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 Assessing the Efficacy and Safety of IV Vitamin C in Combination With Standard Chemotherapy for Pancreatic Ca (NCT01555489), a na phase 2 study. The primary outcome is Safety of Ascorbic Acid in Combination With Gemcitabine and Erlotinib for Stage IV Pancreatic Cancer.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01555489 |
| Phase | Phase 2 |
| Condition | Stage IV Pancreatic Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 11 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Thomas Jefferson University |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people with stage IV, metastatic pancreatic cancer. The registry describes the treatment as front-line therapy and records 11 participants enrolled. The intended recruitment was up to 35 subjects, but the trial ended because of lack of accrual. The registry does not report participant characteristics such as age, sex, disease history, or eligibility details beyond the condition listed.
Intervention
The intervention combined intravenous ascorbic acid with gemcitabine and erlotinib. The arm description specifies ascorbic acid at 50-100g, 3x weekly, alongside standard chemotherapy. The trial summary describes the phase II study as an initial evaluation of the 100 gram dose. Treatment exposure and adherence details are not reported in the registry record.
Comparator
There was no separate comparison group. The registry classifies the study as single-group, with no masking and no randomized allocation. Consequently, the record does not offer a like-for-like control group receiving another regimen or chemotherapy alone. Within-person changes, if collected, would not substitute for a concurrent control comparison.
Primary question
The stated primary question was whether intravenous ascorbic acid combined with gemcitabine and erlotinib could be assessed for safety in stage IV pancreatic cancer. Safety was to be evaluated by counting adverse events and serious adverse events over 15 weeks. The registry says the trial closed due to lack of accrual and that the data for this primary outcome were not collected. It therefore does not report an evaluable primary safety result or an efficacy estimate.
3. Trial Design
NCT01555489 was an open-label phase II study of intravenous ascorbic acid combined with gemcitabine and erlotinib for metastatic pancreatic cancer. Its design was single-group, without masking or randomized allocation. All participants were assigned to the combination regimen described in the registry; there was no separate control arm. The intervention description lists ascorbic acid at 50-100g, 3x weekly, with standard chemotherapy. The study summary frames the 100 gram dose as an initial test of efficacy and a further assessment of safety after an earlier phase I study. That background is the investigators’ stated rationale, not a result established by this trial’s posted primary outcome.
The registry records 11 participants enrolled and says the intended recruitment was up to 35. The trial status is terminated. The reason given is lack of accrual: the standard-of-care chemotherapy regimen in the original study changed, preventing the team from enrolling additional patients. The study began in 2011-10 and its primary completion was listed as 2016-01. These registry dates do not establish when each participant began or completed treatment.
The primary outcome was safety, intended to count adverse events and serious adverse events over 15 weeks. The registry explicitly states that data for this outcome were not collected. A quality-of-life assessment using the FACT-G instrument is listed among secondary outcomes, but its results are not reported in the registry record. The record lists two outcome measures but no analyses. Further protocol details, including a statistical analysis plan and a sample-size justification, are not reported in the registry record.
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 | Ascorbic Acid, Gemcitabine & Erlotinib |
|---|---|
| STARTED | 11 |
| COMPLETED | 11 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: The trial was closed due to lack of accrual. The standard of care treatment that was part of the study as initially written changed to a different chemotherapy regimen thus not enabling the team to enroll additional patients. The data were not collected.
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 | Ascorbic Acid, Gemcitabine & Erlotinib |
|---|---|---|
| Participants analysed | 11 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 6 |
| Age, Categorical: >=65 years | Participants | 5 |
| Sex: Female, Male: Female | Participants | 3 |
| Sex: Female, Male: Male | Participants | 8 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 11 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 |
| Race (NIH/OMB): White | Participants | 10 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 11 |
6. Primary Endpoint
The registry lists the primary outcome as Safety of Ascorbic Acid in Combination With Gemcitabine and Erlotinib for Stage IV Pancreatic Cancer, measured over 15 weeks.
| 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 intended to assess safety by evaluating the number of adverse events and serious adverse events among participants during 15 weeks. An adverse event is an untoward medical occurrence recorded during a study; a serious adverse event is a category of event defined by seriousness criteria. Counting events is a descriptive way to characterize the kinds and frequency of problems observed during treatment. It does not, by itself, establish that a study treatment caused an event.
The registry states that the primary endpoint data were not collected because the trial closed due to lack of accrual. As a result, no primary safety summary over the specified 15-week timeframe is reported. The adverse-event counts separately listed in the registry do not fill that gap: they are not presented as a completed analysis of the planned primary endpoint over its stated timeframe. The record does not report the event-level details, timing, or causal assessments needed to interpret those counts fully.
