This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for A Study of Recombinant AAV2/6 Human Factor 8 Gene Therapy SB-525 (PF-07055480) in Subjects With Severe Hemophilia A (NCT03061201), a na phase 2 study. The primary outcome is Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03061201 |
| Phase | Phase 2 |
| Condition | Hemophilia A |
| Allocation | Not applicable (single group) |
| Design model | Sequential |
| Masking | None (open label) |
| Enrollment | 13 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pfizer |
| Results posted | Yes |
2. Clinical Question
Population
Adults with severe hemophilia A were enrolled. The registry describes the safety population as participants who enrolled and received any portion of the study intervention. The record does not give further eligibility details or demographic characteristics in the registry record.
Intervention
Participants received SB-525 (PF-07055480), a recombinant AAV2/6 human factor 8 gene therapy, as a single infusion. The study used sequential dose escalation across four cohorts, with dose levels listed as 9*10^11 vg/kg, 2*10^12 vg/kg, 1*10^13 vg/kg, and 3*10^13 vg/kg.
Comparator
There was no randomized control arm described. Allocation is recorded as NA, and the cohorts represent sequential dose levels rather than a like-for-like controlled comparison. The registry record does not report a placebo or standard-care comparator.
Primary question
The primary outcome counts participants with adverse events and serious adverse events over the period from baseline, defined as one week prior to infusion, up to five years post-infusion. The study also aimed to evaluate tolerability and the time-course profile of FVIII activity after dosing.
3. Trial Design
This was a phase 1/2, open-label, adaptive, dose-ranging study of SB-525 (PF-07055480) in adults with severe hemophilia A. Its stated purpose was to assess safety and tolerability and to evaluate the time-course profile of FVIII activity after dosing. The intervention was administered as a single infusion, and the record describes sequential dose escalation rather than randomized allocation.
The registry lists four dose cohorts: 9*10^11 vg/kg, 2*10^12 vg/kg, 1*10^13 vg/kg, and 3*10^13 vg/kg. The posted safety counts are reported separately for each cohort. Because these are sequential dose groups without a randomized control, differences between their counts should not be read as controlled estimates of dose effects. Cohort membership, follow-up, and other features could differ, and the registry record does not provide details that would resolve those concerns.
The record lists enrollment of 13 and a completed study. The study start date is 2017-06-21, and primary completion is recorded as 2024-07-16. The primary outcome timeframe extends from baseline, defined as one week prior to infusion, up to five years post-infusion. The registry record does not report whether every participant completed that full timeframe or how follow-up was handled in the posted safety counts.
Secondary outcomes included bleeding rates, infusion rates, quality-of-life scores, FVIII inhibitor levels, and AAV2/6 vector DNA measurements in several body samples. The registry record lists 32 outcome measures but does not report posted statistical analyses in the registry record. The absence of a randomized comparator means the study is best read as a safety and dose-ranging record, not as a controlled comparison of treatment strategies.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Cohort 1: PF-07055480 9*10^11 vg/kg | Cohort 2: PF-07055480 2*10^12 vg/kg | Cohort 3: PF-07055480 1*10^13 vg/kg | Cohort 4: PF-07055480 3*10^13 vg/kg |
|---|---|---|---|---|
| STARTED | 2 | 2 | 2 | 5 |
| COMPLETED | 1 | 1 | 2 | 4 |
| NOT COMPLETED | 1 | 1 | 0 | 1 |
Reasons for not completing this period:
| Reason | Cohort 1: PF-07055480 9*10^11 vg/kg | Cohort 2: PF-07055480 2*10^12 vg/kg | Cohort 3: PF-07055480 1*10^13 vg/kg | Cohort 4: PF-07055480 3*10^13 vg/kg |
|---|---|---|---|---|
| Participants Terminated at Month 36 | 0 | 1 | 0 | 1 |
| Lost to Follow-up | 1 | 0 | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Safety population included all participants enrolled in this study who received any portion of study intervention.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Cohort 1: PF-07055480 9*10^11 vg/kg | Cohort 2: PF-07055480 2*10^12 vg/kg | Cohort 3: PF-07055480 1*10^13 vg/kg | Cohort 4: PF-07055480 3*10^13 vg/kg | Total |
|---|---|---|---|---|---|---|
| Participants analysed | 2 | 2 | 2 | 5 | 11 | |
| Age, Continuous | Years | 30.50 (SD 9.192) | 35.50 (SD 16.263) | 32.00 (SD 1.414) | 26.80 (SD 6.301) | 30 (SD 7.937) |
| Sex: Female, Male: Female | Participants | 0 | 0 | 0 | 0 | 0 |
| Sex: Female, Male: Male | Participants | 2 | 2 | 2 | 5 | 11 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 0 | 2 | 2 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 2 | 2 | 2 | 3 | 9 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 | 0 | 0 |
| Race/Ethnicity, Customized: Race – Asian | Participants | 0 | 1 | 0 | 0 | 1 |
| Race/Ethnicity, Customized: Race – White | Participants | 2 | 1 | 2 | 4 | 9 |
| Race/Ethnicity, Customized: Race – Other | Participants | 0 | 0 | 0 | 1 | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs), measured over From Baseline (1 week prior to infusion) up to 5 years post-infusion (approximately 5 Years).
