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 Peginterferon α-2b as a Maintenance Therapy in Participants With Multiple Myeloma Who Responded to Induction Therapy (P01972-AM7) (NCT00732641), a randomized phase 3 study. The primary outcome is Number of Days With Progression Free Survival (PFS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00732641 |
| Phase | Phase 3 |
| Condition | Multiple Myeloma |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 244 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Merck Sharp & Dohme LLC |
| Results posted | Yes |
2. Clinical Question
Population
Adults with multiple myeloma who responded to prior induction therapy. The primary outcome population is described as the intent-to-treat population, defined in the registry record as those who received at least one dose of study drug.
Intervention
Peginterferon α-2b 35 μg, given once weekly by subcutaneous injection. Treatment was planned until disease progression or relapse, or for up to a maximum of 5 years.
Comparator
Observation without maintenance treatment. Participants in this group received no treatment.
Primary question
How did progression-free survival, measured as the time from randomization to first documented progression or relapse, compare between maintenance peginterferon α-2b and observation?
The clinical question concerns maintenance treatment after a response to induction therapy, rather than treatment of previously untreated disease or a comparison between induction regimens. The study’s brief description frames its aim as assessing efficacy against a control group that received no maintenance treatment. The primary endpoint was reported as median time in days, with a 95% confidence interval for each arm.
The registry record also lists overall survival, response categories, progressive disease or relapse from complete response, and quality of life among the secondary outcomes. Those outcomes may address different aspects of the disease course and participants’ experience, but the primary result is progression-free survival. The record does not report a hazard ratio or a comparative test result for this endpoint, so the medians and their confidence intervals should not be treated as a complete account of every possible treatment comparison.
3. Trial Design
This was a phase 3, randomized, prospective, multicenter, parallel-group trial comparing peginterferon α-2b maintenance with observation in participants with multiple myeloma who responded to induction therapy. The registry record identifies Merck Sharp & Dohme LLC as the sponsor and gives the overall enrollment as 244. The study status is completed. The recorded start was 2000-12, and primary completion was 2010-11.
The active-treatment arm received peginterferon α-2b 35 μg by subcutaneous injection once weekly, until progression or relapse or for up to a maximum of 5 years. The comparison arm received no treatment and was observed. The design is described as unmasked, so masking was not used. The record does not describe the randomization sequence, allocation concealment, or any procedures intended to reduce awareness of treatment assignment.
For the primary endpoint, the registry reports 122 participants in the peginterferon α-2b group and 121 in the no-treatment group. These are the endpoint group counts; the record does not explain how they relate to the overall enrollment of 244. The primary outcome population is called intent-to-treat, but its registry definition is participants who received at least one dose of study drug. That wording should be retained when interpreting the analysis population rather than replaced with a broader assumption about who was analyzed.
The registry record does not report the planned sample-size justification, the randomization ratio, recruitment details, or an analysis plan. It also does not report interim analyses or the rules, if any, for stopping early. The trial’s phase and randomized parallel-group structure provide important design context, but they do not supply these missing procedural details.
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 | Peginterferon α-2b | No Treatment |
|---|---|---|
| STARTED | 123 | 121 |
| COMPLETED | 17 | 9 |
| NOT COMPLETED | 106 | 112 |
Reasons for not completing this period:
| Reason | Peginterferon α-2b | No Treatment |
|---|---|---|
| Relapse or Progressive Disease | 65 | 101 |
| Serious Adverse Events | 12 | 3 |
| Physician Decision | 6 | 0 |
| Withdrawal by Subject | 4 | 2 |
| Unable to Complete | 1 | 1 |
| Other | 18 | 5 |
Analysis population for the primary outcome, as defined in the registry: Intent-to-treat population (those who received at least one dose of study drug)
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 | Peginterferon α-2b | No Treatment | Total |
|---|---|---|---|---|
| Participants analysed | 122 | 121 | 243 | |
| Age, Continuous | years | 61.0 (SD 8.5) | 62.3 (SD 8.6) | 61.7 (SD 8.6) |
| Sex: Female, Male: Female | Participants | 53 | 60 | 113 |
| Sex: Female, Male: Male | Participants | 69 | 61 | 130 |
| Region of Enrollment: Italy | participants | 123 | 121 | 244 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Days With Progression Free Survival (PFS), measured over Baseline and up to 5 years (or to the date of the first documented tumor progression or relapse).
