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 Rituximab or Zevalin - Efficacy Trial of Therapeutic Alternatives (RoZetta) (NCT01662102), a randomized phase 3 study. The primary outcome is Progression Free Survival.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01662102 |
| Phase | Phase 3 |
| Condition | Follicular Lymphoma |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 1 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Spectrum Pharmaceuticals, Inc |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned previously untreated participants with follicular lymphoma who had an initial therapeutic response to rituximab plus chemotherapy. The registry describes the intended study as multicenter, but the primary outcome note says enrollment was low at only 1 site. It reports that 0 participants are included in the primary outcome population because of the risk of identifying a person.
Intervention
The experimental strategy was consolidation with Zevalin, described in the arm record as 90Y-ibritumomab tiuxetan administered 8 to 12 weeks after the last chemotherapy infusion. The study question concerns this consolidation strategy after the initial response to rituximab plus chemotherapy.
Comparator
The comparison strategy was maintenance treatment with rituximab. The arm description says it was to be administered by intravenous infusion every 8 weeks, beginning 8 to 12 weeks after the last R-chemotherapy cycle. The treatment descriptions specify planned regimens, not evidence that participants received them.
Primary question
The primary question was whether the two post-response strategies differed in progression-free survival. The registry defines progression-free survival from randomization until progression, relapse, death from any cause, or introduction of a new anti-lymphoma treatment. No comparative estimate or participant-level outcome result is reported.
3. Trial Design
RoZetta is listed as a phase 3, randomized, open-label, parallel-group study. Its official title describes a multicenter comparison in previously untreated follicular lymphoma after response to rituximab plus chemotherapy. The registry lists Spectrum Pharmaceuticals, Inc as sponsor and gives the status as terminated. The recorded start date is 2012-12-11, and the primary completion date is 2013-03-05. The reason for termination is not reported in the registry record.
The planned comparison assigned participants to Zevalin regimen consolidation or rituximab maintenance. The Zevalin description places treatment 8 to 12 weeks after the last chemotherapy infusion. The rituximab description specifies intravenous treatment every 8 weeks, starting 8 to 12 weeks after the last R-chemotherapy cycle. These descriptions characterize intended treatment strategies; the record does not report how many participants received either regimen or their treatment adherence.
Although the study is described as multicenter, the primary outcome note says enrollment was low at only 1 site. The registry lists enrollment as 1. It also says 0 participants are reported for the primary outcome because of the risk of identification. That privacy-related reporting statement is important when interpreting the absence of results: it does not provide comparative outcome data. The record lists 14 outcome measures and 0 analyses. It does not report a sample-size justification, detailed statistical analysis plan, or reason for stopping the study.
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 | Zevalin Regimen Consolidation (Group A) | Rituximab Maintenance (Group B) |
|---|---|---|
| STARTED | 1 | 0 |
| COMPLETED | 0 | 0 |
| NOT COMPLETED | 1 | 0 |
Reasons for not completing this period:
| Reason | Zevalin Regimen Consolidation (Group A) | Rituximab Maintenance (Group B) |
|---|---|---|
| Sponsor's decision | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: Due to the low number of participants enrolled at only 1 site, 0 participants are reported due to the risk of identification of a person.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
Population: 1 participant was enrolled in the Zevalin Regimen Consolidation (Group A) arm. Due to confidentiality considerations, baseline data is not being provided to protect participant privacy.
