Bendamustine Hydrochloride in Combination With Rituximab in Patients With Relapsed Refractory Mantle Cell Lymphoma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Bendamustine Hydrochloride in Combination With Rituximab in Patients With Relapsed Refractory Mantle Cell Lymphoma (NCT00891839), a na phase 2 study. The primary outcome is Overall Response Rate (Complete Response + Partial Response) at the End of Cycles 3 and 6 Using the 2007 International Working Group Criteria.

2. Clinical Question

3. Trial Design

The registry identifies this as a Phase 2, open-label study of bendamustine hydrochloride in combination with rituximab for patients with relapsed or refractory mantle cell lymphoma. The design is single-group; allocation is listed as NA and masking as none. These features mean that the registry record describes outcomes among participants receiving the combination rather than a randomized treatment comparison. No control-group estimate is available in the record for interpreting differences between regimens.

The recorded enrollment is 45. The study status is completed, with a start in 2009-06 and primary completion in 2011-12. The primary endpoint population is described as the safety population, consisting of all participants treated with at least 1 dose of bendamustine HCL. The adverse-event group also records 45 participants at risk for serious and other adverse events. The record does not give additional details about participant flow, withdrawals, or the number assessed for response at each time.

The treatment description specifies bendamustine at 90 mg/m^2 intravenously on days 1 and 2, and rituximab at 375 mg/m^2 intravenously on day 1 of each 28-day cycle. Six 28-day cycles were planned; up to 8 cycles were permitted for participants who did not have progressive disease and had not achieved a complete response. This description gives the regimen as recorded, but does not establish how many participants received each cycle or whether treatment exposure differed across participants.

Secondary outcomes include Kaplan-Meier estimates for duration of response, progression-free survival, and overall survival, along with shifts in PET and ECOG performance status. The registry lists no statistical analyses. It does not report the methods used to handle incomplete follow-up, the analysis population for each secondary outcome, or a comparative statistical plan. Because the design is not randomized, all outcomes should be read as descriptions of this treated cohort rather than causal estimates relative to an alternative.

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: Forty-five patients were screened and all were enrolled.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Safety population consisting of all participants treated with at least 1 dose of bendamustine HCL.

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: Safety

6. Primary Endpoint

The registry lists the primary outcome as Overall Response Rate (Complete Response + Partial Response) at the End of Cycles 3 and 6 Using the 2007 International Working Group Criteria, measured over Month 3 (end of cycle 3), Month 6 (end of cycle 6).

The primary endpoint is the overall response rate, defined as the percentage of participants with a complete response or partial response at the end of cycles 3 and 6. The registry specifies the 2007 International Working Group criteria. A complete response means disappearance of all detectable clinical evidence of disease and disease-related symptoms, if present before therapy. A partial response requires at least a 50% decrease in the sum of the product of the diameters of up to 6 of the largest dominant nodes or nodal masses, with no increase in other nodes, liver, or spleen and no new sites of disease.

Response rate is a binary endpoint at a specified assessment: each assessed participant is classified as having met or not met the response definition. Reporting a proportion gives a concise description of how often the prespecified response state was observed in the assessed population. The two assessment times also distinguish response status at the end of cycle 3 from status at the end of cycle 6; they should not be treated as interchangeable measurements or as evidence about the durability of response.

The registry describes 95% confidence intervals calculated using the binomial exact method. A confidence interval expresses uncertainty around an estimated proportion; its width depends in part on the amount of information in the observed data. The record does not report the response counts, percentages, or confidence limits at either assessment. Thus, the endpoint definition is available, but the response magnitude and its precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical information in the registry record is limited. It specifies a binary response endpoint, two assessment times, and the intended confidence-interval method, but the registry lists no statistical analyses. The following concepts explain how these methods are generally interpreted; they do not fill in unreported details of the study’s analysis plan.

What does a response proportion describe?

