Trial Outcomes & Findings for A Study to Evaluate the Efficacy and Safety of Factor IX Gene Therapy With PF-06838435 in Adult Males With Moderately Severe to Severe Hemophilia B (NCT NCT03861273)

Results Overview

ABR = number of total bleeding episodes on study during the given time period) \*365.25/ (Date of last day - date of first day +1) in that time period. Surgical procedures were excluded from summary/analyses. Treated Bleed: An event necessitating administration of coagulation factor within 72 hours of signs or symptoms of bleeding (protocol definition, unless specifically referring to untreated bleed). Untreated Bleed: A bleeding event not necessitating administration of coagulation factor within 72 hours of signs or symptoms of bleeding. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002.

Recruitment status

ACTIVE_NOT_RECRUITING

Study phase

PHASE3

Target enrollment

51 participants

Primary outcome timeframe

Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm)

Results posted on

2025-09-30

Participant Flow

Participants with moderately severe to severe hemophilia B, who completed a minimum 6 months of routine Factor IX prophylaxis therapy during the lead-in study C0371004 (NCT03587116), were enrolled in this study.

A total of 51 participants were screened in this study and 45 participants received a single dose of PF-06838435 (fidanacogene elaparvovec). Results presented are for primary outcome measures and only those secondary measures whose analysis was complete on a data cutoff date of 16 November 2022 (primary completion date \[PCD\]).

Participant milestones

Participant milestones
Measure	PF-06838435 Participants received PF-06838435 infusion on Day 1 at a dose of 5\*10\^11 vector genomes per kilogram (kg) of body weight. Short term follow-up: Participants were followed up for 52 weeks/Year 1 post infusion. Long term follow-up: Participants were followed up from Year 2 to 6.
Screening Phase (3 Weeks) STARTED	51
Screening Phase (3 Weeks) COMPLETED	45
Screening Phase (3 Weeks) NOT COMPLETED	6
Treatment Phase (Day 1) STARTED	45
Treatment Phase (Day 1) COMPLETED	45
Treatment Phase (Day 1) NOT COMPLETED	0
Follow-up Phase (Year 1) STARTED	45
Follow-up Phase (Year 1) COMPLETED	43
Follow-up Phase (Year 1) NOT COMPLETED	2
Long-Term Follow-Up (Year 2 to Year 6) STARTED	43
Long-Term Follow-Up (Year 2 to Year 6) COMPLETED	0
Long-Term Follow-Up (Year 2 to Year 6) NOT COMPLETED	43

Reasons for withdrawal

Reasons for withdrawal
Measure	PF-06838435 Participants received PF-06838435 infusion on Day 1 at a dose of 5\*10\^11 vector genomes per kilogram (kg) of body weight. Short term follow-up: Participants were followed up for 52 weeks/Year 1 post infusion. Long term follow-up: Participants were followed up from Year 2 to 6.
Screening Phase (3 Weeks) Other	1
Screening Phase (3 Weeks) Screen failure	5
Follow-up Phase (Year 1) Ongoing	2
Long-Term Follow-Up (Year 2 to Year 6) Ongoing	42
Long-Term Follow-Up (Year 2 to Year 6) Withdrawal by Subject	1

Baseline Characteristics

A Study to Evaluate the Efficacy and Safety of Factor IX Gene Therapy With PF-06838435 in Adult Males With Moderately Severe to Severe Hemophilia B

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	PF-06838435 n=45 Participants All participants enrolled in the study and who received PF-06838435 infusion.
Age, Continuous	33.18 Years STANDARD_DEVIATION 10.947 • n=5 Participants
Sex: Female, Male Female	0 Participants n=5 Participants
Sex: Female, Male Male	45 Participants n=5 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	2 Participants n=5 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	35 Participants n=5 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	8 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants
Race (NIH/OMB) Asian	7 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants
Race (NIH/OMB) Black or African American	1 Participants n=5 Participants
Race (NIH/OMB) White	33 Participants n=5 Participants
Race (NIH/OMB) More than one race	0 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	4 Participants n=5 Participants

PRIMARY outcome

Timeframe: Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm)

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion.

