Trial Outcomes & Findings for Study of the Efficacy and Safety PF-06741086 in Adult and Teenage Participants With Severe Hemophilia A or Moderately Severe to Severe Hemophilia B (NCT NCT03938792)

A total of 188 participants were enrolled in the study: 128 in non-inhibitor cohort (no history of inhibitors) and 60 in inhibitor cohort (current/documented history of inhibitor). The study consisted of observational phase (OP) and active treatment phase (ATP) \[participants received study drug PF-06741086 (marstacimab)\]. Participants receiving prior on-demand (OD) therapy or prior routine prophylaxis (RP) therapy in either non-inhibitor cohort or inhibitor cohort were enrolled into OP.

Data from participants with inhibitors who were on RP therapy were pooled for safety analyses only and were not included in efficacy hypothesis testing.

Study of the Efficacy and Safety PF-06741086 in Adult and Teenage Participants With Severe Hemophilia A or Moderately Severe to Severe Hemophilia B

ABR is defined as number of bleeding episodes per year. ABR was calculated as number of bleeds requiring treatments/ (days on treatment period/365.25). If a participant did not complete a treatment period, days on treatment ended at last dosing date + 6 days. Treated bleed: If a bleed was treated with factor replacement or bypass agents within 48 hours of start of bleeding, regardless of the type of treatment (preventive, prophylaxis or OD medication). A model-based ABR using a repeated measures negative binomial model is reported for this outcome measure.

ABR is defined as number of bleeding episodes per year. ABR was calculated as number of bleeds requiring treatments/ (days on treatment period/365.25). If a participant did not complete a treatment period, days on treatment ended at last dosing date + 6 days. Treated bleed: If a bleed was treated with factor replacement or bypass agents within 48 hours of start of bleeding, regardless of the type of treatment (preventive, prophylaxis or OD medication). A model-based ABR using a repeated measures negative binomial model is reported for this outcome measure.

ABR is defined as number of bleeding episodes per year. ABR was calculated as number of bleeds requiring treatments/ (days on treatment period/365.25). If a participant did not complete a treatment period, days on treatment ended at last dosing date + 6 days. Treated bleed: If a bleed was treated with factor replacement or bypass agents within 48 hours of start of bleeding, regardless of the type of treatment (preventive, prophylaxis or OD medication). A model-based ABR using a repeated measures negative binomial model is reported for this outcome measure.

An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. AEs included both serious AEs and all other AEs.

AE: any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. SAE: any untoward medical occurrence at any dose that resulted in any of the following outcomes: death; life-threatening; required inpatient hospitalization or prolongation of existing hospitalization; persistent or significant disability/incapacity; congenital anomaly/birth defect; or that was considered as an important medical event.

Thrombotic events are when a blood clot (thrombus) forms in a blood vessel in the arm, leg, lung, or head and can be life-threatening. A thrombus can occur in veins (venous thrombosis) or arteries (arterial thrombosis).

Thrombotic microangiopathy: pathological state where micro-vessels are occluded by platelet rich thrombi leading to thrombocytopenia (low platelets) and microangiopathic haemolytic anaemia (red blood cell destruction) and potential end organ damage.

Disseminated intravascular coagulation is characterized by widespread clotting in small blood vessels, and consumption of platelets and clotting factors by the clots, leading to bleeding.

ADA positive: A participant with \>=1 treatment induced or treatment-boosted ADA response. NAb positive: An ADA positive participant with \>=1 treatment induced or treatment boosted NAb response.

Persistent ADA: participant with treatment-induced or treatment-boosted ADA detected at 2 or more times during treatment including any follow-up, where first and last ADA positive samples separated by \>=16 weeks. Transient ADA: treatment-induced or treatment-boosted ADA detected at only 1 time during treatment or follow-up. Persistent NAb: NAb-positive participant with first and last positive NAb samples detected \>=16 weeks posttreatment, irrespective of any negative samples in between. Transient NAb: NAb-positive participant with (1) treatment-induced/treatment-boosted NAb sample detected at only 1 time posttreatment or (2) treatment-induced/treatment-boosted NAb samples detected at 2 or more times where first and last positive samples separated by \<16 weeks, and participant's last sample was NAb or ADA negative.

