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 Anti-Tac(Fv)-PE38 (LMB-2) to Treat Chronic Lymphocytic Leukemia (NCT00077922), a na phase 2 study. The primary outcome is Response Rate.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00077922 |
| Phase | Phase 2 |
| Condition | Leukemia, Lymphocytic, Chronic |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 15 |
| Arms in the primary outcome | n/a |
| Lead sponsor | National Cancer Institute (NCI) |
| Results posted | Yes |
2. Clinical Question
Population
Adults with chronic lymphocytic leukemia (CLL), CD25 proteins on their cancer cells, and disease progression within 2 years of fludarabine treatment were the intended study population. The registry describes 15 enrolled participants.
Intervention
Participants received LMB-2, a recombinant immunotoxin. The described regimen was 40 micrograms/kg every other day on cycle days 1, 3, and 5, with cycles every 4 weeks and up to six cycles.
Comparator
There was no comparison group. The registry describes a single-group study with no allocation to treatment groups, so the treatment outcome cannot be contrasted with a concurrent control group in this trial.
Primary question
The primary endpoint was Response Rate, measured as the number of participants. Response was classified using the 1996 National Cancer Institute Working Group Criteria. The observed response result is not reported in the registry record.
The clinical question was whether participants meeting the eligibility description had a response to LMB-2 during the study’s follow-up. The registry says participants were followed for at least 30 days after their last treatment; because the study allowed six treatment cycles, follow-up could extend up to 7 months. The available record does not state how many participants met response criteria, how many had complete or partial responses, or how the endpoint was analyzed.
The intervention is described as an antibody-toxin construct: an engineered antibody binds to cells bearing CD25, and a bacterial toxin is intended to kill cells to which it binds. That description explains the treatment’s proposed targeting mechanism, but does not establish that the treatment produced a clinical response in this study. The record’s primary outcome result is not reported in the registry record, so the trial-specific answer to the response question cannot be determined from the posted results.
3. Trial Design
This was a Phase II, single-group clinical trial sponsored by the National Cancer Institute. The registry lists the study as completed, with enrollment of 15. It records a start date of 2004-02-29 and a primary completion date of 2011-12-31. These dates describe the study record and do not, by themselves, explain how long any individual participant was followed.
The intervention was LMB-2 for CLL. The registry describes a dose of 40 micrograms/kg every other day for three doses on cycle days 1, 3, and 5, with each cycle lasting 4 weeks. Participants could receive up to six cycles. The treatment was infused over 30 minutes through an intravenous catheter or central venous line, according to the study summary. The registry lists no masking and no allocation to different groups.
Because this was a single-group study, outcomes are descriptive of the participants who received LMB-2. There was no concurrent control group in the registry record against which to estimate a comparative treatment effect. Changes in disease status cannot be separated, using this design alone, from other influences on outcomes over time. This does not prevent describing the response endpoint or adverse events; it limits what causal comparisons can be made.
The registry identifies Response Rate, measured in participants, as the primary outcome. It describes response classification using the 1996 National Cancer Institute Working Group Criteria and gives follow-up as at least 30 days after the final treatment, potentially up to 7 months if all six cycles were allowed. The record does not report the observed primary endpoint result, an analysis plan, or a sample-size justification. Those details should not be inferred from the Phase II label or enrollment count.
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 | LMB-2 in Chronic Lymphocytic Leukemia |
|---|---|
| STARTED | 15 |
| COMPLETED | 15 |
| NOT COMPLETED | 0 |
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 | LMB-2 in Chronic Lymphocytic Leukemia |
|---|---|---|
| Participants analysed | 15 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 9 |
| Age, Categorical: >=65 years | Participants | 6 |
| Age, Continuous | years | 61.36 (SD 7.6) |
| Sex: Female, Male: Female | Participants | 5 |
| Sex: Female, Male: Male | Participants | 10 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 1 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 14 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 2 |
| Race (NIH/OMB): White | Participants | 13 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 15 |
6. Primary Endpoint
The registry lists the primary outcome as Response Rate, measured over Patients were followed for at least 30 days after last treatment. Because the study allows 6 treatment cycles, this can be up to 7 months..