ABR = number of total bleeding episodes on study during the given time period) \*365.25/ (Date of last day - date of first day +1) in that time period. Surgical procedures were excluded from summary/analyses. Treated Bleed: An event necessitating administration of coagulation factor within 72 hours of signs or symptoms of bleeding (protocol definition, unless specifically referring to untreated bleed). Untreated Bleed: A bleeding event not necessitating administration of coagulation factor within 72 hours of signs or symptoms of bleeding. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=45 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 n=45 Participants Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
Annualized Bleeding Rate (ABR) for Total Bleeds (Treated and Untreated) From Week 12 to Month 15	4.43 Total bleeds per year Interval 1.81 to 7.05	1.30 Total bleeds per year Interval 0.59 to 2.02

SECONDARY outcome

Timeframe: Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm)

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion.

ABR = number of total bleeding episodes on study during the given time period) \*365.25/ (Date of last day - date of first day +1) in that time period. Surgical procedures were excluded from summary/analyses. Treated Bleed: An event necessitating administration of coagulation factor within 72 hours of signs or symptoms of bleeding (protocol definition, unless specifically referring to untreated bleed). This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=45 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 n=45 Participants Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
ABR for Treated Bleeds From Week 12 to Month 15	3.35 Treated bleeds per year Interval 1.71 to 4.98	0.73 Treated bleeds per year Interval 0.25 to 1.21

SECONDARY outcome

Timeframe: Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm)

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion.

AIR = number of exogenous infusions (for any reason) received during given time period \*365.25/ (Date of last day - date of first day +1) in that time period. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=45 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 n=45 Participants Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
Annualized Infusion Rate (AIR) of Exogenous FIX From Week 12 to Month 15	58.83 Exogenous infusions per year Standard Deviation 29.056	4.46 Exogenous infusions per year Standard Deviation 10.028

SECONDARY outcome

Timeframe: Week 12 to Month 15

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. The assessments at the visits following participant withdrawal/dropout/FIX prophylaxis resumption were imputed as 1.9%. Here, "Number Analyzed" signifies number of participants evaluable for specified rows of respective arms.

The certified central clinical laboratory analyzed the sample by two one-stage assays and a chromogenic assay. The first one-stage assay was performed on BCSXP analyzer with Actin-FSL reagent. The second one-stage assay used the same analyzer but SynthAsil as reagent. Data reported in this Outcome Measure is the geometric mean of all assessments from week 12 to Month 15.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=45 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
Steady State Circulating Factor IX (FIX:C) From Week 12 to Month 15 Week 12 to Month 15: One-stage Assay (Actin-FSL Reagent)	12.62 Percentage of Normal Standard Deviation 8.92	—
Steady State Circulating Factor IX (FIX:C) From Week 12 to Month 15 Week 12 to Month 15: One-stage Assay (SynthASil Reagent)	25.90 Percentage of Normal Standard Deviation 16.89	—
Steady State Circulating Factor IX (FIX:C) From Week 12 to Month 15 Week 12 to Month 15: Chromogenic Assay	13.49 Percentage of Normal Standard Deviation 10.40	—

SECONDARY outcome

Timeframe: Week 12, Week 24, Week 65

Population: Dosed analysis set: participants enrolled in the study who received PF-06838435 infusion. The assessments at the visits following participant withdrawal/dropout/FIX prophylaxis resumption were imputed as 1.9%. "Number Analyzed": at each row represents the number of participants with valid FIX:C assessments at the respective time points. All participants reported under 'Number of Participants Analyzed' contributed data to the table; however, may not have evaluable data for every row.