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | Days |
| Endpoint classification | Time-to-Event Analysis |
The primary endpoint was the number of days with progression-free survival, summarized as the median. The registry defines progression-free survival as the duration from randomization until the first documented tumor progression or relapse. Its description also characterizes it as time during and after treatment in which a participant is living with cancer that has not worsened. The stated timeframe was baseline and up to 5 years, or until the date of first documented progression or relapse.
A time-to-event endpoint accounts for both whether an event occurs and how long participants remain event-free before it occurs. The median is the time by which half of the relevant participants have experienced the event and half have not, as estimated by the analysis. It is useful for describing the middle of the observed time-to-event distribution without requiring the average event time to be meaningful or fully observed for everyone.
The registry reports a median of 1166 days for peginterferon α-2b, with a 95% confidence interval of 682 to 1519 days, and a median of 519 days for no treatment, with a 95% confidence interval of 403 to 634 days. The endpoint is clinically relevant to disease control over time, but it is not interchangeable with overall survival, response rate, quality of life, or safety. Those outcomes address different questions.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary result gives a median progression-free survival of 1166 days in the peginterferon α-2b arm, with a 95% confidence interval of 682 to 1519 days. In the no-treatment arm, the median was 519 days, with a 95% confidence interval of 403 to 634 days. These are arm-specific summaries of time to documented progression or relapse in the endpoint population specified by the registry record.
The confidence intervals convey uncertainty around the estimated medians. They are not ranges containing a known proportion of individual participants’ event times, and they do not by themselves establish the probability that one treatment is better than the other. The intervals describe uncertainty for each arm’s median separately; a formal comparison ordinarily requires an appropriate between-arm estimate and its uncertainty or a test result. No hazard ratio, comparative confidence interval, or primary-endpoint p-value is reported in the registry record.
The reported medians differ in their point estimates, while the intervals communicate that each estimate is imprecise. The record does not include enough comparative statistical output to quantify the relative event rate over follow-up or to establish a formal statistical significance claim. The medians also cannot show whether the difference was consistent throughout follow-up: time-to-event curves can differ in shape, and medians alone do not describe those patterns.
Interpretation should account for the endpoint population description. The record calls it intent-to-treat but specifies participants who received at least one dose of study drug. It lists 122 participants for peginterferon α-2b and 121 for no treatment for this endpoint, while overall enrollment is 244; no explanation for the distinction is reported. The record also does not state how censoring, incomplete follow-up, or missing endpoint information was handled.
Randomization and the parallel-group structure support a comparative design, but the record does not describe allocation procedures, masking, or the statistical model used for the primary analysis. The intervention was compared with observation, not with another maintenance treatment. These results therefore describe the comparison registered for this trial and should not be extended to other populations, treatment regimens, or comparators without additional evidence.
The study also lists secondary outcomes, including overall survival and several response categories. Their presence does not mean their results are available: the record lists six secondary outcomes as posted, but reports no analyses in its analysis count. The primary endpoint figures should therefore be read as a limited description of the registry’s reported result, not as a complete evaluation of every outcome or of the trial’s full statistical evidence.
9. Statistical Methods Explained
Progression-free survival is a time-to-event outcome: the event is the first documented tumor progression or relapse, and the time origin is randomization. Participants who have not had a documented event by the end of their observed follow-up generally contribute information up to the point at which follow-up ends. In general, time-to-event methods use this partial follow-up rather than treating every participant without a recorded event as if an event had occurred. The registry record does not specify the censoring rules or analytic method used for this result.
What does a median time-to-event estimate describe?
In general, a median time-to-event estimate marks the time at which the estimated proportion remaining event-free reaches one half. It summarizes the center of the event-time distribution and can be useful when follow-up is incomplete or event times are not symmetrically distributed. It does not summarize every feature of the distribution. In particular, the median does not show whether differences between groups emerged early, late, or steadily across follow-up, and it does not describe the range of individual experiences.
The registry reports median progression-free survival in days for each arm. The peginterferon α-2b estimate is 1166 days, with a 95% confidence interval of 682 to 1519 days; the no-treatment estimate is 519 days, with a 95% confidence interval of 403 to 634 days. These are separate arm estimates. A comparison based only on the two medians is not the same as a time-to-event model comparing the groups across follow-up.
