This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Comparison of Pixantrone + Rituximab With Gemcitabine + Rituximab in Patients With Aggressive B-cell Non-Hodgkin Lymphoma or Follicular Grade 3 Lymphoma Who Have Relapsed After Therapy and Are Not Eligible for Stem Cell Transplant (NCT01321541), a randomized phase 3 study. The primary outcome is Progression Free Survival (PFS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01321541 |
| Phase | Phase 3 |
| Condition | Diffuse Large B-cell Lymphoma, de Novo DLBCL, DLBCL Transformed From Indolent Lymphoma |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 312 |
| Arms in the primary outcome | 2 |
| Lead sponsor | CTI BioPharma |
| Results posted | Yes |
2. Clinical Question
Population
Patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL), or follicular grade 3 lymphoma, who had relapsed after therapy and were not eligible for stem cell transplant. The official title specifies prior CHOP-R or an equivalent regimen and describes aggressive B-cell non-Hodgkin lymphoma.
Intervention
Pixantrone + Rituximab.
Comparator
Gemcitabine + Rituximab.
Primary question
How did progression-free survival, measured from randomization to progressive disease or death due to any cause, compare between the two treatment groups? The registry reports the median and 95% confidence interval for each group.
The study also included secondary outcomes concerning overall survival, complete response rate, overall response rate, and treatment-emergent adverse events related to study drug. The registry record identifies the target population and treatment comparison, but does not report a more detailed account of eligibility criteria or the analysis population for each outcome.
3. Trial Design
This was a randomized, parallel-group Phase 3 study with single masking. The record lists an enrollment of 312 participants and describes a multicenter comparison. The two groups received pixantrone + rituximab or gemcitabine + rituximab. The arm-level outcome records include 155.0 participants for pixantrone + rituximab and 157.0 for gemcitabine + rituximab for the primary endpoint.
The study began on 2011-04-20, had primary completion on 2018-06-28, and is listed as completed. These dates describe the trial record; they do not by themselves establish how long each participant was followed. The primary outcome timeframe is described as up to 100 weeks, from randomization to progressive disease or death due to any cause, whichever was first reported.
Random allocation is intended to reduce systematic differences between treatment groups at the start of a trial. A parallel design assigns participants to one group rather than having each participant receive both treatments. The masking designation is single, but the identity of the masked party is not reported in the registry record. Details of allocation procedures, concealment, treatment schedules, adherence, and any protocol deviations are also not reported in the registry record.
The registry describes the study as evaluating efficacy in relapsed or refractory DLBCL or follicular grade 3 lymphoma. The primary endpoint is a time-to-event outcome, while the listed secondary outcomes include response outcomes and safety. The posted results do not include a reported comparative analysis for the primary outcome.
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
| Stage | Pixantrone + Rituximab | Gemcitabine + Rituximab |
|---|---|---|
| STARTED | 155 | 157 |
| COMPLETED | 72 | 61 |
| NOT COMPLETED | 83 | 96 |
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.
| Characteristic | Unit | Pixantrone + Rituximab | Gemcitabine + Rituximab | Total |
|---|---|---|---|---|
| Participants analysed | 155 | 157 | 312 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 36 | 30 | 66 |
| Age, Categorical: >=65 years | Participants | 119 | 127 | 246 |
| Sex: Female, Male: Female | Participants | 86 | 90 | 176 |
| Sex: Female, Male: Male | Participants | 69 | 67 | 136 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 1 | 1 | 2 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 4 | 1 | 5 |
| Race (NIH/OMB): White | Participants | 147 | 155 | 302 |
| Race (NIH/OMB): More than one race | Participants | 2 | 0 | 2 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 1 | 0 | 1 |
| IPI Score: IPI Score 0-2 | Participants | 73 | 73 | 146 |
| IPI Score: IPI Score 3 or more | Participants | 82 | 84 | 166 |
| Ann Arbor Stage: I-III | Participants | 81 | 76 | 157 |
| Ann Arbor Stage: IV | Participants | 74 | 81 | 155 |
| Number ofprior lines of therapy: 0-2 | Participants | 137 | 139 | 276 |
| Number ofprior lines of therapy: 3 or more | Participants | 18 | 18 | 36 |
6. Primary Endpoint
The registry lists the primary outcome as Progression Free Survival (PFS), measured over From the date of randomization to the date of progressive disease or death due to any cause (whichever is first reported) (Up to 100 weeks).