For a binary endpoint, each participant assessed at a stated time is classified according to whether the response definition was met. The response proportion is the number meeting that definition relative to the relevant assessed group. It describes the frequency of the endpoint in that group at that assessment. It is not a measure of how much an individual participant improved, and it does not by itself describe how long a response lasted.

Here the registry defines overall response as complete response plus partial response under the 2007 International Working Group criteria. The response definition is detailed, but the registry record does not post the response counts or proportions. It also does not state the observed denominator for the end of cycle 3 or end of cycle 6. For that reason, no numerical response calculation can be interpreted from the posted results.

What does a confidence interval add?

A confidence interval represents uncertainty around an estimate. For a response proportion, the interval helps convey how much the observed proportion might vary because it is based on a limited group of participants. A narrower interval indicates greater precision under the method’s assumptions; a wider interval indicates more uncertainty. It is not a guarantee that a particular range contains the true value, and it does not correct for bias caused by missing observations, participant selection, or lack of a comparator.

The registry says that 95% confidence intervals are calculated using the binomial exact method. The binomial framework is appropriate for a binary response outcome when observations are treated as response or nonresponse. An exact method derives confidence limits from the binomial model rather than relying on a large-sample approximation. The record does not report the resulting intervals, so their width and the precision of the response estimate cannot be evaluated.

Why do assessment times matter?

The endpoint is assessed at the end of cycle 3 and at the end of cycle 6. Each time point answers a time-specific question about response status. A proportion at the earlier assessment would not automatically describe response at the later assessment, and a response at either assessment would not alone establish durability. Duration of response is listed separately as a secondary outcome, emphasizing that response status and time until response ends are distinct quantities.

Repeated assessment also raises analysis questions. For example, analysts need to define the eligible and evaluable population at each time, and how participants without an assessment are handled. The registry record does not report those rules, the numbers assessed at each time, or whether any adjustment was made for examining multiple endpoints or time points. No such procedures should be inferred from the endpoint description alone.

How should the single-group design be understood?

A single-group study estimates outcomes among participants who received the study regimen. It does not provide a direct within-trial comparison with a separate control regimen. Random allocation is listed as NA, and the study is described as open-label with no masking. Consequently, the record does not support a randomized contrast. In general, open-label assessments may be susceptible to knowledge of treatment, although the record does not specify how response assessments were conducted or whether independent review occurred.

The absence of a comparator also affects interpretation of uncertainty. A confidence interval around a response proportion can quantify sampling uncertainty under its statistical model, but it cannot quantify all uncertainty about whether the outcome was caused by treatment. Precision and causal interpretation are different issues: an estimate can be statistically precise while still lacking a controlled comparison.

What can be learned from the secondary outcomes?

The registry lists Kaplan-Meier estimates for duration of response, progression-free survival, and overall survival. In general, Kaplan-Meier methods estimate the probability of remaining event-free over time while accounting for participants whose follow-up ends before an event is observed. The method relies on assumptions about censoring and requires information about event and follow-up times. Those estimates, event counts, censoring details, and analysis methods are not reported in the registry record.

PET and ECOG performance status are listed as shift outcomes from baseline to post-treatment. A shift analysis describes changes in categories or status between assessments, but interpretation depends on how categories are defined, when measurements were taken, and how unavailable assessments are handled. The record does not provide those details or the resulting shifts. No conclusion about the direction or extent of change can be drawn from the outcome names alone.

What is the role of planning calculations?

Planning sample-size illustrations are not observed results and are not observed power. The registry record does not report its own sample-size justification or a statistical design rationale. Any illustrative calculation based on an observed effect would depend on assumptions, including a specified effect fraction, significance level, allocation, and approximation. Such calculations cannot establish what the trial was designed to detect unless that design information is reported, and they cannot replace the missing outcome estimates.

Overall, the record identifies an exact binomial confidence-interval method for the primary binary endpoint, but the analysis details and numerical output needed to assess the endpoint are absent. General statistical concepts clarify what the stated methods mean; they do not permit reconstruction of the trial’s missing results.

