Study of Angiogenic Cell Therapy for Progressive Pulmonary Hypertension: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Angiogenic Cell Therapy for Progressive Pulmonary Hypertension (NCT03001414), a randomized phase 2, phase 3 study. The primary outcome is Change in 6 Minute Walk Distance (6MWD) From Baseline.

2. Clinical Question

The trial was registered as a Phase 2 and Phase 3 study, with randomized allocation, triple masking, and a crossover model. Its stated aim was to study the efficacy and safety of repeated monthly dosing of autologous eNOS-enhanced cells in patients with symptomatic severe disease on existing PAH-targeted medical therapy. The registry status is terminated. The record does not report why the trial was terminated or whether the planned enrollment was reached.

3. Trial Design

The registry describes a randomized, triple-masked crossover trial with three intervention schedules. The first schedule began with 4 monthly intravenous injections of placebo during Course 1, followed by 4 monthly injections of autologous endothelial progenitor cells transfected with human eNOS during Course 2. The cell therapy amount for that course was described as a total of 80 million cells. The second schedule reversed the order: cell therapy during Course 1, followed by placebo during Course 2. The third schedule used cell therapy in both courses, with a total of 160 million cells across the courses. The record does not explain how the third schedule was incorporated into the primary comparison.

The primary endpoint was assessed at baseline and 6 months. The reported comparison is labeled as placebo during the first 6 months versus Arms 2 and 3 during the first 6 months. This is a first-period comparison in the registry's arm labels; it should not be treated as a complete analysis of every treatment sequence or of the crossover structure. The statistical handling of period effects, carryover, sequence effects, and within-participant correlation is not reported in the registry record.

The registry lists enrollment of 22, while the primary outcome groups have n=5 and n=7. These are the group sizes attached to the posted outcome results, not a complete account of participant flow. Reasons for the difference between enrollment and the outcome denominators, the number of participants assigned to each schedule, and any exclusions are not reported in the registry record. The registry status is terminated, and the available record does not explain the termination or specify whether all planned trial procedures were completed.

The design includes both placebo-controlled sequences and a sequence receiving cell therapy during both courses. That structure can address more than an initial treatment-versus-placebo contrast, but interpreting all comparisons requires clarity about timing and the analysis model. The record lists secondary outcomes involving six-minute walk distance, pulmonary vascular resistance, and quality-of-life measures, including an incremental comparison of 8 versus 4 doses. Details of how these secondary outcomes were incorporated into the main analysis are not reported.

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: Of 22 enrolled participants, 12 met the required inclusion criteria and were randomized to receive treatment with the study product.

Overall Study

Analysis population for the primary outcome, as defined in the registry: All participants for whom the 6MWD test was completed at baseline and 6 months.

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.

6. Primary Endpoint

The registry lists the primary outcome as Change in 6 Minute Walk Distance (6MWD) From Baseline, measured over Baseline, 6 months.

The primary endpoint was change in six-minute walk distance, measured in meters, from baseline to 6 months. The record defines change as the distance walked at 6 months minus the distance walked at baseline. A positive change therefore denotes a greater measured distance at follow-up than at baseline, while a negative change would denote a shorter distance. The registry reports group means and standard deviations for this continuous measure.

In general, six-minute walk distance is a functional measure: it records the distance a participant can walk during a standardized timed test. In a clinical trial, measuring change from baseline helps describe how the outcome differs over time rather than relying only on follow-up values. The baseline-to-follow-up change can be compared between randomized groups, although the interpretation depends on the population included and the statistical method used.

The registry defines the primary outcome population as all participants for whom the test was completed at both baseline and 6 months. That definition makes completion of both measurements central to inclusion in the reported outcome. The record does not report how many eligible participants lacked one of these measurements or why any measurements were unavailable. The primary endpoint is therefore a measure of change among the stated completer population, and the posted results should not be assumed to describe participants without both assessments.

The record also lists change in six-minute walk distance among the secondary outcomes, alongside pulmonary vascular resistance and quality-of-life measures. Those entries suggest that the trial assessed several dimensions, but the registry does not report a complete rationale for the endpoint hierarchy or how the secondary outcomes were used to support the primary comparison.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry reports an ANOVA analysis for the primary continuous endpoint and two Wilcoxon (Mann-Whitney) analyses. The primary endpoint is change in six-minute walk distance from baseline to 6 months, and the ANOVA entry reports a mean difference in final values. The listed groups are Arm 1, placebo during the first 6 months, and Arms 2 and 3 during the first 6 months.