How should confidence intervals be read?
In general, a confidence interval describes the uncertainty associated with an estimate under the assumptions of the statistical procedure. A narrower interval indicates greater precision than a wider interval, all else equal. A 95% confidence interval is not a statement that 95% of participants’ outcomes fall inside its limits. Nor is overlap or non-overlap of two separate confidence intervals a substitute for a direct test or confidence interval for the between-group contrast.
The registry supplies confidence intervals for the two medians but does not report a comparative confidence interval, hazard ratio, or p-value for the primary endpoint. Consequently, the arm-specific estimates and their uncertainty can be described, but a formal comparative claim cannot be reconstructed from the posted figures alone. No additional calculation is presented as a sponsor analysis.
Why might a hazard ratio be reported?
In general, a hazard ratio from a time-to-event model compares the event rates between groups over follow-up, conditional on participants remaining event-free up to each time. It can use information across the observed follow-up, whereas medians focus on one point in each group’s event-time distribution. The interpretation of a hazard ratio depends on the model and its assumptions, including whether a single relative event rate adequately represents the time pattern. No hazard ratio is reported in the registry record, and the record does not state which model, if any, was used to produce the medians.
Time-to-event analyses also rely on assumptions about censoring and follow-up. In general, censoring is most straightforward to interpret when the reason observation ends is not related to the participant’s underlying event risk in a way that would distort the comparison. The registry does not describe follow-up completeness, reasons for censoring, or checks of analytic assumptions. Those omissions limit how fully the reported medians can be assessed.
What do the planning illustrations mean?
In general, sample-size planning estimates how many participants may be needed to detect a chosen effect under specified assumptions about the significance level, allocation, and statistical model. The planning illustrations associated with this trial are based on fractions of the observed effect and use a two-sided significance level of 0.05, equal allocation, and a normal approximation. For time-to-event outcomes, the illustration concerns a total number of events; for other outcomes, it concerns participants per arm. These calculations are planning illustrations, not observed power, and they do not show the power the completed trial actually had.
The registry record does not report the trial’s own sample-size justification or planning assumptions. The planning illustrations therefore should not be mistaken for the original design rationale, an independently verified power calculation, or evidence that a particular effect was detected. They are conditional on their stated assumptions and on the observed effect used as their reference.
What is not available for statistical verification?
The record does not report a detailed analysis plan, interim analyses, adjustment for multiple outcomes, handling of missing data, or sensitivity analyses. It also does not report a primary-endpoint test statistic or comparative estimate. Without these details, readers cannot assess all modeling choices, verify robustness to alternative assumptions, or determine whether analyses were prespecified. The posted information supports a descriptive reading of the arm-specific medians and confidence intervals, but not a reconstruction of the complete statistical analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists six secondary outcomes: overall survival, complete response, partial response, minimal response, progressive disease or relapse from complete response, and quality of life. It reports seven outcome measures in total, but no analyses in its analysis count. The listing of multiple outcomes raises a general multiplicity issue: when many outcomes are tested, the chance of at least one apparently notable result can increase unless testing is planned and interpreted appropriately. Whether and how this trial addressed multiplicity is not reported in the registry record.
The record does not describe a prespecified hierarchy of outcomes, any adjustment to significance thresholds, or which analyses were considered confirmatory. It also does not provide results for the listed secondary outcomes in the registry record for this account. They should not be treated as evidence for or against the primary endpoint in the absence of their estimates and methods.
Missing-data methods are also not reported in the registry record. The endpoint definition depends on documented progression or relapse and follow-up time, but the record does not explain how participants without a recorded event were handled, how censoring was determined, or whether incomplete assessments affected inclusion. No imputation, sensitivity analysis, or missingness summary is reported.
The registry describes the primary outcome population as intent-to-treat, defined as those who received at least one dose of study drug. This definition is important to preserve when interpreting the results. The endpoint counts are 122 in the peginterferon α-2b arm and 121 in the no-treatment arm; the record does not explain how those counts relate to overall enrollment of 244. It does not report exclusions, withdrawals, or the number with complete endpoint follow-up. These gaps prevent a full assessment of whether missing information or analysis-population choices could have affected the estimates.