10. Multiplicity, Missing Data and Analysis Populations

The registry record does not report a multiplicity plan. The primary endpoint includes overall response assessments at the end of cycle 3 and at the end of cycle 6, and several secondary outcomes are listed. When a study examines multiple outcomes or assessment times, general statistical practice may consider how the totality of testing affects interpretation. The record does not state whether any adjustment, hierarchy, or prespecified prioritization was used, so none should be assumed.

Missing-data methods are also not reported in the registry record. The primary population is described as the safety population, consisting of all participants treated with at least 1 dose of bendamustine HCL. However, that definition does not explain how participants without a response assessment were counted, whether they were included in an endpoint denominator, or how withdrawals and incomplete follow-up were handled. The record gives no assessed counts at the end of cycle 3 or cycle 6.

For secondary outcomes, the registry lists time-to-event measures and shifts in PET and ECOG performance status, but does not report endpoint-specific analysis populations, censoring rules, missing-measurement rules, or sensitivity analyses. These details matter because the interpretation of a statistical estimate depends not only on its formula but also on who contributes data and how unavailable observations are treated.

The registry lists 0 analyses. This means the record does not present analysis entries that would clarify the statistical procedures or numerical findings. It does not establish that no analyses were conducted outside the registry record. The distinction is between information absent from the record and actions that may or may not have occurred; the latter cannot be inferred.

11. Safety Results

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

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: pneumonia (6.7%), confusional state (4.4%), pleural effusion (4.4%), febrile neutropenia (2.2%), neutropenia (2.2%).

The adverse-event summary records 45 participants at risk for serious adverse events and 18 affected participants in the bendamustine-plus-rituximab group. It also records 45 participants at risk for other adverse events and 45 affected participants. These are participant counts in the registry summary. They should not be treated as counts of individual events, since a participant may experience more than one event.

The listed serious adverse event terms and percentages are pneumonia, 6.7%; confusional state, 4.4%; pleural effusion, 4.4%; febrile neutropenia, 2.2%; neutropenia, 2.2%; and cardiac failure congestive, 2.2%. These entries describe reported terms and their recorded percentages. The record does not provide additional details about event timing, duration, severity grading beyond the serious classification, recurrence, or attribution to treatment.

Safety counts are descriptive. Without a comparator group, they do not quantify excess risk relative to another regimen. The registry record does not report deaths in this adverse-event group. These safety summaries should not be used to infer efficacy, and the response results are not reported in the registry record.

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

The registry record establishes the intended clinical and statistical question: whether participants with relapsed or refractory mantle cell lymphoma met the stated complete- or partial-response criteria at the end of cycles 3 and 6 while receiving bendamustine with rituximab. It also specifies that 95% confidence intervals were to use the binomial exact method. Those details define the target outcome and the planned way to express its uncertainty.

The record does not report the numerical response rates or their confidence intervals. It therefore does not show how many participants met response criteria at either assessment, how precise an estimate might be, or whether response status changed between assessments. A missing result cannot be interpreted as a zero response, a universal response, or a particular intermediate outcome. It is simply not reported in the registry record.

Even if response estimates were available, a response proportion would answer a narrower question than whether a treatment improves survival or is superior to another treatment. Response is a status measured at specified assessments. Duration of response, progression-free survival, and overall survival are separate outcomes, each with distinct definitions and analysis requirements. They are listed as secondary outcomes, but their estimates are not reported in the registry record.

The single-group, open-label design further limits causal interpretation. Results from a treated cohort do not provide a randomized comparison, and allocation is listed as NA. General statistical reasoning distinguishes a description of outcomes among treated participants from an estimate of what would have happened under another treatment. The latter requires a suitable comparison and assumptions that this record does not establish.

The safety summary does provide participant counts and several serious adverse event terms with percentages. These figures describe reported safety experience in the study group, but they do not indicate comparative risk or prove that any event was caused by the regimen. The registry record does not provide event-level context sufficient for broader causal conclusions.

