing) or current signs of thromboembolic disease Participants with other conditions (for example [e.g.], certain autoimmune diseases) that may increase the risk of bleeding or thrombosis History of clinically significant hypersensitivity associated with monoclonal antibody therapies or components of the emicizumab injection Known human immunodeficiency virus (HIV) infection with cluster of differentiation 4 (CD4) count < 200 cells per microliter (cells/mcL) within 24 weeks prior to screening Use of systemic immunomodulators (e.g., interferon or rituximab) at enrolment or planned use during the study, with the exception of antiretroviral therapy Participants who are at high risk for thrombotic microangiopathy (TMA; e.g., 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 or that would, in the opinion of the investigator or Sponsor, preclude the participant's safe participation in and completion of the study or interpretation of the study results Planned surgery (excluding minor procedures such as tooth extraction or incision and drainage) during the study Receipt of emicizumab in a prior investigational study; An investigational drug to treat or reduce the risk of hemophilic bleeds within 5 half-lives of last drug administration; A non-hemophilia-related investigational drug within last 30 days or 5 half-lives, whichever is shorter; An investigational drug concurrently Unwillingness to use highly effective contraception methods for the specified duration in the protocol (females only, unless required otherwise by the local health authority) Clinically significant abnormality on screening evaluations or laboratory tests that, in the opinion of the investigator, may pose an additional risk in administering study drug to the participant Pregnancy or lactation, or intent to become pregnant during the study

Ages Eligible for Study
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Minimum Age: 12 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Arm A: 1.5 mg/kg Emicizumab QW<br>Participants who were receiving episodic treatment with bypassing agents prior to study entry and were randomized to study Arm A started to receive emicizumab prophylaxis. Emicizumab was administered at a loading dose of 3 milligrams per kilogram (mg/kg) once a week (QW) subcutaneously (SC) for the first 4 weeks followed by a maintenance dose of 1.5 mg/kg emicizumab QW SC up to the end of study. Participants continued to receive bypassing agent therapy to treat any breakthrough bleeds. | Drug: Emicizumab<br>* Emicizumab will be administered at a loading dose of 3 milligrams per kilogram per week (mg/kg/week) subcutaneously (SC) for the first 4 weeks followed by a maintenance dose of 1.5 mg/kg/week SC up to the end of study. After at least 24 weeks on prophylactic emicizumab, individuals who experience suboptimal bleeding control on emicizumab (according to protocol-defined criteria) will have the opportunity to increase their dose to 3 mg/kg weekly.<br>* Other names: ACE910;Drug: rFVIIa<br>* Participants will continue to receive rFVIIa.<br>* Other names: NovoSeven®;Drug: aPCC<br>* Participants will continue to receive aPCC.<br>* Other names: Factor Eight Inhibitor Bypassing Activity (FEIBA®);|
| Active Comparator: Arm B (Control): No Prophylaxis, Then Emicizumab<br>Participants who were receiving episodic treatment with bypassing agents prior to study entry and were randomized to study Arm B continued with their prior episodic treatment regimen for the first 24 weeks of the study; they did not receive emicizumab prophylaxis during that time. After completing at least 24 weeks on study, participants in Arm B were allowed to switch to emicizumab prophylaxis (as described for Arm A) up to the end of study. Participants continued to receive bypassing agent therapy to treat any breakthrough bleeds. | Drug: Emicizumab<br>* Emicizumab will be administered at a loading dose of 3 milligrams per kilogram per week (mg/kg/week) subcutaneously (SC) for the first 4 weeks followed by a maintenance dose of 1.5 mg/kg/week SC up to the end of study. After at least 24 weeks on prophylactic emicizumab, individuals who experience suboptimal bleeding control on emicizumab (according to protocol-defined criteria) will have the opportunity to increase their dose to 3 mg/kg weekly.<br>* Other names: ACE910;Drug: rFVIIa<br>* Participants will continue to receive rFVIIa.<br>* Other names: NovoSeven®;Drug: aPCC<br>* Participants will continue to receive aPCC.<br>* Other names: Factor Eight Inhibitor Bypassing Activity (FEIBA®);|
