Multicenter Phase II Study of IMC-A12 in Patients With Thymoma and Thymic Carcinoma Who Have Been Previously Treated With Chemotherapy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Multicenter Phase II Study of IMC-A12 in Patients With Thymoma and Thymic Carcinoma Who Have Been Previously Treated With Chemotherapy (NCT00965250), a non-randomized phase 2 study. The primary outcome is Objective Response Rate (Partial Response (PR)+Complete Response (CR)) to IMC-A12 Monotherapy in Patients With Advanced or Recurrent Thymoma or Thymic Carcinoma..

2. Clinical Question

The study asked whether IMC-A12 monotherapy was associated with objective tumor responses in patients with advanced or recurrent thymoma or thymic carcinoma. Participants had previously received chemotherapy; the registry description focuses on disease that had progressed despite standard treatment. The record also lists thymic carcinoid and thymic neuroendocrine tumors among the conditions, but the primary endpoint title specifies thymoma or thymic carcinoma.

This is a descriptive treatment-response question, not a randomized estimate of the effect of IMC-A12 relative to another option. The endpoint combines complete and partial responses, while other listed outcomes include disease control, time to progression, overall survival, adverse events, and imaging-related measures. Their presence in the registry does not establish that each outcome was fully reported or analyzed in the posted record.

3. Trial Design

The registry classifies the study as Phase II, non-randomized, unmasked, and single-group. It lists enrollment of 49 participants and a completed status. With no concurrent comparison arm, the design can describe outcomes observed among treated participants but cannot, by itself, separate treatment-associated changes from the natural course of disease, measurement variation, or other influences.

The intervention was IMC-A12, described in the arm information as 20 mg/kg intravenously once every three weeks. The study summary describes treatment in 21-day cycles. Response assessments were scheduled every two cycles, identified as every 6 weeks, while participants were receiving study drug. These details describe the planned treatment and assessment schedule; they do not establish how many participants completed treatment or how many had each assessment.

The primary outcome was the number of participants with an objective response, defined as a partial response or complete response using RECIST criteria. The registry also lists safety, response percentage, disease control, time to progression, overall survival, treatment cycles, and a relationship between response and FDG-PET imaging among secondary outcomes. The record lists 8 outcome measures and 2 analyses, but further details about those analyses are not reported in the registry record.

The trial's single-group structure is important when interpreting every outcome. A response observed during treatment is a within-study observation. Without a randomized or otherwise clearly defined comparison group, the record does not estimate how outcomes would have differed under another treatment or without IMC-A12. Randomization procedures, masking, and control-arm details are not reported because the registry explicitly identifies the study as non-randomized, unmasked, and single-group.

The registry record does not report a sample-size justification or a statistical analysis plan. It also does not report whether interim analyses were planned or conducted. These omissions limit assessment of the study's intended precision, decision thresholds, and analysis procedures.

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.

Before assignment: The thymic carcinoma cohort was closed after enrolment of 12 participants because of lack of activity.

Overall Study

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.

6. Primary Endpoint

The registry lists the primary outcome as Objective Response Rate (Partial Response (PR)+Complete Response (CR)) to IMC-A12 Monotherapy in Patients With Advanced or Recurrent Thymoma or Thymic Carcinoma., measured over Patients were assessed for response every 2 cycles (every 6 weeks) while receiving the study drug..

The primary endpoint counts participants whose best recorded tumor response was complete response or partial response under RECIST. A complete response means disappearance of all target lesions. A partial response requires at least a 30% decrease in the sum of the longest diameters of target lesions relative to the baseline sum. The endpoint therefore focuses on measurable tumor shrinkage rather than stable disease or time-to-event outcomes.

RECIST provides prespecified categories for interpreting changes in tumor measurements. Progressive disease is defined in the registry description by at least a 20% increase in the sum of target-lesion diameters, using the smallest sum recorded since treatment began as reference, or by the appearance of one or more new lesions. Stable disease is neither enough shrinkage to meet the partial-response criterion nor enough increase to meet the progressive-disease criterion, using the stated reference. These definitions distinguish objective shrinkage from disease stability and progression.