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | Months |
| Endpoint classification | Time-to-Event Analysis |
Progression-free survival (PFS) measures the time from randomization until disease progression or death due to any cause, whichever occurs first. The registry describes the timeframe as up to 100 weeks. A participant who has neither an observed progression event nor death during follow-up may have a censored observation; censoring means the exact event time is not known within the observed follow-up period.
PFS is used in trials because it combines disease progression and death into a time-to-event endpoint. It reflects both whether an event occurred and how long participants remained free of the defined event. The median is the time by which the estimated event-free proportion has reached the midpoint of the survival distribution. It is not the mean follow-up time, and it does not describe the outcome for every participant.
For pixantrone + rituximab, the reported median PFS was 7.3 months, with a 95% confidence interval from 5.2 to 8.4. For gemcitabine + rituximab, the median was 6.3 months, with a 95% confidence interval from 4.4 to 8.1. These are group-specific estimates. A median comparison alone does not account for the full event-time pattern, and the registry record does not report a hazard ratio or other sponsor-reported comparative estimate for PFS.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary results are medians of 7.3 months for pixantrone + rituximab and 6.3 months for gemcitabine + rituximab. Their respective 95% confidence intervals are 5.2 to 8.4 months and 4.4 to 8.1 months. Each estimate describes the midpoint of the observed time-to-event distribution for its group, with uncertainty represented by the interval.
The confidence intervals overlap. Overlap does not establish that the treatments are equivalent, nor does it provide a formal test of the between-group difference. The registry record does not report a sponsor analysis of the primary comparison, such as a hazard ratio, a confidence interval for a comparative effect, or a p-value. Because the endpoint is time-to-event, the two medians alone are not enough to characterize the comparison across the full follow-up period. The record also does not report the number of PFS events or the survival curve estimates needed to assess the event pattern in more detail.
The primary result should therefore be read as two separate estimates, not as a demonstrated treatment contrast. No new difference or ratio is calculated from the medians. The interval around each median conveys uncertainty about that group’s estimate; it is not an interval for the difference between groups.
For the secondary response outcomes, the registry contains participant counts and an unadjusted recalculation of group comparisons. Those calculations are descriptive and do not replace a sponsor-reported analysis. The record lists no reported analyses for those outcomes. The secondary response findings therefore offer context but should not be treated as a substitute for a reported primary-endpoint comparison or as confirmatory evidence on their own.
In particular, a nominal p-value for a secondary outcome does not establish that the primary endpoint differs between groups. The secondary outcomes also raise the issue of multiple testing: when several outcomes are examined, chance findings become more likely unless the analysis plan accounts for that multiplicity. Whether and how the study addressed this issue is not reported in the registry record.
These results are specific to the trial population and endpoint definitions recorded. They do not establish outcomes for patients outside the stated disease and transplant-eligibility context, and they do not provide a complete account of longer-term outcomes or safety. The registry record identifies overall survival as a secondary outcome, but does not include a result for it in the posted endpoint details.
9. Statistical Methods Explained
How should the primary estimates be read?
The primary endpoint is a time-to-event measure, and the registry reports a median and 95% confidence interval for each treatment group. A confidence interval expresses statistical uncertainty around an estimate under the method used to calculate it. It is not a range that contains every participant’s outcome, and it is not a direct estimate of the difference between treatment groups. Here, the intervals belong to the separate group medians. The registry record does not give a comparative confidence interval for PFS.
General statistical explanation: time-to-event analysis can use information from participants whose event has not been observed by the end of follow-up, rather than treating them as though they had an event at that time. Such participants are generally censored. Valid interpretation depends on how censoring and follow-up are handled. Specific details of those procedures are not reported in the registry record.
Why do medians not tell the whole comparison?
A median condenses a survival distribution to one point. Two groups can have medians that do not capture differences in the timing and pattern of events across the full follow-up. Comparative analyses commonly use the full event-time information, for example through a hazard ratio or a test of the survival curves. The registry record does not report a sponsor comparative analysis for the primary endpoint, so no such result can be interpreted from the posted primary estimates alone.
General statistical explanation: a hazard ratio summarizes a relative event rate over time under assumptions about how that relative rate behaves. It is not the same quantity as a ratio of medians. The record does not provide a hazard ratio for PFS, and one should not be inferred from the medians.
