Phase 2
N=11
A Study of Recombinant AAV2/6 Human Factor 8 Gene Therapy SB-525 (PF-07055480) in Subjects With Severe Hemophilia A
Hemophilia A
Bottom Line
View on ClinicalTrials.gov: NCT03061201 ↗Enrolled (actual)
11
Serious AEs
27.3%
Results posted
Sep 2025
Primary outcome: Primary: Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs) — 2; 2; 2; 5 Participants
Study Design & Population
- Study type
- Interventional
- Phase
- Phase 2
- Interventions
- SB-525 (PF-07055480) (Biological)
- Age
- Adult, Older Adult · 18+ yrs
- Sex
- Male
- Sponsor
- Pfizer
- Primary completion
- Jul 2024
Outcome Measures
| Outcome | Result | p-value |
|---|---|---|
| PRIMARY Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs) |
2; 2; 2; 5; 0; 2 | — |
| PRIMARY Central FVIII Activity Levels by Chromogenic Assay at Year 1 (Week 52) |
0.90; 11.90; 42.60 | — |
| PRIMARY Central FVIII Activity Levels by Chromogenic Assay at Year 2 (Week 104) |
19.30; 8.25; 25.44 | — |
| PRIMARY Central FVIII Activity Levels by Chromogenic Assay at Year 3 (Week 156) |
0.90; 4.40; 25.46 | — |
| PRIMARY Central FVIII Activity Levels by Chromogenic Assay at Year 4 (Week 208) |
0.90; 3.20; 26.55 | — |
| PRIMARY Central FVIII Activity Levels by Chromogenic Assay at Year 5 (Week 260) |
0.90; 3.30; 23.55 | — |
| PRIMARY Central FVIII Activity Levels by One-Stage Clotting Assay at Year 1 (Week 52) |
1.75; 19.90; 66.37 | — |
| PRIMARY Central FVIII Activity Levels by One-Stage Clotting Assay at Year 2 (Week 104) |
19.00; 13.95; 38.86 | — |
| PRIMARY Central FVIII Activity Levels by One-Stage Clotting Assay at Year 3 (Week 156) |
3.30; 5.70; 40.52 | — |
| PRIMARY Central FVIII Activity Levels by One-Stage Clotting Assay at Year 4 (Week 208) |
4.80; 13.80; 38.78 | — |
| PRIMARY Central FVIII Activity Levels by One-Stage Clotting Assay at Year 5 (Week 260) |
4.00; 6.10; 41.00 | — |
| PRIMARY Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 1 (Week 9 Through Week 53) |
67.89 | — |
| PRIMARY Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 2 (Week 54 Through Week 108) |
40.38 | — |
| PRIMARY Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 3 (Week 109 Through Week 160) |
27.66 | — |
| PRIMARY Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 4 (Week 161 Through Week 212) |
24.31 | — |
| PRIMARY Geometric Mean of Central FVIII Activity Levels for Cohort 4 by Chromogenic Assay at Yearly Interval 5 (Week 213 Through Week 264) |
24.87 | — |
| PRIMARY 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 | — |
| PRIMARY 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 | — |
| PRIMARY 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 | — |
| PRIMARY 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 | — |
| PRIMARY 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 | — |
| SECONDARY Total Annualized Bleeding Rate (ABR) |
3.50; 14.00; 1.50; 8.80; 7.93; 3.07 | — |
| SECONDARY Total ABR by Severity |
7.93; 0.87; 0.17; 1.22; 0.00; 1.73 | — |
| SECONDARY Annualized Infusion Rate (AIR) |
0.00; 2.10; 0.00; 1.62; 100.43; 81.15 | — |
| SECONDARY 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 |
0.902; 0.577; 0.922; 0.946; 0.011; 0.244 | — |
| SECONDARY Change From Baseline in the EQ-5D-5L- VAS Score at Week 12, 24, 52 and Month 24, 36, 48, 60 |
75.0; 73.5; 80.0; 92.6; 4.5; 10.0 | — |
| SECONDARY Number of Participants With Positive FVIII Inhibitor Levels During the Study |
1; 0; 0; 0 | — |
| SECONDARY Peak Value of AAV2/6 (Adeno-associated Vector 2/6) Deoxyribonucleic Acid (DNA) in Plasma, Saliva, Semen, Stool and Urine |
25680000; 292600000; 1787000000; 3442000000; 44550; 159500 | — |
| SECONDARY Time to Peak Value of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine |
1.5; 1.0; 1.0; 1.4; 11.5; 7.5 | — |
| SECONDARY Time to Undetectable (Negative) Value of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine |
22.0; 15.0; 56.5; 84.7; 28.5; 29.0 | — |
| SECONDARY Time to Last of 3 Consecutive Negative Values of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine |
71.0; 57.0; 113.5; 166.7; 85.0; 84.5 | — |
| SECONDARY Time to Last Positive Value Prior to First of 3 Consecutive Negatives of AAV2/6 Vector DNA in Plasma, Saliva, Semen, Stool and Urine |
11.5; 7.5; 28.5; 47.3; 15.5; 15.0 | — |
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)
Eligibility Criteria
Inclusion Criteria
- Male ≥18 years of age
- Severe hemophilia A (past evidence of circulating FVIII activity of grade 2 liver fibrosis on elastography for subjects with history of treated Hepatitis C or suspicion of chronic liver disease
Data sourced from ClinicalTrials.gov (NCT03061201). Outcome figures and adverse-event rates are extracted automatically from the registry's posted results and are provided for clinician reference, not as a substitute for the primary publication.