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is named Response Rate, with the unit recorded as participants. Response status was assessed using the 1996 National Cancer Institute Working Group Criteria for CLL. The criteria described in the registry distinguish complete response, partial response, progressive disease, and stable disease. Complete response involves the absence of hepatomegaly, splenomegaly, or lymphadenopathy by physical examination and appropriate imaging, with specified lymph-node size criteria. Partial response includes at least a 50% decrease in peripheral blood lymphocyte count from pretreatment baseline. Progressive disease includes at least a 50% increase in the summed products of the greatest perpendicular dimensions of at least two lymph nodes on consecutive examinations 2 weeks apart, subject to the stated node-size condition, or the appearance of new palpable lymph nodes. Stable disease is defined as not meeting the other criteria.
These categories provide a structured way to describe disease status using clinical examination, imaging, and blood counts. General statistical context: a response endpoint can make a trial outcome easier to interpret by reducing several measurements to a clinically defined classification. The classification depends on the recorded criteria and assessment schedule, however, and the registry does not provide participant-level assessments or the resulting category counts.
The record does not specify exactly which response categories were counted as a response for the named Response Rate endpoint. Most importantly, the number of participants meeting the primary endpoint is not reported in the registry record. Thus, the endpoint definition is available, but its observed result and precision cannot be assessed from the posted results.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a primary response endpoint but does not report its observed result. It gives no number of participants meeting the response definition, no response proportion, and no confidence interval or test result for that endpoint. As a result, the posted information does not establish the size or precision of the observed response finding. The absence of a reported response result is not evidence that no responses occurred; it means the primary endpoint outcome is not reported in the registry record.
The available adverse-event summary is descriptive. The record lists 7 participants with serious adverse events among 15 at risk, and 15 participants with other adverse events among 15 at risk. It also reports 0 deaths. These summaries concern the group receiving LMB-2 and do not provide a comparative safety estimate. The listed serious-event terms and percentages describe what the registry record reports, but the record does not give participant-level timing, duration, severity grades, or event overlap for those terms.
General statistical context: a confidence interval conveys uncertainty around an estimate, with its width reflecting both the amount of information and the method used. Without the primary response count or an interval, readers cannot assess how precisely the response outcome was estimated. A p-value, if reported, would address compatibility between data and a specified statistical model or null hypothesis; it would not by itself measure clinical importance. The registry record does not report a primary-endpoint p-value or statistical model.
The single-group design also defines the scope of interpretation. It can describe outcomes observed among enrolled participants, but without a concurrent comparison group it cannot, on its own, quantify how outcomes would have differed under another treatment or no study treatment. Differences between this enrolled population and other populations may also limit how broadly the findings apply. The eligibility description is specific to CD25-positive CLL and disease progression within 2 years of fludarabine treatment.
The reported enrollment of 15 is relevant context for the scale of the trial, but it does not substitute for the missing response result. No effect estimate should be reconstructed from enrollment, the endpoint definition, or the adverse-event figures. The registry record does not report an analysis of the primary endpoint, and no recalculated response estimate is available in the record. The defensible interpretation is therefore limited: the trial design and endpoint are described, adverse-event summaries are posted, and the primary response finding is not reported in the registry record.
9. Statistical Methods Explained
What can be inferred from the design?
The registry describes a single-group Phase II study with no allocation to treatment groups and no masking. The statistical description should therefore begin with a distinction between within-group outcome description and a comparison between treatments. General statistical context: a single-group study can summarize how many participants experienced an outcome under the study conditions. It does not supply the concurrent counterfactual outcome that a randomized comparison can use to estimate what might have happened under a different treatment.
The primary outcome is named Response Rate and its unit is participants. The registry does not give the response count or a reported analysis. Consequently, it is not possible to reproduce an estimate, assess its uncertainty, or evaluate whether a particular statistical test was used. The record lists 0 analyses. It does not report a statistical analysis plan, model, confidence interval method, hypothesis test, or adjustment procedure. The Phase II label does not fill in those missing methods.
How should a response outcome be understood?
General statistical context: a binary outcome classifies each assessed participant according to whether a defined event occurred. A response-rate analysis usually relates the number meeting the response definition to the number assessed for that endpoint. That interpretation depends on a clear endpoint rule and a known analysis population. Here, the registry names a participant-count endpoint and gives clinical classification criteria, but it does not report the response count, the number assessed, or how missing assessments were handled. It also does not state exactly which status categories were included in the response-rate numerator.
