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 Maximal Use Systemic Exposure Study of Levulan Kerastick (MUSE 2) (NCT02628236), a na phase 2 study. The primary outcome is Maximum Baseline Corrected Plasma Concentration (Cmax) for ALA.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02628236 |
| Phase | Phase 2 |
| Condition | Keratosis, Actinic |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 14 |
| Arms in the primary outcome | n/a |
| Lead sponsor | DUSA Pharmaceuticals, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
People with multiple actinic keratoses involving the upper extremities were the intended population. The registry record lists 14 enrolled participants; it does not report further details about the participants’ characteristics or the number included in the primary endpoint analysis.
Intervention
The study evaluated 20% aminolevulinic acid applied with Kerastick to individual actinic keratosis lesions on the upper extremities. Lesions were covered with an occlusive dressing for 3 hours before BLU-U treatment.
Comparator
There was no separate control group. The registry classifies the study as single group, with allocation listed as not applicable and no masking. The results therefore do not provide a like-for-like treatment comparison.
Primary question
The primary question was whether topical aminolevulinic acid under maximal-use conditions was associated with measurable systemic exposure. The primary endpoint was maximum baseline-corrected plasma concentration of aminolevulinic acid, described as a geometric mean over the stated sampling period. The registry record does not report the numerical concentration result or its uncertainty.
This is a pharmacokinetic question, not a comparison of clinical effectiveness. The study focused on aminolevulinic acid and protoporphyrin IX exposure when aminolevulinic acid was applied topically under occlusion in a maximal-use setting. The listed intervention also included BLU-U treatment after the occlusion period. The record does not establish a separate question about how the treatment changes actinic keratoses, nor does it provide comparative evidence about alternative treatment strategies.
3. Trial Design
The registry describes a phase 2, single-group study with 14 participants enrolled. Its status is completed. The listed study dates are 2016-02 for study start and 2016-05 for primary completion. Allocation is recorded as not applicable, and masking is recorded as none. These design features mean the study was not set up as a randomized, masked comparison between treatment groups.
Participants received aminolevulinic acid applied to individual actinic keratosis lesions on the upper extremities. The application was covered with an occlusive dressing for 3 hours before BLU-U treatment. The study’s stated purpose was to evaluate potential systemic exposure to aminolevulinic acid and protoporphyrin IX under maximal-use conditions. The registry lists aminolevulinic acid and BLU-U as interventions.
The primary endpoint is maximum baseline-corrected plasma concentration of aminolevulinic acid, reported in ng/mL as a geometric mean with geometric coefficient of variation as the dispersion measure. The endpoint description refers to a 24-hour sampling period, while the listed sampling schedule continues through 48 hours. The record does not explain this difference or specify how observations after 24 hours were handled in the primary endpoint calculation.
The registry lists 34 outcome measures and no analyses. It also lists hyperpigmentation, hypopigmentation, and erythema among secondary outcomes, but does not provide detailed numerical results for those outcomes in the registry record for this analysis. The registry record does not report the protocol’s eligibility details, analysis population definitions, handling of missing observations, or a statistical analysis plan. The single-group design and absence of a reported numerical primary result limit what can be concluded about systemic exposure from the posted 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 | ALA-PDT |
|---|---|
| STARTED | 14 |
| COMPLETED | 14 |
| 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.
| Characteristic | Unit | ALA-PDT |
|---|---|---|
| Participants analysed | 14 | |
| Age, Continuous | years | 65.6 (SD 7.7) |
| Sex: Female, Male: Female | Participants | 3 |
| Sex: Female, Male: Male | Participants | 11 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 14 |
| 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 | 0 |
| Race (NIH/OMB): White | Participants | 14 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | Participants | 14 |
6. Primary Endpoint
The registry lists the primary outcome as Maximum Baseline Corrected Plasma Concentration (Cmax) for ALA, measured over 2 days.
| Element | Registry entry |
|---|---|
| Result type | Geometric Mean |
| Measure of spread | Geometric Coefficient of Variation |
| Unit | ng/mL |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is maximum baseline-corrected plasma concentration (Cmax) for aminolevulinic acid, measured in ng/mL. Cmax is a pharmacokinetic measure: it identifies the highest concentration observed over a specified sampling period. Baseline correction means the concentration is interpreted relative to a pre-application measurement, rather than as an unadjusted post-application value. The registry describes the result using a geometric mean and a geometric coefficient of variation.
General statistical context: concentration measurements can be right-skewed, with a small number of relatively high values. A geometric mean is often used for such data because it summarizes values on a multiplicative scale. The geometric coefficient of variation describes relative spread on that scale; it is not the same as a standard deviation expressed in the original units. Neither measure alone describes every participant’s concentration profile.