What do the response outcomes show statistically?
Complete response and overall response are binary outcomes: each participant is classified according to whether the defined response occurred. For a binary outcome, a percentage or proportion describes the frequency in a group. A risk difference describes the absolute contrast between group proportions; a risk ratio describes their relative contrast. These measures answer different questions and should not be interchanged.
The registry includes unadjusted recalculations for the secondary response outcomes. These are simple comparisons based on the posted summary statistics, not sponsor-reported analyses. For complete response, the recalculated risk difference is -0.138, with a 95% confidence interval from -0.237 to -0.039 and p = 0.007. For overall response, the recalculated risk difference is -0.180, with a 95% confidence interval from -0.289 to -0.071 and p = 0.001. The comparison is expressed as gemcitabine + rituximab relative to pixantrone + rituximab, so the negative signs indicate lower observed response proportions in the gemcitabine + rituximab group in these recalculations. These values do not constitute reported sponsor analyses, and the registry record does not state whether any multiplicity adjustment was used.
General statistical explanation: a p-value measures how incompatible the observed data are with a specified null hypothesis under the assumptions of the test. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of an effect. A confidence interval is useful alongside a p-value because it communicates a range of estimates compatible with the data and method. The recalculated intervals above concern unadjusted binary-outcome contrasts, not PFS.
How should the sample-size illustrations be understood?
The planning illustrations are based on the observed effect, not the trial’s own design. They assume a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation. They show participants per arm for 80% or 90% power when planning for 100%, 75%, or 50% of the observed effect. For complete response, the illustrations range from 167 participants per arm for 80% power when planning for 100% of the observed effect to 714 participants per arm when planning for 50% of the observed effect; the corresponding 90% figures are 223 and 955. For overall response, the corresponding 80% figures are 120 and 474, and the 90% figures are 160 and 634.
These are planning scenarios, not observed power and not the study’s actual sample-size justification. The justification and protocol assumptions are not reported in the registry record. General statistical explanation: a planning calculation depends on assumptions about the effect to detect and the design; using an effect estimated from trial data can be optimistic or unstable. The illustrations do not show the probability that the completed trial detected an effect.
Why can over-dispersion matter?
General statistical explanation: over-dispersion occurs when observed variability is greater than a model assumes. If ignored, standard errors can be too small and confidence intervals too narrow, which can make statistical evidence appear stronger than warranted. It is especially relevant to count or rate outcomes when outcomes vary more than expected under a simple model. The primary endpoint is time-to-event and the secondary response measures are binary; no over-dispersion assessment is reported in the registry record. This general issue should not be taken to mean that over-dispersion affected this trial.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists several secondary outcomes in addition to the primary PFS endpoint: overall survival, complete response rate, overall response rate, and treatment-emergent adverse events related to study drug. It includes unadjusted recalculations for the two response measures, but does not list reported analyses for those outcomes. A prespecified hierarchy for testing outcomes, a multiplicity adjustment, or a statement that secondary analyses were exploratory is not reported in the registry record.
Multiplicity matters because repeated testing across outcomes can increase the chance of at least one nominally notable finding even when there is no true effect. An unadjusted p-value addresses a single comparison under its model and assumptions; it does not account for other tests unless an adjustment is applied. The registry record does not establish whether any such adjustment was used in the sponsor’s analysis. The recalculated response comparisons should consequently be treated as unadjusted and not as confirmation of the primary result.
Missing-data procedures and analysis populations are also not reported in the registry record. The primary outcome is defined from randomization to progression or death, but the posted information does not describe how participants with incomplete follow-up, missing assessments, or other deviations were handled. It does not identify an intention-to-treat, per-protocol, or other analysis population for each endpoint. The number at risk and event counts over time are not included in the primary endpoint details.
