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CompletedNCT03061201Updated Sep 30, 2025Results posted

A Study of Recombinant AAV2/6 Human Factor 8 Gene Therapy SB-525 (PF-07055480) in Subjects With Severe Hemophilia A

A Phase 2 interventional study of SB-525 (PF-07055480) in Hemophilia A, sponsored by Pfizer. Completed at 22 sites in United States. Open to male participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-09-30.

Sponsored by Pfizer · Phase 2, Interventional, and Treatment

Phase
Phase 2
Study type
Interventional
Enrollment
13
Allocation
Not applicable
Ages
18 Years and older
Sex
Male
01

Study summary

The purpose of the study is to evaluate the safety, tolerability and time-course profile of FVIII activity after dosing with SB-525 (PF-07055480)

Read the detailed description

The proposed clinical study uses a recombinant adeno-associated virus 2/6 (AAV2/6) vector encoding the cDNA for the B-domain deleted human F8 (hF8). The secreted FVIII has the same amino acid sequence as approved recombinant anti hemophilic factors (Refacto® and Xyntha®). The SB-525 (PF-07055480) vector encodes a liver-specific promotor module and AAV2/6 exhibits liver tropism, thus providing the potential for long-term hepatic production of FVIII in hemophilia A subjects.

The constant production of FVIII after a single SB-525 (PF-07055480) administration may provide potential benefit in durable protection against bleeding and the complications thereof without lifelong repetitive IV factor replacement administration.

02

Conditions studied

  • Hemophilia A

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03

In context

Hemophilia A

865 studies on the registry are indexed under Hemophilia A; 135 are open to participants now.

This study's enrollment of 13 is below the median of 28 across 512 interventional studies indexed under Hemophilia A.

Browse Hemophilia A studies →

Lead sponsor

Pfizer is the lead sponsor of 3,244 studies on the registry; 139 are open to participants now.

Of its 582 completed or terminated interventional studies of FDA-regulated products, 381 (65%) have results posted.

Browse Pfizer studies →

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
Male
Accepts healthy volunteers
No

Inclusion criteria

  • Male ≥18 years of age
  • Severe hemophilia A (past evidence of circulating FVIII activity of \< 1% normal)
  • Treated or exposed to FVIII concentrates or cryoprecipitate for at least 150 exposure days
  • ≥12 bleeding episodes if receiving on-demand therapy over the preceding 12 months
  • Agree to use double barrier contraceptive until at least 3 consecutive semen samples are negative for AAV 2/6 after SB-525 infusion

Exclusion criteria

Exclusion Criteria:

  • Presence of neutralizing antibodies
  • Current inhibitor, or history of FVIII inhibitor (except for transient low titer inhibitor detected in childhood)
  • History of hypersensitivity response to FVIII
  • History of Hepatitis B or HIV-1/2 infection
  • History of Hepatitis C, unless viral assays in two samples, collected at least 6 months apart, are negative
  • Evidence of any bleeding disorder in addition to hemophilia A
  • Markers of hepatic inflammation or overt or occult cirrhosis
  • History of chronic renal disease or creatinine ≥ 1.5 mg/dL
  • Presence of liver mass on magnetic resonance imaging (MRI), or, positive alpha fetoprotein
  • Presence of > grade 2 liver fibrosis on elastography for subjects with history of treated Hepatitis C or suspicion of chronic liver disease
05

Study design

Phase
Phase 2
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Sequential assignment
Masking
None (open label)
Enrollment
13 participants (actual)

Study arms

  • Experimental
    Sequential dose escalation

    SB-525 (PF-07055480) is administered as a single infusion

    Biological: SB-525 (PF-07055480)

Interventions

  • BiologicalSB-525 (PF-07055480)

    Single dose of investigational product SB-525 (PF-07055480)

06

What researchers measure

Primary outcomes

  1. Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs)

    An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of study intervention. An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the criteria as follows: death, life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, congenital anomaly/birth defect and other situations per protocol. AEs included both SAEs and all non-SAEs.

    Time frame: From Baseline (1 week prior to infusion) up to 5 years post-infusion (approximately 5 Years)

  2. Central FVIII Activity Levels by Chromogenic Assay at Year 1 (Week 52)

    FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by chromogenic assay are reported.

    Time frame: At Year 1 (Week 52)

  3. Central FVIII Activity Levels by Chromogenic Assay at Year 2 (Week 104)

    FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by chromogenic assay are reported.

    Time frame: At Year 2 (Week 104)

  4. Central FVIII Activity Levels by Chromogenic Assay at Year 3 (Week 156)

    FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by chromogenic assay are reported.

    Time frame: At Year 3 (Week 156)

  5. Central FVIII Activity Levels by Chromogenic Assay at Year 4 (Week 208)

    FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by chromogenic assay are reported.

    Time frame: At Year 4 (Week 208)

  6. Central FVIII Activity Levels by Chromogenic Assay at Year 5 (Week 260)

    FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by chromogenic assay are reported.

    Time frame: At Year 5 (Week 260)

  7. Central FVIII Activity Levels by One-Stage Clotting Assay at Year 1 (Week 52)

    FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by one-stage clotting assay are reported.

    Time frame: At Year 1 (Week 52)

  8. Central FVIII Activity Levels by One-Stage Clotting Assay at Year 2 (Week 104)

    FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by one-stage clotting assay are reported.

    Time frame: At Year 2 (Week 104)

  9. Central FVIII Activity Levels by One-Stage Clotting Assay at Year 3 (Week 156)

    FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by one-stage clotting assay are reported.

    Time frame: At Year 3 (Week 156)

  10. Central FVIII Activity Levels by One-Stage Clotting Assay at Year 4 (Week 208)

    FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by one-stage clotting assay are reported.

    Time frame: At Year 4 (Week 208)

  11. Central FVIII Activity Levels by One-Stage Clotting Assay at Year 5 (Week 260)

    FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by one-stage clotting assay are reported.