What does the mean difference describe?

A mean difference expresses the separation between group averages on the measured scale. Because the endpoint is measured in meters, the reported estimate is interpretable in meters. The registry reports group mean changes of 22.3 and 36.0 meters and an ANOVA mean difference of 13.70 meters. These are posted summary statistics; they are not a new calculation of an adjusted effect. The record does not describe covariate adjustment or provide an adjusted estimate.

How should the confidence interval be read?

In general, a confidence interval communicates uncertainty around an estimated effect under the assumptions of the statistical method. A narrower interval indicates greater precision than a wider interval, while an interval that includes zero means the data are compatible with no group difference as well as with effects in either direction. The ANOVA interval runs from -20.08 to 47.48 meters. It is wide and crosses zero, so the point estimate should not be interpreted in isolation. The record does not provide a clinically important difference threshold against which to judge the interval.

What does the p-value say?

In general, a p-value describes how unusual results at least as incompatible with a specified null hypothesis would be if that hypothesis and the model assumptions held. It is not a measure of effect size, a probability that the null is true, or a direct measure of clinical importance. The ANOVA p-value is 0.42. That value does not supply evidence of a statistically significant difference under a conventional significance threshold, but it does not establish equivalence or rule out an important difference. No equivalence or non-inferiority margin is reported in the registry record.

Why are two methods listed?

ANOVA is a model-based method commonly used to compare means, with its interpretation depending on assumptions about the outcome and the model. The Wilcoxon (Mann-Whitney) method uses the ordering of observations rather than relying on the same mean-based model. In general, rank-based methods can be useful when distributional assumptions for a mean-based analysis are a concern, but they answer a related, not always identical, question. The registry labels both Wilcoxon results as mean differences, and the record does not explain the calculation or interpretation of those estimates.

The registry reports the ANOVA mean difference as 13.70, with a 95% confidence interval from -20.08 to 47.48 and p = 0.42. The Wilcoxon entries report p-values of 0.57 and 0.53, with listed estimates of 13.70 and 4.55 respectively; confidence intervals are not reported for those entries. Because the reason for the difference between the Wilcoxon estimates is not stated, they should not be treated as interchangeable with the ANOVA estimate or as a transparent robustness analysis.

What does the crossover structure require?

In general, a crossover trial assigns participants to treatment sequences so that outcomes can be observed under different treatments over time. Analysis may need to account for period, sequence, and possible carryover effects, as well as the correlation between measurements from the same participant. The registry labels this study as crossover and describes two courses, but the posted primary comparison is labeled for the first 6 months. The specific model for the crossover data and any treatment of period or carryover effects are not reported in the registry record. It would therefore be inappropriate to assume that the posted primary estimate incorporates the full crossover design.

The sample-size planning illustration is based on the observed effect, uses a two-sided significance level of 0.05, equal allocation, and a normal approximation, and considers effects at stated fractions of the observed effect. It is a planning illustration rather than observed power. The registry does not report a design-stage sample-size justification, and no sample-size estimates are stated in the record. The illustration should not be treated as evidence that the trial had a particular probability of detecting an effect.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Arm 1 - Placebo During First 6 Months", "Arm 2 and 3 During First 6 Months")
n   <- c(5, 7)
m   <- c(22.3, 36)
sp  <- c(38.49, 31.11)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Arm 1 - Placebo During First 6 Months  5  22.300  38.490  -25.492  70.092
CARM  Arm 2 and 3 During First 6 Months  7  36.000  31.110  7.228  64.772

11. Analyses Reported by the Sponsor

The sponsor-reported ANOVA result is a mean difference of 13.70 meters, with a 95% confidence interval from -20.08 to 47.48 and p = 0.42. The registry also lists two Wilcoxon (Mann-Whitney) entries for the same group labels, with estimates of 13.70 and 4.55 and p-values of 0.57 and 0.53. The Wilcoxon entries have no reported confidence intervals, and the record does not explain why their listed estimates differ.

A recalculation from posted summary statistics is an unadjusted check, not a replacement for the sponsor's analysis plan or its analysis of participant-level data. No discrepancy is flagged between the sponsor result and the recalculation in the registry-derived analysis. Accordingly, the sponsor's own analysis remains the primary reported inferential result, while any recalculation should be understood as a descriptive cross-check and not as an adjusted or definitive reanalysis.