These omissions limit assessment of robustness. Without an account of analysis populations, missing-data handling, censoring, and the prespecified testing strategy, readers cannot fully evaluate whether the posted estimates follow the intended analysis plan or how sensitive they may be to alternative assumptions. These are reporting limitations; they do not establish that any particular analysis choice was inappropriate.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Pixantrone + Rituximab | 59 | 153 | 38.6% |
| Gemcitabine + Rituximab | 57 | 149 | 38.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Pixantrone + Rituximab | 12 of 153 |
| Gemcitabine + Rituximab | 16 of 149 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Pixantrone + Rituximab | 153 of 153 |
| Gemcitabine + Rituximab | 148 of 149 |
Most frequent serious adverse event terms
| Event term | Organ system | Pixantrone + Rituximab | Gemcitabine + Rituximab |
|---|---|---|---|
| Anemia | Blood and lymphatic system disorders | 5 of 153 | 8 of 149 |
| Pneumonia | Infections and infestations | 8 of 153 | 4 of 149 |
| Pyrexia | General disorders | 4 of 153 | 8 of 149 |
| Febrile neutropenia | Blood and lymphatic system disorders | 5 of 153 | 1 of 149 |
| Urinary tract infection | Infections and infestations | 2 of 153 | 3 of 149 |
| Thrombocytopenia | Blood and lymphatic system disorders | 2 of 153 | 3 of 149 |
| Cardiac failure | Cardiac disorders | 3 of 153 | 2 of 149 |
| Dyspnea | Respiratory, thoracic and mediastinal disorders | 2 of 153 | 3 of 149 |
| Dehydration | Metabolism and nutrition disorders | 2 of 153 | 3 of 149 |
| Atrial fibrillation | Cardiac disorders | 2 of 153 | 2 of 149 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Pixantrone + Rituximab | Gemcitabine + Rituximab |
|---|---|---|---|
| Neutropenia | Blood and lymphatic system disorders | 105 of 153 | 87 of 149 |
| Thrombocytopenia | Blood and lymphatic system disorders | 23 of 153 | 95 of 149 |
| Anaemia | Blood and lymphatic system disorders | 37 of 153 | 67 of 149 |
| Fatigue | General disorders | 45 of 153 | 34 of 149 |
| Nausea | Gastrointestinal disorders | 38 of 153 | 22 of 149 |
| Constipation | Gastrointestinal disorders | 35 of 153 | 20 of 149 |
| Pyrexia | General disorders | 20 of 153 | 30 of 149 |
| Oedema peripheral | General disorders | 19 of 153 | 30 of 149 |
| Anorexia | Metabolism and nutrition disorders | 28 of 153 | 16 of 149 |
| Diarrhoea | Gastrointestinal disorders | 23 of 153 | 19 of 149 |
Serious events with the highest arm-level rate: anemia (5.4%), pyrexia (5.4%), pneumonia (5.2%), febrile neutropenia (3.3%), urinary tract infection (2.0%).
The registry reports serious adverse event counts for each treatment group: 59 of 153 participants at risk in the pixantrone + rituximab group and 57 of 149 in the gemcitabine + rituximab group. It also reports other adverse event counts of 153 of 153 and 148 of 149, respectively. Death counts are 12 and 16, respectively. These are descriptive counts from the registry and should not be interpreted as proof that one treatment caused more or fewer events.
The record lists anemia and pyrexia at 5.4% each, pneumonia at 5.2%, febrile neutropenia at 3.3%, urinary tract infection at 2.0%, and erysipelas at 2.0% among the top serious adverse event terms. The registry entries do not identify an arm for these term percentages, so they should not be assigned to one treatment group. Nor do the figures alone establish event severity beyond the serious-event classification, duration, recurrence, or causal relationship to study drug.
Comparing safety requires consistent definitions, exposure time, follow-up, and statistical methods. Those details are not reported in the registry record. The counts are useful as a description of reported events, but cannot support a complete comparative safety assessment on their own.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a randomized Phase 3 trial compared pixantrone + rituximab with gemcitabine + rituximab in patients with relapsed aggressive B-cell lymphoma or follicular grade 3 lymphoma who were not eligible for stem cell transplant. It reports group-specific median PFS estimates and confidence intervals. Those figures describe the observed primary endpoint summaries for the two groups.
The posted primary results do not, by themselves, establish a statistically supported difference between treatments. There is no sponsor-reported comparative estimate or test for PFS in the registry record. The median estimates cannot be turned into a valid comparative effect by subtracting them, and their confidence intervals are not a confidence interval for a treatment contrast. No conclusion about equivalence or non-equivalence follows from the available primary summaries alone.
The response outcomes offer additional information, but the recalculated comparisons are unadjusted and no sponsor-reported analyses are listed for them. Several secondary outcomes are named, while complete results for all of them are not reported in the registry record. The safety counts and serious-event terms likewise do not provide a full comparative assessment or establish causation.