    Time frame: At Year 5 (Week 260)

  12. Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 1 (Week 9 Through Week 53)

    FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by chromogenic assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 1 included assessments from Week 9 through Week 53). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

    Time frame: Year 1 (Week 9 through Week 53)

  13. Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 2 (Week 54 Through Week 108)

    FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by chromogenic assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 2 included assessments from Week 54 through Week 108). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

    Time frame: Year 2 (Week 54 through Week 108)

  14. Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 3 (Week 109 Through Week 160)

    FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by chromogenic assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 3 included assessments from Week 109 through Week 160). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

    Time frame: Year 3 (Week 109 through Week 160)

  15. Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 4 (Week 161 Through Week 212)

    FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by chromogenic assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 4 included assessments from Week 161 through Week 212). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

    Time frame: Year 4 (Week 161 through Week 212)

  16. Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 5 (Week 213 Through Week 264)

    FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by chromogenic assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 5 included assessments from Week 213 through Week 264). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

    Time frame: Year 5 (Week 213 through Week 264)

  17. Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 1 (Week 9 Through Week 53)

    FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by one-stage clotting assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 1 included assessments from Week 9 through Week 53). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

    Time frame: Year 1 (Week 9 through Week 53)

  18. Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 2 (Week 54 Through Week 108)

    FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by one-stage clotting assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 2 included assessments from Week 54 through Week 108). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

    Time frame: Year 2 (Week 54 through Week 108)

  19. Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 3 (Week 109 Through Week 160)

    FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by one-stage clotting assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 3 included assessments from Week 109 through Week 160). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

    Time frame: Year 3 (Week 109 through Week 160)

  20. Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 4 (Week 161 Through Week 212)

    FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by one-stage clotting assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 4 included assessments from Week 161 through Week 212). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

    Time frame: Year 4 (Week 161 through Week 212)

  21. Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 5 (Week 213 Through Week 264)

    FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by one-stage clotting assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 5 included assessments from Week 213 through Week 264). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

    Time frame: Year 5 (Week 213 through Week 264)

Secondary outcomes

  1. Total Annualized Bleeding Rate (ABR)

    Total ABR included both treated and untreated bleeding episodes. In this outcome measure total ABR for pre-screening and post-infusion are reported. Pre-screening total ABR was based on the total number of reported bleeding episodes during 12 months prior to screening visit as reported on CRF's Hemophilia A History page. Screening was 2 months before baseline. Post- infusion total ABR = number of all bleeding episodes starting 3 weeks after investigational product/ PF-07055480 (IP) infusion up to date of day before start of prophylaxis (or date of data cut or conclusion date)/ observation period in years, where observation period in years = date of day before start of prophylaxis or date of data cut or conclusion date - 3 weeks after date of IP infusion + 1)/365.25. For a participant who did not start prophylaxis the data cut date or conclusion date is used.

    Time frame: Pre-screening period: 12 months prior to screening; Post-infusion period: 3 weeks post-infusion up to date of day before start of prophylaxis or date of data cut or conclusion date, whichever was earlier (maximum up to 5 years)

  2. Total ABR by Severity

    Total ABR include both treated and untreated bleeding episodes. In this outcome measure total ABR by severity for post-infusion period is reported. Severity was categorized as mild, moderate and severe. Post- infusion total ABR = number of all bleeding episodes starting 3 weeks after IP infusion up to date of day before start of prophylaxis (or date of data cut or conclusion date)/ observation period in years, where observation period in years = date of day before start of prophylaxis or date of data cut or conclusion date - 3 weeks after date of IP infusion + 1)/365.25. For a participant who did not start prophylaxis the data cut date or conclusion date is used.

    Time frame: Post-infusion period: 3 weeks post-infusion up to date of day before start of prophylaxis or date of data cut or conclusion date, whichever was earlier (maximum up to 5 years)

  3. Annualized Infusion Rate (AIR)

    AIR was calculated and reported for pre-infusion and post-infusion. AIR for pre-infusion was calculated as, a) Excluding prophylaxis: number of FVIII replacement infusions for reasons other than prophylaxis prior to IP infusion/ (\[date of IP infusion - date of screening\] + 30)\] \*365.25, or b) number of FVIII replacement infusions for any reason prior to IP infusion/ (\[date of IP infusion - date of screening\] + 30)\] \*365.25. Screening was 2 months before baseline and baseline was approximately 1-week prior to IP infusion. AIR for post- infusion was calculated as: number of FVIII replacement infusions started at 3 weeks after IP infusion up to date of data cut or conclusion date/ number of days in the observation period for the participant in years, where observation period in years = date of data cut or conclusion date - 3 weeks after date of IP infusion + 1)/365.25.

    Time frame: Pre-infusion period: 30 days before screening up to pre-infusion (approximately up to 3.23 months); post-infusion period: 3 weeks post-infusion up to up to date of data cut or conclusion date (maximum up to 5 years)

  4. Change From Baseline in the EuroQol, 5 Dimensions, 5 Levels (EQ-5D-5L) Index Score at Weeks 12, 24 and 52; Months 24, 36, 48 and 60

    EQ-5D-5L is a standardized measure of health status developed by the EuroQol Group. It measures 5 dimensions (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression) of health on a 5-point scale. Each dimension had 5 levels: 1= no problems, 2= slight problems, 3= moderate problems, 4= severe problems, and 5= extreme problems. EQ-5D-5L had 2 components: Index score and visual analogue scale (VAS). Index score was obtained, according to the health state defined by the 5 dimensions scores, from the Crosswalk Index value calculator and table lookup document under the target country population. A health state is defined by the combination of one level from each of the 5 dimensions. For this study, weights under the US population were used to obtain the Index score. Index score ranged between 0-1, where higher score indicates a better health state, and lower score indicate worse health state. Baseline was defined as the latest non-missing value before IP infusion.