| Characteristic | Unit | Zevalin Regimen Consolidation (Group A) | Rituximab Maintenance (Group B) | Total |
|---|---|---|---|---|
| Participants analysed | 0 | 0 | 0 | |
| Age, Categorical: <=18 years | — | — | — | |
| Age, Categorical: Between 18 and 65 years | — | — | — | |
| Age, Categorical: >=65 years | — | — | — | |
| Sex: Female, Male: Female | — | — | — | |
| Sex: Female, Male: Male | — | — | — | |
| Ethnicity (NIH/OMB): Hispanic or Latino | — | — | — | |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | — | — | — | |
| Ethnicity (NIH/OMB): Unknown or Not Reported | — | — | — | |
| Race (NIH/OMB): American Indian or Alaska Native | — | — | — | |
| Race (NIH/OMB): Asian | — | — | — | |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | — | — | — | |
| Race (NIH/OMB): Black or African American | — | — | — | |
| Race (NIH/OMB): White | — | — | — | |
| Race (NIH/OMB): More than one race | — | — | — | |
| Race (NIH/OMB): Unknown or Not Reported | — | — | — |
6. Primary Endpoint
The registry lists the primary outcome as Progression Free Survival, measured over Up to approximately 2.7 months.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was progression-free survival, or PFS. The registry defines PFS as the time from randomization until progression, relapse, death from any cause, or the introduction of a new anti-lymphoma treatment, including chemotherapy, radiation therapy, or immunotherapy. It is a time-to-event measure: it captures both whether an event occurs and how long participants remain without a qualifying event after randomization.
In general, PFS can be useful when a study seeks to compare how long participants remain free of disease progression or other specified events. Its interpretation depends on a clear event definition, consistent follow-up, and an analysis that accounts for participants who have not experienced an event by the end of observation. The registry definition includes several event types, so PFS is not limited to recorded progression alone.
The registry gives the primary endpoint timeframe as up to approximately 2.7 months. It does not report a PFS estimate, event count, confidence interval, or comparison between treatment groups. It states that 0 participants are reported for the primary outcome because low enrollment at only 1 site could create a risk of identifying a person. Thus, the endpoint is defined, but the record does not provide results with which to assess the comparative PFS experience.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a clinically framed randomized comparison, but it does not provide the outcome information needed to estimate a treatment difference. Although the primary endpoint is defined as PFS, no group-specific PFS values, event counts, hazard ratio, confidence interval, or significance test are reported. The record lists 0 analyses. Consequently, the posted record cannot establish the direction or magnitude of any difference between Zevalin consolidation and rituximab maintenance.
The registry lists enrollment as 1 and separately states that 0 participants are reported for the primary outcome. The outcome note attributes this reporting choice to low enrollment at only 1 site and the risk of identifying a person. The absence of reported PFS values therefore should not be interpreted as proof that no progression, relapse, death, or new anti-lymphoma treatment occurred. Nor does it show that the treatment groups had identical outcomes. It means the record does not disclose usable comparative endpoint results.
The trial status is terminated, but the reason for termination is not reported in the registry record. Termination alone does not identify whether recruitment, operational issues, safety, or another consideration led to stopping. Those explanations should not be inferred. The record also does not give a statistical analysis plan or explain how the planned randomized comparison would have been analyzed.
General statistical interpretation: a point estimate describes the observed effect under a specified analysis, while a confidence interval conveys uncertainty around that estimate. Neither can be interpreted for this comparison because neither is reported. A p-value, even if available, would not by itself describe the size or precision of an effect; here, no p-value is reported either. With the outcomes withheld and no analyses listed, the appropriate conclusion is that comparative efficacy is not estimable from this registry record, rather than that one strategy performed better or worse.
The listed adverse-event fields do not resolve this gap. The record gives zero at-risk and affected counts for serious and other adverse events in both arms, while deaths are recorded as null. Given the absence of reported outcome populations and the explicit privacy-related suppression of the primary outcome population, these entries cannot be read as evidence that participants experienced no adverse events. They should be described as registry entries, not as a complete safety comparison.
9. Statistical Methods Explained
What was the randomized design intended to compare?
Randomization is a method for assigning participants to treatment strategies by chance. In general, it aims to make groups comparable with respect to both known and unknown characteristics at the time of assignment. A randomized parallel-group design assigns participants to one strategy or the other, with each participant following an assigned group. The record identifies this study as randomized and parallel, but does not report the allocation sequence method, concealment procedures, or actual treatment receipt. Masking is listed as none, consistent with an open-label description; the record does not describe any additional measures to reduce bias in outcome assessment.
How is a time-to-event outcome analyzed?
General explanation: time-to-event methods analyze the time from a defined starting point to a specified event. Participants who have not had an event by the end of observation, or whose observation ends earlier, may be censored rather than counted as having experienced the event. A survival curve can describe the estimated proportion remaining event-free over follow-up, while a hazard ratio can compare event rates over time under a model. These methods require information about event times, censoring, follow-up, and the analysis population.
