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 Lenalidomide as Chemoprevention in Treating Patients With High-Risk, Early-Stage B-Cell Chronic Lymphocytic Leukemia (NCT01649791), a na na study. The primary outcome is Median Progression-free Survival.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01649791 |
| Phase | NA |
| Condition | B-cell Chronic Lymphocytic Leukemia, Chronic Lymphocytic Leukemia, Stage 0 Chronic Lymphocytic Leukemia |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 8 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Roswell Park Cancer Institute |
| Results posted | Yes |
2. Clinical Question
Population
Patients with high-risk, early-stage B-cell chronic lymphocytic leukemia were the intended population. The primary endpoint population is described as all treated and eligible patients. The registry lists stage 0, stage I, and stage II chronic lymphocytic leukemia among the conditions. Enrollment was 8.
Intervention
The intervention was lenalidomide used as chemoprevention. Patients were to take it by mouth once daily for 4 weeks, with treatment repeating every 4 weeks for up to 12 courses if disease progression or unacceptable toxicity did not occur. Laboratory biomarker analysis, lymph node biopsy, bone marrow aspiration, pharmacological study, and flow cytometry were also listed.
Comparator
There was no separate comparator group. The study is registered as a single-group trial, with allocation listed as NA and masking listed as none. Its design therefore does not provide a randomized, like-for-like control comparison.
Primary question
The primary endpoint was median progression-free survival, with a 24-month timeframe and a planned 95% confidence interval. The registry record does not report the median, its confidence interval, or a sponsor analysis. The question is therefore identifiable from the study description, but the posted record does not establish an observed estimate of progression-free survival.
3. Trial Design
This was a pilot study of lenalidomide as a chemopreventive agent for patients with high-risk, early-stage B-cell chronic lymphocytic leukemia. It is listed as single-group, with phase recorded as NA, allocation recorded as NA, and no masking. The registry identifies Roswell Park Cancer Institute as the sponsor. Enrollment was 8. The study started in 2010-01, and primary completion was listed as 2012-05. Its current status is terminated; the reason for termination is not reported in the registry record.
The treatment description specifies lenalidomide by mouth once daily for 4 weeks. Treatment was to repeat every 4 weeks for up to 12 courses in the absence of disease progression or unacceptable toxicity. These are the planned treatment conditions; the record does not describe how many courses participants actually received, or how treatment exposure varied among them.
Because there was no comparator arm, outcomes cannot be interpreted as a randomized contrast between lenalidomide and another treatment or observation group. A single-group study can describe outcomes among its treated participants, but it cannot separate an intervention effect from the natural course of disease or other influences using a concurrent control. The registry explicitly identifies the arms as not being a like-for-like control comparison.
Overall response rate, incidence of immune-mediated flare reaction, and expression of B-CLL co-stimulatory ligands, Mic-A, and Mic-B assessed by flow cytometry are listed as secondary outcomes. The record lists 4 outcome measures, but does not report their results. It also does not report a statistical analysis count beyond listing 0 analyses. The primary endpoint is median progression-free survival among all treated and eligible patients, with a 24-month timeframe.
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 | Treatment (Lenalidomide as Chemoprevention) |
|---|---|
| STARTED | 8 |
| COMPLETED | 5 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | Treatment (Lenalidomide as Chemoprevention) |
|---|---|
| Disease Progression | 2 |
| Adverse Event | 1 |
Analysis population for the primary outcome, as defined in the registry: All treated and eligible patients.
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: All treated and eligible patients.
| Characteristic | Unit | Treatment (Lenalidomide as Chemoprevention) |
|---|---|---|
| Participants analysed | 8 | |
| Age, Continuous | years | 63 (SD 8.8) |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 3 |
| Age, Categorical: >=65 years | Participants | 5 |
| Sex: Female, Male: Female | Participants | 1 |
| Sex: Female, Male: Male | Participants | 7 |
6. Primary Endpoint
The registry lists the primary outcome as Median Progression-free Survival, measured over 24 months.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | months |
| Endpoint classification | Time-to-Event Analysis |
Progression-free survival is a time-to-event endpoint. In general, it measures the time from a defined starting point until disease progression or another event specified by the study definition. The registry record does not give a fuller event definition or state how the time origin was set, so those details are not reported in the registry record.
The median is the point in the estimated event-time distribution at which half of the distribution lies on either side. It is often used for time-to-event outcomes because follow-up may end before every participant has experienced the event. Participants without a recorded event by their last follow-up can contribute information up to that time; this is generally described as censoring. The registry does not report follow-up details or explain how censoring was handled in this study.