    Time frame: Baseline; Weeks 12, 24, and 52; Months 24, 36, 48, and 60

  5. Change From Baseline in the EQ-5D-5L- VAS Score at Week 12, 24, 52 and Month 24, 36, 48, 60

    EQ-5D-5L is a standardized measure of health status developed by the EuroQol Group. It measures 5 dimensions of health on a 5-point scale including mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is assessed with 5 levels: 1= no problems, 2= slight problems, 3= moderate problems, 4= severe problems, and 5= extreme problems. EQ-5D-5L had 2 components: Index score and VAS. EQ-5D-5L VAS: Participants were asked to indicate their current health status on a scale of 0 (worst health) to 100 (best imaginable health), higher scores signified better health status. Baseline was defined as the latest non-missing value before IP infusion.

    Time frame: Baseline; Weeks 12, 24, and 52; Months 24, 36, 48, and 60

  6. Number of Participants With Positive FVIII Inhibitor Levels During the Study

    Positive FVIII inhibitor was assessed using central laboratory using Nijmegen method of the Bethesda assay in an individual with no prior history of FVIII inhibitor. Inhibitor assay results \>0.6 Bethesda units (BU) were considered as positive. Positive results at any timepoint were considered, even if subsequent inhibitor assessment was negative.

    Time frame: Baseline (one week prior to IP infusion) up to 5 years post-infusion

  7. Peak Value of AAV2/6 (Adeno-associated Vector 2/6) Deoxyribonucleic Acid (DNA) in Plasma, Saliva, Semen, Stool and Urine

    Peak (maximum) AAV2/6 vector DNA concentration (vg/mL) in plasma, saliva, semen, stool and urine were analyzed with quantitative real-time polymerase chain reaction (PCR). Participants must achieve 3 consecutive negative results for analysis for each sample.

    Time frame: All samples: Baseline, Day 7, Week 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52 and every month after Week 52 until Month 60 until 3 consecutive negative samples are obtained on a sample-type basis; additional for plasma at 12 hours post-infusion

  8. Time to Peak Value of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine

    Time to peak (maximum) AAV2/6 vector DNA concentration (vg/mL) in plasma, saliva, urine, stool and semen were analyzed with quantitative real-time PCR. Participants must achieve 3 consecutive negative results for analysis for each sample; where negative suggests values under the limit of detection.

    Time frame: All samples: Baseline, Day 7, Week 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52 and every month after Week 52 until Month 60 until 3 consecutive negative samples are obtained on a sample-type basis; additional for plasma at 12 hours post-infusion

  9. Time to Undetectable (Negative) Value of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine

    Time to undetectable (negative) value of AAV2/6 vector DNA concentration (vg/mL) in plasma, saliva, urine, stool and semen were analyzed with quantitative real-time PCR. Time to undetectable is defined as the number of days from IP infusion until the first of 3 consecutive specimens under the limit of detection (negative).

    Time frame: All samples: Baseline, Day 7, Week 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52 and every month after Week 52 until Month 60 until 3 consecutive negative samples are obtained on a sample-type basis; additional for plasma at 12 hours post-infusion

  10. Time to Last of 3 Consecutive Negative Values of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine

    Time to last of 3 consecutive negative value of AAV2/6 vector DNA concentration (vg/mL) in plasma, saliva, urine, stool and semen were analyzed with quantitative real-time PCR.

    Time frame: All samples: Baseline, Day 7, Week 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52 and every month after Week 52 until Month 60 until 3 consecutive negative samples are obtained on a sample-type basis; additional for plasma at 12 hours post-infusion

  11. Time to Last Positive Value Prior to First of 3 Consecutive Negatives of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine

    Time to last positive value prior to first of 3 consecutive negatives of AAV2/6 vector DNA concentration (vg/mL) in plasma, saliva, urine, stool and semen were analyzed with quantitative real-time PCR, where positive suggests values above the limit of detection.

    Time frame: All samples: Baseline, Day 7, Week 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52 and every month after Week 52 until Month 60 until 3 consecutive negative samples are obtained on a sample-type basis; additional for plasma at 12 hours post-infusion

07

Results

Posted Sep 30, 2025
Limitations and caveats
Any untoward clinically significant changes from pre vector dosing identified on physical examinations, clinical laboratory assessments, immune parameters, liver imaging, vital signs, Electrocardiogram during the during study were captured as AEs.

Participant flow

Participants with severe hemophilia A were enrolled in this study and received single infusion of SB-525/ PF-07055480. Participants were followed up for maximum of 5 years post-infusion.

Participant flow — Overall Study
MilestoneCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Started2225
Completed1124
Not completed1101
Withdrew: Participants terminated at month 360101
Withdrew: Lost to follow-up1000

Outcome measures

PrimaryNumber of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs)

An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of study intervention. An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the criteria as follows: death, life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, congenital anomaly/birth defect and other situations per protocol. AEs included both SAEs and all non-SAEs.

Time frame:
From Baseline (1 week prior to infusion) up to 5 years post-infusion (approximately 5 Years)
Reported as:
Count of participants · Participants
Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs)
ParticipantsCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Participants With AEs2225
Participants With SAEs0201
PrimaryCentral FVIII Activity Levels by Chromogenic Assay at Year 1 (Week 52)

FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by chromogenic assay are reported.

Time frame:
At Year 1 (Week 52)
Reported as:
Mean · Percentage of Normal
Central FVIII Activity Levels by Chromogenic Assay at Year 1 (Week 52)
Percentage of NormalCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Central FVIII Activity Levels by Chromogenic Assay at Year 1 (Week 52)—0.90 ± 0.00011.9042.60 ± 53.473
PrimaryCentral FVIII Activity Levels by Chromogenic Assay at Year 2 (Week 104)

FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by chromogenic assay are reported.

Time frame:
At Year 2 (Week 104)
Reported as:
Mean · Percentage of Normal
Central FVIII Activity Levels by Chromogenic Assay at Year 2 (Week 104)
Percentage of NormalCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Central FVIII Activity Levels by Chromogenic Assay at Year 2 (Week 104)—19.308.2525.44 ± 27.532
PrimaryCentral FVIII Activity Levels by Chromogenic Assay at Year 3 (Week 156)

FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by chromogenic assay are reported.