Safety was the stated primary question for this phase II trial, while the registry also lists a FACT-G quality-of-life assessment as a secondary outcome. The registry does not report a primary efficacy endpoint result. Therefore, the study’s stated efficacy aim cannot be evaluated from an efficacy estimate in the posted record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive fact is that the planned primary safety data were not collected. Although the registry lists adverse-event counts, it does not report a completed primary endpoint assessment over 15 weeks. The counts can be described as registry entries, but they should not be treated as a full analysis of the endpoint the study set out to measure. The record also lists no analyses. No primary effect estimate, confidence interval, or hypothesis-test result is reported.
The listed adverse-event information includes 1 serious adverse event among 11 participants at risk, 11 other adverse events among 11 participants at risk, and 1 death. Death is the top serious adverse-event term, listed as 9.1%. Those entries describe what the registry reports for the treatment group; they do not establish that the combination caused an event. The record does not provide enough detail to determine event timing, individual clinical circumstances, attribution, or how the adverse-event reporting period relates to the planned 15-week endpoint.
The single-group design also limits interpretation. Without a concurrent control group, observed events cannot be compared against events under another regimen within this study. Any changes in disease status or other outcomes could not be separated statistically from the course of disease, background treatment, or other influences using a randomized comparison. The registry does not report an efficacy result that would support an estimate of treatment effect.
Recruitment stopped at 11 participants, below the stated intention to recruit up to 35. The reason recorded is lack of accrual after a change in the standard chemotherapy regimen made further enrollment impossible. This curtailed enrollment and missing primary data mean that the registry record does not answer the planned safety question as specified. The result is not evidence that the regimen is safe or unsafe, nor a basis for concluding whether it is effective. It is a record of a terminated study, its limited adverse-event entries, and the absence of the planned primary outcome data.
Any sample-size planning illustrations should be interpreted as hypothetical calculations rather than observations from this trial. The stated assumptions use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a fraction of an observed effect. Those assumptions do not describe the actual single-group design. Such planning figures are not observed power, and they do not recover the outcome information that was not collected.
9. Statistical Methods Explained
The registry describes a single-group, open-label phase II study. This is a descriptive design without random allocation to distinct treatment groups. Because there was no randomized control arm, the study cannot estimate a between-group treatment contrast. The lack of masking also means treatment was not concealed from participants and study staff as described in the record. Masking is not a substitute for randomization, and neither design feature can create a control comparison that was not part of the study.
What can a single-group safety count show?
A count of adverse events can describe what was recorded among people in the treatment group. Counts are useful for reporting observed events, but interpretation depends on how events were defined, collected, classified, and followed over time. A count of affected participants is not necessarily the same as a count of total event occurrences if one participant can experience more than one event. The registry’s posted adverse-event fields list participants at risk and affected; detailed event-level counts and definitions are not reported in the registry record. Therefore, the listed figures should be read as the registry’s group-level entries, not as a complete account of every event or its clinical context.
A serious adverse event is distinguished by seriousness criteria rather than simply by whether an event is common or severe in ordinary language. The registry lists 1 participant affected by a serious adverse event among 11 at risk and names Death as the top serious term at 9.1%. A serious-event listing is not, on its own, proof of causation. Establishing whether an event was considered related to a treatment would require attribution information, which is not reported in the registry record.
Why are estimates and uncertainty absent?
The primary safety measure was planned as the number of adverse events and serious adverse events occurring among participants over 15 weeks. The registry explicitly says that these primary outcome data were not collected. With no primary endpoint dataset reported, there is no reported endpoint estimate from which to describe statistical uncertainty. A confidence interval, in general, expresses a range of values compatible with data and a specified statistical procedure; it does not remove uncertainty or correct for missing data. No confidence interval for the planned primary outcome is reported in the registry record.
A p-value, in general, summarizes how unusual data would be under a specified null hypothesis and statistical model. It does not measure the probability that a treatment works, and it cannot replace an effect estimate or a study design capable of supporting the intended comparison. The registry lists no analyses, and no p-value for the primary outcome is reported. No hypothesis test should be inferred from the adverse-event counts alone.
What do the planning illustrations represent?
Planning illustrations are calculations under stated assumptions, not findings from participants. The listed assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They also define the target effect as a stated fraction of an observed effect. Time-to-event planning uses a total number of events; other planning displays use participants per arm. These are generic planning conventions, not the design of this trial, which was single-group. Any such figures are not observed power and cannot tell readers whether this trial had a particular probability of detecting an effect. The record does not report a trial-specific sample-size justification.
