A Study of Obinutuzumab + Bendamustine (BG) in Participants With Previously Untreated Chronic Lymphocytic Leukemia (CLL): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Obinutuzumab + Bendamustine (BG) in Participants With Previously Untreated Chronic Lymphocytic Leukemia (CLL) (NCT02320487), a na phase 2 study. The primary outcome is Percentage of Participants With Complete Response (CR), as Determined by the Investigator Using International Workshop on Chronic Lymphocytic Leukemia National Cancer Institute-Working Group (iwCLL NCI-WG) Guidelines.

2. Clinical Question

3. Trial Design

This was a Phase II, open-label, multicenter study of obinutuzumab plus bendamustine in participants with previously untreated CLL. It enrolled 102 participants and is listed as completed. The registry identifies a single-group model, with no allocation to different treatment arms. The intervention description specifies BG induction therapy in 28-day cycles for 6 cycles, and the study summary gives an anticipated time on treatment of 24 weeks.

The design is important for interpreting the evidence. Because all participants received BG and no randomized comparator is listed, the study can describe response and safety outcomes among those treated, but it cannot isolate a treatment effect relative to another regimen. Differences from outcomes in other populations or studies would not, on their own, establish a comparative effect: participant characteristics, outcome assessment, follow-up, and other aspects could differ.

The primary endpoint was investigator-assessed CR or CRi using iwCLL NCI-WG criteria. The listed assessment window was 2 to 3 months after the last infusion, up to approximately 228 to 258 days. Secondary outcomes included objective response, duration of response, progression-free survival, overall survival, minimal residual disease status in bone marrow and peripheral blood, and time to and duration of MRD-negativity. These are distinct outcomes and should not be treated as interchangeable measures of response.

The registry record does not report a statistical analysis plan, a sample-size justification, details of interim analyses, or numerical efficacy estimates. It lists 15 outcome measures and 0 analyses. Consequently, the trial design and outcome definitions can be described, but the posted registry information does not support an account of the analysis methods used to estimate treatment outcomes.

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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The modified intent-to-treat (mITT) population included enrolled participants who received at least one dose of BG.

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 Percentage of Participants With Complete Response (CR), as Determined by the Investigator Using International Workshop on Chronic Lymphocytic Leukemia National Cancer Institute-Working Group (iwCLL NCI-WG) Guidelines, measured over 2 to 3 months after the last infusion of study treatment (up to approximately 228 to 258 days).

The primary endpoint is the percentage of participants with a complete response, with CRi also included in the CR rate. Investigators assessed response using iwCLL NCI-WG guidelines. The record defines confirmed CR through a set of blood, physical examination, and bone marrow criteria, assessed at least 2 months after completion of therapy. These include peripheral blood lymphocytes < 4 times 10^9 cells/L; absence of significant CLL-related lymphadenopathy, hepatomegaly, or splenomegaly and of constitutional symptoms; specified blood-count criteria without transfusion or exogenous growth factors; and bone marrow findings including < 30% lymphocytes and no CLL activity. Participants meeting CR criteria with persistent anemia, thrombocytopenia, or neutropenia were considered to have CRi.

As a general statistical concept, a response percentage gives the proportion of an analysis population meeting a defined outcome. A standardized definition makes the endpoint more reproducible than an informal judgment, while investigator assessment can still involve clinical interpretation. The timing of assessment matters because response status may depend on when it is evaluated. The registry specifies assessment 2 to 3 months after the last infusion, up to approximately 228 to 258 days.

The endpoint can describe response in the treated group, but without a comparator it cannot estimate a comparative treatment effect. The registry record does not report the CR/CRi estimate or its 95% confidence interval, so the observed response rate and its precision cannot be assessed from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a binary response classification at the participant level: each participant either meets the defined CR/CRi criteria at assessment or does not. The reported summary would ordinarily be a percentage of the analysis population meeting the endpoint. The registry record specifies the outcome and its 95% confidence interval, but it does not report the percentage, interval limits, or a statistical analysis. As a result, the method can be explained conceptually, but the actual estimate cannot be reconstructed from the posted information.

What does a confidence interval express?

In general, a confidence interval communicates uncertainty around an estimate using a method with stated assumptions. It is not a guarantee that the true value lies within the calculated range, nor does it replace the estimate itself. For a response percentage, the interval helps readers judge how precisely the observed response is estimated. The registry record names a 95% confidence interval for the primary endpoint, but gives no numerical bounds. There is therefore no basis to describe its width or the precision of the CR/CRi estimate.

What does the analysis population include?

The modified intent-to-treat population is defined as enrolled participants who received at least one dose of BG. This definition identifies the group intended for the primary analysis, but the registry record does not state how many participants were included in that population or how missing assessments were handled. Enrollment was 102; enrollment and the analysis population should not be assumed to be identical without the corresponding reported count. The record also does not describe exclusions from the analysis population, if any.

Why does the single-group design matter?

