A Phase 2 Extension Study To Enroll Subjects Who Were Enrolled In B5301001 Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Phase 2 Extension Study To Enroll Subjects Who Were Enrolled In B5301001 Study (NCT02205476), a non-randomized phase 2 study. The primary outcome is Physician Scar Assessment Using Complete Patient and Observer Scar Assessment Scale (POSAS) at Part A Visit.

2. Clinical Question

The clinical question is framed as a long-term assessment after earlier surgery and treatment, rather than as a randomized comparison of PF-06473871 with an independent control. The study was open-label, so physicians and participants were not masked to treatment assignment. These design features matter when interpreting a subjective assessment: ratings can reflect the evaluator’s judgment, and comparisons between groups may also reflect differences in their prior treatment history.

The registry describes a two-part study intended to assess long-term efficacy and evaluate safety of retreatment. It does not provide numerical findings for the primary endpoint or the listed secondary outcomes. Thus, the question can be described from the planned endpoint and design, but the record does not establish the observed scar ratings or the precision of any treatment contrast.

3. Trial Design

This was a Phase 2, multicenter, two-part, open-label extension study. It enrolled participants from B5301001 and was intended to assess long-term efficacy following initial scar revision surgery and treatment with PF-06473871, as well as the safety of retreatment. The registry lists the study as non-randomized, with no masking and a parallel-group model. Enrollment was 10. The study status is terminated.

Group 1 and Group 2 were described by the number of doses consistent with the participants’ groups in B5301001: 4 doses for Group 1 and 3 doses for Group 2. The record labels the groups PF-06473871/Placebo regimens, but it does not establish that these groups are exchangeable or form a randomized control comparison. The stated design limitation is explicit: the arms are not a like-for-like control comparison.

The primary endpoint was assessed at Part A Visit, at 52 weeks after initial scar revision surgery in B5301001. It was the physician’s complete POSAS assessment of the scar, summarized as a mean with standard deviation. The listed secondary outcomes include patient global assessment using POSAS, symptom and appearance domains from the Patient-Reported Scar Evaluation Questionnaire, and a physician and participant photoguide assessment.

The record gives a start date of 2014-12 and a primary completion date of 2015-01. The reason for termination, details of recruitment and follow-up, and the planned sample-size justification are not reported in the registry record. The record also does not describe the timing or conduct of each study part in enough detail to reconstruct the full visit schedule.

Because the study was non-randomized and open-label, its design supports describing the enrolled groups and their observed assessments, but does not by itself establish a causal treatment effect. The registry record contains no outcome analyses with which to quantify even a descriptive group difference.

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.

Before assignment: Participants who completed part A of the study had the option to obtain scar revision surgery with PF-06473871 in part B of the study. No participant entered into part B due to premature termination of the study.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Enrolled analysis set included all participants who signed an informed consent and for whom data were collected for Part A of this trial.

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.

Population: Enrolled analysis set included all participants who signed an informed consent and for whom data were collected for Part A of this trial.

6. Primary Endpoint

The registry lists the primary outcome as Physician Scar Assessment Using Complete Patient and Observer Scar Assessment Scale (POSAS) at Part A Visit, measured over 52 weeks after initial scar revision surgery in study B5301001.

The primary endpoint was the physician’s complete Patient and Observer Scar Assessment Scale (POSAS) assessment at Part A Visit. It was scheduled for 52 weeks after initial scar revision surgery in B5301001 and was defined as a continuous measure in units on the scale. The outcome was to be summarized by a mean and standard deviation.

The physician rated vascularity, pigmentation, thickness, relief, pliability, surface area, and overall opinion. Each item was scored on a 10-point scale from 1 for normal skin to 10 for the worst scar imaginable. The complete assessment combines judgments across several visible and tactile aspects of the scar, giving a structured way to describe scar appearance and characteristics rather than relying on an unstructured overall comment.

In general, a continuous scale can capture variation across participants and can be summarized using a mean and standard deviation. The mean describes the average recorded score, while the standard deviation describes how spread out individual scores are around that average. Neither statistic alone indicates how precise an estimate is; uncertainty about the mean or a comparison would require additional information, such as a confidence interval.

The registry defines the measure and its timing but reports no primary endpoint mean, standard deviation, confidence interval, or group comparison. Consequently, the record does not show the observed scar assessment or its precision.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a mean of a continuous measure, with standard deviation as its dispersion summary. It does not report an analysis model, a test statistic, a confidence interval, or an adjusted estimate. The methods that can be discussed are therefore limited to the endpoint definition, the stated group structure, and the general interpretation of continuous outcomes.

What does a mean describe?

