Long Term Follow-up Study for Patients Enrolled on the BP-004 Clinical Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Long Term Follow-up Study for Patients Enrolled on the BP-004 Clinical Study (NCT03733249), a na phase 1, phase 2 study. The primary outcome is Overall Survival.

2. Clinical Question

3. Trial Design

This is a Phase 1/2 long-term follow-up study of patients enrolled in the BP-004 clinical study. Its stated purpose is to evaluate the safety of BPX-501 T cells, also identified in the record as rivogenlecleucel, in pediatric patients who had previously received the cells. The official title describes the earlier treatment as CaspaCIDe T Cells from an HLA-partially matched family donor after negative selection of TCR αβ+T cells. The follow-up is not described as a new study of initial cell infusion.

The registry lists a single-group model, allocation as not applicable, and no masking. There is no randomized allocation or concurrent control group described. Enrollment is listed as 187. The record identifies Bellicum Pharmaceuticals as sponsor, a start date of 2017-01, a primary completion date of 2020-06-30, and a status of terminated. The reason for termination and the timing of termination are not reported in the registry record.

The primary endpoint follows participants after the earlier rivogenlecleucel infusion, with overall survival assessed at 1 and 2 years. Rimiducid is described as an intervention for uncontrolled GVHD in patients who had received rivogenlecleucel. The record specifies a 0.4 mg/kg intravenous infusion for this use. It also states that no further rivogenlecleucel infusions were planned.

The safety summaries list a Rivogenlecleucel Safety Population and a Rimiducid Safety Population. These groups have different reported numbers at risk and are not described as randomized arms. Their labels and counts therefore need to be read as safety summaries, not as a controlled comparison. The record lists three outcome measures and no analyses. Additional details about the follow-up schedule, the study’s operational procedures, or reasons for ending the study are not reported in the registry record.

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: 3 Enrolled patients did not undergo hematopoietic stem cell transplantation (HSCT)

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: ITT Population: Includes all patients treated with HSCT who received rivogenlecleucel at the dose of 1×10E6 cells/kg Study BP-404 is the long-term follow-up study of patients of the BP-004 study who were enrolled at the Italian and Saudi Arabia sites. There is a second long-term follow-up study (BP-004 UK) for patients enrolled at the UK sites. The below results include data from both the BP-404 study and the BP-004 UK study. Individual results for either study are not available.

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: HSCT safety population: All enrolled patients who received hematopoietic stem cell transplantation

6. Primary Endpoint

The registry lists the primary outcome as Overall Survival, measured over 1 and 2 years after rivogenlecleucel infusion.

Overall survival (OS) is the primary endpoint. The registry defines its timeframe as 1 and 2 years after rivogenlecleucel infusion and states that it concerns both malignant and non-malignant subpopulations in the Intent-to-Treat population. That population is described as patients treated with HSCT who received rivogenlecleucel at 1×10E6 cells/kg. The endpoint unit is participants, and its measure is a count of participants.

In general, overall survival records whether participants are alive at a defined point in follow-up. It is useful in long-term follow-up because it gives a direct summary of survival status without requiring the endpoint to distinguish among causes of death. The registry record does not describe a cause-specific survival endpoint or provide further detail on how survival status was established.

Counts at specified time points are not, by themselves, estimates of the full pattern of survival over follow-up. In general, a time-to-event analysis can use both event times and follow-up duration, while a simple count at a landmark reports status at that particular time. The registry record identifies the time points and endpoint but does not report survival counts, estimates, confidence intervals, or analysis methods. It therefore does not show the observed overall survival at either time point.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a single-group follow-up study and identifies overall survival as the primary endpoint. The record lists no analyses. As a result, no inferential method can be attributed to the posted primary endpoint results. Details such as whether the sponsor used a survival curve, a landmark estimate, a model, or an adjustment are not reported in the registry record.

What does a survival endpoint measure?

In general, overall survival is the time from a defined starting point until death from any cause. A study can report survival at chosen time points, such as the 1 and 2 years specified in this record, or describe the pattern of survival over time. A time-point estimate answers a landmark question: what is the survival status at that particular follow-up time? A survival curve gives a broader view of how events accumulate during follow-up. These approaches answer related but not identical descriptive questions.

The registry specifies the time points and a count-based endpoint, but does not say how missing or incomplete follow-up was handled, how a participant’s survival status was determined, or what statistical procedure was used. It would therefore be inappropriate to assign a particular survival method to this study. No survival estimates or uncertainty measures are posted.

Why does the analysis population matter?

In general, an analysis population defines who contributes to an endpoint estimate. The registry names an Intent-to-Treat population and describes it as patients treated with HSCT who received rivogenlecleucel at 1×10E6 cells/kg. This definition is relevant because the overall number enrolled does not necessarily equal the endpoint denominator. Participants may have differing eligibility, treatment, or follow-up status, but the record does not state how many met the endpoint population definition or how many had data available at the specified time points.

