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 Cabozantinib for Adults With Advanced Soft Tissue Sarcoma (NCT01755195), a na phase 2 study. The primary outcome is Objective Response (Complete Response (CR)+Partial Response (PR) of Cabozantinib in Patients With Soft Tissue Sarcomas.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01755195 |
| Phase | Phase 2 |
| Condition | Refractory Soft Tissue Sarcomas |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 55 |
| Arms in the primary outcome | n/a |
| Lead sponsor | National Cancer Institute (NCI) |
| Results posted | Yes |
2. Clinical Question
Population
Adults with soft tissue sarcomas that had not responded to standard treatments were eligible. The study title specifies metastatic, refractory soft tissue sarcoma. The registry record states that 1/55 participants did not start therapy; it does not report further details about the analyzed response population.
Intervention
Participants received cabozantinib, described as a dual inhibitor of MET and VEGFR. The regimen was 60 mg tablets orally once a day in a 28-day cycle. Treatment could continue while the tumor did not worsen and side effects were not too severe, according to the study summary.
Comparator
There was no concurrent control group. The registry record describes a single-group study with no masking and no allocation to comparative arms. Consequently, the study does not provide a randomized, like-for-like comparison against another treatment or control condition.
Primary question
The primary endpoint asked whether participants had an objective response, defined as complete response or partial response under RECIST v1.1. Complete response requires disappearance of target lesions, with pathological lymph nodes reduced to less than 10 mm in short axis. Partial response requires at least a 30% decrease in the sum of target-lesion diameters from baseline. The registry record does not report the response count, response percentage, or 95% confidence interval, so the clinical question cannot be answered from the posted primary outcome result.
3. Trial Design
This was a completed phase 2, single-group study sponsored by the National Cancer Institute (NCI). The registry record lists an enrollment of 55 and describes cabozantinib as the sole intervention. Allocation is listed as not applicable, and masking as none. Those design features mean that the treatment experience is described without a concurrent comparison group or masking intended to conceal treatment assignment.
The study concerned adults with refractory soft tissue sarcoma; its official title specifies metastatic refractory disease. Participants took cabozantinib 60 mg orally once a day in 28-day cycles. The summary describes screening with examination, medical history, blood samples, imaging, and other tumor assessments. Blood tests and imaging were used during treatment monitoring. Treatment was to continue while the tumor did not become worse and side effects were not too severe.
The registry record gives a start date of 2013-01-15, a primary completion date of 2020-09-30, and a completed status. These dates describe the study record, not the duration of treatment for any individual participant. The primary outcome timeframe is described as running from the date treatment consent was signed to the date off study, approximately 86 months and 3 days.
One of the 55 participants did not start therapy. The safety group lists 54 participants at risk. The registry record does not give additional detail about the relationship between the response analysis population and the safety group. It also does not report the rationale for the enrollment target, the selection process for participants included in each outcome analysis, or protocol-specific monitoring procedures beyond the general study summary.
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 | Cabozantinib |
|---|---|
| STARTED | 55 |
| COMPLETED | 42 |
| NOT COMPLETED | 13 |
Reasons for not completing this period:
| Reason | Cabozantinib |
|---|---|
| Participant noncompliance | 2 |
| Switched to alternative treatment | 4 |
| Withdrawal by Subject | 1 |
| Participant refused to start treatment | 1 |
| Participant has been consented for another trial | 1 |
| Refused further treatment | 3 |
| Complicating disease/intercurrent illness | 1 |
Analysis population for the primary outcome, as defined in the registry: 1/55 participants did not start therapy.
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 | Cabozantinib |
|---|---|---|
| Participants analysed | 55 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 50 |
| Age, Categorical: >=65 years | Participants | 5 |
| Age, Continuous | years | 49.69 (SD 12.21) |
| Sex: Female, Male: Female | Participants | 31 |
| Sex: Female, Male: Male | Participants | 24 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 11 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 43 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 1 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 1 |
| Race (NIH/OMB): Asian | Participants | 10 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 9 |
| Race (NIH/OMB): White | Participants | 33 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 2 |
| Region of Enrollment: United States | participants | 55 |
6. Primary Endpoint
The registry lists the primary outcome as Objective Response (Complete Response (CR)+Partial Response (PR) of Cabozantinib in Patients With Soft Tissue Sarcomas, measured over Date treatment consent signed to date off study, approximately 86 months and 3 days..