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 |
|---|---|---|---|
| Peginterferon α-2b | 27 | 123 | 22.0% |
| No Treatment | 21 | 121 | 17.4% |
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 |
|---|---|
| Peginterferon α-2b | 94 of 123 |
| No Treatment | 63 of 121 |
Most frequent serious adverse event terms
| Event term | Organ system | Peginterferon α-2b | No Treatment |
|---|---|---|---|
| DISEASE PROGRESSION | General disorders | 4 of 123 | 5 of 121 |
| PYREXIA | General disorders | 2 of 123 | 1 of 121 |
| BRONCHOPNEUMONIA | Infections and infestations | 2 of 123 | 1 of 121 |
| ANAEMIA | Blood and lymphatic system disorders | 1 of 123 | 1 of 121 |
| ATRIAL FIBRILLATION | Cardiac disorders | 1 of 123 | 1 of 121 |
| VOMITING | Gastrointestinal disorders | 2 of 123 | 0 of 121 |
| CYST | General disorders | 2 of 123 | 0 of 121 |
| HEPATITIS B | Infections and infestations | 1 of 123 | 1 of 121 |
| CACHEXIA | Metabolism and nutrition disorders | 2 of 123 | 0 of 121 |
| GASTRIC CANCER | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 2 of 123 | 0 of 121 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Peginterferon α-2b | No Treatment |
|---|---|---|---|
| PYREXIA | General disorders | 31 of 123 | 19 of 121 |
| INFLUENZA LIKE ILLNESS | General disorders | 21 of 123 | 9 of 121 |
| ANAEMIA | Blood and lymphatic system disorders | 13 of 123 | 15 of 121 |
| ASTHENIA | General disorders | 19 of 123 | 3 of 121 |
| BONE PAIN | Musculoskeletal and connective tissue disorders | 13 of 123 | 9 of 121 |
| THROMBOCYTOPENIA | Blood and lymphatic system disorders | 15 of 123 | 3 of 121 |
| DIARRHOEA | Gastrointestinal disorders | 15 of 123 | 3 of 121 |
| BRONCHITIS | Infections and infestations | 11 of 123 | 6 of 121 |
| INFLUENZA | Infections and infestations | 6 of 123 | 10 of 121 |
| PAIN | General disorders | 7 of 123 | 8 of 121 |
Serious events with the highest arm-level rate: disease progression (4.1%), vomiting (1.6%), cyst (1.6%), pyrexia (1.6%), bronchopneumonia (1.6%).
The registry reports serious adverse events for 27 of 123 participants at risk in the peginterferon α-2b group and 21 of 121 at risk in the no-treatment group. Other adverse events are reported for 94 of 123 and 63 of 121 participants, respectively. These are counts with the listed at-risk group sizes, not estimates of a causal effect. The registry information does not establish whether participants could contribute more than one event to a category or how event collection and follow-up periods were defined.
The serious adverse event terms listed include DISEASE PROGRESSION (4.1%), VOMITING (1.6%), CYST (1.6%), PYREXIA (1.6%), BRONCHOPNEUMONIA (1.6%), and CACHEXIA (1.6%). The record does not attach these term percentages to a specific treatment arm in the information, so they should not be attributed to one group. Death counts are not reported in the registry record.
Adverse event counts describe recorded events under the registry’s reporting conventions; they do not by themselves establish whether an event was caused by treatment. Differences in follow-up, exposure, or reporting can also affect how counts should be interpreted. The record does not provide those details or a comparative safety analysis. These figures therefore offer a limited account of reported safety events, not a complete assessment of comparative risk.
12. What the Result Does, and Does Not, Mean
The registry record reports longer median progression-free survival in the peginterferon α-2b arm than in the no-treatment arm: 1166 days versus 519 days. The corresponding 95% confidence intervals are 682 to 1519 days and 403 to 634 days. This is a descriptive summary of the primary time-to-event outcome as posted for the two groups.
The medians do not establish how the groups compared across the entire follow-up period. No hazard ratio, direct between-group confidence interval, or p-value for the primary endpoint is reported in the registry record. A reader therefore cannot use these figures alone to quantify the relative event rate over time or to verify a formal statistical significance claim. Nor do the medians show the distribution of individual event times or the timing of any separation between groups.
