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 A Study of Abemaciclib in Recurrent Glioblastoma (NCT02981940), a non-randomized phase 2 study. The primary outcome is Intratumoral Abemaciclib Concentration.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02981940 |
| Phase | Phase 2 |
| Condition | Glioblastoma |
| Allocation | Non-Randomized |
| Design model | Crossover |
| Masking | None (open label) |
| Enrollment | 45 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Dana-Farber Cancer Institute |
| Results posted | Yes |
2. Clinical Question
Population
People with recurrent glioblastoma are the condition group named in the registry record. The planned enrollment is 45 participants. For the primary endpoint, the registry describes an analysis of people who received abemaciclib before surgery: 9 received postoperative abemaciclib and 1 did not, according to the protocol. This endpoint population is therefore a surgical subset, not the full enrollment.
Intervention
The drug intervention is abemaciclib. The arm descriptions specify continuous twice-daily administration in the abemaciclib arms. For the surgical cohort, participants received a short preoperative course; the Cohort 1 description specifies 10-14 days before surgery. Surgery is also listed as an intervention and provides the occasion for collecting tumor tissue.
Comparator
The registry lists abemaciclib with surgery, abemaciclib without surgery, and Cohort 1 Surgery Arm. Allocation is non-randomized, and the record cautions that these arms are not a like-for-like control comparison. The record does not establish a randomized untreated comparison. Differences between the groups may reflect their distinct treatment and surgery circumstances as well as other differences not described in the registry record.
Primary question
The primary endpoint concerns intratumoral abemaciclib concentration at surgery. It asks how much drug is measured in contrast-enhancing tumor tissue relative to plasma after preoperative treatment. Tissue and plasma were collected at surgery, at a single time point for each participant. This is a drug-distribution question, not a direct test of clinical benefit. The endpoint result itself is not reported in the registry record.
3. Trial Design
The registry describes NCT02981940, titled “A Study of Abemaciclib in Recurrent Glioblastoma,” with the official title “A Phase 0/2 Study of Abemaciclib in Recurrent Glioblastoma.” Its listed phase is Phase 2. Dana-Farber Cancer Institute is the sponsor. The study began on 2017-02-09, has a primary completion date of 2024-06-30, and is listed as active, not recruiting. Registry enrollment is 45; the record does not clarify in this information whether that figure is a final enrollment count.
Allocation is non-randomized, masking is none, and the model is listed as crossover. The record does not explain the crossover sequence or how that model applies to each arm. It describes abemaciclib with surgery, abemaciclib without surgery, and Cohort 1 Surgery Arm. Participants requiring reoperation were treated before surgery in the surgical cohorts. The arm descriptions also indicate that enrollment to the abemaciclib-without-surgery arm is complete. For the surgical cohort, the protocol was amended to end study treatment after surgery. The record does not give further details about the amendment's timing or rationale.
The primary endpoint analysis is narrower than the overall enrollment: it includes people treated with abemaciclib before surgery, including 9 who received postoperative abemaciclib and 1 who did not. The record describes tissue and plasma collection at surgery. Secondary outcomes listed include tumor pRB expression, treatment-emergent adverse events, plasma exposure measures, radiographic response rate, median progression-free survival, and overall survival. Although the registry lists 9 outcome measures, it lists 0 analyses. The results for those outcomes are not reported in the registry record. The non-randomized arms should not be read as equivalent groups assigned to provide a controlled treatment comparison.
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 | Abemaciclib With Surgery (With Postoperative Abemaciclib) | Abemaciclib Without Surgery | Abemaciclib With Surgery (No Postoperative Abemaciclib) |
|---|---|---|---|
| STARTED | 9 | 32 | 1 |
| COMPLETED | 9 | 31 | 1 |
| NOT COMPLETED | 0 | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: This analysis included patients who received abemaciclib prior to surgery, regardless of whether they received postoperative abemaciclib (n=9) or no postoperative abemaciclib (n=1) as per protocol. The surgical cohort of the protocol was amended to end study treatment after surgery.