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percentage of particpants |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was objective response, defined as complete response plus partial response under RECIST v1.1. It was expressed as a percentage of participants. Complete response means disappearance of all target lesions; pathological lymph nodes, whether target or non-target, must also measure less than 10 mm in short axis. Partial response means at least a 30% reduction in the sum of target-lesion diameters, using the baseline sum as the reference.
As a general statistical concept, objective response is a categorical tumor outcome: each participant is classified according to whether the stated response criteria are met. A response proportion can describe how often that classification occurred in the analysis population. Its confidence interval conveys uncertainty about the underlying response proportion, rather than asserting that the observed proportion is exact for other patients or settings.
The registry record identifies a 95% confidence interval as the endpoint’s dispersion measure, but does not report the response count, percentage, or interval itself. Therefore, the magnitude and precision of the primary endpoint are not reported in the registry record. The record notes that 1/55 participants did not start therapy, but does not specify in the posted primary result how the response denominator was determined.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the study question and the response criteria, but it does not provide the primary endpoint result. No number of complete or partial responses, response percentage, or 95% confidence interval is reported in the registry record. Without those results, the observed response frequency and its statistical precision cannot be described. The endpoint definition alone is not evidence about how participants in the study responded.
The study enrolled 55 participants, and the record states that 1/55 did not start therapy. The safety information lists 54 participants at risk. These registry entries do not, by themselves, establish the denominator used for the objective-response estimate. That analysis population is not reported in the registry record. This distinction matters because an outcome percentage is interpretable only when its numerator and denominator, and the rules used to select participants for analysis, are clear.
The design was single-group and unmasked, with no comparator. The posted data therefore cannot estimate a difference between cabozantinib and another treatment or control condition. Even if an outcome estimate were available, a response proportion in a single group would describe the participants observed under this study’s conditions; it would not alone distinguish treatment effects from other explanations for the observed outcomes. General statistical interpretation of uncontrolled studies calls for this restraint because there is no concurrent group to provide the counterfactual comparison.
The endpoint specifies RECIST v1.1 criteria for complete and partial response. This makes the intended outcome definition explicit, including the required reduction in target-lesion diameters for partial response. However, the registry record does not report assessment timing for each participant, confirmation procedures, reviewer arrangements, or handling of unevaluable observations. Those details are not reported in the registry record and should not be assumed.
The primary outcome timeframe extends from consent to going off study, approximately 86 months and 3 days. That is a study-level timeframe description; it does not establish that every participant was followed for the same duration. No participant-level follow-up distribution or time-specific response breakdown is reported in the registry record.
The listed secondary outcomes concern mean changes from baseline in circulating HGF, sMET, VEGF-A, and sVEGFR-2. Their names identify biomarkers of interest, but the registry record does not report their observed changes, variability, or inferential results. The primary objective-response result is also absent. As a result, the posted results support description of the planned outcome definitions and design, not an estimate of the size or precision of a treatment-associated response.
9. Statistical Methods Explained
The registry record gives the primary endpoint as a percentage of participants with objective response and names a 95% confidence interval as its measure of dispersion. It does not report an estimate or interval. The statistical methods can therefore be explained in general terms, but a study-specific response calculation or interpretation is not possible from the registry record.
What a response proportion represents
In general, a response proportion is the number of participants meeting the response definition divided by the number of participants included in the relevant analysis. The numerator depends on applying the complete-response and partial-response rules consistently. The denominator depends on the analysis population and how participants without an evaluable assessment are handled. Neither the response count nor the denominator used for the posted primary analysis is reported in the registry record. The statement that 1/55 participants did not start therapy does not itself identify the analysis rules.
How to read a confidence interval
In general, a confidence interval describes statistical uncertainty around an estimate under the assumptions of the method used. For a response percentage, a narrower interval indicates greater precision, while a wider interval indicates less precision. The interval does not show the range of individual participant outcomes, and it does not ensure that the true response proportion lies within the particular reported limits. The registry record identifies a 95% confidence interval for the primary endpoint but does not report its limits or the method used to construct it. The interval’s width and statistical procedure are therefore not reported in the registry record.