The registry lists blood collection before application and at 15 and 30 minutes, 1, 2, 4, 8, 12, 16, 24, 36 and 48 hours after application. However, it describes Cmax over a 24-hour sampling period while giving a timeframe of 2 days. The record does not clarify how those timing descriptions relate to the endpoint calculation.
No numerical Cmax result, geometric coefficient of variation, confidence interval, or analysis population is reported in the registry record. Consequently, the endpoint definition is available, but the size and precision of the observed systemic concentration cannot be assessed from this record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record defines a pharmacokinetic endpoint but does not report its numerical result. It is therefore not possible to state the observed maximum baseline-corrected plasma concentration of aminolevulinic acid, its geometric coefficient of variation, or the precision of that estimate. The absence of a posted numerical endpoint result should not be mistaken for evidence that exposure was absent or negligible.
The study’s single-group design is suited to describing measurements made under the stated application conditions. It does not provide a concurrent untreated or alternative-treatment group for separating the effects of aminolevulinic acid application from other influences on measured concentrations. The record lists BLU-U treatment after topical application, but does not describe a comparison that isolates the contribution of each intervention.
The endpoint description includes baseline correction, a geometric mean, and a sampling schedule extending to 48 hours. It also refers to a 24-hour sampling period and gives a timeframe of 2 days. The registry record does not explain the relationship between these descriptions. Without the analysis details and numerical results, readers cannot determine which sampling observations contributed to the reported Cmax or how the concentration data were summarized.
Safety counts are reported for the ALA-PDT group: 1 participant is listed as affected by a serious adverse event, 0 by other adverse events, and 0 deaths. Deep vein thrombosis is listed as a serious adverse event term with a percentage of 7.1%. The record does not report whether the serious event was judged related to study treatment, when it occurred, or how it was managed. These counts describe reported events in this group; they do not establish causation or provide a comparative safety estimate.
General statistical context: an estimate is more informative when paired with a measure of uncertainty, such as a confidence interval. A confidence interval conveys the range of values compatible with the data and analysis assumptions; it is not a guarantee that the true value lies within that range. Since the record does not report a numerical endpoint estimate or interval, neither the magnitude nor the precision of the primary result can be evaluated.
The sample-size assumptions describe planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such illustrations are not observed power and do not transform this single-group study into a two-arm comparison. The numerical planning outputs and the underlying effect estimate are not included in the registry entries available for interpretation.
Overall, the posted information establishes the study’s purpose, design, endpoint definition, and selected safety counts. It does not establish the magnitude of systemic exposure or permit a comparative judgment about safety or effectiveness. Any stronger interpretation would require numerical outcome data and additional methods information not reported in the registry record.
9. Statistical Methods Explained
General statistical context: pharmacokinetic studies describe how measured concentrations change over time after an intervention. A maximum concentration endpoint, Cmax, focuses on the highest observed concentration within a defined sampling window. The window matters: extending or shortening it can change which measurement is eligible to be the maximum. Here, the registry describes a 24-hour sampling period, lists a timeframe of 2 days, and gives collection times through 48 hours. The record does not explain how these descriptions were reconciled in the analysis.
Why use baseline correction?
General statistical context: a baseline-corrected concentration accounts for the measurement obtained before application. It can help distinguish post-application concentration from a participant’s starting level. The exact calculation depends on the prespecified method. The registry identifies the endpoint as baseline-corrected but does not report the calculation details or how baseline values were handled if they were missing.
What does a geometric mean describe?
General statistical context: the geometric mean summarizes positive values on a multiplicative scale and can be suitable when measurements are skewed. It is calculated by transforming values to a logarithmic scale, averaging there, and transforming the result back. This summary is distinct from the arithmetic mean. It does not indicate that all individual measurements were close to the geometric mean, and it should be read alongside a measure of variability and, where available, an uncertainty interval.
The registry specifies geometric coefficient of variation as the dispersion measure. General statistical context: this describes relative variability on a multiplicative scale, rather than an absolute spread in ng/mL. The record does not provide the numerical coefficient or the underlying participant-level concentration data, so the degree of variability cannot be evaluated.
Why does the sampling schedule matter?
Repeated blood collection allows concentrations to be observed at multiple times after application. A schedule with measurements at 15 and 30 minutes and at later listed times can characterize the observed concentration profile more fully than a single measurement. Still, a measured maximum is the highest among the observations collected; it may not be identical to the actual peak between sampling times. The registry record does not state whether any interpolation or other modeling was used to estimate a peak between scheduled collections.
