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 Pralatrexate vs Observation Following CHOP-based Chemotherapy in Undiagnosed Peripheral T-cell Lymphoma Patients (NCT01420679), a randomized phase 3 study. The primary outcome is Progression-Free Survival (PFS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01420679 |
| Phase | Phase 3 |
| Condition | Peripheral T-cell Lymphoma |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 21 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Spectrum Pharmaceuticals, Inc |
| Results posted | Yes |
2. Clinical Question
Population
Participants had peripheral T-cell lymphoma that had not previously been diagnosed and achieved an objective response after initial CHOP-based chemotherapy. The registry describes the study population as patients previously undiagnosed with the disease; further eligibility details are not reported in the registry record.
Intervention
Participants assigned to the pralatrexate arm were to receive pralatrexate injection with vitamins B12 and folic acid until a criterion for stopping pralatrexate treatment was met. The registry does not describe the dosing schedule in the record summarized for this comparison.
Comparator
Participants assigned to observation were to receive vitamins B12 and folic acid and remain under observation until a criterion for ending observation was met. Thus, the intended contrast was sequential pralatrexate versus observation after the initial CHOP-based treatment, rather than a comparison of the initial chemotherapy regimens.
Primary question
The planned primary question was whether the time from randomization to documented disease progression or death differed between the randomized strategies. The registry defines this outcome as progression-free survival (PFS), but states that the outcome was not collected and analyzed because the study ended early. It therefore does not report an estimate of the comparative PFS effect.
3. Trial Design
This was a randomized, phase 3, parallel-group study with no masking. It compared sequential pralatrexate with observation in participants with peripheral T-cell lymphoma who achieved an objective response after initial CHOP-based chemotherapy. The registry lists enrollment as 21 and status as terminated. It does not report the reason for termination in the registry record.
The intended treatment assignment was to pralatrexate injection plus vitamins B12 and folic acid, or to observation with vitamins B12 and folic acid. Treatment or observation was to continue until a stated discontinuation criterion was met. The registry describes regular clinic visits to evaluate disease and health. Details of the visit schedule and the criteria for discontinuation are not reported in the registry record.
The trial began in 2011-08, and the listed primary completion date is 2017-12. These dates do not establish how long any individual participant was followed. The primary outcome timeframe was described as extending from randomization to progression or death, up to 76 months. The registry does not report the randomization procedure, allocation concealment, or a detailed statistical analysis plan. The record lists 4 outcome measures and no statistical analyses. Most importantly for interpreting the planned comparison, the primary PFS outcome was not collected and analyzed following early termination.
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: A total of 21 participants with peripheral T-cell lymphoma (PTCL) were randomized in 2:1 ratio to Pralatrexate arm or Observation arm.
Overall Study
| Stage | Pralatrexate Arm | Observation Arm |
|---|---|---|
| STARTED | 14 | 7 |
| COMPLETED | 0 | 0 |
| NOT COMPLETED | 14 | 7 |
Reasons for not completing this period:
| Reason | Pralatrexate Arm | Observation Arm |
|---|---|---|
| Disease Progression | 3 | 2 |
| Adverse Event | 4 | 0 |
| More Than 28 Days Between Doses of Drug | 1 | 0 |
| Patient Decision | 1 | 0 |
| Investigator Decision | 1 | 2 |
| Sponsor Decision | 3 | 3 |
| Other | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: Data for this outcome measure was not collected and analyzed due to the early termination of the 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.
| Characteristic | Unit | Pralatrexate Arm | Observation Arm | Total |
|---|---|---|---|---|
| Participants analysed | 14 | 7 | 21 | |
| Age, Continuous | years | 72.0 (51 to 83) | 61.0 (44 to 83) | 68.0 (44 to 83) |
| Sex: Female, Male: Female | Participants | 8 | 0 | 8 |
| Sex: Female, Male: Male | Participants | 6 | 7 | 13 |
| Race/Ethnicity, Customized: Asian | Participants | 2 | 0 | 2 |
| Race/Ethnicity, Customized: Black | Participants | 1 | 1 | 2 |
| Race/Ethnicity, Customized: Arabic | Participants | 0 | 1 | 1 |
| Race/Ethnicity, Customized: White | Participants | 10 | 5 | 15 |
| Race/Ethnicity, Customized: Missing | Participants | 1 | 0 | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Progression-Free Survival (PFS), measured over From randomization to the date of progression of disease or death due to any cause (up to 76 months).