ISR included: injection site haematoma, injection site pain, injection site bruising, injection site erythema, injection site induration, injection site oedema, Injection site pruritus and Injection site swelling. ISR graded according to Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 where grade 1: tenderness with or without associated symptoms (warmth, erythema, itching), grade 2: pain, lipodystrophy, edema, phlebitis, grade 3: ulceration or necrosis, severe tissue damage, operative intervention indicated, grade 4: life-threatening consequences, urgent intervention indicated and grade 5: death. In this outcome measure only categories with non-zero values reported.

Physical examination included assessments of the head, ears, eyes, nose, mouth, skin, heart and lung examinations, lymph nodes, gastrointestinal, musculoskeletal, and neurological systems. Height and weight were also measured and recorded. Clinical significance in physical examinations was determined by investigator.

Vital signs included temperature, pulse rate, respiratory rate, and blood pressure. Blood pressure and pulse rate were measured in a supine position using completely automated device after at least 5 minutes of rest for the participant in a quiet setting without distractions. Respiratory rate was measured by observing and counting the respirations of the participant for 30 seconds and multiplied by 2. Clinical significance of vital signs was determined by investigator.

Hematology included: hemoglobin; leukocytes; neutrophils; and platelets. Chemistry included: potassium; aspartate aminotransferase; creatinine; alkaline phosphatase; total bilirubin; albumin; calcium corrected, estimated decreased; sodium; and calcium. Clinical significance of laboratory parameters was determined by investigator.

Systemic hypersensitivity is a complex immune response where the immune system reacts excessively to an antigen, often leading to severe allergic reactions, including widespread symptoms (which may affect multiple organs), such as rash, swelling of your face, lips, mouth, or tongue, trouble breathing, wheezing, dizziness, fainting, fast heartbeat, pounding in your chest or sweating. Anaphylaxis is a severe, potentially fatal, systemic allergic reaction that occurs suddenly after contact with an allergy causing substance.

ABR: number of bleeding episodes per year. ABR was calculated as number of bleeds requiring treatments/ (days on treatment period/365.25). If a participant did not complete a treatment period, days on treatment ended at last dosing date + 6 days. Joint bleed: bleeding episode characterized by rapid loss of range of motion as compared with baseline that was associated with any combination of the following: pain or an unusual sensation in the joint, palpable swelling, and warmth of the skin over the joint. A model-based ABR using a repeated measures negative binomial model is reported for this outcome measure.

ABR: number of bleeding episodes per year. ABR was calculated as the number of bleeds requiring treatments/ (days on treatment period/365.25). If a participant did not complete a treatment period, the days on treatment ended at the last dosing date + 6 days. Spontaneous bleed: Bleeding for no apparent/known reason particularly into the joints, muscles, and soft tissues. A model-based ABR using a repeated measures negative binomial model is reported for this outcome measure.

ABR: number of bleeding episodes per year. ABR was calculated as number of bleeds requiring treatments/ (days on treatment period/365.25). If participant did not complete a treatment period, days on treatment ended at last dosing date + 6 days. Target joint: a major joint into which repeated bleeds occurred. Joint bleed: bleeding episode characterized by rapid loss of range of motion as compared with baseline that was associated with any combination of following: pain or unusual sensation in joint, palpable swelling, and warmth of the skin over joint. A model-based ABR using a repeated measures negative binomial model is reported for this outcome measure.

ABR: number of bleeding episodes per year. ABR was calculated as number of bleeds requiring treatments/ (days on treatment period/365.25). If participant did not complete treatment period, days on treatment ended at last dosing date + 6 days. Treated bleed: If a bleed was treated with factor replacement or bypass agents within 48 hours of start of bleeding, regardless of the type of treatment (preventive, prophylaxis or on-demand medication). Untreated bleed: If a bleed was untreated with factor replacement or bypass agents within 48 hours of start of bleeding, regardless of the type of treatment (preventive, prophylaxis or on-demand medication), it was considered as an untreated bleed. Total bleeds: Treated bleeds + untreated bleeds. A model-based ABR using a repeated measures negative binomial model is reported for this outcome measure.