In short, the record supports interpretation of the study design, treatment schedule, response definition, and selected safety summaries. It does not support a quantitative conclusion about response or survival, nor a claim of comparative benefit. That boundary reflects the posted information, not a judgment about findings that are absent from the registry record.

13. Why This Trial Matters Statistically

This study is statistically instructive because its registry record separates a clearly specified endpoint from the numerical results needed to evaluate it. The response definition identifies what counted as complete or partial response, and the two scheduled assessment times define when the endpoint was to be evaluated. The stated binomial exact confidence-interval method also signals that uncertainty around a proportion was intended to be reported. But without the response estimates, denominators, or confidence limits, the endpoint’s magnitude and precision cannot be assessed.

The single-group design is another important feature. It focuses attention on the difference between describing an outcome and estimating a comparative treatment effect. A single-group response proportion can characterize outcomes in the enrolled cohort, but it cannot supply a randomized estimate against a control. That distinction remains important regardless of how precise a cohort estimate might be.

The record also illustrates why enrollment and endpoint denominators are not interchangeable. Enrollment is recorded as 45, and the primary population is defined by receipt of at least 1 dose of bendamustine HCL. The registry does not report how many participants were assessed at each response time. Without those denominators and missing-data rules, a reader cannot determine exactly which observations would underlie an endpoint estimate.

Finally, the listed secondary outcomes span response durability, disease progression, survival, imaging, and performance status. Those outcomes answer different questions and require different statistical summaries. Their presence in a registry does not mean their results are available or that they can substitute for the unreported primary response findings. The record is a useful example of why design descriptions, outcome definitions, analysis methods, and numerical results must be considered together when interpreting a clinical study.

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 main trial-specific limitation in the registry record is the absence of numerical primary response results. The overall response rate is defined at the end of cycles 3 and 6, but no response counts, percentages, confidence intervals, or evaluable denominators are reported. The record therefore does not permit a quantitative assessment of either response estimate or its precision.

The study is single-group, open-label, and has no recorded allocation to a comparator. Outcomes among treated participants cannot be directly contrasted with outcomes under another regimen using this record. The lack of a control also means that observed outcomes, if reported elsewhere, could not by themselves establish a causal treatment effect. The record does not describe independent response review or masking of outcome assessment.

The registry defines the primary population as all participants treated with at least 1 dose of bendamustine HCL, but does not state how participants with absent or unevaluable response assessments were handled. Participant flow, discontinuations, and endpoint-specific denominators are not reported. The record also does not provide methods for missing data, multiplicity, or the statistical analysis of secondary outcomes.

Although duration of response, progression-free survival, overall survival, PET shifts, and ECOG shifts are listed, no corresponding numerical results or detailed analysis procedures are reported in the registry record. No sample-size justification is reported, and the record lists no statistical analyses. These gaps prevent a fuller evaluation of precision, robustness, or consistency across outcomes. They should be understood as limits of the registry information, not as evidence that the study did not collect or analyze those data.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Bendamustine Hydrochloride in Combination With Rituximab in Patients With Relapsed Refractory Mantle Cell Lymphoma — NCT00891839.
• Registry record last updated 2014-11-04; status last verified 2014-10.
• Results first posted 2014-10-22.
• 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

The registry record describes a completed, open-label, single-group Phase 2 study of bendamustine with rituximab in relapsed or refractory mantle cell lymphoma. Enrollment was 45; the recorded study start was 2009-06 and primary completion was 2011-12. The regimen specified bendamustine at 90 mg/m^2 intravenously on days 1 and 2 and rituximab at 375 mg/m^2 intravenously on day 1 of each 28-day cycle, with six cycles planned and up to 8 permitted under stated conditions.

The primary endpoint was overall response at the end of cycles 3 and 6 using the 2007 International Working Group criteria, with 95% confidence intervals intended by the binomial exact method. Numerical primary response results are not reported in the registry record. Secondary outcomes and selected safety summaries are listed, but the registry lists 0 analyses. Interpretation is therefore limited to the design and methods described and the safety counts posted, without a quantitative conclusion about response or comparative effects.