The primary endpoint description says that samples were taken before application and through 48 hours, while also specifying a 24-hour sampling period. The listed timeframe is 2 days. These details leave an unresolved question about the endpoint window. They do not, by themselves, show that the analysis was incorrect; the record simply does not report enough detail to explain the relationship.
What can a single-group design estimate?
General statistical context: a single-group study can describe outcomes among participants who receive the study regimen. Without a comparison group, it cannot directly estimate a difference between treatment strategies. In this study, there is no randomized comparator, and masking is listed as none. The design therefore does not support an estimate of a between-group treatment effect or a randomized causal comparison.
For this pharmacokinetic question, a single-group concentration summary may describe exposure under the study conditions if the numerical data and analysis are reported. In this record, the primary numerical result is not reported. Details about the analysis population, missing concentration samples, exclusions, and handling of values below an assay limit are also not reported in the registry record.
How should planning illustrations be read?
General statistical context: a sample-size calculation asks how many observations might be required to detect a specified effect under chosen assumptions. The planning assumptions described for this study use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is expressed as a fraction of an observed effect. These are planning assumptions, not evidence that this trial had those design features. The actual registry design is single group, and the calculation does not constitute observed power.
The record also notes that time-to-event planning uses total events, while other planning illustrations are expressed as participants per arm. This distinction is relevant to interpreting the planning outputs, but no numerical outputs or underlying observed effect are reported in the registry entries used. A planning illustration should not be mistaken for an observed result, a justification for the enrolled number, or a report of the trial’s own statistical plan.
What information is needed for a fuller assessment?
For a fuller statistical assessment, readers would need the numerical primary endpoint result, its uncertainty, the analysis population, and the handling of missing or unusable samples. They would also need clarification of the endpoint window and the role of measurements collected after 24 hours. The registry record does not report these details. General statistical principles can explain what the named measures mean, but they cannot recover the study’s unreported results or analysis decisions.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 34 outcome measures and no analyses. It identifies maximum baseline-corrected plasma concentration of aminolevulinic acid as the primary outcome and lists hyperpigmentation, hypopigmentation, and erythema among secondary outcomes. However, the registry record does not report a multiplicity strategy, such as whether testing across outcomes was adjusted or whether some outcomes were treated as exploratory.
General statistical context: when many outcomes or comparisons are examined, the chance of at least one apparently unusual result can increase if each is assessed independently. A prespecified hierarchy, adjustment procedure, or clear distinction between confirmatory and exploratory outcomes can help readers interpret multiple findings. The record does not state whether any such approach was planned or used. The count of outcome measures alone does not establish how many statistical tests were performed.
The registry record does not report how missing concentration measurements were handled, whether participants were excluded from an analysis, or how the primary analysis population was defined. It also does not specify how incomplete sampling schedules, assay issues, or observations outside the endpoint window were treated. These details matter because the primary measure depends on observed concentrations over time.
No numerical primary endpoint analysis is reported in the registry record. Therefore, the analysis population, missing-data impact, and multiplicity implications cannot be assessed from the posted information. These are reporting gaps, not evidence that a particular method was or was not used.
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 |
|---|---|---|---|
| ALA-PDT | 1 | 14 | 7.1% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| ALA-PDT | 0 of 14 |
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 |
|---|---|
| ALA-PDT | 0 of 14 |
Most frequent serious adverse event terms
| Event term | Organ system | ALA-PDT |
|---|---|---|
| deep vein thrombosis | Vascular disorders | 1 of 14 |
Serious events with the highest arm-level rate: deep vein thrombosis (7.1%).
The registry reports safety counts for the ALA-PDT group. Serious adverse events were recorded for 1 participant among 14 at risk; other adverse events were recorded for 0 among 14 at risk, and deaths for 0. Deep vein thrombosis is listed among the serious adverse event terms, with a reported percentage of 7.1%.
These are descriptive counts from a single group, not a comparison against a control group. The registry does not state whether the serious event was considered related to aminolevulinic acid, BLU-U treatment, or another cause. It also does not report event timing, severity details beyond the serious classification, or the participant’s outcome. The listed term and count should therefore be read as a report of an event, not proof of causation.
General statistical context: a small group can provide limited information about uncommon events, and an observed count does not by itself establish the rate that would occur in a broader population. The absence of reported other adverse events or deaths in this group does not establish that such events cannot occur. The registry record also lists hyperpigmentation, hypopigmentation, and erythema as secondary outcomes, but the relevant numerical results are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
This trial addresses a focused pharmacokinetic question: potential systemic exposure to aminolevulinic acid and protoporphyrin IX when topical aminolevulinic acid is used under maximal-use conditions in people with multiple actinic keratoses on the upper extremities. The record specifies the application approach, occlusion period, subsequent BLU-U treatment, and a primary concentration endpoint.