Combining complete and partial responses produces a binary response outcome for each participant: a response is counted if either category is met. The registry lists the endpoint unit as participants and its parameter as a number. Although the title names objective response rate, the primary measure is described as a participant count. The number of participants meeting the criteria, and a response rate calculated from that count, are not reported in the registry record.

Objective response is used in studies of this kind because it summarizes observed tumor shrinkage according to consistent measurement rules. It does not, on its own, describe how long a response lasted, whether symptoms changed, or how outcomes compare with an alternative. Those questions require other outcomes and, for comparative claims, an appropriate comparison design.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design estimate?

In a single-group study, outcomes are observed among participants who receive the study intervention. The primary response count would describe how many participants met the response definition under the study's assessment and analysis procedures. It is not a randomized treatment-effect estimate because outcomes under an alternative intervention are not observed in a concurrent comparison group. This distinction is general to single-group designs.

Randomization is useful in comparative studies because, when implemented appropriately, it helps balance known and unknown prognostic factors between groups. Here, the registry identifies allocation as non-randomized and the model as single-group. Therefore, a comparison with outcomes from another study would require careful attention to differences in eligibility, disease severity, assessment schedules, follow-up, and analysis rules. The registry does not report a comparison group or a plan for such an external comparison.

How is the primary outcome classified?

RECIST converts repeated measurements of target lesions, along with information about new lesions, into response categories. The registry defines complete response as disappearance of all target lesions and partial response as at least a 30% decrease in the sum of their longest diameters relative to baseline. It defines progressive disease using at least a 20% increase relative to the smallest sum recorded since treatment began, or the appearance of new lesions. Stable disease is the category for neither sufficient shrinkage nor sufficient increase to meet the specified thresholds.

The primary endpoint combines complete and partial responses. This gives a binary classification for analysis: participants either meet the objective-response definition or do not. A response count alone is not enough to interpret the outcome; readers also need the analysis denominator, the assessment rules, and information about missing or unevaluable scans. Those analysis details are not reported in the registry record.

Why do assessment timing and follow-up matter?

The registry says that participants were assessed every 2 cycles, or every 6 weeks, while receiving study drug. Scheduled assessment timing affects when a response can first be detected and how changes are classified. For time-to-event outcomes, follow-up duration and censoring rules also affect interpretation. The registry lists time to progression and overall survival as secondary outcomes, but does not report their detailed analysis methods or results.

Repeated imaging can produce more than one measurement per participant. A prespecified rule is generally needed to select or summarize those measurements, such as defining the best response over follow-up. The specific rule used for the reported primary analysis is not reported in the registry record. This is a general methodological issue rather than an assertion about the procedures used in this study.

What do estimates and confidence intervals communicate?

A response proportion, when reported, describes the share of analyzed participants who meet the response definition. A confidence interval communicates sampling uncertainty around an estimate under the assumptions of its statistical method. It does not measure all sources of uncertainty: it cannot correct for selection effects, incomplete outcome ascertainment, measurement differences, or the absence of a control group. No primary response estimate or confidence interval is reported in the registry record, so its statistical precision cannot be evaluated.

For a binary endpoint, the choice of interval method can affect the interval, particularly when the count is small or near the boundaries of the possible range. The registry record does not report an interval method or a primary-outcome analysis plan. This general consideration should not be mistaken for evidence that a particular method was used in this study.

What do the planning illustrations mean?

Sample-size calculations are planning tools that describe the number of participants that might be required under stated assumptions about an effect, significance level, allocation, and statistical method. They are not observed results and are not a measure of the study's achieved power. The planning note associated with this record describes a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a stated share of an observed effect. Those assumptions do not change the registry's description of the actual trial as a single-group, non-randomized study.

Because the study has no randomized comparison arm, a hypothetical two-arm planning calculation should not be read as the trial's actual design. A sample-size justification for the trial itself is not reported in the registry record. The sample sizes in planning illustrations, where present in the site's statistical materials, would be hypothetical requirements under their assumptions—not participants observed in this trial and not observed power.

Why can over-dispersion matter?

Over-dispersion is a general statistical issue that arises when observed variability is greater than a model expects. For count or rate outcomes, ignoring over-dispersion can make uncertainty appear smaller than it is. The primary outcome is described as a participant count for a binary response classification, and the registry record does not state that an over-dispersion adjustment was used. This general concept does not establish that over-dispersion was present or relevant to the study's analysis.

