Bendamustine + Obinutuzumab Induction With Obinutuzumab Maintenance in Untreated Mantle Cell Lymphoma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Bendamustine + Obinutuzumab Induction With Obinutuzumab Maintenance in Untreated Mantle Cell Lymphoma (NCT03311126), a na phase 2 study. The primary outcome is Progression Free Survival (PFS) at 2 Years.

2. Clinical Question

The clinical question concerns outcomes after a treatment sequence rather than a head-to-head comparison. The study also lists secondary questions about minimal residual disease status, agreement between peripheral blood and bone marrow aspirate assessments of that status, objective response under the Lugano Classification, overall survival, and treatment-related adverse events assessed using CTCAE v5.0.

Because there is no control group, the study can describe outcomes among participants receiving the regimen but cannot establish how those outcomes compare with another treatment or with no treatment. Its stated population is also specific: participants had not received prior cytotoxic chemotherapy for mantle cell lymphoma, although the listed prior-treatment allowances apply. The registry record does not report a numerical primary endpoint result, so the central question cannot be answered from the posted results summarized in the record.

3. Trial Design

This is a phase II, open-label, multicenter, single-group study sponsored by the University of Wisconsin, Madison. The registry record lists enrollment of 21 and a terminated status. The study started on 2017-09-29, and its primary completion date is listed as 2023-07-31. The reason for termination is not reported in the registry record.

Participants received bendamustine plus obinutuzumab induction. The listed bendamustine schedule was 90 mg/m2 intravenously on days 1 and 2 of 28-day cycles for 4-6 cycles. Obinutuzumab was given on a different schedule during the first cycle and on day 1 of cycles 2-6. The description then specifies an obinutuzumab consolidation phase of weekly administration for 4 doses. The maintenance description is truncated in the registry record, so its full schedule is not reported in the registry record.

Open-label means the study was not masked, consistent with masking listed as none. A single-group design means that all participants were assigned to the same treatment strategy, rather than being randomized between treatment arms. The allocation field is not applicable, and there is no like-for-like control group. These features are important when interpreting outcomes: observed event rates describe the enrolled group and do not isolate a treatment effect relative to an alternative.

The record does not report a sample-size justification, detailed statistical analysis plan, or explanation for termination. A planning illustration based on an observed effect is not the trial's own design justification. The registry record also does not report outcome-level analysis populations or numerical results for the primary endpoint. These omissions limit assessment of how the protocol's planned analyses compare with the results ultimately posted.

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.

Induction

Reasons for not completing this period:

Consolidation

Restaging Imaging

Reasons for not completing this period:

Maintenance

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 Progression Free Survival (PFS) at 2 Years, measured over Up to 2 years.

The primary endpoint is progression-free survival at 2 years. For each participant, the record defines the measurement period as beginning on cycle 1 day 1 of induction chemoimmunotherapy. An event is disease progression or death, whichever occurs first. If neither event has occurred by the time of analysis, the participant's observation is censored at the date of the last available evaluation.

The registry record specifies that the 2-year probability is estimated using the Kaplan-Meier method. The endpoint is reported as a percentage of participants, with a 95% confidence interval and a timeframe of up to 2 years. However, neither the numerical percentage nor its confidence interval is reported in the registry record.

In general, progression-free survival combines two clinically relevant events into a time-to-event measure. It can account for participants whose follow-up ends before an event is observed by treating their data as censored, rather than assuming that an event occurred at the last assessment. The Kaplan-Meier approach estimates the probability of remaining event-free over time while accounting for such censoring, subject to assumptions about the censoring process.

This endpoint is distinct from response rate, minimal residual disease status, and overall survival, all of which appear among the listed secondary outcomes. The registry record describes minimum follow-up of 24 months after completion of study-related treatment in the absence of progression or death. A 2-year estimate would therefore be an estimate at a specified time point, not a statement that every participant had an event or completed identical follow-up.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a Kaplan-Meier estimate represent?

In general, Kaplan-Meier estimation is a method for describing time until an event when participants can have different lengths of follow-up. For this study, the event is progression or death, whichever occurs first. A participant who has no recorded event by the last available evaluation is censored at that evaluation date, according to the registry endpoint description. Censoring preserves the fact that the participant was observed to be event-free up to a known point without asserting what happened afterward.