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of participants with adverse events (AEs) and serious adverse events (SAEs). It counts participants, rather than the total number of event episodes. An AE is defined as an untoward medical occurrence temporally associated with study intervention, whether or not it is considered related. The definition includes an unfavorable or unintended sign, symptom, disease, or abnormal laboratory finding that is temporally associated with the intervention.
An SAE is an AE meeting one or more specified seriousness criteria, including death, a life-threatening event, inpatient hospitalization or prolonged hospitalization, persistent or significant disability or incapacity, congenital anomaly or birth defect, or other situations per protocol. The registry states that AEs include both SAEs and non-serious AEs. This distinction matters: an SAE is categorized by seriousness criteria, not simply by whether investigators judged the event to have been caused by the intervention.
Participant counts are useful in an early safety study because they indicate how many people experienced at least one event in a category. They do not describe how many episodes occurred, how long events lasted, or whether events were considered treatment-related. The registry record gives a follow-up window from baseline, one week prior to infusion, up to five years post-infusion. The primary safety endpoint can therefore describe observed events during that stated period, but interpretation also depends on the extent and completeness of follow-up, which are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary safety results show that at least one participant in each dose cohort was recorded with an AE other than an SAE: Cohort 1 reports 2 of 2, Cohort 2 reports 2 of 2, Cohort 3 reports 2 of 2, and Cohort 4 reports 5 of 5. For SAEs, the counts are 0 of 2 in Cohort 1, 2 of 2 in Cohort 2, 0 of 2 in Cohort 3, and 1 of 5 in Cohort 4. The record reports no deaths in any cohort. These are descriptive counts within the listed cohorts.
The counts do not establish that the intervention caused the events. The AE definition includes occurrences that may or may not be considered related to study intervention. Nor do the counts compare SB-525 with an untreated or active control group: allocation is recorded as NA, and the cohorts are sequential dose levels. Differences in counts across cohorts cannot be interpreted as causal dose effects from these data alone.
The cohort sizes are small, so each participant contributes substantially to the displayed count. This limits precision: the observed count can change markedly with the experience of an individual participant, and the registry record does not give confidence intervals for these safety counts. The counts also do not convey event duration, recurrence, severity beyond the SAE distinction, or investigator attribution. Those details are not reported in the registry record.
The registry lists serious-event terms and percentages, including cellulitis, perineal cellulitis, thermal burn, pyrexia, and hypotension. These term percentages should not be mistaken for comparative risks across dose groups. The registry record does not give enough information in the registry record to determine the denominator or the event-counting convention for each listed term. They are best read as a set of reported terms, not as evidence about causality or a ranking of dose safety.
Overall, the posted results document participant-level safety observations in a small, sequential dose-ranging study. They are useful for describing what was recorded during the stated follow-up window. They do not, on their own, estimate the excess risk attributable to treatment, establish comparative safety, or support a precise estimate of how frequently a particular event would occur in a broader population.
9. Statistical Methods Explained
The registry presents participant counts for adverse events and serious adverse events, rather than an adjusted treatment-effect estimate. That choice is consistent with a descriptive safety outcome: it records whether participants experienced events in the stated categories. The record does not provide a statistical analysis plan, inferential test, confidence interval, or model for the primary safety outcome. Details of statistical methods are therefore not reported in the registry record.
What does a participant count represent?
A count of participants with an event indicates how many people in a cohort experienced at least one event in the category. It is not the same as a count of all event episodes. A participant with repeated occurrences may still contribute only once to a participant-level count, depending on the registry’s counting convention. The registry entries do not specify whether multiple episodes of the same event were counted separately in other outcome reporting.
Counts are easy to interpret descriptively, but their precision depends on how many participants are observed and how completely events are captured. With small cohorts, an individual participant has a large influence on the displayed count. A count of zero also does not prove that the event cannot occur; it means no participants in that recorded cohort were counted with the event in the posted results.
Why distinguish serious from non-serious events?