For a binary outcome, uncertainty is important because an observed count is only an estimate of the outcome frequency in a broader population. General statistical context: a confidence interval describes a range of values compatible with the observed data and the chosen method. It does not guarantee that the true value falls inside that particular interval, nor does it resolve design limitations such as the lack of a concurrent control. No interval or primary response estimate is reported in the registry record, so precision cannot be evaluated for this endpoint.
What do over-dispersion and model choice mean?
General statistical context: when data are modeled as counts or binary outcomes, a model makes assumptions about how observations vary. Over-dispersion means the observed variability is greater than the model expects. If it is ignored, uncertainty can be understated and inferential results can appear more precise than warranted. Model choice should follow the outcome structure, study design, and analysis plan rather than be inferred from the endpoint label alone. The registry record does not report a model or information that would establish whether over-dispersion was assessed. No conclusion about model fit can be drawn.
What does the planning illustration represent?
The registry describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect. For time-to-event outcomes, the described quantity is total events; for other outcomes, it is participants per arm. These are planning assumptions, not results from this single-group trial and not evidence of observed power. The resulting planning values and the effect estimate underlying that illustration are not reported in the registry record.
General statistical context: a sample-size calculation asks how much information a future study would need under stated assumptions. The result depends on the target effect, variability or event rate, significance level, power target, allocation, and analysis method. If the assumed effect is optimistic or uncertain, the resulting sample-size estimate may not be a reliable guide. A planning calculation does not show that a completed study had a particular probability of detecting an effect after the fact; observed power is not a substitute for an effect estimate and its uncertainty.
What can be said about recalculation?
The record does not provide a primary response count, an analysis result, or summary statistics from which an unadjusted response estimate could be recalculated. No recalculated primary result is therefore reported. General statistical context: recalculation from posted summary data can be useful as a transparent check when the inputs and definitions are available, but it cannot recover absent outcome data or correct an unclear endpoint definition. If a sponsor analysis and a simple recalculation disagree, the sponsor’s own analysis takes precedence; no such discrepancy is reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry record does not report a statistical analysis plan addressing multiplicity, missing outcome data, or analysis populations. It identifies Response Rate as the primary endpoint and lists adverse events as a secondary outcome, but it does not say whether other outcomes or subgroup analyses were tested, or whether any adjustment for multiple comparisons was planned. This is not evidence that multiplicity was or was not addressed outside the information in the registry record.
General statistical context: multiplicity arises when several hypotheses or outcomes are examined. The more analyses considered, the greater the chance that some result may appear unusual by chance if each is interpreted independently. A prespecified primary endpoint and a documented analysis plan help readers distinguish confirmatory analyses from exploratory ones. Here, the endpoint is identified, but the analysis plan and any multiplicity strategy are not reported in the registry record.
The record also does not report how missing or unevaluable response assessments were handled, the number assessed for the primary outcome, or the population included in the primary analysis. General statistical context: excluding participants with missing assessments can change the composition of the analyzed group, while other approaches make different assumptions about unobserved outcomes. Interpretation depends on knowing the approach, the amount of missingness, and whether missingness could be related to outcome or treatment experience. None of those details is reported for the primary response endpoint.
The registry reports adverse-event risk and affected-participant counts, but does not describe the analysis population conventions behind those summaries beyond the listed at-risk counts. No imputation method, sensitivity analysis, or prespecified subgroup strategy is reported in the registry record. These omissions limit assessment of how robust the posted summaries are to choices about outcome definition and participant inclusion.