| Experimental: Arm C: 1.5 mg/kg Emicizumab QW<br>Participants who were receiving prophylactic bypassing agents prior to study entry were enrolled in Arm C to receive prophylactic emicizumab. Emicizumab was administered at a loading dose of 3 mg/kg QW SC for the first 4 weeks followed by a maintenance dose of 1.5 mg/kg emicizumab QW SC up to the end of study. Participants continued to receive bypassing agent therapy to treat any breakthrough bleeds. | Drug: Emicizumab<br>* Emicizumab will be administered at a loading dose of 3 milligrams per kilogram per week (mg/kg/week) subcutaneously (SC) for the first 4 weeks followed by a maintenance dose of 1.5 mg/kg/week SC up to the end of study. After at least 24 weeks on prophylactic emicizumab, individuals who experience suboptimal bleeding control on emicizumab (according to protocol-defined criteria) will have the opportunity to increase their dose to 3 mg/kg weekly.<br>* Other names: ACE910;Drug: rFVIIa<br>* Participants will continue to receive rFVIIa.<br>* Other names: NovoSeven®;Drug: aPCC<br>* Participants will continue to receive aPCC.<br>* Other names: Factor Eight Inhibitor Bypassing Activity (FEIBA®);|
| Experimental: Arm D: 1.5 mg/kg Emicizumab QW<br>Participants who were either: 1) Receiving episodic bypassing agents prior to study entry but were unable to enroll in Arms A or B; or 2) Receiving bypassing agent prophylaxis prior to study entry but were unable to enroll in Arm C, were enrolled in Arm D to receive emicizumab prophylaxis. Emicizumab was administered at a loading dose of 3 mg/kg QW SC for the first 4 weeks followed by a maintenance dose of 1.5 mg/kg emicizumab QW SC up to the end of study. Participants continued to receive bypassing agent therapy to treat any breakthrough bleeds. | Drug: Emicizumab<br>* Emicizumab will be administered at a loading dose of 3 milligrams per kilogram per week (mg/kg/week) subcutaneously (SC) for the first 4 weeks followed by a maintenance dose of 1.5 mg/kg/week SC up to the end of study. After at least 24 weeks on prophylactic emicizumab, individuals who experience suboptimal bleeding control on emicizumab (according to protocol-defined criteria) will have the opportunity to increase their dose to 3 mg/kg weekly.<br>* Other names: ACE910;Drug: rFVIIa<br>* Participants will continue to receive rFVIIa.<br>* Other names: NovoSeven®;Drug: aPCC<br>* Participants will continue to receive aPCC.<br>* Other names: Factor Eight Inhibitor Bypassing Activity (FEIBA®);|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Model-Based Annualized Bleed Rate (ABR) for Treated Bleeds, Arm A: Emicizumab Versus Arm B: No Prophylaxis | The number of treated bleeds over the efficacy period was assessed as an annualized bleed rate (ABR) using a negative binomial (NB) regression model, which accounts for different follow-up times. Treated bleeds were defined as a bleed that was directly followed by a hemophilia medication reported to be a treatment for bleed. The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | From Baseline up to 24 weeks (median [min-max] efficacy observation periods in Arm A vs. Arm B: 29.29 [0.1-48.9] weeks vs. 24.14 [23.0-26.0] weeks) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Model-Based Annualized Bleed Rate (ABR) for All Bleeds, Arm A: Emicizumab Versus Arm B: No Prophylaxis | The number of all bleeds over the efficacy period was assessed as an annualized bleed rate (ABR) using a negative binomial (NB) regression model, which accounts for different follow-up times. All bleeds included both treated bleeds (with coagulation factors) and non-treated bleeds. The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | From Baseline up to 24 weeks (median [min-max] efficacy observation periods in Arm A vs. Arm B: 29.29 [0.1-48.9] weeks vs. 24.14 [23.0-26.0] weeks) | 