HJHS evaluated total joint score for 6 joints (left ankle, right ankle, left elbow, right elbow, left knee, right knee) and the global gait score. Joint total score per joint ranged from 0 to 20 (evaluated as: swelling \[0-3\], duration of swelling \[0-1\], muscle atrophy \[0-2\], crepitus on motion \[0-2\], flexion loss \[0-3\], extension loss \[0-3\], joint pain \[0-2\], and strength \[0-4\]). Global gait score ranged from 0 to 4 based on walking, stairs, running, and hopping on 1 leg. HJHS total score was sum of total joint score for 6 joints (0 to 120) and global gait score (0 to 4). The total HJHS score ranged from 0 to 124, where higher scores indicated worse joint health.

HJHS evaluated total joint score for 6 joints (left ankle, right ankle, left elbow, right elbow, left knee, right knee) and the global gait score. Joint total score per joint ranged from 0 to 20 (evaluated as: swelling \[0-3\], duration of swelling \[0-1\], muscle atrophy \[0-2\], crepitus on motion \[0-2\], flexion loss \[0-3\], extension loss \[0-3\], joint pain \[0-2\], and strength \[0-4\]). Global gait score ranged from 0 to 4 based on walking, stairs, running, and hopping on 1 leg. HJHS total score was sum of total joint score for 6 joints (0 to 120) and global gait score (0 to 4). The total HJHS score ranged from 0 to 124, where higher scores indicated worse joint health.

Haem-A-QoL assessed health-related quality of life (QoL) in adult participants (\>=17 years of age) with hemophilia. It contained 46 items with 10 domains that assessed health in the following areas: physical health; feelings; view of self; sports and leisure; work and school; dealing with haemophilia; treatment; future; family planning; partnership and sexuality. All items were based on a 5-point Likert type scale (1= never, 2= rarely, 3= sometimes, 4= often, 5= all the time). Scoring was performed by averaging non-missing item responses for each domain, then each domain score was rescaled from 0 to 100, lower scores signified higher QoL. Total Haem-A-QoL score was averaged across the 46 items values and then rescaled from 0 to 100, lower Haem-A-QoL scores signified better QoL.

Haem-A-QoL assessed health-related quality of life (QoL) in adult participants (\>=17 years of age) with hemophilia. It contained 46 items with 10 domains that assessed health in the following areas: physical health; feelings; view of self; sports and leisure; work and school; dealing with haemophilia; treatment; future; family planning; partnership and sexuality. All items were based on a 5-point Likert type scale (1= never, 2= rarely, 3= sometimes, 4= often, 5= all the time). Scoring was performed by averaging non-missing item responses for each domain, then each domain score was rescaled from 0 to 100, lower scores signified higher QoL. Total Haem-A-QoL score was averaged across the 46 items values and then rescaled from 0 to 100, lower Haem-A-QoL scores signified better QoL.

Haemo-QoL assessed health-related QoL in adolescent participants (12 to \<17 years of age) with hemophilia. It contains 12 items with 77 domains that assesses health in the following areas: physical health; feelings; attitude/view; family; friends; other people; sport and school; coping/dealing; treatment; perceived support; future and relationship. All items were based on 5-point Likert type scale (1= never, 2= rarely, 3= sometimes, 4= often, 5= all the time). Scoring was performed by averaging non-missing item responses for each domain, then rescaled from 0 to 100, lower scores signified higher QoL. Total Haem-A QoL score was averaged across the 77 items values and then rescaled from 0 to 100, lower Haemo-QoL scores signified better QoL.

Haemo-QoL assessed health-related QoL in adolescent participants (12 to \<17 years of age) with hemophilia. It contains 12 items with 77 domains that assesses health in the following areas: physical health; feelings; attitude/view; family; friends; other people; sport and school; coping/dealing; treatment; perceived support; future and relationship. All items were based on 5-point Likert type scale (1= never, 2= rarely, 3= sometimes, 4= often, 5= all the time). Scoring was performed by averaging non-missing item responses for each domain, then rescaled from 0 to 100, lower scores signified higher QoL. Total Haem-A QoL score was averaged across the 77 items values and then rescaled from 0 to 100, lower Haemo-QoL scores signified better QoL.