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 | Abemaciclib With Surgery (With Postoperative Abemaciclib) | Abemaciclib Without Surgery | Abemaciclib With Surgery (No Postoperative Abemaciclib) | Total |
|---|---|---|---|---|---|
| Participants analysed | 9 | 32 | 1 | 42 | |
| Age, Continuous | years | 64 (41 to 75) | 60 (41 to 76) | 59 (59 to 59) | 60 (41 to 76) |
| Sex: Female, Male: Female | Participants | 6 | 13 | 1 | 20 |
| Sex: Female, Male: Male | Participants | 3 | 19 | 0 | 22 |
| Race/Ethnicity, Customized: White | Participants | 8 | 26 | 1 | 35 |
| Race/Ethnicity, Customized: Other | Participants | 1 | 3 | 0 | 4 |
| Race/Ethnicity, Customized: Asian | Participants | 0 | 3 | 0 | 3 |
| Region of Enrollment: United States | participants | 9 | 32 | 1 | 42 |
6. Primary Endpoint
The registry lists the primary outcome as Intratumoral Abemaciclib Concentration, measured over Single time point for each participant for collection of tissue and blood at surgery.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Full Range |
| Unit | ng/mL |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is named intratumoral abemaciclib concentration, with a listed unit of ng/mL. The record describes its definition as the mean tumor-to-plasma ratio in contrast-enhancing tissue. It says participants received abemaciclib before surgery and that tissue and plasma for this endpoint were obtained at surgery. Each participant contributes a single collection time point, rather than repeated tissue measurements over time. The record lists the summary parameter as a mean and the dispersion as a full range, but it does not report the observed mean, range, or individual endpoint values.
The endpoint addresses whether abemaciclib reaches tumor tissue, a pharmacologic distribution question relevant to treatment of a tumor in the brain. Measuring drug in tumor tissue can help characterize penetration into the target tissue; it does not, by itself, establish that the drug changes tumor growth or improves clinical outcomes. The registry's wording combines a concentration and a tumor-to-plasma ratio, while listing ng/mL as the unit. That reporting description is not fully reconciled in the record, so the intended numerical scale should be interpreted from the registry definition rather than inferred. No result or estimate of precision for this endpoint is reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive limit is that the registry describes the primary endpoint and its analysis population but does not report the endpoint result. There is no posted concentration estimate, full range, confidence interval, or test result from which to assess the magnitude or precision of drug distribution in tumor tissue. The record therefore establishes what was intended to be measured and in whom, but not what the measurement showed.
The primary endpoint population comprises 10 participants: 9 received postoperative abemaciclib and 1 did not, after receiving preoperative abemaciclib. This is a small surgical subset of the registry enrollment of 45. The endpoint concerns tissue and plasma collected at surgery, not a treatment comparison across the full study population. Even if a concentration result were available, it would describe measured drug exposure in this selected cohort at a single time point. It would not alone answer whether abemaciclib improves radiographic response, progression-free survival, or overall survival.
Allocation is non-randomized, and the registry explicitly cautions that the arms are not like-for-like controls. The surgery and non-surgery groups may differ in why surgery was required, when tissue could be collected, and which treatment course they received. Such differences complicate direct comparisons. The record does not report an adjusted comparative estimate or analysis that could address those differences. It also lists 0 analyses, so the listed secondary outcomes cannot be treated as reported efficacy or safety findings.
The safety record reports participants at risk and participants affected by serious and other adverse events for each arm. These are counts, not a randomized comparison or evidence that a particular event was caused by abemaciclib. Follow-up duration and the detailed event-level data are not reported in the registry record. Death counts are also listed, but the registry information does not establish their causes or attribution.
Planning illustrations based on an observed effect are not a measure of the trial's observed power, and the assumptions described for those illustrations are not the study's own design justification. The sample-size justification and the statistical analysis plan are not reported in the registry record. Overall, the posted information supports a description of design, endpoint, and reported safety counts, but not a conclusion about clinical efficacy or the size and precision of the primary endpoint.
9. Statistical Methods Explained
General: A statistical endpoint is a prespecified quantity used to address a study question. Here the primary endpoint is intratumoral abemaciclib concentration, described through a mean tumor-to-plasma ratio in contrast-enhancing tissue. The endpoint is measured from tumor tissue and plasma collected at surgery. It is a pharmacokinetic or drug-distribution measure rather than a direct patient-centered clinical outcome. The registry lists a mean and full range as its summary format, but the numerical results are not reported in the registry record.
What does a mean and full range describe?
General: A mean describes the arithmetic average of measurements, while the full range identifies the smallest and largest observed values. The mean can convey the central level of drug measurement, and the range shows the observed spread from one extreme to the other. A range is not a confidence interval: it describes the observed endpoints of the data, not the uncertainty around an estimated population mean. With a small endpoint population, individual measurements can have a strong influence on the mean and range. Because the registry gives no endpoint values, neither the central level nor the spread can be assessed.