The certified central clinical laboratory analyzed the sample by two one-stage assays and a chromogenic assay. The first one-stage assay was performed on BCSXP analyzer with Actin-FSL reagent. The second one-stage assay used the same analyzer but SynthAsil as reagent.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=45 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 Week 12: One-stage Assay (Actin-FSL Reagent)	13.52 Percentage of Normal Standard Deviation 8.134	—
Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 Week 12: One-stage Assay (SynthASil Reagent)	27.79 Percentage of Normal Standard Deviation 15.226	—
Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 Week 12: Chromogenic Assay	13.91 Percentage of Normal Standard Deviation 9.302	—
Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 Week 24: One-stage Assay (Actin-FSL Reagent)	13.10 Percentage of Normal Standard Deviation 11.144	—
Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 Week 24: One-stage Assay (SynthASil Reagent)	27.67 Percentage of Normal Standard Deviation 21.340	—
Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 Week 24: Chromogenic Assay	14.83 Percentage of Normal Standard Deviation 12.961	—
Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 Week 65: One-stage Assay (Actin-FSL Reagent)	13.10 Percentage of Normal Standard Deviation 12.792	—
Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 Week 65: One-stage Assay (SynthASil Reagent)	27.47 Percentage of Normal Standard Deviation 25.739	—
Circulating Factor IX (FIX:C) at Week 12, Week 24, Week 65 Week 65: Chromogenic Assay	15.82 Percentage of Normal Standard Deviation 16.996	—

SECONDARY outcome

Timeframe: Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm)

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion.

Annualized FIX consumption was reported by International Units per kilogram (IU/kg). This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002. Data reported in this Outcome Measure is average of all assessments from Week 12 to Month 15.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=45 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 n=45 Participants Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
Annualized Factor IX (FIX) Consumption From Week 12 to Month 15	3170.74 IU/kg per year Standard Deviation 1634.753	235.04 IU/kg per year Standard Deviation 538.977

SECONDARY outcome

Timeframe: Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm)

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion.

ABR = number of total bleeding episodes on study during the given time period) \*365.25/ (Date of last day - date of first day +1) in that time period. Surgical procedures were excluded from summary/analyses. Surgical procedures were excluded from summary/analyses. Spontaneous Bleeds: Bleeding for no apparent/known reason particularly into the joints, muscles, and soft tissues. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=45 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 n=45 Participants Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
ABR for Spontaneous Bleeds From Week 12 to Month 15	3.24 Spontaneous bleeds per year Interval 0.92 to 5.56	0.69 Spontaneous bleeds per year Interval 0.19 to 1.2

SECONDARY outcome

Timeframe: Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm)

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion.

ABR = number of total bleeding episodes on study during the given time period) \*365.25/ (Date of last day - date of first day +1) in that time period. Surgical procedures were excluded from summary/analyses. Surgical procedures were excluded from summary/analyses. Traumatic Bleeds: Bleeding event occurring for an apparent/known reason. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=45 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 n=45 Participants Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
ABR for Traumatic Bleeds From Week 12 to Month 15	1.16 Traumatic bleeds per year Interval 0.34 to 1.98	0.59 Traumatic bleeds per year Interval 0.26 to 0.92

SECONDARY outcome

Timeframe: Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm)

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion.

ABR = number of total bleeding episodes on study during the given time period) \*365.25/ (Date of last day - date of first day +1) in that time period. Surgical procedures were excluded from summary/analyses. Surgical procedures were excluded from summary/analyses. Untreated Bleed: A bleeding event not necessitating administration of coagulation factor within 72 hours of signs or symptoms of bleeding. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=45 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 n=45 Participants Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
ABR for Untreated Bleeds From Week 12 to Month 15	1.07 Untreated bleeds per year Interval -0.32 to 2.47	0.57 Untreated bleeds per year Interval 0.14 to 1.0

SECONDARY outcome

Timeframe: Pre-infusion period: minimum of 6 months through first dose of current study, an average of 1.31 years (FIX Prophylaxis arm); Week 12 to Month 15 post infusion in current study (PF-06838435 arm)

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion.