The estimate is built from the timing of events and the participants still under observation at those times. It is not simply the proportion of all enrolled participants who avoided an event, because participants may have different follow-up durations and some may be censored. In general, valid interpretation depends on adequate event and follow-up information, and on assumptions about censoring. The record does not report the numerical estimate, the confidence interval, event counts for the primary endpoint, or details of censoring patterns.

What does the confidence interval add?

The primary endpoint is specified with a 95% confidence interval. In general, a confidence interval communicates the uncertainty around an estimated quantity: a narrower interval indicates greater precision, while a wider interval indicates less precision. The interval does not guarantee that the true value lies within its particular bounds, and it is not a measure of the probability that the treatment works. Here, the interval's numerical bounds are not reported in the registry record, so its precision cannot be assessed.

The confidence interval also matters because the point estimate alone would not describe how much uncertainty accompanies the estimated 2-year probability. With enrollment listed as 21, the amount of information for a time-to-event estimate depends not only on enrollment but also on events and follow-up. Those details are not reported in the registry record, so no further assessment of precision is possible.

Why does the design matter for inference?

In general, randomization helps create comparable groups for evaluating treatment differences. This study is single-group, open-label, and has allocation listed as not applicable. There is no randomized comparator, so the analysis cannot estimate a randomized between-group contrast. The study can describe the course of outcomes in the enrolled group, but other differences between this group and populations treated in other settings may affect comparisons.

Open-label means masking was absent. In general, awareness of treatment can influence assessments or reporting, particularly for outcomes involving judgment. The primary endpoint includes progression, and the record does not describe the specific assessment procedures or any blinded review. Those details are not reported in the registry record. The endpoint also includes death, but the record does not provide separate component results.

How should planning calculations be understood?

In general, a sample-size calculation is a planning tool that describes the number of participants or events needed under specified assumptions. It is not a measure of the probability that a study's result is correct, and it is not observed power. The registry record says a planning illustration was computed from an observed effect using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; it also distinguishes event totals for time-to-event calculations from participants per arm for other calculations. These are illustration assumptions, not evidence that this single-group trial planned a two-arm randomized comparison.

The record does not report the trial's own sample-size justification. Nor does it report the numerical outputs of the planning illustration in the registry record for this account. Since the primary endpoint estimate is also absent, such an illustration cannot establish the study's observed precision or provide evidence of efficacy. Planning quantities should not be confused with actual enrollment, which is listed as 21, or with observed outcome data.

What role do event rates and over-dispersion play?

In general, binary outcomes summarize whether participants experienced an event during a specified period. For those outcomes, interpretation depends on the event definition, the denominator, the follow-up window, and how missing status is handled. When outcomes are counts, over-dispersion means that variation exceeds what a chosen statistical model expects; if ignored, uncertainty can be understated. These general concepts are not numerical findings about this study. The record lists several secondary outcomes, but does not report their estimates or enough analysis detail to determine which statistical models were used.

The listed primary outcome is time-to-event, not a simple binary percentage of all enrolled participants at a single common follow-up time. Although it is expressed as a percentage at 2 years, the stated method is Kaplan-Meier, which accounts for censoring. The percentage label should therefore be interpreted alongside the time-to-event definition, not as a raw event-free fraction calculated from the enrollment count.

Finally, the record reports no analyses and does not include a numerical endpoint result. The method specified for the primary endpoint is therefore a description of the planned or stated approach, not a basis for independently verifying a result. The registry record does not report enough information to reconstruct an estimate or assess whether any unreported assumptions were met.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Bendamustine + Obinutuzumab (BO)")
n      <- c(21)
events <- c(14)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Bendamustine + Obinutuzumab (BO)  21  14  66.7  43.0  85.4  45.4  82.8  45.1  82.8

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists a primary endpoint and several secondary outcomes, but does not report a detailed statistical analysis plan or any analyses. It names minimal residual disease status, agreement between peripheral blood and bone marrow aspirate assessments, objective response, overall survival, and treatment-related adverse events. Numerical results for these secondary outcomes are not reported in the registry record.