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was progression-free survival (PFS), a time-to-event measure. The registry defines it as the time in days from randomization to objective documentation of progressive disease or death from any cause. The event date was defined using the date of progression or death relative to randomization, with a day added according to the registry’s stated convention. Progression was to be assessed using the International Workshop Criteria without positron emission tomography.
As defined in the record, progressive disease included a new lesion or an increase of at least 50 percent in previously involved sites from nadir. Participants alive without documented progression were to be censored at the last disease assessment date or the randomization date, whichever was later. Participants without response assessments after baseline were to be censored at randomization. The record also states that progression dates were not to be imputed when tumor assessments were missing before a progression assessment.
In general, PFS is used to capture how long participants remain alive without documented progression. It combines progression and death into a time-to-event outcome, so it differs from an outcome that counts only tumor response. Here, the endpoint is described as planned, but the registry says it was not collected and analyzed. No comparative PFS estimate is reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry supports a description of the trial’s intent and its available safety counts, but it does not support an estimate of the primary treatment effect. PFS was the primary outcome, yet the record explicitly says that data for this outcome were not collected and analyzed because the study terminated early. Consequently, there is no reported PFS effect estimate, confidence interval, or significance test to interpret. The record does not establish whether the assigned strategies differed in PFS.
Enrollment is listed as 21, but that figure alone cannot show how precisely a treatment effect was estimated. Precision depends on the outcome data and analysis, neither of which is available for the primary endpoint in the registry record. The absence of an analyzed PFS result is not evidence that the strategies had the same outcome, nor is it evidence that one was better. It leaves the central planned comparison unanswered by the posted primary outcome data.
The record lists secondary outcomes including objective response rate and adverse events. It reports safety counts by arm, including serious adverse events, other adverse events, and deaths. Those counts describe events recorded in the groups; they do not replace the missing PFS comparison. The listed serious-event terms each have a reported percentage of 7.1%, but the record does not attach those terms to an arm in the registry record. They should not be treated as a complete comparative safety analysis or as evidence of a causal relationship to treatment.
Randomization was part of the design, but the registry record does not provide analyzed outcome data with which to evaluate the randomized comparison. It also does not report the reason for termination, the planned analysis populations, or a statistical plan. These gaps restrict interpretation: the available record describes what was intended and some event counts, but not the primary outcome result, its uncertainty, or the methods used to analyze outcomes.
In general, a treatment-effect estimate is more informative when accompanied by an interval that conveys uncertainty. No such primary endpoint estimate or interval is reported. Any planning illustrations should be distinguished from observed evidence: a planning calculation is not a measured trial effect and is never observed power. The posted results therefore warrant a narrow conclusion: the intended PFS comparison cannot be assessed from the registry’s analyzed outcomes.
9. Statistical Methods Explained
What does randomization contribute?
Randomization assigns participants to study strategies by chance. In general, this is intended to make the groups comparable, on average, with respect to factors known and unknown before assignment. It does not guarantee identical groups, especially when enrollment is limited, and it does not ensure that an outcome will be measured or analyzed. This study is described as randomized, but the specific procedure used to generate assignments and conceal them before assignment is not reported in the registry record.
What kind of outcome is PFS?
PFS is a time-to-event outcome: the analysis concerns the time from a defined starting point, here randomization, until progression or death. Such outcomes can account for both whether an event occurs and when it occurs. The registry specifies the event definition and describes circumstances in which participants were to be censored. It also states that PFS data were not collected and analyzed after early termination, so the described endpoint rules do not amount to a reported result.
In general, censoring means that the event time is not observed during the period for which a participant’s outcome information is available. A censored observation contributes information up to the specified censoring time, subject to the assumptions of the chosen method. The registry’s planned rules identify some censoring dates, including the last disease assessment for participants alive without documented progression and randomization for participants with no post-baseline response assessments. The statistical method used to combine censored observations is not reported in the registry record.