The registry defines the PFS starting point as randomization and lists progression, relapse, death from any cause, or introduction of new anti-lymphoma treatment as events. It does not report the event times, censoring information, group-specific survival estimates, or a hazard ratio. It also does not name the method used to estimate PFS. Without these data, the statistical properties of a proposed PFS comparison cannot be checked from the record.
What do confidence intervals and significance tests contribute?
General explanation: an estimate summarizes an observed contrast, and a confidence interval indicates the range of values reasonably compatible with the data under the statistical method used. A narrow interval indicates greater precision than a wide interval, while an interval spanning materially different possibilities can signal substantial uncertainty. A significance test evaluates compatibility with a specified null hypothesis under stated assumptions; it is not a measure of clinical importance and does not replace an estimate or its interval.
No effect estimate, confidence interval, or p-value is reported for the primary comparison. There is therefore no statistical basis in the registry record for judging either the size or precision of a difference in PFS. The record also does not report covariate adjustment, stratification factors, handling of protocol deviations, or a prespecified hypothesis-testing procedure.
What is the role of the sample-size assumptions?
The record describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect; time-to-event planning is expressed as a total number of events using the Schoenfeld method, while other planning values are expressed as participants per arm. These are planning assumptions, not a report of the trial's own design justification. The registry does not report the effect estimate needed to interpret such planning illustrations, nor does it report a sample-size justification for this trial. Any planning value is not observed power and does not recover results that are absent from the record.
In general, sample-size planning depends on the target effect, variability or event rate, chosen error threshold, allocation, and analysis method. If the assumed effect differs from the effect ultimately observed, the planning requirement may not describe the precision achieved. Here, the record's enrollment and privacy note prevent a meaningful assessment of whether the intended comparison was adequately informed by outcome data.
Why can over-dispersion matter?
General explanation: over-dispersion occurs when observed variability is greater than a statistical model assumes. If it is ignored, standard errors may be too small and confidence intervals too narrow. The appropriate approach depends on the outcome type and the model. The registry does not identify an over-dispersion issue or a model for the listed outcomes, so this general consideration cannot be linked to a reported analysis in this trial.
Overall, the record provides enough design information to identify the intended randomized comparison and endpoint definition, but not enough analytic detail or outcome data to reproduce, evaluate, or interpret a treatment-effect estimate.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 14 outcome measures, including complete response rate, event-free survival, time to progression, time to next anti-lymphoma treatment, time to next chemotherapy, overall response rate, overall survival, and transformation at first progression. It lists 0 analyses. The record does not report which outcomes were formally tested, how any primary and secondary hypotheses were prioritized, or whether adjustments were planned for multiple comparisons. A multiplicity strategy is therefore not reported in the registry record.
General explanation: when many outcomes, time points, subgroups, or treatment contrasts are examined, the chance of at least one apparently notable result can increase. Prespecifying a primary comparison and an approach to secondary analyses helps readers distinguish confirmatory testing from exploratory findings. No such analysis details are available for this study, so no claim about multiplicity control or selective reporting can be made.
The primary outcome note says 0 participants are reported because of low enrollment at only 1 site and the risk of identifying a person. The record does not report missing-data counts, reasons for missingness beyond that privacy statement, censoring patterns, or methods for handling missing observations. It also does not describe intention-to-treat, per-protocol, or safety analysis populations. These omissions make it impossible to evaluate how participants would have been included in endpoint analyses or whether missingness could affect an estimate.
These are limits of the registry record, not evidence that the investigators did or did not use particular procedures. The analysis population, missing-data strategy, and multiplicity plan are not reported in the registry record.
11. What the Result Does, and Does Not, Mean
The record establishes what investigators intended to compare: Zevalin consolidation versus rituximab maintenance following an initial response to rituximab plus chemotherapy in previously untreated follicular lymphoma. It defines PFS and identifies the study as randomized, open-label, and parallel group. Those details clarify the research question and the planned treatment contrast.