Time frame:
At Year 3 (Week 156)
Reported as:
Mean · Percentage of Normal
Central FVIII Activity Levels by Chromogenic Assay at Year 3 (Week 156)
Percentage of NormalCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Central FVIII Activity Levels by Chromogenic Assay at Year 3 (Week 156)—0.904.4025.46 ± 36.998
PrimaryCentral FVIII Activity Levels by Chromogenic Assay at Year 4 (Week 208)

FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by chromogenic assay are reported.

Time frame:
At Year 4 (Week 208)
Reported as:
Mean · Percentage of Normal
Central FVIII Activity Levels by Chromogenic Assay at Year 4 (Week 208)
Percentage of NormalCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Central FVIII Activity Levels by Chromogenic Assay at Year 4 (Week 208)—0.903.2026.55 ± 42.489
PrimaryCentral FVIII Activity Levels by Chromogenic Assay at Year 5 (Week 260)

FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by chromogenic assay are reported.

Time frame:
At Year 5 (Week 260)
Reported as:
Mean · Percentage of Normal
Central FVIII Activity Levels by Chromogenic Assay at Year 5 (Week 260)
Percentage of NormalCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Central FVIII Activity Levels by Chromogenic Assay at Year 5 (Week 260)—0.903.3023.55 ± 36.270
PrimaryCentral FVIII Activity Levels by One-Stage Clotting Assay at Year 1 (Week 52)

FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by one-stage clotting assay are reported.

Time frame:
At Year 1 (Week 52)
Reported as:
Mean · Percentage of Normal
Central FVIII Activity Levels by One-Stage Clotting Assay at Year 1 (Week 52)
Percentage of NormalCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Central FVIII Activity Levels by One-Stage Clotting Assay at Year 1 (Week 52)—1.75 ± 1.20219.9066.37 ± 83.793
PrimaryCentral FVIII Activity Levels by One-Stage Clotting Assay at Year 2 (Week 104)

FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by one-stage clotting assay are reported.

Time frame:
At Year 2 (Week 104)
Reported as:
Mean · Percentage of Normal
Central FVIII Activity Levels by One-Stage Clotting Assay at Year 2 (Week 104)
Percentage of NormalCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Central FVIII Activity Levels by One-Stage Clotting Assay at Year 2 (Week 104)—19.0013.9538.86 ± 36.738
PrimaryCentral FVIII Activity Levels by One-Stage Clotting Assay at Year 3 (Week 156)

FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by one-stage clotting assay are reported.

Time frame:
At Year 3 (Week 156)
Reported as:
Mean · Percentage of Normal
Central FVIII Activity Levels by One-Stage Clotting Assay at Year 3 (Week 156)
Percentage of NormalCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Central FVIII Activity Levels by One-Stage Clotting Assay at Year 3 (Week 156)—3.305.7040.52 ± 50.231
PrimaryCentral FVIII Activity Levels by One-Stage Clotting Assay at Year 4 (Week 208)

FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by one-stage clotting assay are reported.

Time frame:
At Year 4 (Week 208)
Reported as:
Mean · Percentage of Normal
Central FVIII Activity Levels by One-Stage Clotting Assay at Year 4 (Week 208)
Percentage of NormalCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Central FVIII Activity Levels by One-Stage Clotting Assay at Year 4 (Week 208)—4.8013.8038.78 ± 53.790
PrimaryCentral FVIII Activity Levels by One-Stage Clotting Assay at Year 5 (Week 260)

FVIII activity levels were assessed using chromogenic and one-stage clotting assay and which were analyzed in the central laboratory. In this outcome measure results by one-stage clotting assay are reported.

Time frame:
At Year 5 (Week 260)
Reported as:
Mean · Percentage of Normal
Central FVIII Activity Levels by One-Stage Clotting Assay at Year 5 (Week 260)
Percentage of NormalCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Central FVIII Activity Levels by One-Stage Clotting Assay at Year 5 (Week 260)—4.006.1041.00 ± 56.749
PrimaryGeometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 1 (Week 9 Through Week 53)

FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by chromogenic assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 1 included assessments from Week 9 through Week 53). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

Time frame:
Year 1 (Week 9 through Week 53)
Reported as:
Mean · Percentage of Normal
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 1 (Week 9 Through Week 53)
Percentage of NormalCohort 4: PF-07055480 3*10^13 vg/kg
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 1 (Week 9 Through Week 53)67.89 ± 46.585
PrimaryGeometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 2 (Week 54 Through Week 108)

FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by chromogenic assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 2 included assessments from Week 54 through Week 108). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

Time frame:
Year 2 (Week 54 through Week 108)
Reported as:
Mean · Percentage of Normal
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 2 (Week 54 Through Week 108)
Percentage of NormalCohort 4: PF-07055480 3*10^13 vg/kg
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 2 (Week 54 Through Week 108)40.38 ± 41.498
PrimaryGeometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 3 (Week 109 Through Week 160)

FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by chromogenic assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 3 included assessments from Week 109 through Week 160). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

Time frame:
Year 3 (Week 109 through Week 160)
Reported as:
Mean · Percentage of Normal
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 3 (Week 109 Through Week 160)
Percentage of NormalCohort 4: PF-07055480 3*10^13 vg/kg
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 3 (Week 109 Through Week 160)27.66 ± 41.589
PrimaryGeometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 4 (Week 161 Through Week 212)

FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by chromogenic assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 4 included assessments from Week 161 through Week 212). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

Time frame:
Year 4 (Week 161 through Week 212)
Reported as:
Mean · Percentage of Normal
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 4 (Week 161 Through Week 212)
Percentage of NormalCohort 4: PF-07055480 3*10^13 vg/kg
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 4 (Week 161 Through Week 212)24.31 ± 34.640
PrimaryGeometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 5 (Week 213 Through Week 264)

FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by chromogenic assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 5 included assessments from Week 213 through Week 264). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