Why does the event definition matter?
A time-to-event estimate depends on a consistent definition of when an event has occurred and how follow-up ends for participants without a recorded event. The record defines progression by reference to the International Workshop Criteria, excludes PET from that assessment, and describes progression using new lesions or increases in previously involved sites. It also defines death from any cause as an event. These details establish the planned endpoint’s meaning, but they cannot recover a comparative result when the outcome was not collected and analyzed.
In general, an estimate of a treatment contrast should be interpreted together with its uncertainty. A confidence interval describes a range of values compatible with the data and the method under its assumptions; it is not a guarantee that the true effect lies in the interval. No primary PFS estimate or confidence interval is reported in the registry record. There is therefore no interval width from which to judge the precision of the primary comparison.
What can the safety counts tell a reader?
The record lists participants at risk and affected counts for serious adverse events, other adverse events, and deaths in each arm. These are descriptive counts. A count does not by itself indicate whether an event was caused by study treatment, and differences in counts cannot be interpreted as a causal treatment effect without an appropriate analysis and context. The registry does not report a comparative statistical analysis of these safety outcomes in the registry record.
In general, safety interpretation may depend on event definitions, follow-up time, exposure to treatment, severity, and whether events were judged related to treatment. Such details are not all reported in the registry record. The listed top serious-event terms carry percentages, but the record excerpt does not assign each listed term to a particular arm. Their percentages should not be used to infer arm-specific risks.
How should planning calculations be understood?
The record describes planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. In general, a planning illustration asks how much information might be needed to detect a specified effect under chosen assumptions. It is not an observed result and is not observed power. The registry entries reported for this trial do not include a primary PFS effect estimate from an analysis, because the primary outcome was not collected and analyzed. Any planning figure should not be read as proof that the trial had adequate or inadequate power for its clinical question.
More broadly, statistical methods are only as informative as the outcome data and analysis to which they are applied. The registry identifies a randomized design and a planned endpoint definition, but does not report the primary endpoint analysis, analysis populations, or detailed analysis procedures. Those omissions mean that standard concepts such as adjustment, model choice, and sensitivity analysis cannot be attributed to this trial. The registry record does not report whether such procedures were planned or conducted.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists the primary PFS outcome and secondary outcomes that include objective response rate and adverse events. Testing or estimating several outcomes can raise multiplicity concerns: in general, repeated hypothesis tests may increase the chance of at least one apparently notable result if no adjustment or hierarchy is used. The registry record does not report a multiplicity strategy, a testing hierarchy, or a detailed statistical analysis plan. No claim can therefore be made about whether multiplicity was addressed.
Missingness is central to the primary outcome because the record states that PFS data were not collected and analyzed due to early termination. The planned PFS description includes rules for censoring participants in specified situations, such as being alive without documented progression or having no post-baseline response assessment. Those rules describe how certain incomplete follow-up was to be handled; they do not provide observed PFS data or an analysis. Whether any other missing-data procedures were planned is not reported in the registry record.
The record describes randomization but does not identify the population used for any outcome analysis. It does not report whether analyses were intended to follow randomized assignment, include only treated participants, or use another population definition. These analysis-population details are not reported in the registry record. The record also lists no statistical analyses, so there is no reported analysis set or inferential result to assess.
In general, missing outcomes, censoring, multiplicity, and analysis-population choices can affect what an estimate means and how certain it is. Without an analyzed primary endpoint or a reported statistical plan, those issues cannot be resolved for the intended PFS contrast. The available record should not be read as showing that missing data were successfully handled or that multiplicity had no effect.