Target Joint: Defined as a major joint (e.g., hip, elbow, wrist, shoulder, knee, and ankle) into which repeated bleeds occurred (three or more spontaneous bleeds into a single joint within a consecutive 6-month period). A target joint was considered resolved when there were =\<2 bleeds into the joint within a 12-month period. Joint Bleed: A 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. This outcome measure compared data collected from lead-in study C0371004 and from current study C0371002. Pre-infusion period = at least 6 months of prospectively collected data while receiving FIX prophylaxis replacement therapy in lead-in study C0371004 up to dosing in current study C0371002.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=45 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 n=45 Participants Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
Number of Target Joint Bleeds From Week 12 to Month 15	2.9 Target joint bleeds Standard Deviation 7.81	0.3 Target joint bleeds Standard Deviation 1.02

SECONDARY outcome

Timeframe: Week 12 to Month 15

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion.

Percentage of participants without bleeds (total bleeds and treated bleeds) were summarized by type from Week 12 to Month 15.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=45 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
Percentage of the Participants Without Bleeds From Week 12 to Month 15 Without treated bleeds	73.3 Percentage of participants	—
Percentage of the Participants Without Bleeds From Week 12 to Month 15 Without treated and untreated bleeds	64.4 Percentage of participants	—

SECONDARY outcome

Timeframe: Baseline, Month 12

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. Here, "Number of Participants Analyzed" signifies number of participants evaluable for this outcome measure and "Number Analyzed" signifies number of participants evaluable for specified rows of respective arms.

A qualified healthcare professional assessed six joints (left ankle, right ankle, left elbow, right elbow, left knee, right knee) scored from 0 to 20 based on: duration of swelling, muscle atrophy, crepitus, flexion loss, extension loss, instability, joint pain, and strength. Gait was scored (0 to 4) based on walking, stairs, running, hopping on one leg. Total score = sum of scores from all joints + gait score ranged from 0 to 124, with the higher the number equating to more severe joint damage.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=44 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
Change From Baseline in Joint Health as Measured by the Hemophilia Joint Health Score (HJHS) Instrument at Month 12 Baseline	17.8 Units on a scale Interval 13.1 to 22.5	—
Change From Baseline in Joint Health as Measured by the Hemophilia Joint Health Score (HJHS) Instrument at Month 12 Change at Month 12	-2.6 Units on a scale Interval -4.7 to -0.6	—

SECONDARY outcome

Timeframe: Baseline, Month 12

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. Here, "Number of Participants Analyzed" signifies number of participants evaluable for this outcome measure and "Number Analyzed" signifies number of participants evaluable for specified rows of respective arms.

The Haem-A-QoL questionnaire contained 46 items with ten 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; and Partnership and Sexuality. The physical health domain was considered as the primary domain in this questionnaire, had a transformed score range from 0 to 100, with lower scores representing higher quality of life. In this Outcome Measure Physical Health domain scores of Haem A QoL are reported.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=40 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
Change From Baseline in Hemophilia Quality of Life (Haem A QoL) Physical Health Domain at Month 12 Baseline	31.00 Units on a scale Interval 23.02 to 38.98	—
Change From Baseline in Hemophilia Quality of Life (Haem A QoL) Physical Health Domain at Month 12 Change at Month 12	-7.70 Units on a scale Interval -12.95 to -2.45	—

SECONDARY outcome

Timeframe: Baseline, Month 12

Population: Dosed analysis set included all participants enrolled in the study who received PF-06838435 infusion. Here, "Number of Participants Analyzed" signifies number of participants evaluable for this outcome measure and "Number Analyzed" signifies number of participants evaluable for specified rows of respective arms.

The HAL was a multiple domain measure of the impact of hemophilia on functional abilities in adults. 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. Selected items from five of the domains were used to create three components: upper extremity; basic lower extremity; and complex lower extremity activities. The component score of "complex lower extremity activities" was the most important in this questionnaire, had a transformed score range from 0 to 100, higher values indicated less functional limitations in performing tasks.