In a single-group study, the outcome summary characterizes the participants who received the study treatment. It does not directly estimate a difference between treatments because there is no concurrent comparison group. Random allocation is not listed, and allocation is recorded as NA. As a general principle, comparisons with external results are vulnerable to differences in eligibility, care, outcome measurement, and follow-up. The registry record does not report an adjusted or unadjusted comparative analysis.

How should the response criteria be understood?

The endpoint applies a defined set of iwCLL NCI-WG criteria. The record states that confirmed CR required assessment at least 2 months after therapy and specifies blood, clinical, and bone marrow features. CRi covers participants who fulfilled CR criteria but had persistent anemia, thrombocytopenia, or neutropenia. Including CRi in the primary CR rate means the endpoint is not limited to participants with complete blood count recovery. Consistent criteria can support comparable classification, but the record does not report information about assessor agreement or any independent review.

What can be said about secondary and time-to-event outcomes?

The listed secondary outcomes include objective response and duration of response, progression-free survival, overall survival, and MRD outcomes in bone marrow and peripheral blood. In general, a time-to-event outcome depends on defining both an event and how follow-up is treated when the event has not been observed. The registry record does not report analysis details such as censoring rules, follow-up summaries, or statistical models for these outcomes. It lists 15 outcome measures and 0 analyses, so numerical estimates or inferential results for these endpoints are not available in the posted record.

What analysis details are not reported?

The registry record does not report the statistical analysis plan, the estimator used for the response percentage, the method for calculating its confidence interval, or a hypothesis test for the primary outcome. It also does not report a sample-size justification, interim analyses, or the handling of missing outcome data. These details cannot be inferred from the Phase II label, enrollment count, or stated endpoint. In general, statistical methods should be interpreted alongside their assumptions and analysis population; without the analysis details and results, that assessment is limited.

Planning calculations, when used, are not observed outcomes. Any sample-size illustration based on an observed effect would be a planning exercise and would not establish the trial's original design rationale or the probability that its result is correct. The registry record does not report its original sample-size justification. No power claim or reconstructed result should be inferred from the enrollment count alone.

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("Obinutuzumab + Bendamustine (BG)")
n      <- c(102)
events <- c(51)
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  Obinutuzumab + Bendamustine (BG)  102  51  50.0  39.9  60.1  40.5  59.5  40.5  59.5

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 15 outcome measures, including the primary CR/CRi endpoint and secondary outcomes covering response, survival, and MRD status. When a study examines multiple outcomes, multiplicity is a general statistical concern: the chance of at least one apparently notable result can increase when many hypotheses are tested. Appropriate interpretation depends on the analysis plan, the role assigned to each outcome, and any adjustment or hierarchy used. The registry record does not report a multiplicity strategy, a testing hierarchy, or numerical analyses. It therefore does not support a conclusion about how multiple outcomes were handled.

The record defines the primary analysis population as enrolled participants who received at least one dose of BG. It does not report the population count used for that analysis, the number with evaluable primary endpoint assessments, or the handling of missing response assessments. Missing outcomes can affect a percentage estimate, and the impact depends on how much information is missing and how it is treated. Neither the extent of missing primary endpoint data nor the approach to missingness is reported in the registry record.

For secondary outcomes, including duration and time-to-event measures, the record does not describe censoring, follow-up completeness, or other missing-data procedures. It also does not report whether any analyses used alternative populations or sensitivity analyses. These omissions do not establish that a particular method was or was not used; they mean the method is not reported in the registry record. The listed outcomes should therefore be read as planned outcome topics, not as evidence that each was analyzed or that results were available.

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 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 (6.9%), pyrexia (4.9%), febrile neutropenia (3.9%), tumour lysis syndrome (3.9%), dehydration (2.9%).

For the BG group, the registry lists 102 participants at risk for serious adverse events and 31 affected. It also lists 102 at risk for other adverse events and 101 affected. Seven deaths are recorded. These are counts in the treated group, not comparisons with an untreated or alternative-treatment group. The registry record does not provide a causal assessment for the deaths or establish that every recorded event was caused by study treatment.

The most frequently listed serious adverse event terms are pneumonia (6.9%), pyrexia (4.9%), febrile neutropenia (3.9%), tumour lysis syndrome (3.9%), dehydration (2.9%), and urinary tract infection (2.0%). These percentages describe the listed terms in the registry. The record does not give event-level details or state whether participants could contribute to more than one term, so the percentages should not be added together or interpreted as mutually exclusive categories.

In general, adverse-event summaries depend on definitions, collection procedures, follow-up, and attribution practices. The registry information does not report enough detail to assess those features fully. The counts and percentages describe the posted safety information but cannot, on their own, establish a comparative risk or determine causation.

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

The record establishes that a Phase II, open-label, single-group study evaluated obinutuzumab plus bendamustine in previously untreated CLL. It describes treatment as 28-day cycles for 6 cycles and identifies investigator-assessed CR or CRi as the primary endpoint. It also provides the endpoint criteria, the planned assessment timing, and several secondary outcome topics. These details help clarify what the study set out to assess.