Why the single-group structure matters
As a general concept, a single-group study can describe outcomes observed among participants receiving the study intervention, but it lacks a concurrent control group for estimating a comparative treatment effect. The registry record lists a single-group model and no allocation. It does not describe a randomized comparison. Therefore, a comparative effect estimate, such as a difference in response between cabozantinib and another treatment, is not part of the posted result. No adjustment can turn an uncontrolled response proportion into a randomized comparison.
The registry record also lists no masking. In general, knowledge of treatment and study participation can affect behavior, assessment, or reporting, depending on the outcome and study procedures. The response endpoint is defined using imaging criteria, but the record does not say whether assessments were independently reviewed or whether assessors were masked. Those procedures are not reported in the registry record, so their influence cannot be assessed from the posted information.
Outcome definitions and measurement
RECIST v1.1 provides the stated criteria for classifying complete and partial responses. Complete response requires disappearance of target lesions and reduction of pathological lymph nodes to less than 10 mm in short axis. Partial response requires at least a 30% decrease in the sum of target-lesion diameters relative to baseline. In general, prespecified definitions help make outcome classification more reproducible by stating which changes count. The registry record does not report additional details about the imaging schedule, confirmation of response, independent review, or classification of missing or unevaluable scans.
The timeframe runs from treatment consent to off-study date, approximately 86 months and 3 days. In general, a broad study timeframe should not be interpreted as identical observation time for every participant. The registry record does not provide individual follow-up durations or response timing. It also does not report a time-to-response analysis or a duration-of-response analysis in the posted primary outcome.
Secondary outcomes and multiplicity
The registry lists mean changes from baseline in circulating HGF, sMET, VEGF-A, and sVEGFR-2 as secondary outcomes. In general, testing several outcomes can increase the chance of at least one apparently notable result if each is examined separately without accounting for multiplicity. A statistical plan may address this through a prespecified hierarchy, adjustment, or a clearly exploratory interpretation. The registry record does not report a multiplicity strategy, a hierarchy among outcomes, or results for these biomarker measures. It is not possible to determine whether any adjustment was planned or used.
The record lists 7 outcome measures, while the available description identifies the primary response endpoint and several secondary biomarker outcomes. It does not provide a complete analysis plan or explain how all outcomes were analyzed. The statistical plan, including any interim analyses, is not reported in the registry record. No conclusions about unreported analyses or their timing should be inferred.
Planning calculations versus observed results
As a general concept, sample-size planning asks how many participants may be needed to detect a specified effect under stated assumptions. Such an illustration is not an observed trial result and is not “observed power.” The registry record does not report the study’s own sample-size justification or the assumptions used to choose enrollment of 55. It also does not report a primary response estimate from which an effect-based planning illustration could be interpreted. Any planning figures should therefore be read as illustrations under their stated assumptions, not as evidence that the study had a particular probability of finding an effect.
The statistical methods actually used for the primary outcome, including the confidence-interval procedure and analysis population rules, are not reported in the registry record. This limits reproducibility and prevents a detailed assessment of whether the analysis matched a prespecified plan. General explanations of proportions, confidence intervals, and multiplicity clarify the concepts, but they do not fill in those missing study-specific methods.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists objective response as the primary outcome and describes secondary outcomes involving mean changes from baseline in circulating HGF, sMET, VEGF-A, and sVEGFR-2. It does not report a prespecified testing hierarchy, a correction for multiple comparisons, or whether the biomarker analyses were exploratory. In general, examining multiple outcomes can increase the chance of a statistically notable finding by chance when each is tested separately. Without a reported multiplicity plan and outcome results, the strength of any secondary-outcome inference cannot be assessed.
The record states that 1/55 participants did not start therapy and lists 54 participants at risk for safety reporting. It does not report the primary endpoint analysis denominator, the number with evaluable imaging, or how participants with missing assessments were handled. The missing-data approach is not reported in the registry record. In general, excluding participants with unavailable measurements can affect an estimate if the reasons for missingness are related to outcome, while counting them as nonresponders is a different analysis choice. The registry record does not identify which approach, if any, was used.
