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 Roll-over Study to Assess Safety of Lixivaptan in Participants With ADPKD Who Completed Study PA-ADPKD-303 (NCT05208866), a na phase 3 study. The primary outcome is Number of Participants Who Develop Serum ALT Levels >3 × ULN During the Lixivaptan Re-titration or Maintenance Treatment Periods Assessed to be Related to Lixivaptan and Resulted in Discontinuation of Lixivaptan Treatment.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05208866 |
| Phase | Phase 3 |
| Condition | Polycystic Kidney Disease, Adult |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 1 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Palladio Biosciences |
| Results posted | Yes |
2. Clinical Question
Population
The study was intended for participants with autosomal dominant polycystic kidney disease (ADPKD) who had previously experienced abnormal liver chemistry results while taking tolvaptan, permanently stopped tolvaptan for that reason, and then completed study PA-ADPKD-303, an open-label lixivaptan lead-in study. The registry record reports an enrollment of 1. It does not report further participant characteristics in the primary outcome population.
Intervention
Participants received open-label lixivaptan capsules at a dose of 100-200mg twice daily. The primary outcome timeframe was 120 days, from Screening to the end of the Maintenance Treatment Period. The registry record describes re-titration and maintenance periods, but does not report additional treatment-duration details.
Comparator
There was no comparison group in the single-group study. Allocation is listed as not applicable, and masking was none. The study therefore was not designed as a randomized, like-for-like comparison of lixivaptan with another treatment or with a control group.
Primary question
The primary question was how many participants developed serum ALT levels >3 × the upper limit of normal (ULN), had the finding judged at least probably related to lixivaptan by the independent Hepatic Events Review Committee (HERC), and discontinued lixivaptan as a result. The registry record reports the endpoint definition but no observed primary endpoint result.
3. Trial Design
This was a Phase 3, open-label, rollover study of lixivaptan in participants with ADPKD. The official title identifies it as PA-ADPKD-304 and names it the ALERT Study. It was intended for people who had experienced abnormal liver chemistry test results while treated with tolvaptan, stopped that drug permanently for that reason, and completed PA-ADPKD-303, an open-label lead-in study with lixivaptan. The registry record reports 1 participant enrolled.
The intervention was lixivaptan capsules, 100-200mg twice daily. Masking was none, and the model was single group. Allocation was listed as not applicable. There was no randomized or concurrent control arm, so the study cannot estimate a treatment contrast against a comparator. The rollover design is described as an assessment of long-term safety, with renal efficacy also mentioned in the study summary.
The listed start date was 2022-02-10, and the primary completion date was 2022-06-29. The study status is terminated. The reason for termination is not reported in the registry record, and the record does not state whether termination followed a planned stopping decision or another circumstance.
The primary outcome timeframe was 120 days, running from Screening to the end of the Maintenance Treatment Period. Secondary outcomes included liver-enzyme thresholds associated with dose reduction or discontinuation, treatment-emergent adverse events, potentially clinically important laboratory, vital-sign and ECG findings, and annualized change in eGFR from baseline to final assessment. The registry record does not report a detailed protocol, the planned analysis populations, or a statistical analysis plan.
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.
Lixivaptan Re-titration Period
| Stage | All Enrolled Participants |
|---|---|
| STARTED | 1 |
| COMPLETED | 1 |
| NOT COMPLETED | 0 |
Maintenance Treatment Period
| Stage | All Enrolled Participants |
|---|---|
| STARTED | 1 |
| COMPLETED | 0 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | All Enrolled Participants |
|---|---|
| Sponsor Termination of Study | 1 |
Follow-up Period
| Stage | All Enrolled Participants |
|---|---|
| STARTED | 1 |
| COMPLETED | 1 |
| NOT COMPLETED | 0 |
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.
Population: Since only one participant completed the study, due to confidentiality issues, no data will be reported.
| Characteristic | Unit | All Enrolled Participants |
|---|---|---|
| Participants analysed | 0 | |
| Sex: Female, Male: Female | — | |
| Sex: Female, Male: Male | — | |
| Ethnicity (NIH/OMB): Hispanic or Latino | — | |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | — | |
| Ethnicity (NIH/OMB): Unknown or Not Reported | — | |
| Race (NIH/OMB): American Indian or Alaska Native | — | |
| Race (NIH/OMB): Asian | — | |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | — | |
| Race (NIH/OMB): Black or African American | — | |
| Race (NIH/OMB): White | — | |
| Race (NIH/OMB): More than one race | — | |
| Race (NIH/OMB): Unknown or Not Reported | — |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants Who Develop Serum ALT Levels >3 × ULN During the Lixivaptan Re-titration or Maintenance Treatment Periods Assessed to be Related to Lixivaptan and Resulted in Discontinuation of Lixivaptan Treatment, measured over 120 days (from Screening to the end of the Maintenance Treatment Period).