| Intra-Participant Comparison of the Model-Based Annualized Bleed Rate (ABR) for All Bleeds in Arm A: Emicizumab Versus Previous Episodic Bypassing Agents | This was an intra-participant comparison of the annualized bleed rates (ABRs) for all bleeds in Arm A participants who had previously received episodic bypassing agents during the non-interventional study (NIS) BH29768 (NCT02476942) (Arm A NIS) prior to entry in this study versus emicizumab prophylaxis during this study (Arm A). The number of all bleeds over the efficacy period was assessed as an ABR using a negative binomial (NB) regression model, which accounts for different follow-up times. All bleeds included both treated bleeds (with coagulation factors) and non-treated bleeds. The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | Median [min-max] efficacy observation periods: for Arm A, 1.5 mg/kg Emicizumab QW: 30.86 [0.1-48.9] weeks; for Arm A (NIS), Previous Episodic Bypassing Agents: 21.14 [10.6-33.9] weeks | 
| Intra-Participant Comparison of the Model-Based Annualized Bleed Rate (ABR) for Treated Bleeds in Arm A: Emicizumab Versus Previous Episodic Bypassing Agents | This was an intra-participant comparison of the ABRs for treated bleeds in Arm A participants who had previously received episodic bypassing agents during the non-interventional study (NIS) BH29768 (NCT02476942) (Arm A NIS) prior to entry in this study versus emicizumab prophylaxis during this study (Arm A). The number of treated bleeds over the efficacy period was assessed as an ABR using a negative binomial (NB) regression model, which accounts for different follow-up times. Treated bleeds were defined as a bleed that was directly followed by a hemophilia medication reported to be a treatment for bleed. The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, efficacy period ended the day before the first day on the up-titrated dose. | Median [min-max] efficacy observation periods: for Arm A, 1.5 mg/kg Emicizumab QW: 30.86 [0.1-48.9] weeks; for Arm A (NIS), Previous Episodic Bypassing Agents: 21.14 [10.6-33.9] weeks | 
| Model-Based Annualized Bleed Rate (ABR) for Treated Joint Bleeds, Arm A: Emicizumab Versus Arm B: No Prophylaxis | The number of treated joint bleeds over the efficacy period was assessed as an ABR using a negative binomial (NB) regression model, which accounts for different follow-up times. Treated joint bleeds were defined as treated bleeds in a joint associated with unusual sensation (aura) in a joint, in combination with another symptom: swelling/warmth, pain/decreased range of motion (RoM), or difficulty moving the joint. Bleeds due to surgery/procedure were excluded. | From Baseline up to 24 weeks (median [min-max] efficacy observation periods in Arm A vs. Arm B: 29.29 [0.1-48.9] weeks vs. 24.14 [23.0-26.0] weeks) | 
| Intra-Participant Comparison of the Model-Based Annualized Bleed Rate (ABR) for All Bleeds in Arm C: Emicizumab Versus Previous Prophylactic Bypassing Agents | This was an intra-participant comparison of the annualized bleed rates (ABRs) for all bleeds in Arm C participants who had previously received prophylactic bypassing agents during the non-interventional study (NIS) BH29768 (NCT02476942) (Arm C NIS) prior to entry in this study versus emicizumab prophylaxis during this study (Arm C). The number of all bleeds over the efficacy period was assessed as an ABR using a negative binomial (NB) regression model, which accounts for different follow-up times. All bleeds included both treated bleeds (with coagulation factors) and non-treated bleeds. The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | Median [min-max] efficacy observation periods: for Arm C, 1.5 mg/kg Emicizumab QW: 30.14 [6.9-45.3] weeks; for Arm C (NIS), Previous Prophylactic Bypassing Agents: 32.14 [8.1-49.3] weeks | 
