Ofatumumab and Bendamustine Followed by Maintenance Ofatumumab for Rituximab Relapsed Indolent B-cell Non-Hodgkin's Lymphoma (B-NHL): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Ofatumumab and Bendamustine Followed by Maintenance Ofatumumab for Rituximab Relapsed Indolent B-cell Non-Hodgkin's Lymphoma (B-NHL) (NCT01294579), a registered phase 2 study. The primary outcome is Complete Remission (CR) Rate of Induction Therapy After Cycle 6 (28 Days) (FAS).

2. Clinical Question

3. Trial Design

This was a phase II, open-label study of ofatumumab and bendamustine, followed by maintenance ofatumumab for participants who had a partial or complete response after induction. The registry lists Novartis Pharmaceuticals as sponsor and describes the target population as people with indolent B-cell non-Hodgkin lymphoma that had relapsed after rituximab or a rituximab-containing therapy. The study status is completed, and the registry reports enrollment of 49.

The induction regimen combined ofatumumab 1000 mg intravenously on day 1 with bendamustine 90 mg/m2 intravenously on days 1 and 2, across cycles 1–6. During maintenance, eligible responders were to receive ofatumumab 1000 mg intravenously every 2 months for 2 years. The registry describes a maximum planned enrollment of 53, with 34 participants in Stage 1 and 19 in Stage 2. It does not report the rationale for this planned enrollment, the stage decision rules, or whether the planned stages were completed as intended.

The study was open label, so masking was not used. The record does not describe a randomized control comparison; allocation is not stated. Thus, results from this regimen would be interpreted as observations in the study population rather than as a controlled estimate of the difference between treatments.

The primary outcome was complete remission after cycle 6, with a stated timeframe from baseline through 24 weeks. Secondary outcomes included overall response after cycle 6, conversion from partial to complete response during maintenance, progression-free survival up to 30 months, pharmacokinetic measures, and deaths by preferred term. Outcome values and analysis entries are not reported in the registry record. The start date was 2011-05-17 and primary completion was 2016-12-20.

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: Subjects completed represents subjects who completed treatment.

Overall Study

Reasons for not completing this period:

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 Complete Remission (CR) Rate of Induction Therapy After Cycle 6 (28 Days) (FAS), measured over Baseline up to 24 weeks.

The primary endpoint measures the percentage of participants in the FAS who achieved complete remission after cycle 6 of induction. Complete remission was defined using several dimensions of disease assessment: disappearance of detectable clinical disease and related symptoms, regression of target nodes, resolution of specified non-measurable nodes, return of an enlarged spleen or liver to normal size with disappearance of nodules, and clearance of bone marrow infiltrate when bone marrow had been involved. The registry states that complete remission was not valid without imaging data.

This endpoint is used to describe the depth of response at the end of induction. It is distinct from an overall response measure, which also includes partial remission, and from a time-to-event outcome such as progression-free survival. Because the endpoint depends on multiple clinical and imaging criteria, missing or incomplete assessment information can affect whether a participant can be classified as having complete remission. The registry specifies a two-sided 95% exact confidence interval for the response rate, estimated with the Clopper-Pearson method.

The observed complete remission rate and confidence interval are not reported in the registry record. Accordingly, the endpoint definition can be described, but the response frequency and the precision of its estimate cannot be evaluated from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record names the primary endpoint, the response criteria, and an interval-estimation method. It does not provide the analysis plan or the numerical primary endpoint result. The distinction between a specified method and a reported result is important: the method describes how an estimate was intended to be made, while the result would show the observed response and its uncertainty.

What a response percentage describes

For a binary outcome such as complete remission, each participant is classified according to whether the endpoint was met. The response percentage summarizes the proportion classified as having the event in the analysis population. It is a descriptive estimate for that population and assessment period. It is not, by itself, a comparison with another treatment or a guarantee that the same proportion would be observed in another group.

Here, the stated unit is percentage of participants and the primary timeframe runs from baseline through 24 weeks. The registry names the FAS as the analysis population but does not define it. That means the precise rules for inclusion in the analysis cannot be reconstructed from the record. Enrollment of 49 should not be treated as the endpoint denominator without a reported outcome denominator.

Why a confidence interval accompanies the estimate

A confidence interval conveys the statistical uncertainty around an estimated response proportion. In general, an interval gives a range of values compatible with the observed data under the method’s assumptions. Its width reflects precision: estimates based on limited information tend to be less precise than estimates based on more information. An interval does not remove uncertainty, and it should be read together with the estimate, endpoint definition, and analysis population.

The registry specifies a two-sided 95% exact confidence interval using the Clopper-Pearson method. An exact method is designed for a binomial proportion and avoids relying on the normal approximation used by some simpler interval methods. The interval would be useful for assessing precision if the response estimate and interval were posted. Neither is reported in the registry record, so no numerical confidence-interval interpretation is possible.