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 |
|---|---|---|---|
| Pralatrexate Arm | 4 | 14 | 28.6% |
| Observation Arm | 0 | 7 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Pralatrexate Arm | 3 of 14 |
| Observation Arm | 1 of 7 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Pralatrexate Arm | 14 of 14 |
| Observation Arm | 6 of 7 |
Most frequent serious adverse event terms
| Event term | Organ system | Pralatrexate Arm | Observation Arm |
|---|---|---|---|
| Cardiac arrest | Cardiac disorders | 1 of 14 | 0 of 7 |
| Stomatitis | Gastrointestinal disorders | 1 of 14 | 0 of 7 |
| Non-cardiac chest pain | General disorders | 1 of 14 | 0 of 7 |
| Subdural hematoma | Injury, poisoning and procedural complications | 1 of 14 | 0 of 7 |
| Hyponatraemia | Metabolism and nutrition disorders | 1 of 14 | 0 of 7 |
| Haemorrhage intracranial | Nervous system disorders | 1 of 14 | 0 of 7 |
| Carotid artery occlusion | Nervous system disorders | 1 of 14 | 0 of 7 |
| VIIth nerve paralysis | Nervous system disorders | 1 of 14 | 0 of 7 |
| Confusional state | Psychiatric disorders | 1 of 14 | 0 of 7 |
| Dyspnoea | Respiratory, thoracic and mediastinal disorders | 1 of 14 | 0 of 7 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Pralatrexate Arm | Observation Arm |
|---|---|---|---|
| Fatigue | General disorders | 6 of 14 | 2 of 7 |
| Cough | Respiratory, thoracic and mediastinal disorders | 5 of 14 | 3 of 7 |
| Diarrhoea | Gastrointestinal disorders | 6 of 14 | 1 of 7 |
| Nausea | Gastrointestinal disorders | 6 of 14 | 1 of 7 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 6 of 14 | 1 of 7 |
| Stomatitis | Gastrointestinal disorders | 5 of 14 | 1 of 7 |
| Upper respiratory tract infection | Infections and infestations | 3 of 14 | 2 of 7 |
| Neuropathy peripheral | Nervous system disorders | 4 of 14 | 1 of 7 |
| Epistaxis | Respiratory, thoracic and mediastinal disorders | 5 of 14 | 0 of 7 |
| Pruritus | Skin and subcutaneous tissue disorders | 4 of 14 | 1 of 7 |
Serious events with the highest arm-level rate: cardiac arrest (7.1%), stomatitis (7.1%), non-cardiac chest pain (7.1%), subdural hematoma (7.1%), hyponatraemia (7.1%).
The registry reports serious adverse events for 4 of 14 participants at risk in the pralatrexate arm and 0 of 7 participants at risk in the observation arm. It reports other adverse events for 14 of 14 participants at risk in the pralatrexate arm and 6 of 7 in the observation arm. Deaths are listed for 3 participants in the pralatrexate arm and 1 in the observation arm. These are descriptive counts in the registry record, not estimates of comparative risk.
The listed top serious adverse event terms are cardiac arrest, stomatitis, non-cardiac chest pain, subdural hematoma, hyponatraemia, and haemorrhage intracranial. Each is reported with 7.1%. The registry information does not assign those terms to an arm, so the percentages should not be interpreted as arm-specific rates. The record also does not establish that any listed event was caused by treatment.
In general, comparisons of safety counts need context about exposure, follow-up, event definitions, and attribution. The registry record does not provide a comparative statistical analysis of these counts. They describe events recorded in the study and should not be treated as a complete account of safety or as a substitute for the missing primary outcome analysis.
12. What the Result Does, and Does Not, Mean
The study was designed to compare pralatrexate with observation after an objective response to CHOP-based chemotherapy in peripheral T-cell lymphoma. Its primary question concerned PFS, defined as time from randomization to documented progression or death. The registry states that this outcome was not collected and analyzed because the study terminated early. As a result, the posted record does not provide an answer about the comparative PFS outcome.
This absence of a primary result should not be interpreted as evidence of no difference, and it should not be interpreted as evidence of benefit or harm. Without an analyzed PFS estimate and its uncertainty, the magnitude and precision of any comparative effect are not reported in the registry record. The reason for termination is also not reported, so it cannot be used to infer why the outcome data were unavailable.
The registry does report adverse-event and death counts. Those figures provide descriptive information about recorded events among participants at risk in the listed arms. They do not establish that treatment caused an event, and the record does not present a statistical comparison of safety outcomes. The top serious-event terms and their percentages are not assigned to an arm in the registry record.