| Intra-Participant Comparison of the Model-Based Annualized Bleed Rate (ABR) for Treated Bleeds in Arm C: Emicizumab Versus Previous Prophylactic Bypassing Agents | This was an intra-participant comparison of the ABRs for treated bleeds in Arm C participants who had previously received bypassing agent prophylaxis during the non-interventional study (NIS) BH29768 (NCT02476942) (Arm C NIS) prior to entry in this study versus emicizumab prophylaxis during this study (Arm C). The number of treated bleeds over the efficacy period was assessed as an ABR using a negative binomial (NB) regression model, which accounts for different follow-up times. Treated bleeds were defined as a bleed that was directly followed by a hemophilia medication reported to be a treatment for bleed. The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, efficacy period ended the day before the first day on the up-titrated dose. | Median [min-max] efficacy observation periods: for Arm C, 1.5 mg/kg Emicizumab QW: 30.14 [6.9-45.3] weeks; for Arm C (NIS), Previous Prophylactic Bypassing Agents: 32.14 [8.1-49.3] weeks | 
| Model-Based Annualized Bleed Rate (ABR) for Treated Spontaneous Bleeds, Arm A: Emicizumab Versus Arm B: No Prophylaxis | The number of treated spontaneous bleeds over the efficacy period was assessed as an annualized bleed rate (ABR) using a negative binomial (NB) regression model, which accounts for different follow-up times. Treated spontaneous bleeds were defined as treated (with coagulation factors) bleeds with no known contributing factor (e.g., trauma, surgery). The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | From Baseline up to 24 weeks (median [min-max] efficacy observation periods in Arm A vs. Arm B: 29.29 [0.1-48.9] weeks vs. 24.14 [23.0-26.0] weeks) | 
| Model-Based Annualized Bleed Rate (ABR) for Treated Target Joint Bleeds, Arm A: Emicizumab Versus Arm B: No Prophylaxis | The number of treated target joint bleeds over the efficacy period was assessed as an annualized bleed rate (ABR) using a negative binomial (NB) regression model, which accounts for different follow-up times. Treated target joint bleeds included treated (with coagulation factors) joint bleeds in a target joint, defined as a joint in which greater than or equal to (>/=) 3 treated joint bleeds occurred during the last 24 weeks prior to study entry. The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | From Baseline up to 24 weeks (median [min-max] efficacy observation periods in Arm A vs. Arm B: 29.29 [0.1-48.9] weeks vs. 24.14 [23.0-26.0] weeks) | 
| Mean Calculated Annualized Bleed Rates (ABR) for Treated Bleeds, All Bleeds, Treated Spontaneous Bleeds, Treated Joint Bleeds, and Treated Target Joint Bleeds, Arm A: Emicizumab Versus Arm B: No Prophylaxis | The number of bleeds over the efficacy period was calculated as: ABR = (number of bleeds/number of days during the efficacy period) x 365.25. Treated bleeds: a bleed for which coagulation factors were administered. All bleeds included both treated and non-treated bleeds. Treated spontaneous bleeds: treated bleeds with no known contributing factor (e.g., trauma, surgery). Treated joint bleeds: treated bleeds in a joint associated with unusual sensation (aura) in a joint, in combination with another symptom: swelling/warmth, pain/decreased range of motion (RoM), or difficulty moving the joint. Treated target joint bleeds: treated joint bleeds in a target joint, defined as a joint in which greater than or equal to (>/=) 3 treated joint bleeds occurred during the last 24 weeks prior to study entry. For all types of bleeds: the 72-hour rule was implemented, and bleeds due to surgery/procedure and bleeds after up-titration were excluded. | From Baseline up to 24 weeks (median [min-max] efficacy observation periods in Arm A vs. Arm B: 29.29 [0.1-48.9] weeks vs. 24.14 [23.0-26.0] weeks) | 
| Median Calculated Annualized Bleed Rates (ABR) for Treated Bleeds, All Bleeds, Treated Spontaneous Bleeds, Treated Joint Bleeds, and Treated Target Joint Bleeds, Arm A: Emicizumab Versus Arm B: No Prophylaxis | The number of bleeds over the efficacy period was calculated as: ABR = (number of bleeds/number of days during the efficacy period) x 365.25. Treated bleeds: a bleed for which coagulation factors were administered. All bleeds included both treated and non-treated bleeds. Treated spontaneous bleeds: treated bleeds with no known contributing factor (e.g., trauma, surgery). Treated joint bleeds: treated bleeds in a joint associated with unusual sensation (aura) in a joint, in combination with another symptom: swelling/warmth, pain/decreased range of motion (RoM), or difficulty moving the joint. Treated target joint bleeds: treated joint bleeds in a target joint, defined as a joint in which greater than or equal to (>/=) 3 treated joint bleeds occurred during the last 24 weeks prior to study entry. For all types of bleeds: the 72-hour rule was implemented, and bleeds due to surgery/procedure and bleeds after up-titration were excluded. | From Baseline up to 24 weeks (median [min-max] efficacy observation periods in Arm A vs. Arm B: 29.29 [0.1-48.9] weeks vs. 24.14 [23.0-26.0] weeks) | 