For a continuous measure, the mean is the arithmetic average of recorded values in the analysis population. It gives a compact description of the group’s central level on the scale. The standard deviation describes the spread of individual observations around that mean. A small or large standard deviation is meaningful only in relation to the scale and the distribution of the observations; the registry does not provide either the observed standard deviation or the participant-level distribution for this endpoint.

A mean and standard deviation describe the observed data, not by themselves the precision of an estimate or the strength of evidence for a treatment contrast. A confidence interval is a general statistical way to express uncertainty around an estimate. Its width depends on the amount and variability of data and on the method used. No confidence interval is reported for the primary endpoint in this record, so its precision cannot be assessed.

Why does the scale matter?

The physician POSAS assessment uses scores from 1, representing normal skin, to 10, representing the worst scar imaginable. Higher and lower values thus have an ordered interpretation in the scale description. The endpoint covers vascularity, pigmentation, thickness, relief, pliability, surface area, and overall opinion. Because the record defines the outcome as a mean, it summarizes ratings across the analysis population; it does not show how participants’ individual item scores were distributed or whether one aspect of the scar accounted for more of the overall pattern.

In general, treating a scale score as continuous allows summaries such as a mean and standard deviation. That choice can be useful for describing average scores, but the interpretation remains tied to the scoring system and the way the measure was collected. The registry does not describe any checks of score distributions, assessor consistency, or alternative analyses.

What can a group comparison establish?

In a randomized comparison, random allocation is intended to make groups comparable on average at the start of the study. Here, allocation was non-randomized, and the registry warns that the arms are not a like-for-like control comparison. Group differences could therefore be associated with prior characteristics, treatment history, or other factors in addition to the intervention. In general, statistical adjustment can address measured differences under specified assumptions, but it cannot automatically remove unmeasured confounding. Whether an adjusted method was planned or used is not reported in the registry record.

The record describes parallel groups and no masking. It does not report the number of participants with endpoint data in each group, the group-specific means, or any contrast estimate. Without those details, neither a descriptive contrast nor an inferential comparison can be reconstructed.

What do the planning assumptions mean?

The study record describes a planning illustration based on an observed effect, using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The illustration considers detecting a stated fraction of the observed effect. In general, a sample-size calculation translates assumptions about the target effect, variability, significance level, and desired power into a planning quantity. It is not a count of observed participants or evidence that a study had a particular probability of detecting an effect after it was completed.

For a continuous outcome, assumptions about the effect and variability are important to such planning. The registry record does not report the primary endpoint estimate or the numerical planning outputs in the registry record for interpretation. The study’s enrollment of 10 should not be confused with a sample-size target or with the number required by any planning illustration. Sample-size illustrations are planning quantities, not observed power.

In general, over-dispersion means that the observed variability is greater than a model assumes. If variability is understated in planning or analysis, uncertainty may be understated and a study may be less informative than anticipated. The registry does not report a dispersion comparison or any specific concern about over-dispersion for this endpoint; this is a general statistical consideration, not a finding about this study.

No recalculated estimate is reported. Without posted group summaries, there is no basis for an independent unadjusted calculation. The statistical interpretation should therefore remain descriptive of the registry’s design and endpoint rather than inferential about treatment effects.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists eight outcome measures, including the primary physician POSAS assessment and secondary assessments of patient global opinion, patient-reported symptoms and appearance, and physician and participant photoguide ratings. It lists 0 analyses. No numerical results or inferential tests are reported for the primary or secondary outcomes.

Multiplicity arises in general when several outcomes or comparisons are tested: the more tests considered, the greater the chance that at least one appears notable by chance if each is interpreted without an appropriate strategy. A statistical plan may specify a primary outcome, a hierarchy, or an adjustment method. Whether the study used a multiplicity strategy is not reported in the registry record. The list of outcomes alone does not establish which were formally tested or how their results were to be interpreted.

The record defines the primary enrolled analysis set as participants who signed informed consent and for whom Part A data were collected. It does not report the number meeting that definition, the endpoint-specific denominator, or how participants with unavailable assessments were handled. Missing-data methods, imputation, sensitivity analyses, and reasons for missing assessments are not reported in the registry record.

These omissions matter because the number and pattern of observed assessments can affect both the estimated mean and its uncertainty. If participants with missing assessments differ from those with observed scores, a summary limited to available data may not represent the full enrolled group. This is a general concern, not a claim that such a pattern occurred in this study. Without endpoint availability and missing-data details, the completeness and representativeness of the primary assessment cannot be evaluated.

11. What the Result Does, and Does Not, Mean

The record establishes that a Phase 2 extension study was designed to assess physician-rated scar outcomes at 52 weeks after initial scar revision surgery in B5301001 and to evaluate safety of retreatment with PF-06473871. It identifies the primary measure, its scale, the analysis-set definition, and the non-randomized, open-label group structure. It does not provide numerical endpoint results or analyses.