Because no randomized comparison was conducted, calculations based on two arms do not describe an actual comparison in NCT01555489. A planning illustration can show what a hypothetical design might require under its assumptions, but it cannot create an unobserved comparator, supply the missing primary endpoint, or establish a treatment effect. The registry record does not report the detailed statistical methods used or intended for the clinical outcomes.
How should outcome timing and missingness be considered?
The 15-week timeframe belongs to the planned primary safety endpoint. The registry reports that this data was not collected, but does not give a participant-level account of follow-up, withdrawals, or the reason each observation is absent. The terms missing completely at random, missing at random, and missing not at random describe different assumptions about why data are missing. These are general statistical concepts; the registry does not provide enough information to assign a missing-data mechanism or justify an imputation method.
In a complete analysis, the population being analyzed should be defined, and the handling of participants with incomplete follow-up should be explained. The registry does not report an analysis population or missing-data procedure for the primary endpoint. Given the stated absence of primary endpoint data, there is no basis for reconstructing a completed safety analysis from the record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcome measures, including the primary safety outcome and a secondary FACT-G quality-of-life assessment. It does not report a statistical analysis plan, the hierarchy of outcome tests, or any adjustment for multiple testing. Multiplicity arises when several outcomes or statistical comparisons are examined: without an appropriate plan, the chance of at least one apparently notable result can increase. This is a general statistical concern, not a claim that such testing occurred in this study. No outcome analyses are listed in the registry.
The primary safety data were not collected, according to the registry. Results for the FACT-G assessment are not reported in the registry record. The record does not describe how incomplete follow-up, missing questionnaires, or other missing observations would have been handled. It also does not report an analysis population, such as all enrolled participants or a defined subset. These omissions prevent a reader from assessing whether any planned population or missing-data approach was followed.
Since the primary endpoint data are absent and no analyses are listed, there is no reported inferential analysis to evaluate for multiplicity or missing-data sensitivity. Statistical methods for handling missing outcomes can be useful when their assumptions and data are available, but they cannot replace outcome observations that were not collected. The record also does not state whether interim analyses were planned or conducted; this information is not reported in the registry record.
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 |
|---|---|---|---|
| Ascorbic Acid, Gemcitabine & Erlotinib | 1 | 11 | 9.1% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Ascorbic Acid, Gemcitabine & Erlotinib | 1 of 11 |
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 |
|---|---|
| Ascorbic Acid, Gemcitabine & Erlotinib | 11 of 11 |
Most frequent serious adverse event terms
| Event term | Organ system | Ascorbic Acid, Gemcitabine & Erlotinib |
|---|---|---|
| Death | General disorders | 1 of 11 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Ascorbic Acid, Gemcitabine & Erlotinib |
|---|---|---|
| Low hemoglobin | Blood and lymphatic system disorders | 2 of 11 |
| Low platelets | Blood and lymphatic system disorders | 2 of 11 |
| Diarrhea | Gastrointestinal disorders | 1 of 11 |
| Tinnitus | Ear and labyrinth disorders | 1 of 11 |
| Infection with normal ANC | Immune system disorders | 1 of 11 |
| GI Obstruction | Gastrointestinal disorders | 1 of 11 |
| Increased creatinine | Blood and lymphatic system disorders | 1 of 11 |
| Nausea | General disorders | 1 of 11 |
| Low Potassium | Blood and lymphatic system disorders | 1 of 11 |
| Cardiac Infarction | Cardiac disorders | 1 of 11 |
Serious events with the highest arm-level rate: death (9.1%).
The registry lists 11 participants at risk for other adverse events and 11 affected. For serious adverse events, it lists 11 at risk and 1 affected. Death is the top serious adverse-event term, with 9.1% listed. These are the registry’s treatment-group entries, not a comparison against another treatment group. No control arm was part of the single-group design.
These figures require careful reading. An adverse event recorded during a trial is not automatically an event caused by the study treatment. The registry does not report attribution, detailed event narratives, timing, duration, or the number of event episodes per participant. It also does not establish whether these entries constitute a complete safety assessment over the planned 15 weeks. The planned primary safety outcome data were not collected, so the adverse-event entries should not be mistaken for a completed analysis of that endpoint.
The listed death is a serious-event term in the registry; the record does not give enough context to interpret its circumstances or relationship to treatment. The counts can describe what the registry reports, but they do not establish comparative risk or causation.