Why endpoint definitions matter

Complete remission was defined by multiple clinical and imaging requirements, with bone marrow clearance also required when bone marrow had been involved. The criteria require more than a general judgment that disease improved. They specify disappearance or regression of findings and require imaging data for a valid complete remission classification. This makes consistent assessment and availability of the relevant information important to the endpoint.

In general, an endpoint that requires several criteria can be affected by incomplete assessments: a participant may lack enough information to determine whether every criterion was met. The registry record does not explain how missing imaging, missing clinical assessments, or other incomplete data were handled. It also does not report whether endpoint assessments were independently reviewed or describe any adjudication process. These details should not be inferred.

What open-label and nonrandomized mean for interpretation

Open-label means masking was not used. In general, knowledge of treatment assignment can influence care, reporting, or assessment, although objective criteria may limit some forms of subjectivity. The registry does not describe procedures intended to address potential assessment or reporting effects.

The record does not present a randomized control comparison and states that the study was not a randomized comparison. A response rate observed in a treated group is not the same as a treatment contrast. A comparative treatment effect requires an appropriate comparison and an analysis that accounts for the design. Without a like-for-like control group, changes or responses observed during the study cannot be separated from other possible explanations through randomization.

Time-to-event outcomes and over-dispersion

Progression-free survival is listed as a secondary outcome, including a percentage of participants with progression-free survival up to 30 months and Kaplan-Meier estimates up to 30 months. In general, time-to-event methods use information about both whether an event occurred and when it occurred, while allowing for participants whose event time is not observed before follow-up ends. Kaplan-Meier estimates describe the probability of remaining event-free over follow-up under the method’s assumptions. The registry record does not report those estimates, event counts, censoring details, or the time-to-event analysis plan.

For count outcomes, over-dispersion means that observed variability exceeds what a simple statistical model expects. In general, accounting for over-dispersion can prevent uncertainty from being understated. The registry record does not report a count-model analysis or indicate that over-dispersion was assessed; it is not possible to say whether this issue applied to an analysis.

The record reports no analysis entries. It also does not report interim analyses, model specifications, covariate adjustment, or the statistical plan beyond the stated exact interval method. Any additional analytic choices should therefore be treated as not reported in the registry record.

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("Ofatumumab and Bendamustine")
n      <- c(49)
events <- c(12)
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  Ofatumumab and Bendamustine  49  12  24.5  13.3  38.9  14.6  38.1  14.6  38.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and multiple secondary outcomes, but does not report a multiplicity strategy. When a study evaluates several outcomes or makes several statistical comparisons, the chance of at least one apparently unusual result can increase. General approaches to multiplicity include prespecifying a hierarchy, adjusting significance thresholds, or treating secondary analyses as exploratory. The registry record does not state whether any such approach was planned or used. There are no analysis entries or posted outcome estimates to assess against a multiplicity plan.

Missing-data methods are also not reported in the registry record. This matters for an endpoint that depends on clinical assessment and imaging, because incomplete information can prevent classification against the complete remission criteria. The record does not specify how unevaluable participants, missing imaging, withdrawal, or incomplete follow-up were handled. Nor does it report outcome-specific denominators, so the number contributing to the primary endpoint cannot be confirmed from the record.

The primary outcome is identified as applying to the FAS, but the registry does not define that population. It is therefore unclear from this record which participants were included or how participants with deviations, incomplete assessments, or other circumstances were treated in that analysis. The safety set is named for the death outcome, but its membership rules are not described.

These omissions do not establish that multiplicity or missing data were mishandled; they mean the relevant procedures are not reported in the registry record. The posted material is insufficient to evaluate their effects on the estimates.

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: pyrexia (6.1%), pneumonia (6.1%), myelodysplastic syndrome (6.1%), febrile neutropenia (4.1%), fatigue (4.1%).

The registry lists 49 participants at risk for serious adverse events and reports 18 participants affected. It also lists 49 at risk for other adverse events and reports 47 affected, along with 7 deaths. These are counts from the posted safety information; the registry record does not provide enough detail to interpret them as comparative risks or to attribute every event to treatment.

The listed serious adverse event terms include pyrexia, pneumonia, myelodysplastic syndrome, febrile neutropenia, fatigue, and pancytopenia. Each term is accompanied by a percentage in the registry. Such term-specific percentages describe reported events in the safety record, but the record does not clarify whether participants could contribute to more than one term, whether events were recurrent, or how relatedness to treatment was assessed. The terms should not be added together or treated as mutually exclusive categories.

The death count is reported separately. The registry does not state in this safety summary whether each death was attributed to disease, treatment, or another cause. It also does not provide a comparison group. These figures describe the reported safety experience; they do not, by themselves, establish causation or allow a controlled comparison.