The HAL was a multiple domain measure of the impact of hemophilia on functional abilities in adults (\>=17 years of age). The 7 domains of this instrument contained 42 items in total, as follows: lying/sitting/kneeling/standing; lower (leg) functioning; upper (arm) functioning; transportation; self-care; household tasks; and sports/leisure. Items were rated on 6-point scale 1 (impossible) to 6 (never) that described difficulty due to hemophilia. HAL total score was sum of all items and scored 42 to 252, which were transformed to 0 - 100, where higher scores indicated better functional status.

The HAL was a multiple domain measure of the impact of hemophilia on functional abilities in adults (\>=17 years of age). The 7 domains of this instrument contained 42 items in total, as follows: lying/sitting/kneeling/standing; lower (leg) functioning; upper (arm) functioning; transportation; self-care; household tasks; and sports/leisure. Items were rated on 6-point scale 1 (impossible) to 6 (never) that described difficulty due to hemophilia. HAL total score was sum of all items and scored 42 to 252, which were transformed to 0 - 100, where higher scores indicated better functional status.

The pedHAL was a multiple domain measure of the impact of hemophilia on functional abilities in adolescents (12 to \<17 years of age). The 7 domains of this instrument contained 53 items in total, as follows: sitting/kneeling/standing; functions of the legs; functions of the arms; use of transportation; self-care; household tasks; leisure activities and sports. Items were rated on 6-point scale 1 (impossible) to 6 (never) that described difficulty due to hemophilia. pedHAL total score was normalized in a range of 0 - 100, where higher scores indicated better functional status.

The pedHAL was a multiple domain measure of the impact of hemophilia on functional abilities in adolescents (12 to \<17 years of age). The 7 domains of this instrument contained 53 items in total, as follows: sitting/kneeling/standing; functions of the legs; functions of the arms; use of transportation; self-care; household tasks; leisure activities and sports. Items were rated on 6-point scale 1 (impossible) to 6 (never) that described difficulty due to hemophilia. pedHAL total score was normalized in a range of 0 - 100, where higher scores indicated better functional status.

The PGIC-H was a single item assessment of the participant's overall impression of change in their life with hemophilia, on a 7-point scale (1= greatly improved to 7= greatly worsened, where lower scores indicated better improvement).

The PGIC-H was a single item assessment of the participant's overall impression of change in their life with hemophilia, on a 7-point scale (1= greatly improved to 7= greatly worsened, where lower scores indicated better improvement).

EQ-5D-5L consisted of participant completed questionnaire with 2 components: health state profile index and visual analogue scale (VAS). EQ-5D health state profile index has 5 domains (mobility, self-care, usual activities, pain/discomfort, anxiety/depression), with 5 levels (1= no problems, 2= slight problems, 3= moderate problems, 4= severe problems, 5= extreme problems). Responses to 5 dimensions comprised health state index value. E.g. if a participant responds "no problems" for each 5 dimensions, then health state was coded as "11111" with predefined index value to it. EQ-5D-5L index score ranged from -0.594 to 1, United Kingdom look-up value was applied to all participants, higher scores indicated better health states. The EQ- VAS measured participant's self-rated health state on a scale from 0 (worst imaginable health state) to 100 (best imaginable health state) by VAS, where higher scores indicated better heath states.

EQ-5D-5L consisted of participant completed questionnaire with 2 components: health state profile index and visual analogue scale (VAS). EQ-5D health state profile index has 5 domains (mobility, self-care, usual activities, pain/discomfort, anxiety/depression), with 5 levels (1= no problems, 2= slight problems, 3= moderate problems, 4= severe problems, 5= extreme problems). Responses to 5 dimensions comprised health state index value. E.g. if a participant responds "no problems" for each 5 dimensions, then health state was coded as "11111" with predefined index value to it. EQ-5D-5L index score ranged from -0.594 to 1, United Kingdom look-up value was applied to all participants, higher scores indicated better health states. The EQ- VAS measured participant's self-rated health state on a scale from 0 (worst imaginable health state) to 100 (best imaginable health state) by VAS, where higher scores indicated better heath states.