The result is specific to a randomized comparison of weekly peginterferon α-2b maintenance with observation in participants with multiple myeloma who responded to induction therapy. It does not compare different maintenance medicines, establish results for participants who did not respond to induction, or report the effects of other treatment schedules. The trial was unmasked, and details of allocation procedures and the statistical analysis plan are not reported in the registry record.
Progression-free survival is distinct from overall survival, response, quality of life, and adverse events. Although the registry lists those other outcomes, their results are not reported in the information available for this account. The safety counts also cannot answer whether a treatment caused an event or provide a complete comparison of harm.
Overall, the posted estimates describe median time to documented progression or relapse in the stated analysis population, with uncertainty around each arm’s median. They do not, on their own, provide a complete account of treatment benefit, harm, or the trial’s statistical evidence. The absent comparative analysis, missing-data details, and secondary outcome results limit broader conclusions.
13. Why This Trial Matters Statistically
This trial presents a useful statistical distinction between an arm-specific summary and a direct comparative estimate. The registry reports a median progression-free survival and confidence interval for each group. Those summaries communicate the estimated time point at which half of the group’s event-time distribution has elapsed, along with uncertainty in each estimate. They are not themselves a modeled comparison of the full time-to-event experience.
That distinction matters because time-to-event outcomes contain information about timing and censoring. A direct comparison may use the full follow-up, while medians reduce each group’s distribution to one central point. If the event patterns change over time, the medians alone may not describe the shape or timing of those differences. The absence of a hazard ratio or other comparative estimate means the registry result should be read descriptively rather than as a complete inferential comparison.
The trial also illustrates why analysis-population definitions deserve attention. The record uses the label intent-to-treat but defines the population as participants who received at least one dose. Preserving that stated definition avoids silently assuming a different analysis population. The endpoint group counts and overall enrollment are also distinct registry figures, and no explanation of their relationship is reported.
Finally, a randomized design does not fill in missing reporting details. Information about allocation, censoring, missing data, multiplicity, and analysis planning is needed to assess the robustness and scope of results. The registry’s arm-level estimates can still be described precisely, but uncertainty about these unreported methods should remain part of the 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 registry record provides arm-specific median progression-free survival estimates and 95% confidence intervals, but no hazard ratio, direct comparative confidence interval, or p-value for the primary endpoint. It does not identify the statistical model used to estimate the medians or explain how censoring was handled. The estimates can therefore be read as posted, but the full comparative analysis cannot be independently assessed from this record.
Important design details are not reported in the registry record, including the randomization procedure, allocation concealment, and the statistical analysis plan. The trial is described as unmasked, but the record does not state how outcome assessment was conducted. It also does not report interim analyses or rules for stopping early.
The record does not explain the relationship between overall enrollment of 244 and the endpoint group counts of 122 and 121. The primary population is described as intent-to-treat and defined as those who received at least one dose of study drug. Exclusions, withdrawals, follow-up completeness, and handling of missing endpoint information are not reported.
The registry lists secondary outcomes, but their estimates and analyses are not reported in the information available for this account. The record also does not describe any adjustment for multiple outcomes. The adverse event counts lack details about collection periods, event-level counting, and comparative safety methods; deaths are not reported in the registry record. These reporting gaps limit interpretation of both efficacy and safety and make it difficult to judge how sensitive the findings are to analytic choices.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Peginterferon α-2b as a Maintenance Therapy in Participants With Multiple Myeloma Who Responded to Induction Therapy (P01972-AM7) — NCT00732641.
- Registry record last updated 2017-04-04; status last verified 2017-03.
- Results first posted 2011-12-02.
- 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
NCT00732641 is a completed phase 3 randomized, prospective, multicenter, parallel-group trial of peginterferon α-2b maintenance versus observation in participants with multiple myeloma who responded to induction therapy. The study was unmasked and enrolled 244 participants overall. Peginterferon α-2b was given as a 35 μg weekly subcutaneous injection until progression or relapse, or for up to a maximum of 5 years; the comparison group received no treatment.
The primary outcome was median progression-free survival in days, defined from randomization to first documented progression or relapse. The registry reports 1166 days (95% confidence interval 682 to 1519) for peginterferon α-2b and 519 days (95% confidence interval 403 to 634) for no treatment. It does not report a comparative hazard ratio or primary-endpoint p-value. The record lists secondary outcomes and adverse event counts, but important analysis, missing-data, and safety-reporting details are not reported.