| Percentage of Participants With 0 Bleeds for Treated Bleeds, All Bleeds, Treated Spontaneous Bleeds, Treated Joint Bleeds, and Treated Target Joint Bleeds, Arm A: Emicizumab Versus Arm B: No Prophylaxis | Treated bleeds: a bleed for which coagulation factors were administered. All bleeds included both treated and non-treated bleeds. Treated spontaneous bleeds: treated bleeds with no known contributing factor (e.g., trauma, surgery). Treated joint bleeds: treated bleeds in a joint associated with unusual sensation (aura) in a joint, in combination with another symptom: swelling/warmth, pain/decreased range of motion (RoM), or difficulty moving the joint. Treated target joint bleeds: treated joint bleeds in a target joint, defined as a joint in which greater than or equal to (>/=) 3 treated joint bleeds occurred during the last 24 weeks prior to study entry. For all types of bleeds: the 72-hour rule was implemented, and bleeds due to surgery/procedure and bleeds after up-titration were excluded. | From Baseline up to 24 weeks (median [min-max] efficacy observation periods in Arm A vs. Arm B: 29.29 [0.1-48.9] weeks vs. 24.14 [23.0-26.0] weeks) | 
| Hemophilia-Specific Quality of Life (Haem-A-QoL) Questionnaire Physical Health Score at Week 25 in Adult Participants (>/=18 Years Old), Arm A: Emicizumab Versus Arm B: No Prophylaxis | Haem-A-QoL questionnaire has been developed and used in hemophilia A participants. As a hemophilia-specific questionnaire, this measure assesses very specific aspects of dealing with hemophilia. This questionnaire consists of items pertaining to 10 domains specific to living with hemophilia. The 10 domains are: physical health, sports and leisure, school and work, dealing with hemophilia, family planning, feeling, relationships, treatment, view of yourself, and outlook for the future. The total score for each domain range from 0 to 100 with lower scores reflective of better quality of life. Physical Health domain score is reported (range 0 to 100, with lower scores reflective of better physical health). | Week 25 | 
| Haem-A-QoL Questionnaire Total Score at Week 25 in Adult Participants (>/=18 Years Old), Arm A: Emicizumab Versus Arm B: No Prophylaxis | Haem-A-QoL questionnaire has been developed and used in hemophilia A participants. As a hemophilia-specific questionnaire, this measure assesses very specific aspects of dealing with hemophilia. This questionnaire consists of items pertaining to 10 domains specific to living with hemophilia. The 10 domains are: physical health, sports and leisure, school and work, dealing with hemophilia, family planning, feeling, relationships, treatment, view of yourself, and outlook for the future. The total score for each domain range from 0 to 100 with lower scores reflective of better quality of life. Haem-A-QoL Questionnaire Total Score is the average of the all domain scores and range from 0 to 100, with lower scores reflective of better quality of life. | Week 25 | 
| European Quality of Life-5 Dimensions-5 Levels (EQ-5D-5L) Visual Analog Scale Score at Week 25, Arm A: Emicizumab Versus Arm B: No Prophylaxis | EQ-5D-5L is a standardized, participant-rated questionnaire to assess health-related quality of life. The EQ-5D-5L includes 2 components: the EQ-5D-5L health state profile (descriptive system) and the EQ-5D-5L Visual Analog Scale. The Visual Analogue Scale is designed to rate the participant's current health state on a scale from 0 to 100, where 0 represents the worst imaginable health state and 100 represents the best imaginable health state. | Week 25 | 