General statistical explanation: statistical evidence and clinical importance are related but distinct. An estimate can be uncertain even when its point estimate appears different, and a statistically notable result does not automatically establish a meaningful benefit or harm. The posted information does not provide enough detail to assess all aspects of precision, clinical importance, missing data, or analysis robustness.
The findings also apply to the population and study conditions recorded, not automatically to other lymphoma subtypes, eligibility groups, treatment settings, or follow-up durations. The record does not report enough detail to generalize beyond that context or to draw a complete conclusion about overall survival and long-term safety.
13. Why This Trial Matters Statistically
This trial illustrates why endpoint summaries and comparative analyses must be distinguished. PFS is a time-to-event endpoint, yet the registry reports medians and confidence intervals by group without a sponsor-reported comparative estimate. The group summaries are informative, but they do not provide the same evidence as a comparison that uses the event-time information across the follow-up period.
It also demonstrates the value of keeping primary and secondary outcomes in their intended roles. Response measures can add context about disease response, but they do not answer the same question as PFS or overall survival. When multiple outcomes are examined, unadjusted secondary p-values need cautious interpretation, especially when the registry does not describe a testing hierarchy or multiplicity correction.
The posted safety figures show another reporting distinction: participant counts and adverse-event terms are descriptive, and interpretation depends on consistent definitions, exposure, attribution, and follow-up. The record does not report enough methodological detail to assess those aspects fully.
Finally, planning calculations based on observed effects are not evidence about the power of the completed trial and are not the original design rationale. Separating planning illustrations from trial design helps prevent retrospective calculations from being mistaken for protocol-based justification. Overall, this record is useful for understanding what was measured and the level of detail available, while also showing how missing comparative analyses and methodological reporting constrain interpretation.
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.
Important details for interpreting this particular trial are absent from the registry record. The primary PFS results are reported as separate medians and confidence intervals, without a sponsor-reported hazard ratio, comparative confidence interval, or p-value. Event counts, numbers at risk over time, survival curves, and the handling of censoring are not reported in the primary endpoint details. This restricts evaluation of the full time-to-event pattern and the precision of a treatment contrast.
The registry record does not identify the masked party, explain randomization procedures or allocation concealment, or describe treatment schedules and adherence. It also does not report the analysis populations for the outcomes, missing-data methods, prespecified statistical plan, or multiplicity strategy. These omissions make it difficult to assess whether the posted summaries correspond to the planned analysis and how robust they are to alternative assumptions.
Although overall survival and treatment-emergent adverse events are listed as secondary outcomes, corresponding comparative outcome analyses are not reported in the registry record in the details. Serious-event counts are descriptive, and the top serious-event percentages are not assigned to a treatment arm. The available safety information therefore cannot establish comparative risk or causation.
The response comparisons are unadjusted recalculations from posted summary statistics rather than reported sponsor analyses. Their interpretation is limited by the absence of a stated multiplicity approach and detailed analysis methods. The sample-size illustrations are based on observed effects and are not the trial’s documented design justification.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Comparison of Pixantrone + Rituximab With Gemcitabine + Rituximab in Patients With Aggressive B-cell Non-Hodgkin Lymphoma or Follicular Grade 3 Lymphoma Who Have Relapsed After Therapy and Are Not Eligible for Stem Cell Transplant — NCT01321541.
- Registry record last updated 2021-11-19; status last verified 2021-09.
- Results first posted 2021-11-19.
- 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.
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18. Record Summary
NCT01321541 is a completed, randomized, single-masked, parallel-group Phase 3 study comparing pixantrone + rituximab with gemcitabine + rituximab. The registry lists 312 participants and describes a population with relapsed or refractory aggressive B-cell lymphoma or follicular grade 3 lymphoma who were not eligible for stem cell transplant.
The primary endpoint was progression-free survival, defined as time from randomization to progressive disease or death due to any cause. Median PFS was 7.3 months (95% confidence interval, 5.2 to 8.4) for pixantrone + rituximab and 6.3 months (95% confidence interval, 4.4 to 8.1) for gemcitabine + rituximab. A sponsor-reported comparative PFS analysis is not reported in the registry record.
Secondary outcomes included overall survival, complete response, overall response, and treatment-emergent adverse events related to study drug. The response comparisons available are unadjusted recalculations, and the registry record does not report a multiplicity strategy or complete comparative results for all listed secondary outcomes.