When a study examines multiple outcomes, multiplicity can arise because many statistical questions are considered. In general, testing more hypotheses can increase the chance of at least one apparently notable result arising by chance. A prespecified plan may define which outcomes are primary, how secondary results are interpreted, and whether any adjustment is used. Adjustment procedures, testing hierarchy, and interim analyses are not reported in the registry record, so it is not possible to determine how multiplicity was handled.

The primary endpoint description explains how participants without a recorded event are censored at their last available evaluation. That is a time-to-event analysis convention, not a complete account of missing data. The record does not report missing endpoint assessments, loss to follow-up, reasons for missingness, or sensitivity analyses. It also does not report how participants who discontinued treatment were handled in outcome analyses.

Analysis populations are not described. The record does not report whether results were intended for all enrolled participants, participants who began treatment, or another defined group. The listed enrollment is 21, but the number included in any endpoint analysis is not reported in the registry record. Without such information, denominators and potential exclusions cannot be evaluated.

The registry record's terminated status does not itself explain the amount of missing data or whether analyses were completed. The reason for termination and any consequences for follow-up or analysis are not reported in the registry record.

12. 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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: neoplasms benign, malignant and unspecified (incl cysts and polyps) - other, specify (19.0%), atrial fibrillation / flutter (9.5%), colitis / abdominal infection (9.5%), infusion related reaction (9.5%), pneumonia (9.5%).

The safety summary lists 21 participants at risk for serious adverse events and 9 affected. For other adverse events, it lists 21 at risk and 21 affected. These are participant counts in the registry record; they do not describe the number of individual event episodes, their duration, or their severity. The record also lists 9 deaths, but does not report their causes, timing, or relationship to treatment. A death count alone does not establish treatment causation.

The selected serious adverse-event terms are reported as percentages: neoplasms benign, malignant and unspecified (including cysts and polyps) — other, specify, 19.0%; atrial fibrillation / flutter, 9.5%; colitis / abdominal infection, 9.5%; infusion related reaction, 9.5%; pneumonia, 9.5%; and myocardial infarction, 4.8%. These percentages should be read as the registry's reported figures for the listed terms. The record does not provide additional detail about event timing, participant overlap across terms, or attribution.

In general, adverse-event summaries describe events observed during a study and do not by themselves establish that the intervention caused them. They are also not direct comparisons of risk when there is no control group. The record identifies treatment-related adverse events as a secondary outcome assessed using CTCAE v5.0, but does not report detailed grades or a numerical result for that outcome.

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

The record establishes that a phase II, open-label, single-group study enrolled 21 participants with previously untreated mantle cell lymphoma to evaluate bendamustine and obinutuzumab induction followed by obinutuzumab consolidation and maintenance. It identifies progression-free survival at 2 years as the primary endpoint and describes a Kaplan-Meier method for estimating it. These registry entries define the study question and its design.

They do not establish the observed 2-year progression-free survival probability. The numerical estimate and its 95% confidence interval are not reported in the registry record. Consequently, the primary endpoint's magnitude and precision cannot be described. The record also does not report numerical findings for the listed secondary outcomes, including response, overall survival, and minimal residual disease.

Even if a numerical outcome estimate were available, a single-group study would not provide a randomized comparison against another treatment. Observed outcomes could describe participants in the study, but would not show what would have happened to comparable participants under a different strategy. The absence of a control group is therefore a central limit on causal interpretation, not a minor statistical detail.

The safety summary provides counts and selected serious adverse-event percentages, along with a death count. These are descriptive registry figures. Without additional detail on timing, attribution, severity, and comparison data, they cannot determine whether treatment caused a particular event or quantify a relative safety difference.

The terminated status should be interpreted narrowly. The reason for termination is not reported in the registry record, and the status alone does not explain why the study ended or what effect it had on follow-up and analysis. Likewise, the enrollment number is not a substitute for the number contributing to each outcome; analysis populations are not reported. The posted record therefore supports description of the design and listed safety information, but not a conclusion about the size or certainty of the primary efficacy result.