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 |
|---|---|---|---|
| LMB-2 in Chronic Lymphocytic Leukemia | 7 | 15 | 46.7% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| LMB-2 in Chronic Lymphocytic Leukemia | 0 of 15 |
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 |
|---|---|
| LMB-2 in Chronic Lymphocytic Leukemia | 15 of 15 |
Most frequent serious adverse event terms
| Event term | Organ system | LMB-2 in Chronic Lymphocytic Leukemia |
|---|---|---|
| Infection (documented clinically or microbiologically) | Infections and infestations | 2 of 15 |
| Hypoxia | Respiratory, thoracic and mediastinal disorders | 2 of 15 |
| Platelets | Blood and lymphatic system disorders | 1 of 15 |
| Cardiac-ischemia/infarction | Cardiac disorders | 1 of 15 |
| Cardiac troponin I (cTnI) | Cardiac disorders | 1 of 15 |
| Hypotension | Cardiac disorders | 1 of 15 |
| Infection | Infections and infestations | 1 of 15 |
| Infection with normal ANC or Grade 1 or 2 neutrophils::Lung (pneumonia) | Infections and infestations | 1 of 15 |
| Glucose, serum-low (hypoglycemia) | Metabolism and nutrition disorders | 1 of 15 |
| Potassium, serum-low (hypokalemia) | Metabolism and nutrition disorders | 1 of 15 |
Most frequent non-serious adverse event terms
| Event term | Organ system | LMB-2 in Chronic Lymphocytic Leukemia |
|---|---|---|
| Albumin, serum-low (hypoalbuminemia) | Metabolism and nutrition disorders | 14 of 15 |
| Fever (in the absence of neutropenia, where neutropenia is defined as ANC <1.0 x 10e9/L) | General disorders | 11 of 15 |
| AST, SGOT(serum glutamic oxaloacetic transaminase) | Metabolism and nutrition disorders | 11 of 15 |
| Edema: limb | Blood and lymphatic system disorders | 10 of 15 |
| Hemoglobin | Blood and lymphatic system disorders | 9 of 15 |
| Weight gain | General disorders | 9 of 15 |
| Neutrophils/granulocytes (ANC/AG) | Blood and lymphatic system disorders | 8 of 15 |
| Magnesium, serum-low (hypomagnesemia) | Metabolism and nutrition disorders | 8 of 15 |
| Platelets | Blood and lymphatic system disorders | 7 of 15 |
| Fatigue (asthenia, lethargy, malaise) | General disorders | 7 of 15 |
Serious events with the highest arm-level rate: infection (documented clinically or microbiologically) (13.3%), hypoxia (13.3%), platelets (6.7%), cardiac-ischemia/infarction (6.7%), cardiac troponin i (ctni) (6.7%).
The registry lists 15 participants at risk for serious adverse events and reports 7 participants affected. For other adverse events, it lists 15 at risk and 15 affected. It reports 0 deaths. These are counts for the LMB-2 group; the registry does not provide a comparison group. The figures should be read as descriptive safety summaries, not as estimates of comparative risk.
The serious adverse-event terms with the largest listed percentages are Infection (documented clinically or microbiologically), 13.3%, and Hypoxia, 13.3%. The registry also lists Platelets, Cardiac-ischemia/infarction, Cardiac troponin I (cTnI), and Hypotension, each at 6.7%. Those percentages are reproduced as recorded. The record does not provide the corresponding exact participant counts for each term, explain the denominator used for the term percentages, or state whether participants could appear under more than one term.
General statistical context: an adverse-event count indicates how many participants were recorded as affected under a category; it does not by itself describe event severity, duration, timing, or causal attribution. A participant may experience more than one event, so event terms should not be added to obtain a participant total. The record does not provide enough detail to infer such totals or overlaps. The reported counts and terms are useful for describing what was recorded, but the small single-group study and absence of a comparator limit comparative safety interpretation.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a Phase II, single-group study of LMB-2 in CD25-positive CLL was completed and that 15 participants were enrolled. It identifies a response-based primary endpoint, describes the criteria used to classify disease status, and reports adverse-event summaries. It does not report the observed primary response result. Readers therefore cannot determine from the posted results how many participants met the response definition, what the response rate was, or how precisely it was estimated.
The adverse-event data show that the registry recorded serious adverse events affecting 7 participants, other adverse events affecting 15 participants, and 0 deaths. The listed serious-event terms and percentages provide additional descriptive detail. These data do not establish that an event was caused by LMB-2, and they do not support a comparison with another treatment because the study has no concurrent control group. The record also lacks details such as event timing and overlap that would help characterize the reported safety experience.