Time frame:
Year 5 (Week 213 through Week 264)
Reported as:
Mean · Percentage of Normal
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 5 (Week 213 Through Week 264)
Percentage of NormalCohort 4: PF-07055480 3*10^13 vg/kg
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 5 (Week 213 Through Week 264)24.87 ± 39.509
PrimaryGeometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 1 (Week 9 Through Week 53)

FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by one-stage clotting assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 1 included assessments from Week 9 through Week 53). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

Time frame:
Year 1 (Week 9 through Week 53)
Reported as:
Mean · Percentage of Normal
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 1 (Week 9 Through Week 53)
Percentage of NormalCohort 4: PF-07055480 3*10^13 vg/kg
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 1 (Week 9 Through Week 53)107.44 ± 72.860
PrimaryGeometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 2 (Week 54 Through Week 108)

FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by one-stage clotting assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 2 included assessments from Week 54 through Week 108). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

Time frame:
Year 2 (Week 54 through Week 108)
Reported as:
Mean · Percentage of Normal
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 2 (Week 54 Through Week 108)
Percentage of NormalCohort 4: PF-07055480 3*10^13 vg/kg
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 2 (Week 54 Through Week 108)58.55 ± 56.752
PrimaryGeometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 3 (Week 109 Through Week 160)

FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by one-stage clotting assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 3 included assessments from Week 109 through Week 160). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

Time frame:
Year 3 (Week 109 through Week 160)
Reported as:
Mean · Percentage of Normal
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 3 (Week 109 Through Week 160)
Percentage of NormalCohort 4: PF-07055480 3*10^13 vg/kg
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 3 (Week 109 Through Week 160)43.95 ± 57.466
PrimaryGeometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 4 (Week 161 Through Week 212)

FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by one-stage clotting assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 4 included assessments from Week 161 through Week 212). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

Time frame:
Year 4 (Week 161 through Week 212)
Reported as:
Mean · Percentage of Normal
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 4 (Week 161 Through Week 212)
Percentage of NormalCohort 4: PF-07055480 3*10^13 vg/kg
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 4 (Week 161 Through Week 212)39.60 ± 51.623
PrimaryGeometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 5 (Week 213 Through Week 264)

FVIII activity levels were analyzed in the central laboratory using chromogenic and one-stage clotting assay. In this outcome measure FVIII activity levels were assessed by one-stage clotting assay. As pre-specified, for each participant geometric mean of central FVIII activity levels was calculated of all eligible FVIII activity measurements for each yearly interval (for this outcome measure: Yearly Interval 5 included assessments from Week 213 through Week 264). Following this mean and standard deviation as summary statistics across all evaluable participants was calculated and is reported as data for this outcome measure.

Time frame:
Year 5 (Week 213 through Week 264)
Reported as:
Mean · Percentage of Normal
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 5 (Week 213 Through Week 264)
Percentage of NormalCohort 4: PF-07055480 3*10^13 vg/kg
Geometric Mean of Central FVIII Activity Levels for Cohort 4 by One-Stage Clotting Assay at Yearly Interval 5 (Week 213 Through Week 264)38.62 ± 51.844
SecondaryTotal Annualized Bleeding Rate (ABR)

Total ABR included both treated and untreated bleeding episodes. In this outcome measure total ABR for pre-screening and post-infusion are reported. Pre-screening total ABR was based on the total number of reported bleeding episodes during 12 months prior to screening visit as reported on CRF's Hemophilia A History page. Screening was 2 months before baseline. Post- infusion total ABR = number of all bleeding episodes starting 3 weeks after investigational product/ PF-07055480 (IP) infusion up to date of day before start of prophylaxis (or date of data cut or conclusion date)/ observation period in years, where observation period in years = date of day before start of prophylaxis or date of data cut or conclusion date - 3 weeks after date of IP infusion + 1)/365.25. For a participant who did not start prophylaxis the data cut date or conclusion date is used.

Time frame:
Pre-screening period: 12 months prior to screening; Post-infusion period: 3 weeks post-infusion up to date of day before start of prophylaxis or date of data cut or conclusion date, whichever was earlier (maximum up to 5 years)
Reported as:
Mean · Bleeds per year
Total Annualized Bleeding Rate (ABR)
Bleeds per yearCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Pre-screening total ABR3.50 ± 0.70714.00 ± 16.9711.50 ± 2.1218.80 ± 8.319
Post infusion total ABR -until prophylaxis is resumed7.93 ± 3.1393.07 ± 2.8983.24 ± 4.5861.53 ± 3.235
SecondaryTotal ABR by Severity

Total ABR include both treated and untreated bleeding episodes. In this outcome measure total ABR by severity for post-infusion period is reported. Severity was categorized as mild, moderate and severe. Post- infusion total ABR = number of all bleeding episodes starting 3 weeks after IP infusion up to date of day before start of prophylaxis (or date of data cut or conclusion date)/ observation period in years, where observation period in years = date of day before start of prophylaxis or date of data cut or conclusion date - 3 weeks after date of IP infusion + 1)/365.25. For a participant who did not start prophylaxis the data cut date or conclusion date is used.

Time frame:
Post-infusion period: 3 weeks post-infusion up to date of day before start of prophylaxis or date of data cut or conclusion date, whichever was earlier (maximum up to 5 years)
Reported as:
Mean · Bleeds per year
Total ABR by Severity
Bleeds per yearCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Mild7.93 ± 3.1390.87 ± 0.0810.17 ± 0.2411.22 ± 2.725
Moderate0.00 ± 0.0001.73 ± 2.1593.07 ± 4.3450.31 ± 0.528
Severe0.00 ± 0.0000.47 ± 0.6580.00 ± 0.0000.00 ± 0.000
SecondaryAnnualized Infusion Rate (AIR)

AIR was calculated and reported for pre-infusion and post-infusion. AIR for pre-infusion was calculated as, a) Excluding prophylaxis: number of FVIII replacement infusions for reasons other than prophylaxis prior to IP infusion/ (\[date of IP infusion - date of screening\] + 30)\] \*365.25, or b) number of FVIII replacement infusions for any reason prior to IP infusion/ (\[date of IP infusion - date of screening\] + 30)\] \*365.25. Screening was 2 months before baseline and baseline was approximately 1-week prior to IP infusion. AIR for post- infusion was calculated as: number of FVIII replacement infusions started at 3 weeks after IP infusion up to date of data cut or conclusion date/ number of days in the observation period for the participant in years, where observation period in years = date of data cut or conclusion date - 3 weeks after date of IP infusion + 1)/365.25.