14. Why This Trial Matters Statistically

This study illustrates why the design and the endpoint definition are essential to interpreting clinical trial statistics. Its primary question concerns progression-free survival at 2 years, a time-to-event endpoint that accounts for participants who have not had an event by their last recorded evaluation. The registry specifies Kaplan-Meier estimation and a 95% confidence interval, making clear that both the estimated event-free probability and its uncertainty matter.

At the same time, a statistical method cannot compensate for missing results. The numerical primary estimate and interval are not reported in the registry record. Without them, readers cannot judge the observed outcome or its precision, regardless of the method named in the endpoint description.

The single-group design also demonstrates the distinction between describing an outcome and estimating a comparative treatment effect. A group-level outcome can be clinically informative as a description, but no randomized control group is available to distinguish the regimen's effect from other influences. This distinction matters whenever results from a nonrandomized, uncontrolled study are compared informally with other studies or historical expectations.

The listed secondary endpoints span response, disease measurement, survival, and safety. Their presence indicates a range of questions of interest, but the record does not report numerical results or a detailed plan for multiplicity. A list of outcomes should not be mistaken for evidence that each was analyzed or that findings were conclusive.

Finally, the safety counts underscore the importance of denominators and context. Counts of affected participants, selected event-term percentages, and deaths convey different kinds of information. None alone establishes causality. Careful statistical reading keeps these distinctions visible and avoids turning a registry description into a comparative or causal claim that the design and results do not support.

15. 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 central limitation for interpreting efficacy is that the numerical 2-year progression-free survival estimate and its 95% confidence interval are not reported in the registry record. The registry describes the endpoint and method, but not the result needed to assess its magnitude or precision. Numerical results for the listed secondary outcomes are also not reported.

The study is single-group and has no randomized comparator. Its open-label design provides no masking, and the record does not describe blinded endpoint review or detailed progression assessment procedures. These design features limit causal interpretation and may matter for outcomes involving assessment judgments.

Enrollment is listed as 21, but the number of participants included in each analysis, event counts for progression-free survival, and follow-up distribution are not reported. The record does not report missing assessments, loss to follow-up, or sensitivity analyses. Thus, the completeness of outcome ascertainment and the influence of censoring cannot be evaluated.

The record lists a terminated status but does not report the reason. It also does not report the trial's sample-size justification, a detailed analysis plan, interim analyses, or how multiplicity was addressed. The maintenance regimen description is incomplete, so its full schedule is not reported in the registry record.

For safety, selected serious adverse-event terms and participant counts are available, but detailed grades, timing, attribution, and participant overlap are not reported. The death count is not accompanied by causes or relationship to treatment. These limitations prevent a fuller assessment of the safety pattern and reinforce that the figures should be treated as descriptive rather than comparative or causal.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Bendamustine + Obinutuzumab Induction With Obinutuzumab Maintenance in Untreated Mantle Cell Lymphoma — NCT03311126.
• Registry record last updated 2024-10-24; status last verified 2024-10.
• Results first posted 2024-10-24.
• 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.

19. Record Summary

NCT03311126 is a phase II, open-label, multicenter, single-group study sponsored by the University of Wisconsin, Madison. It evaluated bendamustine plus obinutuzumab induction followed by obinutuzumab consolidation and maintenance in previously untreated mantle cell lymphoma. Prior single-agent rituximab and involved-field radiotherapy were permitted; prior cytotoxic chemotherapy for mantle cell lymphoma was not.

The registry lists 21 enrolled participants, a start date of 2017-09-29, a primary completion date of 2023-07-31, and a terminated status. The primary endpoint is progression-free survival at 2 years, estimated by Kaplan-Meier and specified with a 95% confidence interval. The numerical estimate and interval are not reported in the registry record.

Secondary outcomes include minimal residual disease, concordance between peripheral blood and bone marrow aspirate assessments, objective response, overall survival, and treatment-related adverse events. Numerical results for these outcomes, the reason for termination, and detailed analysis populations are not reported in the registry record. The safety summary includes participant counts, selected serious adverse-event percentages, and 9 deaths.