General statistical context: a treatment effect is a comparison between outcomes under different treatment conditions. A single-group outcome can describe what occurred in the study but cannot, by itself, show what would have occurred to the same population under another condition. Eligibility restrictions also matter for interpretation: the study concerned CLL with CD25 on cancer cells and disease progression within 2 years of fludarabine treatment. The registry description does not justify extending conclusions to other populations.
The study’s completed status should not be confused with a fully reported primary outcome. Nor should the enrollment count be mistaken for an effect estimate or a measure of statistical certainty. The registry record does not report the primary response result, its uncertainty, or the analysis methods. The responsible conclusion is that the design and outcome definitions can be described, and some adverse-event counts are available, but the primary efficacy question remains unanswered by the posted results.
13. Why This Trial Matters Statistically
This trial illustrates why a registered endpoint definition and a reported endpoint result are both needed for statistical interpretation. The record describes how CLL response was classified, including clinical examination, imaging, and blood-count criteria. That makes the intended outcome more interpretable than an undefined label alone. However, without the number of participants meeting the response criteria, the endpoint cannot be summarized quantitatively from the registry record.
The single-group design is also important. It allows an account of outcomes among participants receiving LMB-2, but does not create a concurrent treatment comparison. This distinction matters because a change observed during treatment is not the same as an estimated treatment effect relative to another strategy. The design therefore places a clear boundary on causal interpretation, regardless of how the endpoint is defined.
The record also offers a practical lesson about safety summaries. Counts of participants affected and percentages for specific terms answer different descriptive questions. They should not be added together without information about overlap and denominators. Serious-event counts, other adverse-event counts, listed terms, and deaths provide a record of reported safety categories, but not a complete account of severity, timing, or comparative risk.
Finally, the absence of a reported primary analysis plan, missing-data approach, and analysis population makes it difficult to assess the path from endpoint definition to result. These details are part of statistical transparency: they allow readers to understand which participants and assessments contributed to an estimate and how uncertainty was handled. In this record, the response outcome itself is not reported, so those questions cannot be resolved. The statistical importance lies in keeping the available descriptive evidence distinct from conclusions that require missing outcome data or a controlled comparison.
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 most consequential limitation for interpreting the primary endpoint is that its observed result is not reported in the registry record. The response definition is described, but the record does not give the number meeting the definition, the number assessed, an effect estimate, or a measure of precision. No primary-endpoint analysis is listed. This prevents readers from evaluating the magnitude or uncertainty of the response finding.
The single-group design provides no concurrent control group. As a result, the trial record cannot support a direct comparison with another treatment or separate treatment-associated outcomes from other changes over time. The study is also specific to participants with CD25-positive CLL and the eligibility history described in the registry; applicability to other groups is not established by this record.
The registry does not report the statistical analysis plan, handling of missing or unevaluable response assessments, definition of analysis populations, or multiplicity procedures. It does not state which response categories counted toward the named Response Rate endpoint. These missing details make it harder to assess the reproducibility and interpretation of any primary result, even though the clinical classification criteria are described.
For safety, the record supplies participant counts and selected serious-event terms, but does not report event-level details such as timing, duration, severity grades, or overlap among terms. The at-risk counts are listed, but the denominator for the individual term percentages is not specified in the record. Without a comparator, these summaries cannot quantify a relative safety difference. The record also does not report a sample-size justification, interim analyses, or a complete statistical plan; those details should not be inferred from the study phase or its enrollment.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Anti-Tac(Fv)-PE38 (LMB-2) to Treat Chronic Lymphocytic Leukemia — NCT00077922.
- Registry record last updated 2018-01-23; status last verified 2017-12.
- Results first posted 2012-11-15.
- 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
The registry describes NCT00077922 as a completed Phase II, single-group study of LMB-2 in CD25-positive chronic lymphocytic leukemia, sponsored by the National Cancer Institute. Enrollment was 15. The described regimen was 40 micrograms/kg every other day on cycle days 1, 3, and 5, with cycles every 4 weeks and up to six cycles.
The primary endpoint was Response Rate, measured in participants using the 1996 National Cancer Institute Working Group Criteria. The primary response result and its statistical analysis are not reported in the registry record. Safety summaries list 7 participants with serious adverse events, 15 with other adverse events, and 0 deaths. The registry also lists selected serious-event terms with percentages. The single-group design and missing primary result limit efficacy and comparative safety interpretation.