In general, a trial’s design and its results are different kinds of evidence. Randomization describes how a comparison was intended to be made; it does not supply an outcome estimate when the endpoint was not analyzed. Likewise, a planning calculation is not an observed treatment effect and is not observed power. The appropriate reading is limited to what the registry reports: the intended randomized comparison, the early termination and missing primary analysis, and the listed safety counts.
The record does not establish how the result would apply beyond the population described, nor does it give a basis for recommendations about care. Its central statistical limitation is that the planned primary endpoint cannot be evaluated from the posted analyzed outcomes.
13. Why This Trial Matters Statistically
This trial illustrates why a clearly defined endpoint is not the same as an endpoint result. The registry gives a detailed PFS definition, including the event criteria and planned censoring rules. Those details help clarify the intended question, but they do not yield a treatment comparison when the registry says PFS data were not collected and analyzed.
It also shows why design labels need to be interpreted alongside the available results. Randomization and a phase 3 designation describe important features of the planned study. They do not by themselves show whether the study answered its primary question, how precise an estimate was, or whether an observed difference would be credible. Here, the primary outcome analysis is unavailable in the registry record, and no statistical analyses are listed.
Another statistical lesson concerns the distinction between event counts and comparative inference. The record provides serious and other adverse-event counts, as well as deaths. These counts can describe what was recorded in each arm, but they do not alone establish a treatment-related difference. Interpretation depends on information such as follow-up and exposure, and on an analysis that the registry does not report.
Finally, early termination can leave a record with design and safety information but no analyzed primary endpoint. The registry reports termination but not its reason. Avoiding speculation about that reason is important: the registry entries support a careful account of what was planned and what was reported, not a reconstruction of decisions or outcomes that are absent from the record.
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 main limitation is that the primary PFS outcome was not collected and analyzed because the study terminated early. No PFS estimate, confidence interval, or statistical test is reported. The reason for termination is not reported in the registry record, so its relationship to recruitment, follow-up, or study operations cannot be determined.
The registry lists enrollment as 21, but that figure does not provide the missing endpoint information. Follow-up duration by arm, the number of progression or death events, and a primary analysis population are not reported in the registry record. Although the outcome definition describes planned censoring, the record does not provide analyzed PFS data with which to assess the consequences of censoring or missing assessments.
The record describes randomization but does not report the allocation procedure, allocation concealment, or the statistical analysis plan. It does not identify the analysis populations or report how multiplicity was handled across the primary and secondary outcomes. These omissions limit assessment of the intended analysis and its robustness.
The safety information is also limited. Counts are reported by arm for serious adverse events, other adverse events, and deaths, but no comparative statistical analysis is reported. The registry information does not assign each listed top serious-event term to an arm, and it does not provide enough context to interpret the listed percentages as arm-specific risks. The counts should therefore remain descriptive.
Finally, the registry does not report further eligibility details, discontinuation criteria, or the treatment schedule beyond the named intervention and supplements. These gaps restrict assessment of who entered the study, how long participants received their assigned strategy, and how the observed safety counts relate to exposure.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Pralatrexate vs Observation Following CHOP-based Chemotherapy in Undiagnosed Peripheral T-cell Lymphoma Patients — NCT01420679.
- Registry record last updated 2021-11-19; status last verified 2021-11.
- Results first posted 2021-11-19.
- 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
This randomized, phase 3, parallel-group study compared pralatrexate with observation after an objective response to initial CHOP-based chemotherapy in participants with peripheral T-cell lymphoma. The registry lists enrollment as 21 and status as terminated. Participants assigned to pralatrexate were to receive the injection with vitamins B12 and folic acid; those assigned to observation were to receive the vitamins and remain under observation.
The primary endpoint was PFS, defined as time from randomization to documented progression or death. The registry states that this outcome was not collected and analyzed because of early termination. It therefore reports no primary comparative PFS result. The record lists safety counts by arm, but does not report a statistical comparison of those outcomes. The reason for termination, detailed analysis methods, and analysis populations are not reported in the registry record.