In all cases, the registry record's lack of a reported analysis plan means that the exact statistical procedures, model assumptions, and handling of uncertainty cannot be reconstructed from the available description. Statistical explanations of possible methods should not be treated as documentation of methods used in the trial.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists several outcomes in addition to objective response, including adverse events, disease control, time to progression, overall survival, treatment cycles, and an FDG-PET imaging measure. When a study evaluates multiple outcomes or makes multiple statistical comparisons, the chance of at least one apparently notable result can increase. A multiplicity plan may specify which outcomes are primary, how comparisons are ordered, or whether statistical error rates are adjusted. These are general considerations; a multiplicity strategy is not reported in the registry record.

The primary endpoint is identified as the number of participants with complete or partial response. The registry also lists 8 outcome measures and 2 analyses, but does not provide enough detail to determine the full set of statistical comparisons or how they were handled. Interim analyses, stopping rules, and any adjustment for multiple testing are not reported in the registry record.

Missing-data handling is another essential part of interpreting response results. Participants may lack an assessment for reasons such as withdrawal, progression, or incomplete imaging; how such cases are classified can affect the denominator and response estimate. The registry record does not report the number of participants with missing or unevaluable response assessments, the analysis population for the primary endpoint, or the rules used to handle missing data.

The record lists enrollment of 49, but does not establish that all enrolled participants were included in every outcome analysis. It does not report whether analyses used all enrolled participants, only those who received treatment, or an evaluable subset. These details are not reported in the registry record, so an analysis population cannot be inferred from enrollment alone.

Without information on multiplicity, missing outcomes, and analysis populations, readers cannot fully judge whether reported estimates—if available elsewhere—followed prespecified rules or how sensitive they might be to alternative choices. These reporting gaps limit reproducibility and interpretation; they do not demonstrate that a particular analysis choice was inappropriate.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: death nos (44.9%), dyspnea (6.1%), hypoxia (4.1%), neoplasms benign, mailgnant and unspecified (4.1%), respiratory failure (4.1%).

The registry safety summary lists 49 participants at risk for serious adverse events, with 29 affected. For other adverse events, it lists 49 at risk and 49 affected. These counts describe the registry's reported safety categories. They should not be interpreted as treatment-attributable event counts unless the record separately establishes causality.

The serious-event terms include Death NOS at 44.9%, Dyspnea at 6.1%, Hypoxia at 4.1%, Neoplasms benign, mailgnant and unspecified at 4.1%, Respiratory failure at 4.1%, and Mucositis Oral at 2.0%. These percentages are listed as serious-event terms. The record does not explain whether terms overlap within participants, so they should not be added together or treated as mutually exclusive categories.

In particular, the label Death NOS and its listed percentage do not establish that deaths were caused by IMC-A12. The registry summary does not report a causal attribution analysis, event-level timing, or the relationship of each event to treatment or underlying disease. A serious adverse event is a safety classification; it is not by itself proof of a drug effect. The figures also do not give a comparison with an untreated or alternative-treatment group, so they cannot estimate excess risk relative to another treatment.

12. What the Result Does, and Does Not, Mean

The registry record establishes that this was a completed, single-group Phase II study of IMC-A12 in a previously treated thymic-cancer population, and it specifies how objective response was defined. It also reports safety counts and lists several secondary outcomes. These details help identify the question the study was designed to address and the types of outcomes considered.

The primary response result itself is not reported in the registry record. The response count, the response rate, and an uncertainty interval are absent from the information available for this analysis. As a result, the primary endpoint cannot be quantified, and no conclusion about the observed frequency of tumor response can be drawn from this record alone.

Even with a response result, the single-group design would describe outcomes among participants receiving IMC-A12 rather than establish how outcomes differed from another treatment. A randomized comparison can address a different question by comparing groups under a shared study framework. This study's registry design does not include that comparison. The response definitions also do not answer questions about response duration, survival, or differences in symptoms.

The listed safety figures are descriptive. They do not establish that the intervention caused the reported events, and no concurrent control group is available to estimate comparative safety. The serious-event term percentages should be read as registry-listed categories, not as proof of drug-related harm or benefit.