Accordingly, the record does not show the average physician POSAS assessment, the spread of scores, or the precision of an estimate. It also does not show whether Group 1 and Group 2 differed in their assessments. Since allocation was non-randomized and the arms are not a like-for-like control comparison, even a reported difference would need careful interpretation and would not, on its own, establish that treatment caused the difference.

The record also does not support a conclusion about safety. The adverse-event entries show zero participants at risk and zero affected in each group, with deaths marked null. Those fields are not interpretable as evidence that no events occurred, because the record reports no participants at risk in the groups. Detailed safety findings and an explanation of the entries are not reported.

In general, an endpoint definition describes what a study intended to measure; it is not itself an outcome. The fact that a study was terminated does not identify the reason for termination, indicate whether all assessments were completed, or explain the absence of analyses. Those details are not reported in the registry record.

The appropriate statistical conclusion is limited: the registry describes a planned long-term assessment and its design, but does not provide the results needed to judge observed outcomes, uncertainty, or comparative effects. This is not evidence for or against a treatment effect; the relevant estimates are simply not reported in the registry record.

12. Why This Trial Matters Statistically

This study illustrates how an extension design can address a different question from an initial treatment trial. The primary endpoint was intended to describe physician-rated scar status at 52 weeks after surgery in the earlier B5301001 study, while the broader study summary also identifies safety of retreatment as an objective. Long-term assessment and retreatment safety are distinct aims, and the record’s outcome definitions should be interpreted in that context.

It also highlights why group labels do not automatically imply a controlled comparison. The registry identifies non-randomized allocation and explicitly cautions that the arms are not a like-for-like control comparison. Because the groups reflect different dose histories in B5301001, their comparison would require attention to baseline and treatment-history differences. The design description alone cannot establish exchangeability.

The primary outcome is an assessor-rated scale with several scar characteristics. This provides structured measurement, but an open-label design leaves potential for ratings to be influenced by knowledge of treatment or history. That is a general risk of unmasked subjective assessment, not proof of bias in the study.

Finally, the record demonstrates the difference between a defined endpoint and an analyzable result. It reports the measurement framework and an overall enrollment of 10, but lists 0 analyses and does not report endpoint estimates, participant counts with data, or uncertainty. Without those elements, readers cannot evaluate magnitude or precision, and a planning illustration cannot substitute for observed findings.

13. 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 main limitation for statistical interpretation is that the registry record contains no numerical primary outcome results or analyses. Means, standard deviations, group-specific denominators, confidence intervals, and comparisons are not reported. Therefore, the size and precision of any observed scar assessment cannot be evaluated.

The overall enrollment of 10 does not reveal how many participants contributed to the primary endpoint. The record defines the analysis set but does not give its size, the number with missing assessments, or how incomplete data were handled. The reason for termination and whether planned assessments were completed are also not reported in the registry record.

The study was non-randomized and open-label. Its two groups were associated with different dose histories in B5301001, and the registry warns that the arms are not a like-for-like control comparison. These features limit causal interpretation of any between-group contrast and leave open the possibility of confounding or observer influence. The record does not describe adjustment methods, assessor procedures, or sensitivity analyses.

Safety interpretation is also constrained. The adverse-event fields report zero participants at risk and zero affected in each group, and deaths are marked null. These entries do not provide an interpretable estimate of event frequency. Detailed safety data and an explanation of the reporting fields are not reported in the registry record.

Although the record lists eight outcome measures, it reports 0 analyses and does not specify a multiplicity strategy or missing-data approach. These omissions prevent assessment of outcome selection, inferential control, and robustness.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: A Phase 2 Extension Study To Enroll Subjects Who Were Enrolled In B5301001 Study — NCT02205476.
• Registry record last updated 2016-01-28; status last verified 2015-12.
• Results first posted 2016-01-28.
• 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.

17. Record Summary

NCT02205476 is a Phase 2, multicenter, two-part, open-label extension study of PF-06473871 in adults enrolled in B5301001. The study concerned hypertrophic scars resulting from prior breast scar revision surgery and included a long-term assessment after surgery and an evaluation of retreatment safety. It was non-randomized, used parallel groups, enrolled 10, and is listed as terminated.

The primary outcome was the physician’s complete POSAS assessment at Part A Visit, 52 weeks after initial scar revision surgery in B5301001. The registry defines the scale and the enrolled analysis set, but lists 0 analyses and reports no numerical primary or secondary outcome results. Group comparisons are not like-for-like controls. Endpoint-specific sample sizes, missing-data handling, the reason for termination, and detailed safety results are not reported in the registry record.