The posted record does not include the numerical primary endpoint result. It therefore cannot show the observed maximum baseline-corrected plasma concentration, how variable concentrations were, or how precisely the result was estimated. The endpoint’s description is informative about what was intended to be measured, but not about the measured magnitude.
The single-group design provides no concurrent comparator. It cannot quantify a difference from an untreated group or another treatment, and it cannot support a randomized comparison of safety or effectiveness. The study is not described as an effectiveness comparison, and the registry entries do not provide a clinical outcome result that would establish a treatment effect.
The safety listing records a serious adverse event in the group and no other adverse events or deaths. The record does not report the event’s attribution, so the count alone cannot establish that the study regimen caused it. The small enrolled group and absence of a control comparison also limit what the safety counts can establish.
General statistical context: statistical interpretation depends on both the estimated result and its uncertainty, as well as the design and analysis choices. When the numerical estimate, uncertainty measure, analysis population, and missing-data methods are not reported, readers cannot assess the precision or robustness of the finding. These limitations do not imply a particular direction or size of the unreported result; they define what can and cannot be concluded from the registry record.
13. Why This Trial Matters Statistically
This study is statistically notable for linking a defined maximal-use application regimen to a concentration-based pharmacokinetic endpoint. Cmax is a direct summary of the highest measured concentration within a specified window, while baseline correction and geometric summaries reflect choices about how concentration data are represented. Understanding these choices is important when interpreting systemic exposure measurements.
The registry record also illustrates why endpoint timing must be clear. It describes a 24-hour sampling period, lists a 2-day timeframe, and gives sampling times through 48 hours. The analysis window determines which observations can contribute to a maximum. Without clarification, readers cannot establish how the endpoint’s stated window relates to the full sampling schedule.
The single-group design is another important statistical feature. It can describe outcomes within the treated group but does not supply a randomized comparator for estimating a treatment difference. The study’s stated purpose is exposure assessment, so the absence of a control group fits a descriptive question, while also restricting comparative conclusions.
Finally, the registry record lists outcome measures and safety counts but does not report a numerical primary result or key analysis details. This makes transparent reporting especially important: readers need an estimate, its variability or uncertainty, a clearly defined analysis population, and an account of missing measurements to judge the evidence. The record’s planning assumptions should be kept separate from trial results; planning calculations are not observed power and do not substitute for reported endpoint data.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The main limitation for interpreting the registry record is that it does not report a numerical result for the primary pharmacokinetic endpoint. The geometric mean Cmax, geometric coefficient of variation, and uncertainty around the estimate are not reported in the registry record. As a result, the magnitude and precision of systemic exposure cannot be assessed.
The primary endpoint’s timing is not fully clear from the record. It describes a 24-hour sampling period, lists a timeframe of 2 days, and includes collection times through 48 hours. The record does not explain which observations were used to define the primary maximum or how the timing descriptions fit together.
The study has a single-group design, with allocation not applicable and masking none. There is no like-for-like control comparison, so the record cannot support a comparative treatment-effect estimate. The registry also does not report the primary analysis population, missing-sample handling, assay-related rules, or participant-level concentration summaries.
The record lists 34 outcome measures and no analyses, but does not describe a multiplicity approach or clarify which secondary outcomes were considered confirmatory. Safety reporting includes selected event counts, but attribution, timing, and additional clinical details for the serious event are not reported in the registry record. Together, these gaps constrain interpretation of both the exposure endpoint and the safety information.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Maximal Use Systemic Exposure Study of Levulan Kerastick (MUSE 2) — NCT02628236.
- Registry record last updated 2017-09-18; status last verified 2017-09.
- Results first posted 2017-09-18.
- 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
NCT02628236 is a completed phase 2, single-group study sponsored by DUSA Pharmaceuticals, Inc., with 14 participants enrolled. It evaluated potential systemic exposure to aminolevulinic acid and protoporphyrin IX under maximal-use topical conditions in people with multiple actinic keratoses involving the upper extremities.
The regimen involved 20% aminolevulinic acid applied to individual lesions under an occlusive dressing for 3 hours before BLU-U treatment. The primary outcome was maximum baseline-corrected plasma concentration of aminolevulinic acid, summarized as a geometric mean with geometric coefficient of variation. The registry record does not report its numerical result.
The safety listing reports 1 participant with a serious adverse event, 0 with other adverse events, and 0 deaths. Deep vein thrombosis is listed as a serious event term. The record does not report whether the event was attributed to treatment.