Multi-agent Low Dose Chemotherapy GAX-CI Followed by Olaparib and Pembro in Metastatic Pancreatic Ductal Cancer.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Multi-agent Low Dose Chemotherapy GAX-CI Followed by Olaparib and Pembro in Metastatic Pancreatic Ductal Cancer. (NCT04753879), a na phase 2 study. The primary outcome is Progression-free Survival (PFS) Rate at 6 Months.

2. Clinical Question

3. Trial Design

This is a phase 2, single-group study of a treatment sequence for untreated metastatic pancreatic ductal adenocarcinoma. The registry record lists enrollment of 36 and identifies Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins as sponsor. Allocation is NA and masking is none, so the design is not a randomized, masked comparison. No control arm is described.

The planned sequence begins with GAX-CI chemotherapy: gemcitabine, nab-paclitaxel, capecitabine, cisplatin, and irinotecan. The arm description states that the chemotherapy phase consists of 6 cycles, followed by maintenance pembrolizumab and olaparib. The primary endpoint is defined only among patients who have disease stabilization after chemotherapy and receive at least 1 maintenance dose. The record reports that 19/36 patients met that description. The duration or stopping rules for maintenance are not reported in the registry record.

The registry lists the study status as completed, with a start date of 2021-09-29 and primary completion date of 2026-05-07. Those record dates describe study administration, not the timing or completeness of every participant's follow-up. The registry record does not report details such as the recruitment process, a sample-size justification, or an interim monitoring plan. The design can describe outcomes among the treated group, but without a randomized comparator it cannot isolate a treatment effect relative to another regimen.

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

Analysis population for the primary outcome, as defined in the registry: 19/36 patients had disease stabilization after 6 cycles of GAXCI and received at least 1 dose of maintenance therapy (pembrolizumab and olaparib).

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 Progression-free Survival (PFS) Rate at 6 Months, measured over 6 Months.

The primary endpoint is the 6-month progression-free survival (PFS) rate. It is defined as the Kaplan-Meier estimate of the proportion of patients without disease progression or death at 6 months from the first dose of maintenance pembrolizumab and olaparib. The clock starts at maintenance, not at the beginning of GAX-CI chemotherapy. The endpoint is restricted to patients with disease stabilization after 6 cycles of GAX-CI who received at least 1 dose of maintenance treatment; the record reports 19/36 patients in that population.

Progression is assessed using RECIST 1.1 criteria as described in the record. Complete response means disappearance of all target lesions; partial response is a >30% decrease in the sum of target-lesion diameters; progressive disease is a >20% increase; and stable disease is a <30% decrease or <20% increase. These categories determine whether patients have disease stabilization before maintenance and how progression is classified.

A fixed-time PFS rate combines progression and death into a clinically interpretable time-to-event outcome. Kaplan-Meier estimation is commonly used when follow-up times vary or some event times are not observed. The registry record gives a 95% confidence interval as the measure of dispersion, but the estimate and interval are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation begins by separating the endpoint definition from the endpoint result. The registry record defines 6-month PFS as a Kaplan-Meier estimate, but does not report the estimate or its 95% confidence interval. Without those values, there is no numerical result to interpret. A stated endpoint and analysis method indicate what investigators intended to measure; they do not reveal the observed outcome.

What does a Kaplan-Meier estimate represent?

In general, Kaplan-Meier estimation describes the probability of remaining free of an event over time while allowing participants to have different lengths of observation. For this endpoint, the event is progression or death, and time begins with the first dose of maintenance pembrolizumab and olaparib. Participants who have not had an observed event by their last known follow-up can contribute information up to that time and then be censored. Censoring means the event time is not observed during the participant's recorded follow-up; it does not mean that the participant is known to remain event-free indefinitely.

Kaplan-Meier interpretation depends on adequate follow-up and on censoring not being systematically related to the future event risk in a way the analysis fails to address. The registry record does not report follow-up completeness, censoring counts, censoring reasons, or the number at risk over time. These details matter because a fixed-time estimate is supported by the participants still under observation near that time. Without them, the strength of the evidence at 6 months cannot be assessed from the record.

How should the confidence interval be read?

In general, a confidence interval describes uncertainty around an estimated quantity under the assumptions of the analysis. A narrower interval indicates greater statistical precision, while a wider interval indicates less precision. A 95% confidence interval is the dispersion measure named for this endpoint. Its actual width and position cannot be assessed because neither limit is reported in the registry record. A confidence interval is not a guarantee that the true value lies within a particular interval for this one study, nor does it resolve limitations such as selection into maintenance or absence of a comparator.