The registry defines serious events by criteria such as death, life-threatening status, hospitalization, persistent or significant disability, congenital anomaly, or other protocol-defined situations. This is a classification of seriousness. It does not mean that the event was necessarily caused by the intervention. The broader AE definition includes events temporally associated with study intervention regardless of whether investigators considered them related.
Because AEs include both serious and non-serious events, the categories are related but not interchangeable. Seriousness helps communicate the nature of an event’s consequences, while relatedness addresses a different question about attribution. The registry record does not provide event-level assessments of relatedness in the registry record. Therefore, the posted categories should not be recast as counts of events caused by SB-525.
Why does the study design matter?
Allocation is recorded as NA, and the study is described as open-label with sequential dose escalation. This means the reported cohorts are not randomized treatment and control groups. In a randomized comparison, allocation can help balance factors that influence outcomes, on average, between groups. In a sequential design, the groups may differ for reasons other than dose, including differences in timing, follow-up, or participant characteristics. The registry record does not report enough detail to assess such differences.
Without a concurrent control, the observed counts cannot isolate what would have happened without the intervention. Descriptive comparisons between dose cohorts can be informative for documenting events during dose escalation, but they are not equivalent to a controlled estimate of a dose-response relationship. No causal effect estimate or adjusted analysis is reported in the registry record.
What does precision mean for these counts?
Precision describes how narrowly the data constrain an estimate. A confidence interval, when reported, expresses a range of values compatible with the data under the assumptions of the statistical method. The registry entries do not include confidence intervals for the safety counts, so the numerical uncertainty around a population-level event rate is not quantified in the posted results.
Small cohort counts can be unstable: a different experience for a single participant could change the descriptive result. This is why raw counts should be read alongside the cohort sizes and design, rather than treated as exact estimates of risk in a wider population. No additional risk percentage or pooled figure is calculated; the cohort-specific counts are the direct basis for interpretation.
What is not reported?
The registry record does not report the statistical plan for the primary outcome, any planned interim analyses, a sample-size justification, or methods for handling missing safety observations. It also does not report whether event counts were adjusted for follow-up duration or how incomplete follow-up was handled. These details matter because participants may have different opportunities for events to be observed, especially when the stated timeframe extends up to five years post-infusion.
General statistical practice would consider the design, observation time, event definitions, and missingness when interpreting safety data. Those are general principles, not a description of methods confirmed for this study. In the absence of reported analysis details, the most defensible reading is descriptive: the posted data state how many participants in each cohort were counted with the listed categories, without establishing causation or comparative risk.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary safety outcome and numerous secondary outcomes, including bleeding rates, infusion rates, quality-of-life measures, FVIII inhibitor levels, and vector DNA measurements. Testing many outcomes can raise multiplicity concerns: when many statistical tests are conducted, the chance of at least one apparently notable result can increase. Whether that issue was addressed depends on the prespecified analysis plan and reporting approach. Multiplicity procedures are not reported in the registry record, and no statistical analyses are listed in the registry record for this account.
The registry entries also do not state how missing outcome data were handled, whether participants who did not complete follow-up were included in particular analyses, or whether any imputation methods were used. These details are important for outcomes assessed over time, including the primary safety timeframe from baseline up to five years post-infusion. Without information about follow-up completeness and missingness, the extent to which the posted counts reflect the full intended observation period cannot be determined from the registry record.
The primary endpoint description defines the safety population as enrolled participants who received any portion of study intervention. The record does not report how that population was operationalized for each outcome or whether any exclusions occurred. It also does not describe a separate intention-to-treat population, per-protocol population, or other analysis population in the registry record. These are not assumptions that can be filled in from the design label alone.