The record also refers to malignant and non-malignant subpopulations. A result for each subgroup would require its own denominator and outcome information. The registry does not report subgroup counts or results. No subgroup-specific interpretation can therefore be made from the posted results.

What does a confidence interval add?

In general, a confidence interval expresses the statistical uncertainty around an estimate. It helps readers distinguish a relatively precise estimate from one that remains compatible with a wide range of values. A point estimate alone does not show this uncertainty. For a survival endpoint, the estimate and interval would need to be interpreted in light of follow-up and the population contributing data. The registry record reports neither survival estimates nor confidence intervals, so precision cannot be assessed.

What can be inferred from the safety summaries?

The safety data are counts of participants affected and participants at risk, alongside other adverse-event and death counts. In general, these summaries can describe what was recorded in the listed safety populations. They do not by themselves identify causation. A treatment-related interpretation would require details about event definitions, timing, attribution, ascertainment, and relevant clinical context. Those details are not reported in the registry record.

Over-dispersion is a general statistical concern when event counts vary more than a simple statistical model expects. It can make uncertainty estimates from an overly restrictive model too small. This concern is relevant in general when modeling count outcomes, but no such model or count analysis is reported for this study. It should not be presented as an identified feature of the posted results.

Why is a control comparison not available?

In general, randomization and an appropriate concurrent comparator help separate treatment effects from differences in participant characteristics, follow-up, and other influences. This study is listed as single-group, with allocation not applicable and no masking; the record does not describe a randomized comparison. The two safety populations are not a like-for-like control comparison. A difference in their observed counts would not isolate the effect of either intervention.

Sample-size calculations are planning tools, not observed outcomes. The registry record does not report the study’s sample-size justification or statistical analysis plan. It also does not report a primary endpoint effect estimate on which to base an interpretation of statistical power. Any planning illustration should not be mistaken for observed power or evidence that the study detected a survival effect.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures, identifies overall survival as primary, and reports no analyses. The record does not describe a multiplicity strategy, such as how statistical testing across multiple endpoints, time points, or subpopulations would be handled. It also does not report whether formal hypothesis tests were planned. Because no analyses are posted, there are no reported p-values to assess for multiplicity.

In general, multiplicity matters when several statistical questions are tested: the more tests conducted, the greater the chance that at least one appears statistically notable by chance alone. A prespecified strategy can help control that risk. Here, the record names two survival time points and malignant and non-malignant subpopulations, but does not explain whether these were treated as separate tests or how any testing would be interpreted. It is not possible to infer a correction or testing hierarchy.

The registry record does not report missing-data counts or methods for handling missing survival status. It also does not report loss to follow-up, censoring details, or completeness of outcome ascertainment. In general, missing outcome information can affect both the denominator and the interpretation of an estimate; the direction and magnitude of any effect depend on why information is missing. No conclusion about the extent or consequences of missing data can be drawn from the posted record.

The primary population is described, but the number of participants contributing to the endpoint is not reported. The safety populations have their own reported numbers at risk, which should not be substituted for the missing primary endpoint denominator. Analysis-population details beyond the stated definition, including handling of protocol deviations or participants without endpoint information, are not reported in the registry record.

11. 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: acute graft versus host disease (12.5%), gastrointestinal haemorrhage (6.2%), parotid gland enlargement (6.2%), sepsis (6.2%), septic shock (6.2%).

The Rivogenlecleucel Safety Population summary lists 171 participants at risk and 52 affected by serious adverse events. The Rimiducid Safety Population summary lists 16 at risk and 7 affected. The record also lists 140 participants affected by other adverse events in the Rivogenlecleucel group and 9 in the Rimiducid group. These figures are descriptive summaries of the named safety populations; they are not results from a randomized comparison.

The serious-event terms listed include Acute graft versus host disease at 12.5%, and Gastrointestinal haemorrhage, Parotid gland enlargement, Sepsis, Septic shock, and Staphylococcal bacteraemia at 6.2% each. These percentages are reproduced as recorded. The registry record does not provide additional detail about the denominator or event-level counting rules for these term percentages, so they should not be reinterpreted as comparative risks.

The safety summaries list 7 deaths in the Rivogenlecleucel Safety Population and 0 in the Rimiducid Safety Population. The record does not provide further information connecting these counts to cause, timing, or the primary endpoint analysis. In general, adverse-event counts describe recorded events and do not, on their own, establish that an intervention caused an event. The unequal group sizes and lack of a like-for-like control comparison further limit comparisons between these summaries.

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

The registry record establishes that this study was intended as long-term follow-up after earlier treatment with rivogenlecleucel in pediatric patients enrolled in BP-004. It identifies overall survival at 1 and 2 years as the primary endpoint and lists safety summaries for rivogenlecleucel and rimiducid populations. It also reports enrollment of 187 and a terminated status. These details describe the study and the information posted, but they do not provide a numerical answer to the primary survival question.