The posted information does not include a numerical primary response estimate or its 95% confidence interval. It also does not report numerical results for the listed secondary outcomes. Consequently, the registry record does not show how many participants achieved CR or CRi, how precisely that proportion was estimated, or what the study found for survival or MRD outcomes. A planned endpoint is not itself a result.

Even if a response estimate were available, the design would remain a single-group study. The outcome could describe participants treated with BG, but it would not be a randomized estimate of the difference between BG and another treatment. The registry record does not provide a control group, comparative analysis, or adjusted estimate. No claim about superiority, equivalence, or relative safety follows from these data.

The safety counts also require careful interpretation. The record reports serious adverse events affecting 31 of 102 participants, other adverse events affecting 101 of 102, and 7 deaths. These figures describe events recorded in the study group; without a comparator and further causal information, they do not determine how many events were attributable to treatment or how risks compare across regimens.

Overall, the record supports an account of the study's design, endpoint definitions, and selected safety summaries. It does not provide the efficacy analyses needed to quantify response or assess its precision, and it does not report enough statistical detail to evaluate missing-data handling, multiplicity, or the analysis procedures. Conclusions should be confined to those reported features.

14. Why This Trial Matters Statistically

This study illustrates why design and reporting details matter as much as an endpoint label. A percentage of participants meeting a clearly defined response criterion can be clinically interpretable as a description of a treated group. Its statistical interpretation also depends on the analysis population, assessment timing, missing outcomes, and uncertainty around the estimate. Here, the registry defines the CR/CRi endpoint and names a 95% confidence interval, but does not report the estimate or interval bounds. The reader can understand what was intended to be measured, but cannot judge the observed rate or its precision.

The single-group structure is another important statistical feature. Without a randomized comparator, an outcome summary cannot quantify a difference attributable to one treatment rather than another. This distinction prevents a descriptive response result from being mistaken for comparative evidence. In this record, no numerical efficacy result is available in any case.

The registry also lists a broad set of secondary outcomes, including response duration, progression-free survival, overall survival, and MRD measures. Each addresses a different question and may require distinct analysis choices. The record lists 15 outcomes and 0 analyses, while not reporting a statistical plan or results for these measures. This makes clear why outcome registration and outcome reporting are not the same: a list of outcomes identifies topics of interest but does not supply the evidence needed to evaluate them.

Finally, the safety counts show the value of distinguishing event summaries from causal or comparative conclusions. Counts among treated participants are informative descriptions, but they cannot alone determine attribution or relative risk. The record's limits are therefore not merely technical; they define what readers can responsibly conclude from the posted information.

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 main limitation for interpreting efficacy is the absence of numerical primary and secondary outcome results in the registry record. The primary endpoint is described, and a 95% confidence interval is named, but neither the response estimate nor its interval is reported. Without those values, the magnitude and precision of the primary outcome cannot be assessed. The registry lists 15 outcome measures and 0 analyses, so the presence of secondary endpoints should not be taken as evidence of reported findings.

The single-group design limits comparative interpretation. There is no randomized control group, and the record identifies allocation as NA. Outcomes in the BG group therefore cannot establish how results would differ under another treatment. The open-label design also means masking was not used; the record does not describe any independent endpoint review or other procedures intended to reduce assessment bias.

Several analysis details are not reported in the registry record: the statistical analysis plan, the sample-size justification, interim analyses, the handling of missing data, and the methods used for confidence intervals or time-to-event outcomes. The number included in the modified intent-to-treat population and the completeness of endpoint assessment are also not reported. These gaps prevent a full appraisal of precision, missingness, and analysis choices.

Safety interpretation is limited as well. The record gives affected counts and selected serious adverse event percentages but does not provide a comparator or detailed causal assessments. The posted figures describe events in this study group and should not be interpreted as comparative risks.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of Obinutuzumab + Bendamustine (BG) in Participants With Previously Untreated Chronic Lymphocytic Leukemia (CLL) — NCT02320487.
• Registry record last updated 2020-02-11; status last verified 2020-02.
• Results first posted 2017-12-21.
• 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

NCT02320487 is a completed Phase II, open-label, multicenter, single-group study of obinutuzumab plus bendamustine in previously untreated CLL. Enrollment was 102. Participants received BG induction therapy in 28-day cycles for 6 cycles, with an anticipated 24 weeks on study treatment.

The primary endpoint was the percentage of participants with investigator-assessed CR or CRi using iwCLL NCI-WG criteria, assessed 2 to 3 months after the last infusion, up to approximately 228 to 258 days. The modified intent-to-treat population included enrolled participants who received at least one dose of BG. The registry lists 15 outcome measures and 0 analyses; a numerical primary response result and its 95% confidence interval are not reported in the registry record.

Safety information lists serious adverse events affecting 31 of 102 participants, other adverse events affecting 101 of 102, and 7 deaths. The study has no randomized comparator, so the record supports descriptive interpretation of its treated group rather than a like-for-like treatment comparison.