The defensible conclusion is limited to what the record documents: the treatment and assessment schedule, the stated RECIST definitions, the trial's single-group design, and the reported safety counts. The registry record does not report enough primary-outcome, uncertainty, missing-data, or analysis detail to assess the size and precision of the objective-response finding. The absence of a reported result should not be interpreted as evidence that there were no responses or that there was no effect; it means the result is not reported in the registry record.

13. Why This Trial Matters Statistically

This study is statistically notable because its primary question concerns objective response in a defined, previously treated thymic-cancer population, while its design is single-group and non-randomized. That combination clarifies both what the study can describe and what it cannot establish. The study can characterize outcomes among treated participants if the relevant outcome data are reported, but it cannot provide a randomized contrast with another treatment.

The use of RECIST makes the response definition explicit. Complete and partial response are based on prespecified tumor-measurement criteria, while stable and progressive disease have distinct definitions. Such operational rules are important because they make the endpoint more interpretable than an informal description of tumor change. The registry also states when response assessments were scheduled, which is relevant to understanding how repeated measurements were collected.

The record is also a reminder that a registered endpoint is not the same as a reported endpoint result. The primary endpoint title and definition are available, but the result count and its precision are not reported in the registry record. Without these, readers cannot judge the observed response frequency or its statistical uncertainty.

Finally, the safety summary requires separation of event occurrence from causal attribution. Counts and listed terms can describe what the registry reports, but they do not establish that treatment caused an event or how risks compare with another treatment. This is particularly important for serious outcomes in a population with advanced disease. Clear design descriptions, complete outcome reporting, transparent analysis populations, and careful separation of association from causation are all needed for sound statistical interpretation.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most consequential limitation for interpreting efficacy is that the primary response result is not reported in the registry record. The record does not provide the number of complete or partial responses, the analysis denominator, or an uncertainty interval. This prevents assessment of the magnitude and precision of the primary endpoint.

The single-group, non-randomized design has no concurrent control group. Consequently, the observed course of participants cannot be contrasted within the trial with outcomes under another treatment. Any comparison with external experience would require information about comparability of patient populations, assessment schedules, outcome definitions, and follow-up; such a comparison is not reported in the registry record.

Although enrollment is listed as 49, the record does not report how many participants received treatment, had evaluable imaging, completed the response assessments, or contributed to each outcome analysis. Missing-data rules, response adjudication details, and the primary analysis population are not reported. The assessment schedule is described, but the registry does not state how best response over repeated assessments was selected or analyzed.

The record lists multiple secondary outcomes, but their numerical results and the approach to multiplicity are not reported. Interim analyses, stopping rules, and a statistical analysis plan are also not reported in the registry record. These omissions constrain assessment of prespecification and reproducibility.

The safety summary provides counts and serious-event terms but does not establish causal relationships with treatment, event timing, or comparative risks. The registry's listed terms should therefore be interpreted descriptively. These limitations arise from what is documented in the registry record and should not be treated as evidence that unreported procedures or results did not exist.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Multicenter Phase II Study of IMC-A12 in Patients With Thymoma and Thymic Carcinoma Who Have Been Previously Treated With Chemotherapy — NCT00965250.
• Registry record last updated 2016-12-23; status last verified 2016-10.
• Results first posted 2012-11-14.
• 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.

18. Record Summary

The registry identifies NCT00965250 as a completed Phase II, non-randomized, unmasked, single-group study sponsored by the National Cancer Institute. Enrollment is listed as 49. The study evaluated IMC-A12 monotherapy in patients with advanced or recurrent thymoma or thymic carcinoma who had previously received chemotherapy.

The primary endpoint was the number of participants with complete or partial response by RECIST. Assessments were scheduled every 2 cycles, or every 6 weeks, while participants received study drug. The registry record describes an intravenous dose of 20 mg/kg once every three weeks.

The record lists 8 outcome measures and 2 analyses, and reports safety counts of 29 affected participants among 49 at risk for serious adverse events and 49 affected among 49 at risk for other adverse events. The primary response count, response rate, confidence interval, analysis population, and detailed statistical analysis plan are not reported in the registry record.