A confidence interval expresses uncertainty around an estimate. The planned dispersion measure is a 95% confidence interval, which would indicate the precision of the median estimate under the analysis method. No median progression-free survival or confidence interval is reported in the registry record. The endpoint is named, but its observed value and precision cannot be assessed from this record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies median progression-free survival as the primary endpoint, with a 24-month timeframe, and defines the endpoint population as all treated and eligible patients. It does not give the median estimate or its 95% confidence interval. No sponsor analysis is reported, and the record lists 0 analyses. Consequently, the primary outcome's magnitude and precision cannot be described from the posted results.
This absence matters for interpretation. A named endpoint is not itself an outcome result. Without an estimate, there is no registry-based basis for describing the duration of progression-free survival in the study population. Without an interval, the uncertainty around an estimate also cannot be characterized. These omissions do not show that the endpoint was measured or analyzed in a particular way; those details are not reported in the registry record.
The study's single-group design further limits what an outcome estimate could establish. Even if a group-level outcome were reported, there would be no randomized comparator in this record against which to judge the outcome. Natural disease history, participant characteristics, follow-up, and other factors could influence an outcome in an uncontrolled study. The registry itself flags that the arms are not a like-for-like control comparison. It would therefore be inappropriate to interpret a hypothetical within-group outcome as a randomized treatment effect.
The record describes enrollment of 8, but does not provide participant-level outcome data, the number with evaluable endpoint information, or a breakdown of follow-up. It does not report why the study was terminated. These gaps prevent assessment of how complete the endpoint data were or whether termination affected follow-up or reporting. They also prevent an explanation of why the observed record contains no sponsor analyses.
The listed secondary outcomes include overall response rate, immune-mediated flare reaction, and biomarker expression assessed by flow cytometry. Their results are not reported in the registry record. The existence of these outcome descriptions does not establish that measurements were completed or that a result was favorable or unfavorable. Overall, the posted information establishes the study question and some design details, but does not provide the outcome results needed to estimate benefit, harm, or precision.
9. Statistical Methods Explained
Several statistical ideas help clarify what the specified endpoint could have conveyed, and what cannot be concluded from the registry. These are general explanations; they do not establish which analysis procedures the investigators used. The statistical analysis plan is not reported in the registry record.
What does a median time-to-event endpoint represent?
For a time-to-event outcome, each participant contributes information about the length of time until an event or until observation ends. The median is a central summary of the event-time distribution. It is different from an average: the median is not pulled in the same way by unusually long or short observed times. In a clinical study, this summary can be useful when the distribution of times is skewed or when some participants have not experienced the event by the end of their observed follow-up.
Progression-free survival usually concerns time until disease progression or another defined event, but the exact event definition matters. The registry names progression-free survival and states a 24-month timeframe; it does not specify the full event definition, time origin, assessment schedule, or handling of deaths. Those details are not reported in the registry record and should not be presumed.
Why does censoring matter?
When a participant has not had the event by the last time their status is known, the event time is not observed in full. In general, such information is treated as censored rather than as though the event occurred at the last contact. Time-to-event methods can use the observed follow-up while accounting for this incomplete event time. The quality of the estimate depends in part on the amount and pattern of follow-up, and on the assumptions used to handle censoring. Follow-up and censoring details are not reported in the registry record, so the adequacy of any such assumptions cannot be assessed.
A median may also be difficult to estimate if the observed follow-up does not include enough events. The registry record does not report the event count, the median, or whether the median was estimable. No conclusion about those features can be drawn from an endpoint title alone.
What does a confidence interval add?
A point estimate gives one summary value, while a confidence interval communicates its statistical uncertainty under a chosen method. A narrower interval generally indicates greater precision; a wider interval indicates less precision. The registry identifies a 95% confidence interval as the dispersion measure for the primary endpoint, but neither its limits nor the estimate itself are reported. Thus the endpoint's precision cannot be evaluated.
A confidence interval is not a guarantee that the true value lies within the particular interval, and it does not repair design limitations. In a single-group study, an interval around a group outcome would describe uncertainty in that outcome estimate, not uncertainty in a randomized comparison with an untreated or alternative-treatment group. No such comparison is specified in this record.
What is the role of a comparator?
A concurrent comparator helps distinguish changes associated with an intervention from changes that might otherwise have occurred. Random allocation, when used, helps balance measured and unmeasured characteristics on average, though it does not eliminate all uncertainty. This trial is listed as single-group, with allocation NA and no masking. There is no comparator arm to support a treatment-versus-control estimate. The registry cautions that the arms are not a like-for-like control comparison.
Accordingly, an outcome observed in the treated group would be descriptive of that group and its follow-up. It would not by itself identify what would have happened to comparable participants without the intervention. This distinction is central to interpreting pilot and single-group studies, regardless of the size or direction of an observed outcome.
How should planning calculations be read?