The record does not report survival counts, estimates, confidence intervals, or analyses. It therefore cannot establish the observed overall survival at either stated time point, the precision of a survival estimate, or whether outcomes differed between malignant and non-malignant subpopulations. The enrollment figure does not supply the missing endpoint denominator, because the primary population has a specific treatment and HSCT definition and endpoint-specific follow-up counts are not reported.

The safety counts indicate that serious adverse events and other adverse events were recorded in the named populations. They do not demonstrate that an intervention caused those events. Nor do the differing safety group counts provide a valid comparative estimate: the record describes a single-group study and does not identify randomized allocation or a concurrent control group. The death counts in the safety summaries should not be substituted for the unreported primary endpoint results.

In general, a study’s design and posted results answer different questions. A design can specify what investigators intended to evaluate; an estimate requires outcome data and an analysis. The registry describes the intended follow-up question but does not post the analyses needed to quantify its result. The reason for termination, details of missing follow-up, and statistical methods are not reported in the registry record.

13. Why This Trial Matters Statistically

Long-term follow-up addresses a different statistical question from an initial treatment study. It focuses on outcomes after the earlier intervention, over a stated follow-up period. In this record, the central endpoint is overall survival at 1 and 2 years after rivogenlecleucel infusion. Clear definition of the time origin, target population, and follow-up status is important for interpreting such an endpoint. The registry supplies a population description and time points, but does not report the survival results or all details needed to assess their estimation.

The study also illustrates why design labels matter. A single-group follow-up can describe outcomes in the population under observation, but without a concurrent like-for-like control it cannot isolate the effect of a treatment from other explanations. The separate safety summaries for rivogenlecleucel and rimiducid do not change that design limitation. Their group sizes differ, and the record does not describe randomized allocation between them.

It is statistically important to distinguish the number enrolled from the number contributing to a particular analysis. The registry lists enrollment of 187, while the primary endpoint is defined for patients meeting a more specific description. The record does not state the endpoint denominator, subgroup sizes, or completeness of follow-up. Without those details and the outcome estimates, neither precision nor the extent of missing information can be evaluated.

Finally, a registry entry can state a meaningful clinical question while leaving the result unavailable in the posted record. Here, the endpoint is identifiable, but its numerical answer and analysis are not reported. That distinction prevents descriptive safety counts or study status from being mistaken for evidence about the primary survival outcome.

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 most direct limitation is that the registry record does not report results or analyses for the primary overall-survival endpoint. There are no survival counts, estimates, confidence intervals, or reported statistical tests. The endpoint’s named time points and population definition therefore cannot be used to quantify survival or its precision.

The primary population is described as patients treated with HSCT who received rivogenlecleucel at 1×10E6 cells/kg, but the number meeting that definition is not reported. Nor are the numbers contributing data at 1 and 2 years or the counts in the malignant and non-malignant subpopulations. Enrollment of 187 should not be treated as the denominator for each endpoint analysis.

The registry lists the study as terminated but does not report the reason for termination. It also does not report loss to follow-up, missing-data handling, survival-status ascertainment, censoring details, or the statistical analysis plan. These omissions prevent assessment of whether follow-up was complete and how incomplete information may have affected any intended analysis.

The safety summaries are descriptive and come from differently sized populations. The registry identifies no randomized comparison, and the groups are not presented as like-for-like controls. The event counts and listed percentages cannot establish causation or support a direct treatment comparison. The record does not provide details about event attribution, timing, or the counting rules behind the listed term percentages.

These limitations concern what is reported in the registry record. They do not establish that additional information was not collected or analyzed elsewhere; such information is not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Long Term Follow-up Study for Patients Enrolled on the BP-004 Clinical Study — NCT03733249.
• Registry record last updated 2023-09-26; status last verified 2023-09.
• Results first posted 2023-09-26.
• 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.

18. Record Summary

This is a Phase 1/2 single-group long-term follow-up study of pediatric patients previously enrolled in BP-004 and treated with rivogenlecleucel. The registry lists Bellicum Pharmaceuticals as sponsor, enrollment of 187, a start date of 2017-01, primary completion on 2020-06-30, and status as terminated. The reason for termination is not reported in the registry record.

The primary endpoint is overall survival at 1 and 2 years after infusion in the described Intent-to-Treat population, across malignant and non-malignant subpopulations. No primary endpoint results or analyses are reported. Safety summaries list 171 at risk and 52 affected by serious adverse events in the Rivogenlecleucel Safety Population, and 16 at risk and 7 affected in the Rimiducid Safety Population. These groups are not a randomized, like-for-like comparison.

The record lists three outcome measures. Details of the statistical analysis plan, missing-data handling, and survival estimates are not reported in the registry record.