The analysis populations are not described beyond the enrollment and safety figures. The record does not state whether the primary response analysis included all enrolled participants, only participants who started treatment, or another defined group. No interim-analysis plan, protocol-specific statistical analysis plan, or outcome-specific analysis rules are reported in the registry record. These omissions limit the ability to reconstruct the inferential process, even though the response criteria and primary endpoint timeframe are stated.
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 |
|---|---|---|---|
| Cabozantinib | 14 | 54 | 25.9% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Cabozantinib | 3 of 54 |
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 |
|---|---|
| Cabozantinib | 53 of 54 |
Most frequent serious adverse event terms
| Event term | Organ system | Cabozantinib |
|---|---|---|
| Thromboembolic event | Vascular disorders | 3 of 54 |
| Vomiting | Gastrointestinal disorders | 3 of 54 |
| Abdominal pain | Gastrointestinal disorders | 2 of 54 |
| Nausea | Gastrointestinal disorders | 2 of 54 |
| Pleural effusion | Respiratory, thoracic and mediastinal disorders | 2 of 54 |
| Small intestinal obstruction | Gastrointestinal disorders | 2 of 54 |
| Anemia | Blood and lymphatic system disorders | 1 of 54 |
| Cerebrospinal fluid leakage | Nervous system disorders | 1 of 54 |
| Dehydration | Metabolism and nutrition disorders | 1 of 54 |
| Diarrhea | Gastrointestinal disorders | 1 of 54 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Cabozantinib |
|---|---|---|
| Hypertension | Vascular disorders | 43 of 54 |
| Alanine aminotransferase increased | Investigations | 29 of 54 |
| Palmar-plantar erythrodysesthesia syndrome | Skin and subcutaneous tissue disorders | 29 of 54 |
| Diarrhea | Gastrointestinal disorders | 28 of 54 |
| Aspartate aminotransferase increased | Investigations | 25 of 54 |
| Fatigue | General disorders | 24 of 54 |
| Nausea | Gastrointestinal disorders | 24 of 54 |
| Alkaline phosphatase increased | Investigations | 22 of 54 |
| Headache | Nervous system disorders | 20 of 54 |
| Anorexia | Metabolism and nutrition disorders | 19 of 54 |
Serious events with the highest arm-level rate: thromboembolic event (5.6%), vomiting (5.6%), abdominal pain (3.7%), nausea (3.7%), pleural effusion (3.7%).
The safety group lists 54 participants at risk. Serious adverse events affected 14 of those participants. The registry record lists 53 participants at risk for other adverse events, with 53 affected. These are distinct registry categories, and they should not be combined or treated as mutually exclusive without additional information about the coding rules. The record also lists 3 deaths; it does not state in the posted safety information whether those deaths were attributed to cabozantinib or to the underlying disease or other causes.
The most frequently listed serious-event terms and their reported percentages are thromboembolic event, 5.6%; vomiting, 5.6%; abdominal pain, 3.7%; nausea, 3.7%; pleural effusion, 3.7%; and small intestinal obstruction, 3.7%. These percentages describe the registry’s listed serious-event terms. They are not estimates of comparative risk because the study had no concurrent control group. The registry record does not provide the event-level narratives, timing, duration, severity grading beyond the serious-event classification, or causal attribution for these terms.
In general, safety counts describe events recorded during observation and should be interpreted with their population and reporting definitions in mind. The safety figures do not establish whether an event was caused by treatment. Causal attribution and more detailed safety methods are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The posted information establishes that a completed phase 2, single-group study evaluated cabozantinib in adults with refractory soft tissue sarcoma, with a primary endpoint based on objective response under RECIST v1.1. It also documents the dose schedule, study-level timeframe, and selected safety counts. These details explain what the study was designed to assess and how the primary response categories were defined.
The central primary result is not reported in the registry record: there is no response count, percentage, or 95% confidence interval. Consequently, the posted information does not show the observed frequency of complete or partial response, nor how precisely that frequency was estimated. The endpoint definition cannot substitute for an outcome estimate. The registry record also does not provide results for the listed secondary biomarker outcomes.