The registry's sample-size assumptions describe a planning illustration based on the observed effect, rather than the trial's own design. The stated illustration uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; its effect to detect is a stated fraction of the observed effect. For time-to-event tables, the described quantity is total events, using the Schoenfeld method; other tables give participants per arm. These assumptions describe planning calculations, not observed results, and they do not establish that the trial enrolled participants according to such a design.
Planning sample sizes are not observed power. They are hypothetical quantities calculated under assumptions about an effect and analysis. In this case, the trial is registered as single-group, while the stated illustration assumes two-arm equal allocation. That difference is important: an illustration using a hypothetical two-arm structure does not turn this study into a controlled comparison. No resulting sample-size values are stated in the registry record, and no observed power should be inferred.
What can be said about sponsor analyses?
The record lists 0 analyses and does not report a sponsor statistical analysis for the primary endpoint. It also does not provide hazard ratios. For a time-to-event comparison, a hazard ratio is a relative measure of event rates over follow-up under the model used; interpreting one requires the comparison, model, and assumptions to be clear. Since no sponsor hazard ratio is reported, there is no such estimate to describe. A recalculated estimate would not substitute for a sponsor analysis, and no recalculation is warranted without the necessary outcome data.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary endpoint and several secondary outcomes, but does not report a statistical analysis plan, a multiplicity adjustment, or a hierarchy for testing outcomes. Multiplicity refers generally to the increased chance of obtaining at least one apparently notable result when multiple hypotheses are tested. Methods for addressing it depend on which outcomes and comparisons were planned and how they were analyzed. No specific approach can be attributed to this study because it is not reported in the registry record.
The record does not report how missing outcome data were handled, whether follow-up was complete, or how participants who discontinued treatment were included in analyses. It also does not give the number of participants with evaluable progression-free survival data. The primary endpoint population is described as all treated and eligible patients, but the registry does not explain eligibility adjudication or the analysis population's implementation. These omissions prevent assessment of missing-data assumptions or the degree to which the endpoint population matched the intended population.
The registry lists 0 analyses. No endpoint estimates, confidence limits, hypothesis tests, or sponsor statistical methods are reported. Accordingly, the choice of analysis population, treatment of censoring, multiplicity strategy, and missing-data method are not reported in the registry record. A statistical result should not be reconstructed from the trial description or adverse-event counts.
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 |
|---|---|---|---|
| Treatment (Lenalidomide as Chemoprevention) | 2 | 8 | 25.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Treatment (Lenalidomide as Chemoprevention) | 8 of 8 |
Most frequent serious adverse event terms
| Event term | Organ system | Treatment (Lenalidomide as Chemoprevention) |
|---|---|---|
| Muscular weakness | Musculoskeletal and connective tissue disorders | 1 of 8 |
| Basal cell carcinoma | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 1 of 8 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Treatment (Lenalidomide as Chemoprevention) |
|---|---|---|
| Diarrhoea | Gastrointestinal disorders | 7 of 8 |
| Fatigue | General disorders | 7 of 8 |
| Neutropenia | Blood and lymphatic system disorders | 5 of 8 |
| Upper respiratory tract infection | Infections and infestations | 5 of 8 |
| Rash | Skin and subcutaneous tissue disorders | 5 of 8 |
| Muscle spasms | Musculoskeletal and connective tissue disorders | 4 of 8 |
| Tumour flare | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 4 of 8 |
| Dyspnoea | Respiratory, thoracic and mediastinal disorders | 4 of 8 |
| Rhinorrhoea | Respiratory, thoracic and mediastinal disorders | 4 of 8 |
| Sinusitis | Infections and infestations | 3 of 8 |
Serious events with the highest arm-level rate: muscular weakness (12.5%), basal cell carcinoma (12.5%).
The registry's safety entry lists one treatment group with 8 at risk for serious adverse events and 2 affected. For other adverse events, it lists 8 at risk and 8 affected. These are the posted counts; they do not indicate severity beyond the registry's serious-versus-other categorization. The record does not provide event-level detail for these totals or specify the observation period used for the safety counts.
The top serious terms are muscular weakness and basal cell carcinoma, each listed as 12.5%. The registry does not clarify in this entry whether a term's percentage represents participants or events, nor does it describe timing, duration, recurrence, or a causal assessment. These terms therefore should be read as safety entries, not as proof that lenalidomide caused the events.
Deaths are listed as null, so death information is not reported in the registry record. The record also does not provide a full breakdown of event grades, relatedness, or treatment discontinuations attributed to adverse events. Small-group safety summaries can be descriptive, but they cannot precisely characterize uncommon harms. No comparison with another group is available in this single-group record.