As a result, the safety counts can be interpreted as the registry’s reported participant counts, but the analysis population, missing-data handling, and any multiplicity strategy are not reported in the registry record. This limits evaluation of the precision and completeness of the findings and makes it inappropriate to infer an unreported statistical plan.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Cohort 1: PF-07055480 9*10^11 vg/kg | 0 | 2 | 0.0% |
| Cohort 2: PF-07055480 2*10^12 vg/kg | 2 | 2 | 100.0% |
| Cohort 3: PF-07055480 1*10^13 vg/kg | 0 | 2 | 0.0% |
| Cohort 4: PF-07055480 3*10^13 vg/kg | 1 | 5 | 20.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Cohort 1: PF-07055480 9*10^11 vg/kg | 0 of 2 |
| Cohort 2: PF-07055480 2*10^12 vg/kg | 0 of 2 |
| Cohort 3: PF-07055480 1*10^13 vg/kg | 0 of 2 |
| Cohort 4: PF-07055480 3*10^13 vg/kg | 0 of 5 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Cohort 1: PF-07055480 9*10^11 vg/kg | 2 of 2 |
| Cohort 2: PF-07055480 2*10^12 vg/kg | 2 of 2 |
| Cohort 3: PF-07055480 1*10^13 vg/kg | 2 of 2 |
| Cohort 4: PF-07055480 3*10^13 vg/kg | 5 of 5 |
Most frequent serious adverse event terms
| Event term | Organ system | Cohort 1: PF-07055480 9*10^11 vg/kg | Cohort 2: PF-07055480 2*10^12 vg/kg | Cohort 3: PF-07055480 1*10^13 vg/kg | Cohort 4: PF-07055480 3*10^13 vg/kg |
|---|---|---|---|---|---|
| Pyrexia | General disorders | 0 of 2 | 0 of 2 | 0 of 2 | 1 of 5 |
| Cellulitis | Infections and infestations | 0 of 2 | 1 of 2 | 0 of 2 | 0 of 5 |
| Perineal cellulitis | Infections and infestations | 0 of 2 | 1 of 2 | 0 of 2 | 0 of 5 |
| Thermal burn | Injury, poisoning and procedural complications | 0 of 2 | 1 of 2 | 0 of 2 | 0 of 5 |
| Hypotension | Vascular disorders | 0 of 2 | 0 of 2 | 0 of 2 | 1 of 5 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Cohort 1: PF-07055480 9*10^11 vg/kg | Cohort 2: PF-07055480 2*10^12 vg/kg | Cohort 3: PF-07055480 1*10^13 vg/kg | Cohort 4: PF-07055480 3*10^13 vg/kg |
|---|---|---|---|---|---|
| Alanine aminotransferase increased | Investigations | 2 of 2 | 2 of 2 | 1 of 2 | 4 of 5 |
| Aspartate aminotransferase increased | Investigations | 2 of 2 | 1 of 2 | 1 of 2 | 3 of 5 |
| Upper respiratory tract infection | Infections and infestations | 2 of 2 | 1 of 2 | 0 of 2 | 2 of 5 |
| Pyrexia | General disorders | 0 of 2 | 0 of 2 | 0 of 2 | 3 of 5 |
| Lymphopenia | Blood and lymphatic system disorders | 0 of 2 | 0 of 2 | 0 of 2 | 2 of 5 |
| Tachycardia | Cardiac disorders | 0 of 2 | 0 of 2 | 0 of 2 | 2 of 5 |
| Otitis media | Infections and infestations | 0 of 2 | 0 of 2 | 0 of 2 | 2 of 5 |
| Fall | Injury, poisoning and procedural complications | 0 of 2 | 2 of 2 | 0 of 2 | 0 of 5 |
| Skin laceration | Injury, poisoning and procedural complications | 1 of 2 | 1 of 2 | 0 of 2 | 0 of 5 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 0 of 2 | 0 of 2 | 2 of 2 | 0 of 5 |
Serious events with the highest arm-level rate: cellulitis (50.0%), perineal cellulitis (50.0%), thermal burn (50.0%), pyrexia (20.0%), hypotension (20.0%).
The registry reports serious adverse events by dose cohort. Cohort 1 reports 0 participants with an SAE among 2 at risk; Cohort 2 reports 2 among 2; Cohort 3 reports 0 among 2; and Cohort 4 reports 1 among 5. No deaths are reported in any cohort. These are participant counts over the registry’s stated safety period, from baseline up to five years post-infusion.
These figures should be read as descriptive observations, not as comparative estimates of safety. The study was open-label and sequential, with no randomized control group described. The cohorts are small, and the registry record does not provide confidence intervals, event-level details, or an adjustment for differences in observation time. The fact that an event meets the SAE definition does not by itself establish that it was caused by the intervention.
The registry also lists serious-event terms with percentages: cellulitis, perineal cellulitis, and thermal burn at 50.0%, and pyrexia and hypotension at 20.0%. The registry entries do not specify the denominator or counting convention for each term. Those percentages should therefore not be treated as incidence estimates or direct comparisons between dose cohorts. They describe terms recorded in the registry, while the SAE counts give the cohort-level participant counts.
12. What the Result Does, and Does Not, Mean
The posted results provide a record of adverse events observed during a study of SB-525 in adults with severe hemophilia A. They show that non-serious AE counts were reported for participants in every cohort, while SAE counts varied across the listed cohorts. The registry reports no deaths in any cohort. These observations are relevant to describing the study’s safety experience, but they are not a controlled estimate of treatment effect.