12. What the Result Does, and Does Not, Mean
The record documents a phase II, open-label study of intravenous ascorbic acid with gemcitabine and erlotinib in metastatic pancreatic cancer. It was single-group, enrolled 11 participants, and was terminated after lack of accrual. The stated reason was that the standard-of-care chemotherapy regimen changed, preventing further enrollment. The primary safety endpoint was intended to count adverse events and serious adverse events over 15 weeks, but the registry says those data were not collected.
The posted adverse-event entries describe 1 serious adverse event among 11 participants at risk, 11 other adverse events among 11 at risk, and Death as the top serious term at 9.1%. They do not supply a complete primary safety analysis, a comparison with another regimen, or evidence about causation. The registry lists no analyses and does not report an efficacy estimate. It also lists a FACT-G quality-of-life outcome without reporting its results.
Accordingly, the record does not establish whether the regimen changed tumor response, survival, quality of life, or safety relative to another treatment. The study’s stated aim to examine efficacy does not itself constitute evidence of efficacy. A single-group design cannot provide a randomized between-treatment estimate, and the missing primary outcome data further limit what can be concluded.
This does not mean the regimen was demonstrated to be ineffective or unsafe. It means that the registry record does not contain the planned primary outcome results or an efficacy analysis needed to answer those questions. The observed registry entries should be understood as limited descriptive reporting, with important details and context not reported.
13. Why This Trial Matters Statistically
This trial is statistically important because it illustrates the difference between a study’s stated objective and the data available to answer it. The primary endpoint was a safety measure with a defined 15-week timeframe, yet the registry says its data were not collected. A trial can have a clear question and a stated outcome without producing an analyzable result for that outcome.
The record also shows why enrollment and study design matter to interpretation. Recruitment was intended to reach up to 35 subjects, but 11 participants were enrolled before the trial was terminated because of lack of accrual after a change in the standard chemotherapy regimen. The smaller-than-intended enrollment is not itself a result about treatment; it describes the limits of the evidence that could be gathered. A single-group design further means that the study has no concurrent control comparison, even if all planned participants had been enrolled.
Finally, the registry’s adverse-event entries illustrate why counts need context. The listed numbers can be reported descriptively, but they do not establish attribution, comparative risk, or a complete assessment over the planned timeframe. Statistical interpretation requires more than counts: it depends on outcome definitions, follow-up, analysis populations, missing-data handling, and a design that matches the question. Several of those details or results are not reported in the registry record. The appropriate statistical conclusion is therefore bounded: the record describes a terminated study and limited safety entries, but it does not answer the planned primary safety or efficacy questions.
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 trial’s single-group design means there was no concurrent control group for a direct treatment comparison. Open-label conduct also means masking was absent, as stated in the registry. These features limit the kinds of causal and comparative conclusions the study could support, apart from the fact that its primary outcome data were not collected.
Enrollment was 11, while the summary described a plan to recruit up to 35 subjects. Recruitment stopped because of lack of accrual, and the registry attributes this to a change in the standard-of-care chemotherapy regimen that prevented additional enrollment. The record does not report a trial-specific sample-size justification, so it is not possible to assess the intended precision or power from the registry record.
The primary safety outcome was defined over 15 weeks, but its data were not collected. The registry does not report a participant-level description of follow-up, detailed adverse-event timing, event attribution, or how many distinct event episodes occurred. The listed adverse-event entries therefore cannot be treated as a full analysis of the planned endpoint. Results for the FACT-G quality-of-life outcome are also not reported.
The record lists no analyses and does not describe the statistical analysis plan, analysis populations, missing-data handling, multiplicity strategy, or interim analyses. These details are not reported in the registry record. Together, the absence of the planned primary outcome data, lack of a control group, curtailed enrollment, and limited reporting leave substantial uncertainty about the questions the study was intended to address.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Assessing the Efficacy and Safety of IV Vitamin C in Combination With Standard Chemotherapy for Pancreatic Ca — NCT01555489.
- Registry record last updated 2025-05-04; status last verified 2025-05.
- Results first posted 2018-08-28.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT01555489 was an open-label, single-group phase II study of intravenous ascorbic acid with gemcitabine and erlotinib for stage IV pancreatic cancer. The registry records 11 participants enrolled and a plan to recruit up to 35. The intervention description lists ascorbic acid at 50-100g, 3x weekly, with standard chemotherapy.
The trial was terminated because of lack of accrual after the standard chemotherapy regimen changed. The primary safety outcome was intended to count adverse events and serious adverse events over 15 weeks; the registry states that the data were not collected. The registry lists adverse-event entries, including 1 serious adverse event among 11 at risk and Death at 9.1% as the top serious term. No analyses are listed, and no efficacy result or FACT-G quality-of-life result is reported in the registry record.