Why is the tissue-to-plasma comparison relevant?
General: A tumor-to-plasma measure relates drug concentration at the target tissue to concentration in the circulation. It can help characterize whether drug is detectable in tumor tissue relative to plasma at the collection time. A single surgical sample is a snapshot; it cannot describe how concentration changes over time or establish the full exposure profile. The registry also lists plasma area under the concentration-versus-time curve and peak plasma concentration among secondary outcomes, but their results are not reported in the registry record. The record's endpoint wording names a concentration, defines it as a mean ratio, and lists ng/mL as its unit. Since these descriptions do not fully clarify the scale, interpretation should follow the stated definition without resolving that ambiguity by assumption.
What does non-randomized allocation mean for comparisons?
General: Random allocation is intended to balance, on average, both measured and unmeasured participant characteristics between comparison groups. In a non-randomized study, group membership can be related to clinical circumstances or other characteristics. Consequently, an observed difference between arms can reflect those differences, treatment exposure, or both. The registry specifically cautions that these arms are not a like-for-like control comparison. The record does not describe a comparative statistical adjustment that would resolve this limitation. Its listed crossover model does not, on its own, establish a particular sequence or valid within-participant contrast; those details are not reported in the registry record.
How should uncertainty and significance be understood?
General: A confidence interval gives a range of values compatible with the data under a specified statistical procedure. Its width reflects precision: wider intervals indicate less precise estimation than narrower intervals. A hypothesis test evaluates compatibility with a specified null model, but a p-value does not measure the size or clinical importance of an effect. No confidence interval, p-value, or primary endpoint estimate is reported in the registry record. There is therefore no basis in the posted results to describe statistical significance or precision for the primary endpoint.
What do the planning assumptions mean?
General: The record describes planning illustrations based on a fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Those are assumptions for an illustrative calculation, not evidence that the trial was designed using those assumptions. For time-to-event illustrations, the stated quantity is total events using the Schoenfeld approach; other illustrations describe participants per arm. Such calculations are planning aids, not observed power, and cannot replace the study's own sample-size justification. The justification and the trial's statistical analysis plan are not reported in the registry record. The observed effect used for planning and numerical planning results are not included in this record information, so their values cannot be interpreted.
How should a non-significant or missing result be read?
General: A missing result is not equivalent to a result showing no effect, and it is not evidence of equivalence. Without an estimate and its uncertainty, the data cannot distinguish a small effect from a larger one or assess compatibility with a null value. In this case, the primary result is not reported in the registry record, so neither a positive nor a null statistical conclusion is supported by the posted information.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 9 outcome measures, including the primary intratumoral concentration endpoint and secondary measures covering tumor pRB expression, adverse events, plasma exposure, radiographic response, progression-free survival, and overall survival. Multiple outcomes create a multiplicity issue when investigators perform several statistical tests: the chance of at least one apparently unusual result can increase as tests accumulate. Statistical approaches can address this, for example by prespecifying a hierarchy or adjusting tests, but the choice depends on the study questions and analysis plan. The registry record does not report a multiplicity strategy, endpoint hierarchy beyond naming the primary endpoint, or detailed testing plan.
The record lists 0 analyses. It does not report primary endpoint results, secondary outcome results, analysis-specific denominators, or uncertainty estimates. Missing results must not be read as null findings. The registry record also does not describe how missing endpoint or follow-up data were handled, whether any participants were excluded from particular analyses, or whether sensitivity analyses were performed. These details are not reported in the registry record.
The primary endpoint population is described as participants treated before surgery, with the postoperative treatment status of each participant summarized in the record. That population description does not provide a general analysis-population definition for all outcomes. The registry does not say whether analyses followed intention-to-treat, per-protocol, or another principle. It also does not explain how the protocol amendment ending study treatment after surgery affected analysis populations beyond the primary endpoint description. The sample-size justification and formal statistical analysis plan are not reported in the registry record. As a result, the extent to which analyses were prespecified, how multiplicity was managed, and how incomplete data were handled cannot be evaluated from the posted information.