Time frame:
Pre-infusion period: 30 days before screening up to pre-infusion (approximately up to 3.23 months); post-infusion period: 3 weeks post-infusion up to up to date of data cut or conclusion date (maximum up to 5 years)
Reported as:
Mean · Infusions per year
Annualized Infusion Rate (AIR)
Infusions per yearCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Pre-infusion AIR (Excluding Prophylaxis)0.00 ± 0.002.10 ± 2.970.00 ± 0.001.62 ± 2.26
Pre-infusion AIR100.43 ± 2.7481.15 ± 108.8287.93 ± 118.73120.86 ± 30.04
Post-infusion AIR58.95 ± 73.9732.79 ± 25.3229.03 ± 33.273.56 ± 7.55
SecondaryChange From Baseline in the EuroQol, 5 Dimensions, 5 Levels (EQ-5D-5L) Index Score at Weeks 12, 24 and 52; Months 24, 36, 48 and 60

EQ-5D-5L is a standardized measure of health status developed by the EuroQol Group. It measures 5 dimensions (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression) of health on a 5-point scale. Each dimension had 5 levels: 1= no problems, 2= slight problems, 3= moderate problems, 4= severe problems, and 5= extreme problems. EQ-5D-5L had 2 components: Index score and visual analogue scale (VAS). Index score was obtained, according to the health state defined by the 5 dimensions scores, from the Crosswalk Index value calculator and table lookup document under the target country population. A health state is defined by the combination of one level from each of the 5 dimensions. For this study, weights under the US population were used to obtain the Index score. Index score ranged between 0-1, where higher score indicates a better health state, and lower score indicate worse health state. Baseline was defined as the latest non-missing value before IP infusion.

Time frame:
Baseline; Weeks 12, 24, and 52; Months 24, 36, 48, and 60
Reported as:
Mean · Units on a scale
Change From Baseline in the EuroQol, 5 Dimensions, 5 Levels (EQ-5D-5L) Index Score at Weeks 12, 24 and 52; Months 24, 36, 48 and 60
Units on a scaleCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Baseline0.902 ± 0.1390.577 ± 0.2540.922 ± 0.1100.946 ± 0.122
Change at Week 120.011 ± 0.0160.2440.078 ± 0.1100.016 ± 0.035
Change at Week 24-0.033 ± 0.1290.317 ± 0.1030.078 ± 0.110-0.036 ± 0.080
Change at Week 52-0.165 ± 0.2660.294 ± 0.0710.000-0.002 ± 0.004
Change at Month 24———0.000 ± 0.000
Change at Month 36-0.099 ± 0.1400.334-0.2100.000 ± 0.000
Change at Month 48-0.0130.219-0.1970.000 ± 0.000
Change at Month 60——-0.087 ± 0.047-0.053 ± 0.105
SecondaryChange From Baseline in the EQ-5D-5L- VAS Score at Week 12, 24, 52 and Month 24, 36, 48, 60

EQ-5D-5L is a standardized measure of health status developed by the EuroQol Group. It measures 5 dimensions of health on a 5-point scale including mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is assessed with 5 levels: 1= no problems, 2= slight problems, 3= moderate problems, 4= severe problems, and 5= extreme problems. EQ-5D-5L had 2 components: Index score and VAS. EQ-5D-5L VAS: Participants were asked to indicate their current health status on a scale of 0 (worst health) to 100 (best imaginable health), higher scores signified better health status. Baseline was defined as the latest non-missing value before IP infusion.

Time frame:
Baseline; Weeks 12, 24, and 52; Months 24, 36, 48, and 60
Reported as:
Mean · Units on a scale
Change From Baseline in the EQ-5D-5L- VAS Score at Week 12, 24, 52 and Month 24, 36, 48, 60
Units on a scaleCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Baseline75.0 ± 7.0773.5 ± 9.1980.0 ± 14.1492.6 ± 10.67
Change at Week 124.5 ± 6.3610.05.0 ± 21.21-0.4 ± 5.32
Change at Week 2410.0 ± 7.0715.0 ± 0.0019.5 ± 14.85-3.0 ± 7.52
Change at Week 52-1.0 ± 12.7316.0 ± 1.41-10.0-4.2 ± 6.57
Change at Month 24———-4.0 ± 5.66
Change at Month 360.0 ± 0.08.00.0-0.7 ± 9.02
Change at Month 480.010.00.0-3.0 ± 3.00
Change at Month 60——4.5 ± 6.36-1.3 ± 9.07
SecondaryNumber of Participants With Positive FVIII Inhibitor Levels During the Study

Positive FVIII inhibitor was assessed using central laboratory using Nijmegen method of the Bethesda assay in an individual with no prior history of FVIII inhibitor. Inhibitor assay results \>0.6 Bethesda units (BU) were considered as positive. Positive results at any timepoint were considered, even if subsequent inhibitor assessment was negative.

Time frame:
Baseline (one week prior to IP infusion) up to 5 years post-infusion
Reported as:
Count of participants · Participants
Number of Participants With Positive FVIII Inhibitor Levels During the Study
ParticipantsCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Number of Participants With Positive FVIII Inhibitor Levels During the Study1000
SecondaryPeak Value of AAV2/6 (Adeno-associated Vector 2/6) Deoxyribonucleic Acid (DNA) in Plasma, Saliva, Semen, Stool and Urine

Peak (maximum) AAV2/6 vector DNA concentration (vg/mL) in plasma, saliva, semen, stool and urine were analyzed with quantitative real-time polymerase chain reaction (PCR). Participants must achieve 3 consecutive negative results for analysis for each sample.