Even with a response estimate, a single-group, unmasked design would describe outcomes in the participants studied rather than provide a randomized comparison. Without a control group, the data cannot quantify how the response experience differs from another treatment or from what would otherwise have occurred. This is a design limitation for comparative interpretation, not evidence for or against a treatment effect.
The safety information records serious events in the safety group and lists 3 deaths, but it does not report causal attribution. The listed event counts and percentages should therefore be read as descriptive registry data, not as proof that the intervention caused or did not cause a particular event. The record does not give the additional detail needed to characterize event timing, duration, or individual circumstances.
Overall, the registry record supports a description of study design, response criteria, and selected safety reporting. It does not provide enough posted outcome information to quantify primary response or its precision, establish a comparative effect, or resolve the causal interpretation of safety events. Those limits should remain explicit when drawing statistical conclusions from the record.
13. Why This Trial Matters Statistically
This trial is statistically instructive because the registry record states a specific primary endpoint and response definition while omitting the endpoint’s numerical result. A clearly defined outcome is necessary for reproducibility, but it does not by itself tell readers what was observed. The absence of a response count, estimate, and confidence interval means that the central outcome cannot be evaluated quantitatively from the posted results.
The design also makes the distinction between description and comparison important. This was a single-group study with no masking and no concurrent comparator. A response proportion, if reported, would summarize the observed group. It would not estimate a randomized contrast. Understanding that distinction prevents descriptive outcomes from being overstated as comparative evidence.
The record further illustrates why analysis populations matter. It reports enrollment of 55, states that 1/55 did not start therapy, and lists a safety group of 54 at risk. However, the primary response denominator and missing-assessment rules are not reported in the registry record. Readers cannot fully reproduce or judge a percentage without knowing which participants were included and how unavailable assessments were handled.
Finally, the record identifies several secondary biomarker outcomes and safety events, but does not provide their outcome analyses or a multiplicity strategy. Statistical interpretation depends not only on which measures were named, but also on how they were analyzed and how uncertainty was handled. The record’s limits make transparent reporting especially consequential: design and endpoint details can be understood, while outcome magnitude and precision remain unavailable.
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 trial-specific limitation for interpreting the registry record is that the primary objective-response result is absent. Although the endpoint definition and its intended 95% confidence interval are described, the response count, percentage, and interval are not reported in the registry record. The secondary biomarker outcomes are listed without their numerical results or uncertainty measures.
The single-group design provides no concurrent control. The registry record therefore cannot support a direct comparative estimate, and the absence of masking may also matter for outcome assessment or reporting. Whether imaging assessments were independently reviewed or masked is not reported in the registry record.
The record states that 1/55 participants did not start therapy and lists 54 participants at risk for safety reporting, but does not identify the analysis population for the primary endpoint. It does not state how missing or unevaluable imaging was handled, or report the number of participants with complete outcome assessments. These details are needed to understand the response denominator and potential effects of missing data.
The primary endpoint timeframe is described as approximately 86 months and 3 days from consent to off-study date, but participant-level follow-up and response timing are not reported. The registry record also does not report the primary analysis method, multiplicity procedures, interim analyses, or the trial’s sample-size justification. The listed serious-event counts lack causal attribution and detailed event-level information. These limitations concern what can be concluded from the registry record; they do not establish that unreported procedures or analyses were absent from study conduct.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Cabozantinib for Adults With Advanced Soft Tissue Sarcoma — NCT01755195.
- Registry record last updated 2024-01-03; status last verified 2023-12.
- Results first posted 2021-09-16.
- 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
NCT01755195 is a completed phase 2, single-group study of cabozantinib in adults with refractory soft tissue sarcoma. The study title specifies metastatic refractory disease. Enrollment was 55; 1/55 participants did not start therapy. The intervention was cabozantinib 60 mg orally once a day in 28-day cycles. The primary endpoint was objective response, defined as complete response plus partial response under RECIST v1.1, with a 95% confidence interval specified as the dispersion measure.
The registry record does not report the primary response count, percentage, or confidence interval. It lists secondary circulating biomarker outcomes but does not report their results. The safety group lists 54 participants at risk, 14 affected by serious adverse events, 53 affected by other adverse events, and 3 deaths. The design has no comparator, and causal attribution for the listed safety events is not reported in the registry record.