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 |
|---|---|---|---|
| Abemaciclib With Surgery | 5 | 9 | 55.6% |
| Abemaciclib Without Surgery | 7 | 32 | 21.9% |
| Cohort 1 Surgery Arm | 1 | 1 | 100.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Abemaciclib With Surgery | 9 of 9 |
| Abemaciclib Without Surgery | 31 of 32 |
| Cohort 1 Surgery Arm | 1 of 1 |
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 |
|---|---|
| Abemaciclib With Surgery | 5 of 9 |
| Abemaciclib Without Surgery | 21 of 32 |
| Cohort 1 Surgery Arm | 1 of 1 |
Most frequent serious adverse event terms
| Event term | Organ system | Abemaciclib With Surgery | Abemaciclib Without Surgery | Cohort 1 Surgery Arm |
|---|---|---|---|---|
| Seizure | Nervous system disorders | 2 of 9 | 0 of 32 | 0 of 1 |
| Renal calculi | Renal and urinary disorders | 0 of 9 | 2 of 32 | 0 of 1 |
| Confusion | Psychiatric disorders | 0 of 9 | 2 of 32 | 0 of 1 |
| Muscle weakness lower limb | Musculoskeletal and connective tissue disorders | 0 of 9 | 2 of 32 | 0 of 1 |
| Urinary Urgency | Renal and urinary disorders | 0 of 9 | 2 of 32 | 0 of 1 |
| Dysphasia | Nervous system disorders | 0 of 9 | 2 of 32 | 0 of 1 |
| Death NOS | General disorders | 0 of 9 | 2 of 32 | 0 of 1 |
| Decreased Motivation, Abulia | Nervous system disorders | 1 of 9 | 0 of 32 | 0 of 1 |
| Hypokalemia | Metabolism and nutrition disorders | 1 of 9 | 0 of 32 | 0 of 1 |
| Gait disturbance | General disorders | 1 of 9 | 0 of 32 | 0 of 1 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Abemaciclib With Surgery | Abemaciclib Without Surgery | Cohort 1 Surgery Arm |
|---|---|---|---|---|
| White blood cell decreased | Investigations | 2 of 9 | 6 of 32 | 0 of 1 |
| Neutrophil count decreased | Investigations | 2 of 9 | 5 of 32 | 0 of 1 |
| Lymphocyte count decreased | Investigations | 1 of 9 | 3 of 32 | 1 of 1 |
| Diarrhea | Gastrointestinal disorders | 0 of 9 | 1 of 32 | 1 of 1 |
| Platelet count decreased | Investigations | 0 of 9 | 2 of 32 | 0 of 1 |
| Anemia | Blood and lymphatic system disorders | 0 of 9 | 1 of 32 | 0 of 1 |
| Alanine aminotransferase increased | Investigations | 0 of 9 | 1 of 32 | 0 of 1 |
| Lipase increased | Investigations | 0 of 9 | 1 of 32 | 0 of 1 |
| Hypokalemia | Metabolism and nutrition disorders | 1 of 9 | 0 of 32 | 0 of 1 |
| Rash maculo-papular | Skin and subcutaneous tissue disorders | 0 of 9 | 1 of 32 | 0 of 1 |
Serious events with the highest arm-level rate: positive blood cultures with unknown source (100.0%), seizure (22.2%), decreased motivation, abulia (11.1%), hypokalemia (11.1%), gait disturbance (11.1%).
The registry separates serious adverse events from other adverse events and gives, for each arm, the number at risk and the number affected. In Abemaciclib With Surgery, 5 of 9 participants at risk were affected by serious adverse events, and 5 of 9 were affected by other adverse events. In Abemaciclib Without Surgery, 7 of 32 participants at risk were affected by serious adverse events, and 21 of 32 were affected by other adverse events. In Cohort 1 Surgery Arm, 1 of 1 participants at risk was affected by serious adverse events, and 1 of 1 was affected by other adverse events. These are arm-specific counts; they should not be treated as a randomized comparison because allocation was non-randomized and the registry cautions that the arms are not like-for-like controls.
The listed serious-event terms include Positive blood cultures with unknown source at 100.0%, Seizure at 22.2%, and several other terms at 11.1%. The registry information does not make clear the denominator or precise basis for each listed term percentage, so those percentages should not be converted into participant counts. The record also lists death counts of 9, 31, and 1 across the three arms. These counts do not establish cause or attribution, and no causal relationship to treatment should be inferred from them. The registry record does not report detailed event timing, duration of exposure, follow-up time, or event-level attribution information.
12. What the Result Does, and Does Not, Mean
The study's primary question is about drug distribution in tumor tissue after preoperative abemaciclib, not whether treatment improves clinical outcomes. Its endpoint is measured at surgery from tissue and plasma, and the registry describes a small surgical analysis population. The primary concentration result is not reported in the registry record. As a result, the posted information does not show the observed drug level, its range, or the precision of an estimate.