The outcome group sizes are n=5 and n=7, and the primary outcome population is defined by completion of both baseline and 6-month tests. The record does not report enough detail to reconstruct the sponsor's full analysis, including the treatment of the crossover structure or the reasons for missing measurements. The ANOVA estimate, its interval, and its p-value therefore remain the clearest reported inferential summary, with substantial uncertainty around the estimated difference.

12. Multiplicity, Missing Data and Analysis Populations

The registry lists several secondary outcomes, including change in six-minute walk distance, change in pulmonary vascular resistance, the incremental effect of 8 versus 4 doses on pulmonary vascular resistance, and change in quality-of-life measures. It reports 8 secondary outcomes and 13 analyses. When multiple outcomes or analyses are considered, the chance of at least one apparently notable result can increase. In general, prespecified testing hierarchies or multiplicity adjustments can address that issue, but the registry record does not report whether either was used.

The primary outcome is defined for participants who completed the six-minute walk test at baseline and 6 months. The group summaries are based on n=5 and n=7. The record does not report how many participants had missing primary outcome measurements, why measurements were missing, or whether missingness was handled through imputation, a model-based approach, or another method. It is therefore not possible to assess whether the complete-measurement population differs systematically from participants without both measurements.

The enrollment field lists 22, but the registry does not provide a participant-flow account that connects enrollment, treatment sequences, completion of each course, and inclusion in the primary analysis. The reason the outcome denominators are limited to the posted group sizes is not reported in the registry record. It would be inappropriate to infer the causes of missing data or to treat the enrollment figure as the analysis population.

The record identifies the analysis population for the primary endpoint but does not report a full statistical analysis plan, the handling of crossover-specific effects, or the intended role of each secondary analysis. Interim analyses and stopping rules are also not reported in the registry record. The terminated status is stated, but the reason for termination is not reported. Without these details, the results are best read as the posted analyses for the defined endpoint population, with uncertainty about missing data, multiplicity, and the full analysis strategy.

13. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: volume overload (25.0%), pneumonia (20.0%).

The registry reports serious adverse events for each intervention schedule as counts among participants at risk. In the placebo-followed-by-cell-therapy group, 1 participant was affected by a serious adverse event among 5 at risk. In the cell-therapy-followed-by-placebo group, 0 were affected among 3 at risk. In the cell-therapy-in-both-courses group, 1 was affected among 4 at risk. The record lists 0 deaths in each of these groups.

The most frequently listed serious adverse event terms are Volume Overload at 25.0% and Pneumonia at 20.0%. The registry does not provide enough context in these entries to infer how these terms were distributed across schedules or how they relate to the participant-level serious-event counts. They should be read as event-term summaries rather than as a complete comparison of safety between treatment strategies.

These figures are descriptive. The risk groups are small, and counts alone cannot establish whether the observed events were caused by a treatment or whether rates differ between schedules. The record does not report event timing, severity beyond serious-event classification, attribution, or a detailed exposure-adjusted analysis. Nor does it provide enough information to account for the crossover periods when interpreting safety. The posted counts should therefore be read as the recorded safety observations, not as a definitive estimate of comparative risk.

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

The primary posted result estimates the difference in change in six-minute walk distance between the placebo-first group and the group labeled Arms 2 and 3 during the first 6 months. The ANOVA estimate is 13.70 meters, with a 95% confidence interval from -20.08 to 47.48 and p = 0.42. The point estimate is positive, but the interval includes zero and values in both directions. This means the data are not precise enough to establish the direction or size of a group difference with confidence.

The result does not show that the groups are equivalent. Equivalence requires a prespecified margin and an analysis designed to assess whether differences lie within that margin; no such margin is reported. A non-significant p-value also does not establish that the intervention has no effect. It indicates that the posted analysis does not provide strong evidence against its null hypothesis under the method used. The interval conveys more about the uncertainty than the p-value alone.

The observed means and standard deviations describe the outcome values among the participants included in the posted comparison. They do not establish that treatment caused those changes. The primary endpoint population includes participants with completed baseline and 6-month tests, and the registry does not report the reasons for unavailable measurements or how missing data were handled. The result also concerns the specified first-6-month comparison, not every phase or sequence in the crossover trial.

The record includes two additional Wilcoxon entries, but does not explain why their estimates differ or how they relate to the ANOVA result. It also lists secondary outcomes without reporting the role of multiplicity adjustment. These omissions limit the scope of conclusions that can be drawn across analyses. The trial's terminated status is recorded, but the reason is not reported.