Time frame:
All samples: Baseline, Day 7, Week 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52 and every month after Week 52 until Month 60 until 3 consecutive negative samples are obtained on a sample-type basis; additional for plasma at 12 hours post-infusion
Reported as:
Mean · Vector genome per milliliter (vg/mL)
Peak Value of AAV2/6 (Adeno-associated Vector 2/6) Deoxyribonucleic Acid (DNA) in Plasma, Saliva, Semen, Stool and Urine
Vector genome per milliliter (vg/mL)Cohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Plasma25680000 ± 26620000292600000 ± 3839000001787000000 ± 13900000003442000000 ± 2809000000
Saliva44550 ± 21710159500 ± 898701555000 ± 4172006972000 ± 5158000
Semen14600 ± NA36500 ± NA145500 ± 495099780 ± 151900
Stool604 ± 407.3—2490 ± 24612277 ± 2814
Urine———9697 ± 6166
SecondaryTime to Peak Value of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine

Time to peak (maximum) AAV2/6 vector DNA concentration (vg/mL) in plasma, saliva, urine, stool and semen were analyzed with quantitative real-time PCR. Participants must achieve 3 consecutive negative results for analysis for each sample; where negative suggests values under the limit of detection.

Time frame:
All samples: Baseline, Day 7, Week 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52 and every month after Week 52 until Month 60 until 3 consecutive negative samples are obtained on a sample-type basis; additional for plasma at 12 hours post-infusion
Reported as:
Mean · Days
Time to Peak Value of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine
DaysCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Plasma1.5 ± 0.711.0 ± 0.001.0 ± 0.001.4 ± 0.55
Saliva11.5 ± 4.957.5 ± 0.7112.0 ± 4.2411.8 ± 3.96
Semen8.015.011.0 ± 4.2414.4 ± 8.99
Stool8.0 ± 0.00—7.5 ± 0.7117.0 ± 10.32
Urine———9.7 ± 3.79
SecondaryTime to Undetectable (Negative) Value of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine

Time to undetectable (negative) value of AAV2/6 vector DNA concentration (vg/mL) in plasma, saliva, urine, stool and semen were analyzed with quantitative real-time PCR. Time to undetectable is defined as the number of days from IP infusion until the first of 3 consecutive specimens under the limit of detection (negative).

Time frame:
All samples: Baseline, Day 7, Week 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52 and every month after Week 52 until Month 60 until 3 consecutive negative samples are obtained on a sample-type basis; additional for plasma at 12 hours post-infusion
Reported as:
Mean · Days
Time to Undetectable (Negative) Value of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine
DaysCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Plasma22.0 ± 8.4915.0 ± 0.0056.5 ± 0.7184.7 ± 47.92
Saliva28.5 ± 0.7129.0 ± 0.0056.5 ± 0.7160.5 ± 17.62
Semen18.0 ± 14.1415.042.0 ± 18.3842.2 ± 27.51
Stool15.015.042.0 ± 18.3872.6 ± 62.10
Urine8.0 ± 0.007.5 ± 0.718.5 ± 0.7114.8 ± 8.17
SecondaryTime to Last of 3 Consecutive Negative Values of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine

Time to last of 3 consecutive negative value of AAV2/6 vector DNA concentration (vg/mL) in plasma, saliva, urine, stool and semen were analyzed with quantitative real-time PCR.

Time frame:
All samples: Baseline, Day 7, Week 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52 and every month after Week 52 until Month 60 until 3 consecutive negative samples are obtained on a sample-type basis; additional for plasma at 12 hours post-infusion
Reported as:
Mean · Days
Time to Last of 3 Consecutive Negative Values of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine
DaysCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Plasma71.0 ± 19.8057.0 ± 0.00113.5 ± 0.71166.7 ± 92.95
Saliva85.0 ± 0.0084.5 ± 0.71113.5 ± 0.71105.3 ± 27.60
Semen55.5 ± 40.3157.0115.5 ± 43.1395.4 ± 31.41
Stool56.084.0115.5 ± 43.13185.6 ± 164.77
Urine28.5 ± 0.7129.0 ± 0.0028.5 ± 0.7145.4 ± 14.99
SecondaryTime to Last Positive Value Prior to First of 3 Consecutive Negatives of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine

Time to last positive value prior to first of 3 consecutive negatives of AAV2/6 vector DNA concentration (vg/mL) in plasma, saliva, urine, stool and semen were analyzed with quantitative real-time PCR, where positive suggests values above the limit of detection.

Time frame:
All samples: Baseline, Day 7, Week 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52 and every month after Week 52 until Month 60 until 3 consecutive negative samples are obtained on a sample-type basis; additional for plasma at 12 hours post-infusion
Reported as:
Mean · Days
Time to Last Positive Value Prior to First of 3 Consecutive Negatives of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine
DaysCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Plasma11.5 ± 4.957.5 ± 0.7128.5 ± 0.7147.3 ± 31.75
Saliva15.5 ± 0.7115.0 ± 0.0028.5 ± 0.7135.5 ± 14.34
Semen15.0—21.5 ± 9.1918.6 ± 9.56
Stool8.0—21.5 ± 9.1921.4 ± 9.66
Urine———9.7 ± 3.79

Adverse events

Collected over From Baseline (1 week prior to infusion) up to 5 years post-infusion (approximately 5 Years). Non-serious events are listed at a 5% frequency threshold.