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts participants who experienced a specific combination of events during the lixivaptan re-titration or maintenance periods: serum ALT levels >3 × ULN, an HERC assessment that the abnormality was at least probably related to lixivaptan, and discontinuation of lixivaptan treatment as a result. The registry record defines the normal ALT range as 0-55 U/L and gives the outcome timeframe as 120 days, from Screening to the end of the Maintenance Treatment Period.
The endpoint is used to capture a clinically consequential liver-chemistry event rather than an ALT elevation alone. Its definition combines a laboratory threshold, an independent causality assessment, and a treatment discontinuation. The HERC was to review demographic, medical and medication history, safety data, and other relevant data for participants with liver abnormalities. It was to assess causality using the Drug-Induced Liver Injury Network probability criteria.
That specificity also limits what the endpoint represents. It is not a count of every ALT increase, every liver-related event, or all aspects of hepatic safety. The registry record reports no observed count for this endpoint. Without that result, and with an enrollment of 1, the record does not establish how often the defined event occurred in the study population.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record describes a narrowly targeted, single-group safety study, not a randomized comparison. Its population was intended to include participants with ADPKD who had previously stopped tolvaptan after abnormal liver chemistry results and had completed a lixivaptan lead-in study. That clinical context is important when considering generalizability: the study was not described as enrolling a broad ADPKD population. The registry reports 1 participant enrolled, which makes the scope of any study-level inference especially limited.
The primary endpoint is a participant count, not a treatment-effect estimate. It requires ALT levels >3 × ULN, an HERC judgment of at least probable relation to lixivaptan, and discontinuation. The registry record states the definition and the 120-day timeframe but reports no observed result. It therefore does not support a conclusion about the frequency of this event in the enrolled participant, much less its frequency in a larger population.
The trial status is terminated, with a primary completion date of 2022-06-29. The reason for termination is not reported in the registry record. Termination alone does not explain whether the study ended as planned, ended early, or stopped for another reason. The record does not provide enough information to attribute termination to safety, efficacy, recruitment, or operational circumstances.
The posted adverse-event summary gives event counts by treatment period. In the Titration and Maintenance Periods, 1 participant was at risk for serious adverse events and 0 were affected; 1 was at risk for other adverse events and 1 was affected; deaths were 0. In the Follow-up Period, 1 participant was at risk for serious adverse events and 0 were affected; 1 was at risk for other adverse events and 0 were affected; deaths were 0. These are descriptive counts from a very small study, not comparative estimates. The record does not identify the specific non-serious adverse event in the summary.
No statistical analysis results are reported: the registry lists 0 analyses. There is no primary endpoint estimate, uncertainty interval, or reported analysis comparing groups. General statistical interpretation: an interval estimate can show how compatible the data are with a range of underlying values, but no interval for the primary endpoint is reported. The absence of a reported result should not be interpreted as evidence that the event did or did not occur.
Secondary outcomes cover additional safety measures and annualized eGFR change. Their inclusion in the registry does not establish that results were collected or analyzed. Results for those outcomes are not reported in the registry record. In particular, the study summary's statement that renal efficacy was to be assessed is not itself evidence of a renal outcome result.
9. Statistical Methods Explained
The registry describes a single-group, open-label study. In general, a single-group design follows participants receiving an intervention without a separate concurrent control group. It can describe events observed among enrolled participants, but it does not by itself separate treatment effects from the course of the condition, other influences, or the way participants were selected. Open-label means masking was none in this study; the registry record does not describe further procedures to reduce the influence of awareness of treatment.
The primary endpoint is a count of participants meeting a compound event definition. The criteria are not interchangeable: an ALT value above the specified threshold alone is insufficient. The event also has to be assessed as at least probably related to lixivaptan by the HERC and lead to treatment discontinuation. In general, compound endpoints can make the counted event more specific to a particular clinical circumstance, while making the result dependent on each component and the rules used to classify it.
The HERC's role was to review participant history, safety information, and other relevant data for liver abnormalities and determine probable causality and relatedness to lixivaptan. The registry names the Drug-Induced Liver Injury Network probability criteria as the basis for that assessment. This independent review is part of the outcome definition; it does not substitute for a reported outcome count. The number of cases assessed by the committee and the committee's individual determinations are not reported in the registry record.
In general, an event count describes how many participants met a definition. A count is not a rate unless it is related to a defined amount of follow-up, and it is not a comparative effect unless a comparator and a suitable analysis are available. The registry defines a 120-day primary outcome timeframe, but it does not report the primary event count or a corresponding uncertainty interval. It also does not report an analysis accounting for different lengths of participant follow-up.