It does not establish the comparative PFS outcome. No group-specific event data, PFS estimates, effect estimates, confidence intervals, or statistical tests are reported, and the registry lists 0 analyses. The primary outcome note says 0 participants are reported because of the risk of identification after low enrollment at only 1 site. This means the posted results do not support a conclusion about which strategy had better, worse, or similar outcomes.
General explanation: an absence of an estimate is not an estimate of no effect. Likewise, an absence of reported adverse events is not equivalent to evidence that no adverse events occurred. The safety entries list zero counts in the specified fields and null deaths, but the record does not provide the underlying participant-level context needed to interpret them as a complete safety assessment.
The terminated status also does not establish why the study ended or what its results would have been if it had continued. The reason for termination is not reported in the registry record. The record therefore supports a description of the trial's design and reporting limitations, but not a treatment recommendation, an efficacy claim, or a conclusion about safety.
12. Why This Trial Matters Statistically
This trial matters statistically because it illustrates the difference between a clearly stated research question and an answer supported by analyzable results. The registry identifies a randomized comparison and defines a time-to-event endpoint, but lists 0 analyses and reports no comparative PFS data. A trial's design label does not, by itself, establish that a treatment effect can be estimated from the posted record.
The privacy note is also important. The registry says the primary outcome population is reported as 0 because the low enrollment at only 1 site creates a risk of identifying a person. This shows how reporting constraints can limit what readers can learn from a study record, even when the endpoint definition and intended comparison are available. It also requires care in distinguishing a suppressed result from a result of zero events or no difference.
General statistical lesson: interpretable comparative estimates require information about outcomes in each randomized group, follow-up, event definitions, and analysis procedures. Precision depends on the amount and pattern of information available, not merely on the phase or randomized design. When results are unavailable, confidence intervals and hypothesis tests cannot compensate for the missing evidence.
The record also demonstrates why termination status should be read descriptively. It identifies the study as terminated, but gives no reason. Statistical interpretation should not fill that gap with speculation. The most defensible account is limited to the stated design, endpoint, enrollment information, and absence of reported analyses.
13. 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 largest trial-specific limitation in the registry record is the lack of a reportable primary outcome population: the record states that 0 participants are reported because enrollment was low at only 1 site and reporting could risk identification. Although enrollment is listed as 1, no participant-level PFS data or treatment-group outcome summaries are given. This prevents estimation of the randomized comparison and assessment of its precision.
The record lists the status as terminated, but does not report the reason. It also does not describe the recruitment history, whether the planned enrollment target changed, or whether participants completed the assigned regimens. The listed treatment descriptions are plans and do not establish treatment exposure or adherence.
Further, the registry reports 0 analyses and does not provide a statistical analysis plan, analysis populations, censoring details, missing-data methods, or multiplicity procedures. The primary endpoint timeframe is stated as up to approximately 2.7 months, but no observed follow-up distribution or event information is reported. The primary outcome note's privacy rationale limits the ability to judge what information was collected and how it was summarized.
The adverse-event record lists zero at-risk and affected counts in both arms, while death counts are null. Without reported participant populations or explanatory detail, these entries do not support a comparative safety interpretation. Taken together, these limitations mean the registry record describes the intended study question more fully than it reports the study's outcomes.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Rituximab or Zevalin - Efficacy Trial of Therapeutic Alternatives (RoZetta) — NCT01662102.
- Registry record last updated 2021-10-04; status last verified 2021-09.
- Results first posted 2016-01-11.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
17. Record Summary
NCT01662102, titled Rituximab or Zevalin - Efficacy Trial of Therapeutic Alternatives (RoZetta), is listed as a phase 3 randomized, open-label, parallel-group study sponsored by Spectrum Pharmaceuticals, Inc. It compared planned Zevalin consolidation with rituximab maintenance after response to rituximab plus chemotherapy in previously untreated follicular lymphoma. The registry lists enrollment as 1 and status as terminated.
The primary endpoint was PFS, defined from randomization to progression, relapse, death from any cause, or new anti-lymphoma treatment. The registry lists 14 outcome measures and 0 analyses. It reports 0 participants for the primary outcome because low enrollment at only 1 site raised a risk of identification. No comparative PFS estimate or statistical result is reported, and the reason for termination is not reported in the registry record.