Outcome measures

Outcome measures
Measure	FIX Prophylaxis n=40 Participants Participants who received routine Factor IX (FIX) prophylaxis replacement therapy during the lead-in study C0371004. Participants subsequently received PF-06838435 infusion. This reporting arm served as control and it used data from lead-in study C0371004 for comparing data from the current study C0371002.	PF-06838435 Eligible participants enrolled in the current study C0371002 and who received PF-06838435 infusion on Day 1. This reporting arm served as experimental arm.
Change From Baseline in Hemophilia Activities List (HAL) Complex Lower Extremity Activities Component Score at Month 12 Baseline	67.06 Units on a scale Interval 59.1 to 75.02	—
Change From Baseline in Hemophilia Activities List (HAL) Complex Lower Extremity Activities Component Score at Month 12 Change at Month 12	7.59 Units on a scale Interval 1.07 to 14.11	—

Adverse Events

PF-06838435

Serious events: 7 serious events

Other events: 37 other events

Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure	PF-06838435 n=45 participants at risk All participants enrolled in the study and who received PF-06838435 infusion and have no significant interruption of efficacy measurement
Blood and lymphatic system disorders Anaemia	4.4% 2/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Gastrointestinal disorders Duodenal ulcer	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Gastrointestinal disorders Duodenal ulcer haemorrhage	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Gastrointestinal disorders Upper gastrointestinal haemorrhage	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Hepatobiliary disorders Drug-induced liver injury	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Infections and infestations COVID-19	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Infections and infestations COVID-19 pneumonia	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Infections and infestations Pilonidal disease	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Injury, poisoning and procedural complications Alcohol poisoning	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Injury, poisoning and procedural complications Femoral neck fracture	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Investigations Coagulation factor IX level decreased	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Metabolism and nutrition disorders Hypokalaemia	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Nervous system disorders Seizure	2.2% 1/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.

Other adverse events

Other adverse events
Measure	PF-06838435 n=45 participants at risk All participants enrolled in the study and who received PF-06838435 infusion and have no significant interruption of efficacy measurement
Gastrointestinal disorders Abdominal pain	6.7% 3/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Gastrointestinal disorders Abdominal pain upper	6.7% 3/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Hepatobiliary disorders Hepatic function abnormal	13.3% 6/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Hepatobiliary disorders Hepatic steatosis	6.7% 3/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Infections and infestations COVID-19	11.1% 5/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Infections and infestations Nasopharyngitis	17.8% 8/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Infections and infestations Upper respiratory tract infection	8.9% 4/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Investigations Alanine aminotransferase increased	26.7% 12/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Investigations Aspartate aminotransferase increased	6.7% 3/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Investigations Hepatic enzyme increased	6.7% 3/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Investigations SARS-CoV-2 test positive	6.7% 3/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Investigations Transaminases increased	6.7% 3/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Musculoskeletal and connective tissue disorders Arthralgia	17.8% 8/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Musculoskeletal and connective tissue disorders Joint swelling	6.7% 3/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Nervous system disorders Headache	13.3% 6/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Psychiatric disorders Insomnia	6.7% 3/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Skin and subcutaneous tissue disorders Acne	6.7% 3/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.
Vascular disorders Hypertension	6.7% 3/45 • Day 1 up to analysis data cut-off 16-Nov-2022 (approximately 3 years 3 months) Same event may appear as both non-SAE and a serious AE. However, what is presented are distinct events. An event may be categorized as serious in one participant and as non-serious in another participant, or one participant may have experienced both a serious and non-serious event during the study. All participants enrolled in the study and who received PF-06838435 infusion.

Additional Information

Pfizer ClinicalTrials.gov Call Center

Pfizer Inc.

Phone: 1-800-718-1021

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee Pfizer has the right to review disclosures, requesting a delay of less than 60 days. Investigator will postpone single center publications until after disclosure of pooled data (all sites), less than 12 months from study completion/termination at all participating sites. Investigator may not disclose previously undisclosed confidential information other than study results.
Publication restrictions are in place

Restriction type: OTHER