Why does the analysis population matter?

The stated PFS population comprises patients with disease stabilization after 6 cycles of GAX-CI who received at least 1 dose of maintenance. In general, restricting an endpoint to people who reach a later treatment phase changes the question being answered: it describes outcomes conditional on reaching that phase, rather than outcomes for everyone entering the study. The record reports 19/36 in this population. It does not provide enough outcome information to combine the maintenance endpoint with the preceding chemotherapy phase into an estimate for the full treatment sequence.

What does a single-group design permit?

In general, a single-group study can estimate outcomes observed among participants receiving the study regimen. It cannot use random assignment to balance measured and unmeasured differences against a concurrent control group. Therefore, even a reported PFS estimate would be descriptive of this study population and would not by itself quantify the difference the regimen caused relative to another treatment. Allocation is listed as NA, masking as none, and the model as single group. No randomized comparison is defined in the record.

How should planning calculations be understood?

The registry record's planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect expressed as a stated fraction of the observed effect. Those are planning assumptions, not observed trial results. Any sample-size outputs based on such assumptions would be planning illustrations, not observed power and not evidence that the study detected an effect. The record does not provide a sponsor's own sample-size justification or a numerical observed effect for interpreting such planning scenarios. The assumptions also describe a two-arm planning framework, whereas this trial is listed as single group; they do not turn this study into a randomized two-arm comparison.

10. Multiplicity, Missing Data and Analysis Populations

The registry record does not report a statistical analysis plan describing how multiple outcomes or analyses were handled. The primary outcome is 6-month PFS, and the record lists a secondary outcome concerning the number of participants experiencing Grade 3 or Above drug-related toxicities. It does not report a multiplicity adjustment, a hierarchy among endpoints, or a plan for choosing among multiple analyses. Those details are not reported in the registry record.

Missing-data methods are also not reported in the registry record. For a Kaplan-Meier endpoint, follow-up can end before an event is observed, and the analysis generally handles such observations through censoring. The record does not state how censoring was handled in practice, how much follow-up was available, or whether sensitivity analyses were planned. It also does not describe how missing assessments or unavailable outcome information were treated.

The endpoint population is defined as patients who had disease stabilization after 6 cycles of GAX-CI and received at least 1 maintenance dose; the record reports 19/36 in this group. The record does not describe an analysis population for all enrolled patients, or explain how patients who did not enter maintenance were accounted for in analyses of the treatment sequence. This makes it important to distinguish the defined maintenance PFS population from enrollment as a whole.

The record reports no analyses. It does not report a detailed statistical analysis plan, interim analyses, or a sample-size justification. Absence of these details in the registry record should not be interpreted as proof that no such procedures were used; their presence and specifics are simply not reported in the registry record.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: disease progression (16.7%), sepsis (11.1%), thromboembolic event (11.1%), anemia (8.3%), abdominal pain (5.6%).

The registry lists 36 at risk for serious adverse events and 22 affected, along with 36 at risk for other adverse events and 36 affected. It also lists 30 deaths. These are registry-reported counts; the record does not provide event timing or enough detail to connect each safety entry to the chemotherapy or maintenance phase. The entries should not be interpreted as comparative risks because the study has no control group.

The listed serious adverse event terms include Disease Progression (16.7%), Sepsis (11.1%), Thromboembolic event (11.1%), Anemia (8.3%), Abdominal pain (5.6%), and Bacteremia (5.6%). The record does not state the denominator or detailed counting rules for each listed percentage. These terms are not necessarily mutually exclusive, so their percentages should not be added. Disease progression appears among serious adverse event terms, but the record does not explain the classification circumstances.

The listed secondary outcome concerns Grade 3 or Above drug-related toxicities, whereas the safety group also reports serious and other adverse events. These categories are not interchangeable: seriousness and severity describe different aspects of adverse events. The result for the Grade 3 or Above drug-related toxicity outcome is not reported in the registry record. The safety figures therefore describe reported event counts and terms, not a complete comparative assessment of tolerability or causation.

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

The record describes a phase 2 investigation of a sequence: GAX-CI chemotherapy followed, for patients with disease stabilization, by maintenance olaparib and pembrolizumab. Its primary question is a 6-month PFS rate measured from the first maintenance dose. The endpoint definition and the reported maintenance population make clear that the endpoint addresses outcomes after patients reach maintenance, not outcomes from initial chemotherapy for all enrolled patients.