| EQ-5D-5L Index Utility Score at Week 25, Arm A: Emicizumab Versus Arm B: No Prophylaxis | EQ-5D-5L is a standardized, participant-rated questionnaire to assess health-related quality of life. The EQ-5D-5L includes 2 components: the EQ-5D-5L health state profile (descriptive system) and the EQ-5D-5L Visual Analog Scale. The EQ-5D-5L health state profile is designed to record the participant's current health state in 5 domains: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Responses from the five domains are used to calculate a single utility index value ranging from 1 to 5, where 1 indicates better health state (no problems) and 5 indicates worst health state (confined to bed). | Week 25 | 
| Hemophilia-Specific Quality of Life - Short Form (Haemo-Qol-SF) Questionnaire Total Score at Baseline and Week 25 in Adolescent Participants (12-17 Years Old) | The Haemo-QoL-SF contains 35 items, which cover nine domains considered relevant for the children's health-related quality of life (physical health, feelings, view of yourself, family, friends, other people, sports and school, dealing with hemophilia and treatment). Items are rated with five respective response options: never, seldom, sometimes, often, and always. Haemo-QoL-SF total score range from 0 to 100, where lower scores reflect better health-related quality of life. Baseline was defined as the last assessment prior to treatment. Because participants in Arm B switched from episodic bypassing agents to start receiving emicizumab prophylaxis after Week 24, the timepoints for Arm B (Emi) are expressed relative to first emicizumab dose; baseline for Arm B (Emi) is the same as Week 25 for Arm B (Control). | Baseline and Week 25 (for Arm B (Emi), Study Weeks are relative to first emicizumab dose) | 
| Long-Term Efficacy of Emicizumab: Model-Based Annualized Bleed Rates (ABR) for Treated Bleeds, All Bleeds, Treated Spontaneous Bleeds, Treated Joint Bleeds, and Treated Target Joint Bleeds, All Enrolled Participants | The number of bleeds over the efficacy period was assessed as an ABR using a negative binomial (NB) regression model, which accounts for different follow-up times. Treated bleeds: a bleed for which coagulation factors were administered. All bleeds included both treated and non-treated bleeds. Treated spontaneous bleeds: treated bleeds with no known contributing factor (e.g., trauma, surgery). Treated joint bleeds: treated bleeds in a joint associated with unusual sensation (aura) in a joint, in combination with another symptom: swelling/warmth, pain/decreased range of motion (RoM), or difficulty moving the joint. Treated target joint bleeds: treated joint bleeds in a target joint, defined as a joint in which greater than or equal to (>/=) 3 treated joint bleeds occurred during the last 24 weeks prior to study entry. For all types of bleeds: the 72-hour rule was implemented, and bleeds due to surgery/procedure and bleeds after up-titration were excluded. | From start of emicizumab treatment to study completion (median [min-max] efficacy observation period for all participants: 109.29 [0.1-249.1] weeks) | 
| Long-Term Efficacy of Emicizumab: Mean Calculated Annualized Bleed Rates (ABR) for Treated Bleeds, All Bleeds, Treated Spontaneous Bleeds, Treated Joint Bleeds, and Treated Target Joint Bleeds, All Enrolled Participants | The number of bleeds over the efficacy period was calculated as: ABR = (number of bleeds/number of days during the efficacy period) x 365.25. Treated bleeds: a bleed for which coagulation factors were administered. All bleeds included both treated and non-treated bleeds. Treated spontaneous bleeds: treated bleeds with no known contributing factor (e.g., trauma, surgery). Treated joint bleeds: treated bleeds in a joint associated with unusual sensation (aura) in a joint, in combination with another symptom: swelling/warmth, pain/decreased range of motion (RoM), or difficulty moving the joint. Treated target joint bleeds: treated joint bleeds in a target joint, defined as a joint in which greater than or equal to (>/=) 3 treated joint bleeds occurred during the last 24 weeks prior to study entry. For all types of bleeds: the 72-hour rule was implemented, and bleeds due to surgery/procedure and bleeds after up-titration were excluded. | From start of emicizumab treatment to study completion (median [min-max] efficacy observation period for all participants: 109.29 [0.1-249.1] weeks) | 