Adverse event summary by group
GroupDeathsSeriousOther
Cohort 1: PF-07055480 9*10^11 vg/kg0/2 (0%)0/2 (0%)2/2 (100%)
Cohort 2: PF-07055480 2*10^12 vg/kg0/2 (0%)2/2 (100%)2/2 (100%)
Cohort 3: PF-07055480 1*10^13 vg/kg0/2 (0%)0/2 (0%)2/2 (100%)
Cohort 4: PF-07055480 3*10^13 vg/kg0/5 (0%)1/5 (20%)5/5 (100%)
Most frequent serious events
Most frequent serious events
EventCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
CellulitisInfections and infestations0/21/20/20/5
Perineal cellulitisInfections and infestations0/21/20/20/5
Thermal burnInjury, poisoning and procedural complications0/21/20/20/5
PyrexiaGeneral disorders0/20/20/21/5
HypotensionVascular disorders0/20/20/21/5
Most frequent other events
Showing 10 of 53
Most frequent other events
EventCohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kg
Upper respiratory tract infectionInfections and infestations2/21/20/22/5
FallInjury, poisoning and procedural complications0/22/20/20/5
Alanine aminotransferase increasedInvestigations2/22/21/24/5
Aspartate aminotransferase increasedInvestigations2/21/21/23/5
ArthralgiaMusculoskeletal and connective tissue disorders0/20/22/20/5
PyrexiaGeneral disorders0/20/20/23/5
SplenomegalyBlood and lymphatic system disorders1/20/20/20/5
TinnitusEar and labyrinth disorders0/20/21/20/5
ConstipationGastrointestinal disorders0/21/20/20/5
Food poisoningGastrointestinal disorders1/20/20/20/5

Baseline characteristics

Age, Continuous
Age, Continuous(Years)Cohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kgTotal
Mean30.50 ± 9.19235.50 ± 16.26332.00 ± 1.41426.80 ± 6.30130 ± 7.937
Sex: Female, Male
Sex: Female, Male(Participants)Cohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kgTotal
Female00000
Male222511
Ethnicity (NIH/OMB)
Ethnicity (NIH/OMB)(Participants)Cohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kgTotal
Hispanic or Latino00022
Not Hispanic or Latino22239
Unknown or Not Reported00000
Race/Ethnicity, Customized
Race/Ethnicity, Customized(Participants)Cohort 1: PF-07055480 9*10^11 vg/kgCohort 2: PF-07055480 2*10^12 vg/kgCohort 3: PF-07055480 1*10^13 vg/kgCohort 4: PF-07055480 3*10^13 vg/kgTotal
Race — Asian01001
Race — White21249
Race — Other00011
08

Study locations

22 sites
  • Arkansas Children's Hospital
    Little Rock, Arkansas 72202, United States
  • City of Hope Medical Center
    Duarte, California 91010, United States
  • Midtown Ambulatory Care Center
    Sacramento, California 95817, United States
  • UC Davis Ambulatory Care Clinic
    Sacramento, California 95817, United States
  • UC Davis Comprehensive Cancer Center
    Sacramento, California 95817, United States
  • UC Davis CTSC Clinical Research Center
    Sacramento, California 95817, United States
  • UC Davis Hemophilia Treatment Center
    Sacramento, California 95817, United States
  • UC Davis Investigational Drug Services Pharmacy
    Sacramento, California 95817, United States
  • UC Davis Medical Center
    Sacramento, California 95817, United States
  • University of California, San Francisco - Investigational Drug Service (IDS) Pharmacy
    San Francisco, California 94143-0622, United States
  • University of California, San Francisco - Outpatient Hematology Clinic
    San Francisco, California 94143, United States
  • University of California, San Francisco -Moffitt Hospital
    San Francisco, California 94143, United States
  • University Of Miami Hospital and Clinics/Sylvester Comprehensive Cancer Center
    Miami, Florida 33136, United States
  • USF Health Morsani Center For Advanced Healthcare
    Tampa, Florida 33612, United States
  • Emory University School of Medicine
    Atlanta, Georgia 30322, United States
  • Hemophilia Center of Western PA
    Pittsburgh, Pennsylvania 15213, United States
  • UPMC Montefiore Clinical and Translational Research Center
    Pittsburgh, Pennsylvania 15213, United States
  • UPMC, Investigational Drug Service
    Pittsburgh, Pennsylvania 15213, United States
  • Vanderbilt University Medical Center Clinical Research Center
    Nashville, Tennessee 37212-8646, United States
  • Vanderbilt Hemostasis Treatment Clinic
    Nashville, Tennessee 37232, United States
  • Vanderbilt Hemostasis-Thrombosis Clinic
    Nashville, Tennessee 37232, United States
  • Washington Institute for Coagulation
    Seattle, Washington 98101, United States
09

References and documents

Publications

  • Leavitt AD, Konkle BA, Stine KC, Visweshwar N, Harrington TJ, Giermasz A, Arkin S, Fang A, Plonski F, Yver A, Ganne F, Agathon D, Resa MLA, Tseng LJ, Di Russo G, Cockroft BM, Cao L, Rupon J. Giroctocogene fitelparvovec gene therapy for severe hemophilia A: 104-week analysis of the phase 1/2 Alta study. Blood. 2024 Feb 29;143(9):796-806. doi: 10.1182/blood.2022018971. PubMed 37871576 ↗
  • Cao L, Ledeboer A, Pan Y, Lu Y, Meyer K. Clinical enrollment assay to detect preexisting neutralizing antibodies to AAV6 with demonstrated transgene expression in gene therapy trials. Gene Ther. 2023 Feb;30(1-2):150-159. doi: 10.1038/s41434-022-00353-2. Epub 2022 Jul 1. PubMed 35778500 ↗

Study documents

  • Study protocol · Apr 11, 2023
  • Statistical analysis plan · Feb 29, 2024

Documents are hosted by the registry — open the source record to download them.

Individual participant data

Plan to share: Yes — Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.

10

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Sep 30, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
11

Registry details

Key details

Study ID
NCT03061201
Lead sponsor
Pfizer
Responsible party
Sponsor
First posted
Feb 23, 2017
Start date
Jun 21, 2017
Primary completion
Jul 16, 2024
Completion
Jul 16, 2024
Results posted
Sep 30, 2025
Last update
Sep 30, 2025

Study contacts

Pfizer CT.gov Call Center
study director · Pfizer

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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