12. What the Result Does, and Does Not, Mean
The registry describes a pilot study that examined lenalidomide as a chemopreventive agent in high-risk, early-stage B-cell chronic lymphocytic leukemia. It specifies a single-group treatment plan and identifies median progression-free survival as the primary endpoint. These details establish the study's focus, but do not amount to evidence of an outcome. The registry does not report a progression-free survival estimate, confidence interval, or sponsor analysis.
The posted safety information includes counts for serious and other adverse events and lists muscular weakness and basal cell carcinoma among top serious terms. Those entries describe reported safety data, but the record does not establish causality, give a comparative safety estimate, or provide enough detail to characterize the events fully. Death information is not reported in the registry record.
Neither the endpoint description nor the treatment schedule establishes that lenalidomide slowed progression. The registry summary describes that possibility as the study's rationale, not as a reported finding. Likewise, the absence of a posted outcome estimate does not show that there was no effect. It means the record does not provide an estimate that can be interpreted.
The single-group design also means that a treated-group outcome, if available, would not supply a randomized comparison. Any interpretation would need to distinguish description of the observed group from a causal claim about treatment. The registry explicitly notes that the arms are not a like-for-like control comparison. The trial's terminated status is recorded, but the reason is not reported; it should not be treated as an explanation for missing results.
In short, the record supports statements about the study question, planned treatment, endpoint, and limited safety entries. It does not support a conclusion about the magnitude, direction, or precision of an effect on progression-free survival, nor a comparison of treatment with an alternative.
13. Why This Trial Matters Statistically
This trial is statistically instructive because its design and its endpoint need to be considered together. The registry specifies a time-to-event primary endpoint, median progression-free survival, but describes a single-group study without a randomized comparator. The endpoint could summarize time to progression-related events among treated participants, yet it would not alone identify what would have happened in a comparable group without lenalidomide.
The record also illustrates the difference between specifying an outcome and reporting its result. It names the measure, timeframe, target population, and confidence interval type, but does not give the median or interval. Readers therefore cannot assess either the estimated outcome or its precision. This is distinct from interpreting a small or uncertain result: no primary estimate is reported in the registry record.
The sample-size assumptions are another useful distinction. The registry describes a planning illustration with a two-arm equal-allocation assumption, while the registered study is single-group. Such planning calculations are not a description of the trial's actual design, and they are not observed power. Keeping those ideas separate prevents a hypothetical calculation from being mistaken for a trial result.
Finally, the safety counts and serious-event terms are descriptive entries without a comparison group or detailed event context. They show why counts, denominators, event definitions, and follow-up matter when reading safety data. The record supports careful description, but not a causal or comparative interpretation. This is the central statistical lesson: design, analysis, and reporting determine which claims a result can support.
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.
The study enrolled 8, and the registry does not report participant-level data or a detailed account of endpoint follow-up. It does not state how many participants contributed evaluable progression-free survival information, how censoring was handled, or whether the median was estimable. The primary endpoint's result and 95% confidence interval are not reported, limiting assessment of both outcome magnitude and precision.
The single-group design has no randomized comparator. It therefore cannot provide a like-for-like control comparison, as the registry itself notes. A descriptive outcome among treated participants would remain vulnerable to influences such as the natural course of disease and differences in participant characteristics. No adjustment strategy is reported.
The trial is listed as terminated, but the reason is not reported in the registry record. The record also does not describe actual treatment exposure, adherence, or the number of courses received. It does not explain missing-data handling, analysis populations beyond the primary endpoint population description, or the statistical analysis plan.
Secondary outcome results are not reported. Safety reporting gives group counts and top serious terms, but does not give event-level context, causal assessments, or death information. Taken together, these trial-specific gaps leave the study's outcomes difficult to assess from the registry record alone.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Lenalidomide as Chemoprevention in Treating Patients With High-Risk, Early-Stage B-Cell Chronic Lymphocytic Leukemia — NCT01649791.
- Registry record last updated 2016-06-30; status last verified 2016-05.
- Results first posted 2014-02-27.
- 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.
18. Record Summary
NCT01649791 is a terminated, single-group pilot study of lenalidomide as chemoprevention in high-risk, early-stage B-cell chronic lymphocytic leukemia. Enrollment was 8. The record lists no masking, allocation NA, phase NA, and no separate comparator group. Treatment was planned as oral lenalidomide once daily for 4 weeks, repeating every 4 weeks for up to 12 courses if progression or unacceptable toxicity did not occur.
The primary endpoint was median progression-free survival over a 24-month timeframe, with a 95% confidence interval specified. The median, confidence interval, and sponsor analysis are not reported in the registry record. Secondary outcomes include overall response rate, immune-mediated flare reaction, and biomarker expression. The safety entry lists 2 affected among 8 at risk for serious adverse events and 8 affected among 8 at risk for other adverse events. Muscular weakness and basal cell carcinoma are each listed as 12.5% among top serious terms. The reason for termination and death information are not reported.