| Long-Term Efficacy of Emicizumab: Median Calculated Annualized Bleed Rates (ABR) for Treated Bleeds, All Bleeds, Treated Spontaneous Bleeds, Treated Joint Bleeds, and Treated Target Joint Bleeds, All Enrolled Participants | The number of bleeds over the efficacy period was calculated as: ABR = (number of bleeds/number of days during the efficacy period) x 365.25. Treated bleeds: a bleed for which coagulation factors were administered. All bleeds included both treated and non-treated bleeds. Treated spontaneous bleeds: treated bleeds with no known contributing factor (e.g., trauma, surgery). Treated joint bleeds: treated bleeds in a joint associated with unusual sensation (aura) in a joint, in combination with another symptom: swelling/warmth, pain/decreased range of motion (RoM), or difficulty moving the joint. Treated target joint bleeds: treated joint bleeds in a target joint, defined as a joint in which greater than or equal to (>/=) 3 treated joint bleeds occurred during the last 24 weeks prior to study entry. For all types of bleeds: the 72-hour rule was implemented, and bleeds due to surgery/procedure and bleeds after up-titration were excluded. | From start of emicizumab treatment to study completion (median [min-max] efficacy observation period for all participants: 109.29 [0.1-249.1] weeks) | 
| Long-Term Efficacy of Emicizumab: Mean Calculated Annualized Bleed Rates (ABR) for Treated Bleeds Per 12-Week Intervals Over Time, All Enrolled Participants | The number of treated bleeds over the efficacy period was calculated as: ABR = (number of bleeds/number of days during the efficacy period) x 365.25. Treated bleeds: a bleed for which coagulation factors were administered. The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | 1-12, 13-24, 25-36, 37-48, 49-60, 61-72, 73-84, 85-96, 97-108, 109-120, 121-132, 133-144, 145-156, 157-168, 169-180, 181-192, 193-204, 205-216, 217-228, and 229-240 weeks | 
| Long-Term Efficacy of Emicizumab: Median Calculated Annualized Bleed Rates (ABR) for Treated Bleeds Per 12-Week Intervals Over Time, All Enrolled Participants | The number of treated bleeds over the efficacy period was calculated as: ABR = (number of bleeds/number of days during the efficacy period) x 365.25. Treated bleeds: a bleed for which coagulation factors were administered. The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | 1-12, 13-24, 25-36, 37-48, 49-60, 61-72, 73-84, 85-96, 97-108, 109-120, 121-132, 133-144, 145-156, 157-168, 169-180, 181-192, 193-204, 205-216, 217-228, and 229-240 weeks | 
| Long-Term Efficacy of Emicizumab: Mean Calculated Annualized Bleed Rates (ABR) for All Bleeds Per 12-Week Intervals Over Time, All Enrolled Participants | The number of all bleeds over the efficacy period was calculated as: ABR = (number of bleeds/number of days during the efficacy period) x 365.25. All bleeds included both treated bleeds (with coagulation factors) and non-treated bleeds. The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | 1-12, 13-24, 25-36, 37-48, 49-60, 61-72, 73-84, 85-96, 97-108, 109-120, 121-132, 133-144, 145-156, 157-168, 169-180, 181-192, 193-204, 205-216, 217-228, and 229-240 weeks | 
| Long-Term Efficacy of Emicizumab: Median Calculated Annualized Bleed Rates (ABR) for All Bleeds Per 12-Week Intervals Over Time, All Enrolled Participants | The number of all bleeds over the efficacy period was calculated as: ABR = (number of bleeds/number of days during the efficacy period) x 365.25. All bleeds included both treated bleeds (with coagulation factors) and non-treated bleeds. The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | 1-12, 13-24, 25-36, 37-48, 49-60, 61-72, 73-84, 85-96, 97-108, 109-120, 121-132, 133-144, 145-156, 157-168, 169-180, 181-192, 193-204, 205-216, 217-228, and 229-240 weeks | 
| Long-Term Efficacy of Emicizumab: Mean Calculated Annualized Bleed Rates (ABR) for Treated Spontaneous Bleeds Per 12-Week Intervals Over Time, All Enrolled Participants | The number of treated spontaneous bleeds over the efficacy period was calculated as: ABR = (number of bleeds/number of days during the efficacy period) x 365.25. Treated spontaneous bleeds were defined as treated (with coagulation factors) bleeds with no known contributing factor (e.g., trauma, surgery). The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | 1-12, 13-24, 25-36, 37-48, 49-60, 61-72, 73-84, 85-96, 97-108, 109-120, 121-132, 133-144, 145-156, 157-168, 169-180, 181-192, 193-204, 205-216, 217-228, and 229-240 weeks | 