The results do not establish that SB-525 caused any particular event. The AE definition includes events whether or not considered related to the intervention, and the registry entries do not give event-level relatedness assessments. The data also do not show how the same participants would have fared without the intervention, because a randomized control group is not described.
The results do not establish that one dose is safer than another. Sequential cohorts are not randomized like-for-like groups, and the registry record does not provide analyses that adjust for differences between them. The counts also do not establish the frequency of events in a broader population. Cohort sizes are small, and no confidence intervals for the participant counts are reported in the registry record.
Nor do the posted SAE counts describe every aspect of safety. They do not, by themselves, communicate event duration, recurrence, severity among non-serious AEs, time to event, or the completeness of follow-up. The record’s stated timeframe extends up to five years post-infusion, but completion of that full period for each participant is not reported in the registry record.
In short, the data document observed participant counts in a phase 1/2 dose-ranging study. They can support a careful description of what the registry recorded, but they cannot substitute for a controlled comparison or answer questions that require unreported follow-up, event-level, or statistical-analysis details.
13. Why This Trial Matters Statistically
This study is statistically informative as an example of how early dose-ranging safety evidence differs from a randomized comparison. Its open-label, sequential design organizes participants by dose cohort and records adverse events during follow-up. That design can describe observations during dose escalation, but it does not provide the balancing features of random allocation or a concurrent control group.
The primary endpoint also illustrates a useful distinction between event counts and participant counts. Counting participants with an event communicates how many people were affected by at least one event in the category, while it does not reveal the total number of episodes or the duration of those events. The registry’s separate serious and non-serious AE reporting categories further demonstrate that event classification and causal attribution are different questions.
The small cohort counts make transparent reporting especially important. A single participant can have substantial influence on a cohort’s displayed count, and the absence of confidence intervals means readers cannot directly see an uncertainty range around a population-level estimate. The registry also lists serious-event terms as percentages, but the denominator and counting convention for those terms are not reported in the registry record. This is a reminder that percentages need their underlying denominator and definition to be interpretable.
Finally, long-term safety outcomes depend on the observation period and follow-up completeness. Although the stated timeframe extends up to five years post-infusion, the registry entries do not describe completion or missing-data methods. The study therefore highlights a central statistical principle: design, outcome definition, denominators, and follow-up determine what a safety result can support. The posted counts are useful as descriptive evidence, while broader comparative claims require information and designs not reported.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The principal limitation is the absence of a randomized control group. Allocation is recorded as NA, and the dose cohorts were sequential. Consequently, cohort differences cannot be attributed to dose alone, and the results do not estimate safety relative to an untreated or active comparator.
The cohort sizes are small, which limits precision and makes the participant counts sensitive to individual observations. The registry entries do not include confidence intervals or other uncertainty estimates for the safety outcomes. Counts of participants with events also do not communicate recurrence, event duration, or the number of episodes.
The AE definition includes events whether or not considered related to study intervention. Event-level relatedness assessments are not reported in the registry record. The SAE term percentages are listed without their denominator or counting convention, limiting their interpretation as rates. The registry record also does not report how follow-up duration differed across participants or whether all participants were observed through the full stated timeframe.
Other details that would help assess the findings are not reported in the registry record: the statistical plan, sample-size justification, interim analyses, missing-data methods, and analysis populations beyond the safety-population description. The registry entries also do not provide event-level descriptions or explain how the secondary outcomes were analyzed. These gaps limit conclusions about precision, completeness, multiplicity, and comparative effects. The appropriate interpretation remains descriptive of the counts posted for this sequential dose-ranging study.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study of Recombinant AAV2/6 Human Factor 8 Gene Therapy SB-525 (PF-07055480) in Subjects With Severe Hemophilia A — NCT03061201.
- Registry record last updated 2025-09-30; status last verified 2025-09.
- Results first posted 2025-09-30.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT03061201 is a completed phase 1/2, open-label, adaptive, dose-ranging study of SB-525 (PF-07055480) in adults with severe hemophilia A. The registry describes a single-infusion intervention administered through sequential dose escalation. Enrollment is listed as 13, with study start on 2017-06-21 and primary completion on 2024-07-16.
The primary outcome counts participants with adverse events and serious adverse events from baseline, one week prior to infusion, up to five years post-infusion. The posted cohort counts report non-serious AEs and SAEs separately, with no deaths reported in any cohort. The study has no randomized control group described, so the cohort results are descriptive rather than controlled comparisons.
Secondary outcomes include bleeding and infusion rates, quality-of-life measures, FVIII inhibitor levels, and AAV2/6 vector DNA measures. The registry record lists 32 outcome measures, but the statistical plan, missing-data methods, and posted analyses are not reported in the registry record.