The record does not report the primary estimate or its 95% confidence interval. It therefore cannot establish the observed 6-month PFS rate or how precisely that rate was estimated. The record also does not report the secondary toxicity outcome result. Although adverse event counts, deaths, and serious-event terms are listed, these do not fill in the missing efficacy result or establish a treatment effect.

Even if a numerical rate were available, this single-group study would describe outcomes in the studied group rather than provide a randomized comparison against another regimen. Without a concurrent control, differences from other settings cannot be attributed to the treatment sequence alone. The record also does not provide sufficient information to assess selection into maintenance, follow-up completeness, censoring, or the handling of missing outcome information.

Accordingly, the registry record supports a description of the regimen, study design, endpoint definition, endpoint population, and safety entries. It does not support a conclusion that the regimen improves or worsens outcomes, nor a comparison with another treatment. Those questions require reported outcome estimates and, for comparative claims, an appropriate comparator and analysis.

13. Why This Trial Matters Statistically

This study raises a statistical question about a treatment sequence rather than a single intervention applied uniformly from enrollment onward. The primary endpoint begins at the first dose of maintenance treatment, after a chemotherapy phase and disease stabilization. That distinction matters: an estimate beginning at maintenance addresses the experience of patients who reached that phase, while a question about the whole regimen would need to account for outcomes from the start of chemotherapy as well.

The registry reports 19/36 patients in the maintenance endpoint population. That selection is important when interpreting any later PFS result because it is conditional on disease stabilization and receiving maintenance. A conditional estimate should not be mistaken for an estimate of the probability of reaching maintenance or for an outcome among everyone enrolled.

The single-group design also clarifies the limits of inference. It can describe what happened in the treatment group, but the lack of a randomized comparator prevents a direct estimate of how outcomes differ from another regimen. Statistical precision, if reported through a confidence interval, would address uncertainty in the group estimate; it would not remove the design's limitations for causal comparison.

Finally, the registry record defines a time-to-event endpoint and names a confidence interval, yet does not report either the estimate or the interval. This gap illustrates why endpoint definitions, analysis populations, observed estimates, and uncertainty measures all matter. Without the latter results, readers can understand the intended question but cannot assess the observed PFS level or its precision. Safety entries add descriptive information, but do not replace a reported efficacy analysis or resolve the lack of a control group.

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 principal limitation for statistical interpretation is that the registry record does not report the primary PFS estimate or its 95% confidence interval. It also does not report the result for the listed Grade 3 or Above drug-related toxicity outcome. Thus the record supports interpretation of the questions and populations, but not evaluation of the magnitude or precision of the primary result.

The study is single group, with allocation listed as NA and masking as none. There is no randomized control group for estimating a comparative treatment effect. Outcomes may be described for the study group, but comparisons with other groups would not be randomized contrasts. The record does not report an external comparator or a prespecified comparative analysis.

The primary endpoint starts at maintenance and is defined for patients who had disease stabilization after 6 cycles of GAX-CI and received at least 1 maintenance dose. The reported 19/36 population is therefore selected after the chemotherapy phase. The registry record does not report a primary endpoint for the full enrollment group that incorporates both reaching maintenance and subsequent PFS.

Follow-up duration and completeness, censoring counts and reasons, missing-data procedures, and detailed statistical analysis methods are not reported in the registry record. Nor are a sample-size justification, interim analysis plan, or multiplicity approach reported. The listed serious adverse event terms and counts also lack timing details and do not provide a complete basis for comparative safety interpretation. These limitations prevent a full assessment of robustness, precision, and the relationship between safety events and treatment phases.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Multi-agent Low Dose Chemotherapy GAX-CI Followed by Olaparib and Pembro in Metastatic Pancreatic Ductal Cancer. — NCT04753879.
• Registry record last updated 2026-11-04; status last verified 2026-10.
• Results first posted 2026-11-04.
• 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 record describes a completed phase 2, single-group study sponsored by Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, with enrollment of 36. The study evaluates GAX-CI chemotherapy followed by maintenance olaparib and pembrolizumab in untreated metastatic pancreatic ductal adenocarcinoma. The listed study dates are 2021-09-29 for start and 2026-05-07 for primary completion.

The primary endpoint is the Kaplan-Meier estimate of PFS at 6 months from the first maintenance dose, among patients with disease stabilization after 6 cycles of GAX-CI who received at least 1 maintenance dose. The record reports 19/36 in that endpoint population, but does not report the PFS estimate or confidence interval. Safety entries include serious and other adverse event counts, deaths, and serious-event terms; the listed drug-related toxicity outcome result is not reported in the registry record.