| Long-Term Efficacy of Emicizumab: Median Calculated Annualized Bleed Rates (ABR) for Treated Spontaneous Bleeds Per 12-Week Intervals Over Time, All Enrolled Participants | The number of treated spontaneous bleeds over the efficacy period was calculated as: ABR = (number of bleeds/number of days during the efficacy period) x 365.25. Treated spontaneous bleeds were defined as treated (with coagulation factors) bleeds with no known contributing factor (e.g., trauma, surgery). The 72-hour rule was implemented: two bleeds of the same type and at the same anatomical location were counted as one bleed if the second bleed occurred within 72 hours from the last treatment for the first bleed. Bleeds due to surgery/procedure were excluded. For participants whose dose was up-titrated, the efficacy period ended the day before the first day on the up-titrated dose. | 1-12, 13-24, 25-36, 37-48, 49-60, 61-72, 73-84, 85-96, 97-108, 109-120, 121-132, 133-144, 145-156, 157-168, 169-180, 181-192, 193-204, 205-216, 217-228, and 229-240 weeks | 
| Safety Summary of the Overall Number and Percentage of Participants With at Least One Adverse Event, Severity Assessed According to the WHO Toxicity Grading Scale | Investigators sought information on adverse events (AEs) at each contact with participants. The WHO toxicity grading scale was used for assessing AE severity (i.e., intensity of an AE); any AEs not specifically listed in the WHO toxicity grading scale were assessed for severity according to the following grades: Grade 1 is mild; Grade 2 is moderate, Grade 3 is severe; Grade 4 is life-threatening; and Grade 5 is death. Regardless of severity, some AEs may have also met seriousness criteria. The terms severe and serious are not synonymous; severity and seriousness were independently assessed for each AE. For participants whose emicizumab dose was up-titrated, only data before up-titration is included. aPCC = activated prothrombin complex concentrate; Hypersens.= hypersensitivity | From Baseline until study completion (median [min-max] safety observation period for all participants: 133.97 [0.1-249.1] weeks) | 
| Number of Participants Testing Negative or Positive for the Presence of Anti-Drug Antibodies (ADAs), Including Neutralizing ADAs, During the Study | 'Total ADA Negative' is the sum of all subjects who tested negative for ADA in the 2 following categories: 'ADA Negative', those who are pre-dose ADA negative or are missing pre-dose ADA data and who have all negative post-dose ADA results; and 'ADA Negative (Treatment Unaffected)', a subset who are pre-dose ADA positive but do not have a ≥4-fold increase in post-dose ADA levels compared to baseline measurement. 'Total ADA Positive' is the sum of all subjects who tested positive for ADA in the 2 following categories: 'ADA Positive (Treatment Boosted)', those who are pre-dose ADA positive and have a ≥4-fold increase in post-dose ADA levels compared to baseline measurement; and 'ADA Positive (Treatment Induced)', those who are pre-dose ADA negative or missing data and who have at least one post-dose ADA positive sample. ADA-positive samples were further analyzed for neutralizing capacity using a modified FVIII chromogenic assay; if also positive, they were considered neutralizing ADAs. | From Baseline until study completion (median [min-max] safety observation period for all participants: 133.97 [0.1-249.1] weeks) | 
| Plasma Trough Concentrations of Emicizumab at Specified Timepoints | Plasma concentrations of emicizumab were analyzed using a validated Enzyme Linked Immunosorbent Assay (ELISA). The lower limit of quantification (LLOQ) was 100 nanograms per milliliter (ng/mL). Because participants in Arm B switched from episodic bypassing agents to start receiving emicizumab prophylaxis after Week 24, the timepoints for Arm B (Emi) are expressed relative to first emicizumab dose. | Pre-dose (0 hour [hr]) on Weeks 1-5, 7, 9, 13, 17, 21, 25, 33, 41, 49, 61, 73, 85, 97, 109, 121, 133, 145, 157, and 169 (For Arm B (Emi), Study Weeks are relative to first emicizumab dose) |