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

The registry record establishes that a phase II, open-label study evaluated an induction regimen of ofatumumab and bendamustine, followed by maintenance ofatumumab for participants with a partial or complete response after induction. It describes the intended population, regimen, primary endpoint criteria, and several secondary outcomes. It reports enrollment of 49 and a completed study status.

The record does not report the primary complete remission rate or its specified confidence interval. It also does not report the listed secondary outcome results. Therefore, the available registry information cannot answer how often complete remission occurred, how precise that estimate was, how many partial responses converted during maintenance, or what progression-free survival estimates were observed. A description of an endpoint is not an outcome result.

Even if a response estimate were available, the design described in the record would support a description of outcomes in the study population rather than a randomized comparison with another treatment. The record does not identify a like-for-like control arm, and allocation is not stated. Open-label assessment and the lack of reported analysis details are further considerations when judging how much can be concluded.

The safety record contains adverse event and death counts, and several serious adverse event terms with percentages. These data can be read as reported counts and descriptions, but the registry does not provide the detail needed to determine cause, timing, participant overlap, or comparative risk. The figures should not be interpreted as proof that treatment caused or did not cause any specific event.

In short, the posted information describes the study and its planned measures, but does not report the efficacy outcome estimates needed to characterize the observed response. It supports neither a conclusion about comparative effectiveness nor a numerical judgment of the precision of the primary response result.

14. Why This Trial Matters Statistically

This study illustrates why a registry record should be read in two steps: first identify what was planned and how outcomes were defined, then check whether the outcome estimates and analysis details are actually reported. Here, the primary endpoint is described in detail, including clinical, imaging, and bone marrow criteria and a specified exact confidence-interval method. Yet the primary estimate and interval are not reported in the registry record.

The distinction matters statistically because an endpoint definition and analysis method do not reveal the observed result. Without the response proportion, its denominator, and its confidence interval, readers cannot assess either the frequency of complete remission or the precision of that estimate. A planned enrollment target and the final enrollment count cannot fill that gap.

The study also demonstrates the limits of interpreting a response proportion without a control comparison. An uncontrolled observation can describe what happened among participants who received a regimen, but does not isolate a treatment contrast. A randomized, like-for-like comparison answers a different statistical question by supporting a comparison between assigned groups, subject to its design and analysis.

Finally, the record names a FAS but does not define it, and it does not describe missing-data or multiplicity procedures. These are not minor technicalities: analysis-population rules, endpoint evaluability, and the handling of multiple outcomes can affect how an estimate should be understood. Since the record does not report those details or the outcome analyses, the most defensible statistical reading is limited to the design and methods that are explicitly described.

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 registry record does not report the primary complete remission result, its confidence interval, or the outcome-specific denominator. It also does not report results for the listed secondary outcomes. These omissions prevent evaluation of the magnitude and precision of the study’s efficacy estimates from the registry information.

The record describes an open-label phase II study and does not identify a randomized control comparison. It states that this was not a randomized comparison, while allocation is not stated. Consequently, the registry does not support a controlled treatment contrast. The record also does not specify whether outcome assessment was independently reviewed or describe procedures to reduce assessment variability.

The intended population and regimen are described, but the record does not report participant flow through induction and maintenance, the number assessed at each outcome, or how many participants received maintenance. The FAS is named but not defined. Missing-data handling and the analysis population rules are not reported, limiting reproducibility and assessment of potential effects of incomplete outcome information.

The registry lists several secondary outcomes but does not report a multiplicity strategy, analysis plan, interim analyses, or model details. The safety entries give counts and selected serious adverse event terms, but the record does not provide sufficient information on event timing, causality, recurrence, overlap between terms, or death attribution. These limitations concern what can be learned from the registry record; they do not establish that unreported procedures were absent or improperly conducted.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Ofatumumab and Bendamustine Followed by Maintenance Ofatumumab for Rituximab Relapsed Indolent B-cell Non-Hodgkin's Lymphoma (B-NHL) — NCT01294579.
• Registry record last updated 2018-08-09; status last verified 2018-08.
• Results first posted 2018-08-09.
• 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

The registry record describes a completed phase II, open-label study of ofatumumab and bendamustine induction followed by maintenance ofatumumab for eligible responders with indolent B-cell non-Hodgkin lymphoma relapsed after rituximab treatment. Enrollment was 49. The primary outcome was complete remission after cycle 6, with a specified two-sided 95% exact confidence interval using the Clopper-Pearson method.

The primary outcome estimate and confidence interval are not reported in the registry record. Secondary outcomes are listed, but their results are not reported. The record also does not define the FAS, describe missing-data handling, or provide a multiplicity strategy. Safety information reports 18 participants with serious adverse events, 47 with other adverse events, and 7 deaths among the listed safety group. These data are descriptive and are not a randomized comparison.