In general, a trial result is most useful when considered together with its design, analysis population, uncertainty, and missing-data context. Here, the registry offers a numerical estimate but leaves important details of participant flow and crossover analysis unreported. The safest statistical reading is that the posted comparison is imprecise and does not settle the size or direction of the difference in this endpoint population.

15. Why This Trial Matters Statistically

This trial is statistically notable because it combines a randomized, triple-masked design with a crossover structure and multiple treatment schedules. Such designs can make efficient use of within-participant comparisons, but their analysis depends on how treatment periods and sequences are handled. The registry record labels the model as crossover and describes two courses, yet the primary result is a comparison during the first 6 months. The lack of reported details about period, sequence, and carryover effects makes it important to distinguish the first-period estimate from a full crossover analysis.

The result also illustrates the difference between an estimated effect and the precision of that estimate. The reported mean difference is accompanied by a wide confidence interval that crosses zero. The interval shows why a point estimate alone can be misleading: the observed direction does not resolve the range of effects compatible with the data. The relatively small outcome groups, n=5 and n=7, reinforce the need to attend to uncertainty rather than treating the estimate as definitive.

Another lesson is that multiple posted analyses do not automatically provide a clear robustness assessment. The registry lists ANOVA and two Wilcoxon entries, but does not explain why the Wilcoxon estimates differ or whether a multiplicity strategy was prespecified. A reader needs the analysis plan and outcome definitions to understand whether these are complementary analyses, alternative estimands, or results generated for different reasons.

Finally, the endpoint population is defined by completing both assessments, while the record does not describe participant flow or missing-data handling. These details matter because an estimate based on available measurements may not represent all enrolled participants. The trial therefore highlights the value of transparent reporting of analysis populations, crossover methods, missing data, and the relationship between primary and secondary analyses.

16. 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.

Several trial-specific limitations restrict interpretation of the posted primary result. The comparison is labeled as placebo during the first 6 months versus Arms 2 and 3 during the first 6 months, while the study is also described as a crossover trial with multiple schedules. The registry does not explain how the third schedule enters the primary comparison or whether the reported estimate is intended to represent an initial-period contrast, a combined group comparison, or another estimand.

The registry record does not report the statistical model for the crossover design, including whether period, sequence, or carryover effects were assessed. It also does not describe the allocation procedure beyond identifying the trial as randomized, or explain how masking was implemented. The record gives no rationale for the planned sample size and does not report interim analyses or stopping rules. The study is listed as terminated, but the reason is not reported in the registry record.

For the primary outcome, the stated population requires completion of baseline and 6-month tests. The record does not report participant flow, reasons for unavailable measurements, or methods for handling missing data. The posted group sizes are n=5 and n=7, but the relationship between those outcome groups and the enrollment figure of 22 is not explained.

The registry lists more than one Wilcoxon result for the same groups, with different estimates, but does not explain the distinction. It does not report confidence intervals for those entries or whether the multiple outcomes and analyses were addressed through a prespecified hierarchy or adjustment. Finally, no clinical-importance threshold is stated for the six-minute walk distance difference. These omissions do not invalidate the reported numbers, but they limit conclusions about precision, clinical relevance, and the consistency of evidence across the trial's planned questions.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Study of Angiogenic Cell Therapy for Progressive Pulmonary Hypertension — NCT03001414.
• Registry record last updated 2025-01-31; status last verified 2024-12.
• Results first posted 2025-01-31.
• 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.

20. Record Summary

The registry describes a randomized, triple-masked crossover study of repeated dosing of autologous endothelial progenitor cells transfected with human eNOS in symptomatic severe pulmonary arterial hypertension. Enrollment is listed as 22, and the status is terminated. The intervention schedules included placebo followed by cell therapy, cell therapy followed by placebo, and cell therapy during both courses.

The primary endpoint was change in six-minute walk distance from baseline to 6 months. The posted outcome groups have n=5 and n=7. Their mean changes were 22.3 meters and 36.0 meters, respectively. The ANOVA comparison reports a mean difference of 13.70 meters, a 95% confidence interval from -20.08 to 47.48, and p = 0.42.

The registry also lists Wilcoxon analyses, secondary outcomes, and serious adverse event counts. Important details—including participant flow, missing-data handling, crossover-specific analysis, multiplicity procedures, and the reason for termination—are not reported in the registry record. The primary result is therefore best read as an imprecise estimate for the stated outcome population and first-6-month comparison.