General explanation: a confidence interval expresses uncertainty around an estimate under the assumptions of the method used. With a small number of participants, estimates and intervals can be imprecise, and an absence of observed events would not demonstrate that the underlying risk is zero. No confidence interval or other precision estimate for the primary endpoint is reported in the registry record, so the degree of statistical uncertainty cannot be quantified from the posted primary outcome information.
The registry lists secondary outcomes involving ALT thresholds, treatment-emergent adverse events, clinical laboratory findings, vital signs, ECG findings, and annualized eGFR change. These outcomes use different kinds of measurements. Counts of participants with events are categorical summaries; eGFR change is a continuous measure summarized over time. The registry record does not describe the statistical methods planned for these outcomes, how repeated measurements would be handled, or how missing measurements would be treated.
The registry also lists 0 analyses. No model estimates, hypothesis tests, or statistical comparison results are reported. The analysis plan, including any adjustment for covariates, is not reported in the registry record. General explanation: adjustment methods can account for specified factors in an analysis, but they cannot be assumed when the plan and results are absent.
The study is not a randomized comparison, and no like-for-like control comparison is available. General explanation: randomization can help balance measured and unmeasured characteristics between groups, while a concurrent comparator can help distinguish changes associated with treatment from changes that might otherwise occur. Without these design features, descriptive observations in this study cannot establish a comparative treatment effect.
The sample-size assumptions describe a planning illustration, not the trial's own design: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect set as a stated fraction of the observed effect. The record does not report numerical planning outputs or an observed primary effect. Such planning counts are hypothetical participants per arm for 80% power when labeled that way; they are not observed power and should not be confused with the 1 participant enrolled in this single-group study. The sample-size justification for the trial itself is not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary endpoint and secondary outcomes spanning liver chemistry, adverse events, clinical laboratory findings, vital signs, ECG findings, and eGFR change. When several outcomes are examined, general statistical practice may consider how repeated testing affects the chance of at least one apparently unusual result. Whether the study used a multiplicity procedure, and how any primary and secondary outcomes were prioritized for formal inference, is not reported in the registry record.
The registry reports 0 analyses. It does not provide p-values, confidence intervals, analysis populations, or a statistical analysis plan. The record also does not describe how missing outcome measurements, withdrawal, or incomplete follow-up were handled. These details matter because an analysis can depend on which participants and observations are included, and on assumptions about unobserved data. None of those assumptions can be inferred from the endpoint definitions.
The planned primary timeframe was 120 days, from Screening to the end of the Maintenance Treatment Period, but the record does not report participant-level follow-up completeness or whether all scheduled assessments were obtained. The number of participants enrolled was 1, and the record is marked terminated; it does not explain the relationship between termination and any missing data or incomplete outcome collection.
Consequently, no adjustment for multiple outcomes, missingness, or analysis population can be assessed from the registry record. These omissions do not establish that no such methods existed; their use and details are simply not reported in the registry record. Any interpretation of the posted counts should remain descriptive and tied to the stated study population and outcome definitions.
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 |
|---|---|---|---|
| Titration and Maintenance Periods | 0 | 1 | 0.0% |
| Follow-up Period | 0 | 1 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Titration and Maintenance Periods | 0 of 1 |
| Follow-up Period | 0 of 1 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Titration and Maintenance Periods | 1 of 1 |
| Follow-up Period | 0 of 1 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Titration and Maintenance Periods | Follow-up Period |
|---|---|---|---|
| Dermatitis contact | Skin and subcutaneous tissue disorders | 1 of 1 | 0 of 1 |
| Arthropod bite | Injury, poisoning and procedural complications | 1 of 1 | 0 of 1 |
The adverse-event summary separates Titration and Maintenance Periods from the Follow-up Period and distinguishes serious events, other events, and deaths. During Titration and Maintenance Periods, 1 participant was at risk for serious adverse events and 0 were affected; 1 participant was at risk for other adverse events and 1 was affected; deaths were 0. During Follow-up, 1 participant was at risk for serious adverse events and 0 were affected; 1 was at risk for other adverse events and 0 was affected; deaths were 0.
These are descriptive counts, not comparative safety estimates. The same participant may contribute to more than one period, so period-specific counts should not be added together to create a total number of unique participants. The registry summary does not identify the other adverse event or give its severity, timing, or relationship to lixivaptan. The event counts therefore should not be read as a complete clinical account of safety.
General explanation: serious adverse events are a separate category from other adverse events, and zero serious events in a small study does not establish that serious events cannot occur. Here, the registry reports 1 participant enrolled, so the counts have a very narrow evidentiary scope. The registry record does not report further details that would support broader frequency estimates.
12. What the Result Does, and Does Not, Mean
The record documents a Phase 3, open-label, single-group rollover study intended to assess long-term safety and renal efficacy of lixivaptan in a selected ADPKD population. The primary outcome definition focuses on ALT elevations >3 × ULN that were judged at least probably related to lixivaptan and resulted in discontinuation. The registry reports an enrollment of 1 and no primary outcome result. It therefore does not show the observed frequency of the defined primary event.