The registry lists secondary clinical and pharmacologic outcomes, including radiographic response rate, median progression-free survival, and overall survival. It does not report analyses for these outcomes. Their presence in the registry is evidence that they were listed as outcomes, not evidence of a particular result. Likewise, the adverse-event counts describe reported affected participants within study arms; they cannot establish treatment causation or comparative safety in non-randomized groups.
The design includes distinct surgery and non-surgery groups, and the record explicitly warns against treating them as equivalent controls. Participants requiring reoperation and those treated without surgery may have different clinical circumstances. No randomized contrast is available to separate those differences from treatment effects. Statistical adjustment details are not reported in the registry record.
Accordingly, the posted record supports conclusions about the study's stated purpose, design, endpoint definition, analysis population, and reported safety counts. It does not support a conclusion that abemaciclib does or does not produce a particular tumor concentration, nor a conclusion about clinical benefit, survival, or comparative safety. Those interpretations would require reported outcome estimates and sufficient detail about analyses, uncertainty, follow-up, and missing data.
13. Why This Trial Matters Statistically
This study illustrates why a clinical trial's endpoint needs to be distinguished from its treatment question. Measuring intratumoral abemaciclib concentration can characterize whether the drug is present in sampled tumor tissue relative to plasma. That pharmacologic information is different from evidence about tumor response, progression, survival, or overall benefit. A registry can identify the intended measurement and still leave the substantive result unavailable.
It also illustrates the limits of comparisons among non-randomized arms. The registry lists a surgical cohort and a non-surgical arm, but those groups are not described as interchangeable controls. Surgery is both part of the treatment context and the point at which the primary endpoint samples can be obtained. The endpoint population is consequently selected by the circumstances allowing surgery and tissue collection. This matters when interpreting both the generalizability of a tissue measurement and any between-arm comparison.
Finally, the record is an example of how outcome registration, analysis reporting, and statistical interpretation are distinct. It lists 9 outcome measures but 0 analyses, and it does not report the primary endpoint estimate or the analysis plan. Safety counts can be described, but without fuller context they do not establish causation or comparative risk. The registry's limitations make clear why a named endpoint, a listed sample size, or a posted adverse-event count is not by itself a complete statistical account of a clinical trial.
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 primary endpoint is based on tissue and plasma collected at surgery at a single time point for each participant. It therefore cannot describe within-person changes in tumor concentration over time. The surgical endpoint population includes 9 participants who received postoperative abemaciclib and 1 who did not, but the registry does not report endpoint values or explain how the protocol amendment affected interpretation beyond noting that surgical-cohort treatment ended after surgery.
The endpoint description has a reporting ambiguity: it names intratumoral concentration in ng/mL but defines the measure as the mean tumor-to-plasma ratio. The record does not explain the relationship between that unit and the stated ratio. It also does not provide individual observations, a confidence interval, or analysis details that would clarify measurement variability and precision.
Non-randomized allocation and the registry's warning that arms are not like-for-like comparisons limit causal interpretation. The crossover model is listed, but sequence, timing, and analytic handling of any crossover are not reported in the registry record. The record does not provide details on eligibility, baseline characteristics, follow-up, missing observations, or treatment adherence sufficient to assess representativeness or potential bias. The sample-size justification, statistical analysis plan, multiplicity approach, and handling of missing data are also not reported. Finally, the registry lists adverse-event and death counts without enough detail to infer causality, timing, or comparative safety.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study of Abemaciclib in Recurrent Glioblastoma — NCT02981940.
- Registry record last updated 2026-09-04; status last verified 2026-08.
- Results first posted 2025-09-02.
- 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
NCT02981940 is a Phase 2, non-randomized, unmasked study of abemaciclib in recurrent glioblastoma, sponsored by Dana-Farber Cancer Institute. The registry lists a crossover model, enrollment of 45, a start date of 2017-02-09, primary completion on 2024-06-30, and status active, not recruiting. The primary endpoint is intratumoral abemaciclib concentration in tissue collected at surgery. Its analysis population includes participants treated with abemaciclib before surgery: 9 with postoperative abemaciclib and 1 without it.
The registry does not report the primary endpoint result or analyses for the listed outcomes. It reports arm-level counts for participants affected by serious and other adverse events, but the non-randomized design does not support treating the arms as like-for-like controls. The sample-size justification, analysis plan, missing-data handling, and multiplicity approach are not reported in the registry record.