The posted safety summary reports 0 participants with serious adverse events in each listed period and 0 deaths. It reports 1 participant with an other adverse event during Titration and Maintenance Periods and 0 during Follow-up. These counts describe the registry summary only. They do not establish that lixivaptan is safe or unsafe, and they are not estimates from a comparison with another treatment.
The study also listed secondary safety outcomes and annualized eGFR change. No results for those outcomes are reported in the registry record. The stated intention to examine renal efficacy is not a finding of efficacy, and the listed outcomes do not establish that the corresponding analyses were completed.
General statistical interpretation: a study with no control group can describe what was observed among its participants, but cannot isolate the effect of treatment by comparison with an untreated or differently treated group. A very small enrolled population also yields limited information about how often uncommon events might occur. The record's terminated status does not, by itself, explain why the study stopped or change the meaning of the counts. The reason for termination and the statistical analysis plan are not reported in the registry record.
Accordingly, the most defensible reading is narrow: the registry contains a protocol-level endpoint definition, a very small enrollment, and period-specific adverse-event counts, but no reported primary endpoint result or statistical analysis results. No conclusion about a treatment effect or the broader frequency of harms can be drawn from those elements alone.
13. Why This Trial Matters Statistically
The study raises a statistical question about how to describe liver safety in a selected rollover population with a prior history of abnormal liver chemistry results during tolvaptan treatment. Its primary outcome did not count ALT elevations alone: it required a threshold, independent assessment of probable relationship to lixivaptan, and treatment discontinuation. That definition shows how endpoint construction can focus a safety question on a particular event with a treatment consequence.
The record also illustrates the limits of evidence from a single-group study. With no randomized comparator, any observed events would be descriptive rather than a direct estimate of a difference between treatments. The enrollment of 1 further limits how much the study can say about the frequency and variability of outcomes. No primary result or statistical analysis is reported, so the registered question cannot be answered from the posted results in this record.
General statistical principle: the amount of information in a study depends not only on the endpoint but also on the number of observed participants and events, the completeness of follow-up, and the design's ability to support the intended comparison. Clear outcome definitions help interpretation, but do not replace outcome data. Likewise, an adverse-event count without details of event type and timing cannot provide a full safety profile.
The record is marked terminated, but does not report the reason. This is consequential for interpretation because the endpoint definitions and study intention do not reveal whether the planned assessment was completed. The record leaves the reader with a clear description of the intended safety question, but insufficient reported outcome information to estimate its answer or quantify its precision.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The most immediate limitation is the small enrollment: the registry reports 1 participant. The study was also single group and open label, with no randomized comparator. These features restrict interpretation to description of the enrolled participant and do not permit a like-for-like treatment comparison.
The registry status is terminated, and the reason for termination is not reported in the registry record. The listed primary completion date is 2022-06-29, but the record does not explain whether the intended follow-up and assessments were completed. The primary endpoint timeframe is 120 days; participant-level follow-up completeness is not reported.
No primary endpoint result, statistical analysis results, or secondary outcome results are reported. The registry lists 0 analyses. It does not report missing-data procedures, analysis populations, the multiplicity approach, or a statistical analysis plan. The sample-size justification for the trial itself is also not reported in the registry record.
The primary event requires a specific ALT threshold, an HERC assessment of at least probable relationship to lixivaptan, and discontinuation. The registry defines this outcome but gives no event count or committee-level assessment details. The adverse-event summary reports sparse counts but does not identify the other adverse event. These limitations prevent a detailed appraisal of the event profile and leave both the primary question and the broader safety and renal questions unanswered in the posted results.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Roll-over Study to Assess Safety of Lixivaptan in Participants With ADPKD Who Completed Study PA-ADPKD-303 — NCT05208866.
- Registry record last updated 2023-05-12; status last verified 2023-04.
- Results first posted 2023-04-10.
- 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
NCT05208866 is a Phase 3, open-label, single-group rollover study of lixivaptan in participants with ADPKD who completed PA-ADPKD-303 after previously stopping tolvaptan because of abnormal liver chemistry results. The listed intervention was lixivaptan capsules 100-200mg twice daily. The study enrolled 1 participant, started on 2022-02-10, had a primary completion date of 2022-06-29, and is marked terminated.
The primary endpoint was a count of participants with ALT levels >3 × ULN judged at least probably related to lixivaptan by the HERC and resulting in treatment discontinuation, over 120 days. The registry reports no primary endpoint result and lists 0 analyses. The reason for termination, statistical analysis plan, missing-data methods, and analysis populations are not reported in the registry record. The adverse-event summary reports no serious adverse events or deaths in the listed periods, with one other adverse event during Titration and Maintenance Periods and none during Follow-up.