A Study to Assess the Safety of GRF6019 Infusions in Subjects With Severe Alzheimer's Disease: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study to Assess the Safety of GRF6019 Infusions in Subjects With Severe Alzheimer's Disease (NCT03765762), a randomized phase 2 study. The primary outcome is Frequency of Treatment-emergent Adverse Events (Safety).

2. Clinical Question

The central question is descriptive and safety-focused: what adverse-event counts were recorded among participants assigned to GRF6019 and placebo? The posted results report 8 participants with at least one treatment-emergent adverse event in the GRF6019 arm and 3 in the placebo arm. The arm denominators are 18 and 8, respectively. These are counts, not a complete estimate of the difference in event risk or its precision.

The study summary also mentions potential cognitive benefit, and the registry record lists cognitive, daily-function, global-change, and neuropsychiatric outcomes. Those outcomes do not replace the stated primary safety question. The registry record does not report analyses for those outcomes, so the posted information does not establish whether cognitive or functional measures changed or differed between groups. The main interpretive focus is therefore the recorded adverse-event experience within the stated follow-up timeframe, not a conclusion about efficacy.

3. Trial Design

This was a randomized, triple-masked, parallel-group Phase 2 study with GRF6019 and placebo arms. The official title describes it as double-blind, placebo-controlled; the registry’s masking classification is triple. The record does not explain which additional study roles were masked, so the masking details beyond those descriptions are not reported in the registry record.

Participants assigned to GRF6019 were scheduled to receive intravenous infusions of 250 mL daily for 5 consecutive days. The placebo arm had the same stated infusion volume and schedule. The primary safety outcome was assessed over a 5-week timeframe. The primary safety population is described as all subjects who received any amount of study treatment.

The registry lists enrollment of 26. The posted arm summaries give denominators of 18 for GRF6019 and 8 for placebo. The study is marked completed. Its listed start date is 2019-01-15, and its listed primary completion date is 2019-12-17. Alkahest, Inc. is identified as sponsor.

Randomization can reduce systematic differences between groups at assignment, while masking can reduce the influence of expectations on care, reporting, or assessment. These are general design principles; the registry record does not report the randomization method, concealment procedures, or specific masking arrangements. It also does not report the planned statistical analysis in enough detail to determine how outcomes were to be compared. The available arm counts can be described, but design labels alone do not supply a treatment-effect estimate or show how uncertainty was handled.

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: Safety: All subjects who received any amount of study treatment

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 Frequency of Treatment-emergent Adverse Events (Safety), measured over 5 weeks.

The primary endpoint is the frequency of treatment-emergent adverse events, expressed as the number of participants with at least one event. The registry describes events by MedDRA preferred term and grouped System Organ Class. The stated timeframe is 5 weeks, and the population is the safety group: subjects who received any amount of study treatment.

A participant count is a binary-outcome summary: each person is classified according to whether at least one qualifying event was recorded during the defined period. This type of endpoint is used in safety assessment because it summarizes how many treated participants experienced an event, rather than counting every episode as though each were an independent participant. Grouping events by preferred term and System Organ Class can also organize the types of events reported.

The posted arm values are 8 participants in the GRF6019 arm and 3 in the placebo arm, with arm denominators of 18 and 8. These counts do not convey event severity, duration, recurrence, or whether an event was considered related to treatment. Although the endpoint description refers to event terms and system-organ-class groupings, those specific results are not reported in the registry record. A count of participants with any event is therefore only one part of the safety picture.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The posted result is a binary endpoint summarized as participant counts. A participant either had at least one treatment-emergent adverse event in the specified timeframe or did not. The registry reports the count with an event and the arm denominator, but it does not provide the underlying participant-level data. That limits the analysis to the summaries recorded and prevents independent checks of event timing, repeated events, or participant-level classifications.

What can an arm count tell us?

An arm count tells how many participants were recorded as having the outcome. It is easy to interpret, but a count alone is not a standardized comparison when group sizes differ. A proportion can describe the share of an arm with an event, and a comparative effect measure can summarize how outcomes differ between arms. Those measures require a defined analysis and should be accompanied by uncertainty estimates when the data permit. No such two-arm estimate is reported in the registry record for this endpoint.

A confidence interval is a general statistical tool for expressing the precision of an estimated effect under a specified method. It reflects uncertainty in the estimate; it is not a guarantee that the true effect lies within a particular interval. Because the registry record gives no estimable comparison or interval, the precision of a treatment contrast cannot be assessed from the posted result. The counts should not be converted into a claim of a reliable difference or no difference.

Why does the comparison need care?

Participants in the two arms are the units being counted. The endpoint concerns whether each participant had at least one event, not whether every event episode was independent. Treating repeated events in the same participant as separate independent observations could overstate the amount of information. The record’s participant-level endpoint avoids that particular interpretation problem for the primary count, but it does not show the frequency or recurrence of episodes.

Random assignment is intended, as a general principle, to make assigned groups comparable on average. Masking is intended to reduce the influence of expectations on treatment, observation, and reporting. Neither principle removes uncertainty, and neither reveals whether the randomization and masking procedures were implemented as planned. The registry record does not describe sequence generation, allocation concealment, or the roles included in masking. The record classifies the study as randomized, triple-masked, and parallel-group; the official title calls it double-blind.

What do the planning assumptions mean?

The registry describes sample-size illustrations as planning exercises based on a fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. These are planning assumptions, not evidence about the trial’s own design or an estimate of observed power. The record does not report the trial’s sample-size justification. In addition, the two-arm comparison for this binary endpoint is marked unavailable or not estimable, so the posted record does not provide a comparative effect that can be interpreted as a basis for those illustrations.

In general, a planning calculation asks how much information a future study might need to detect a specified effect under stated assumptions. It does not show that the completed study had that probability of detecting an effect, and it does not alter what was observed. Planning calculations are sensitive to the chosen target effect, event frequency, allocation, statistical method, and assumptions about variability. Those inputs must be interpreted as design choices, not clinical findings.

Why do serious events require a separate reading?

Serious adverse events are a defined subset of safety events and should not be conflated with all treatment-emergent adverse events. In the posted record, the serious-event counts are 0 for GRF6019 and 0 for placebo; the death counts are also 0 in each arm. The broader primary endpoint includes participants with at least one treatment-emergent event and has nonzero counts in both arms. These summaries answer different safety questions. General statistical caution applies to zero counts: they describe what was recorded in the observed participants and period, not a guarantee about risk outside them.

Overall, the record supports descriptive reporting of the arm counts and the separately posted serious-event and death counts. It does not provide the analysis details needed to reproduce a comparative inference. The analysis method, handling of missing observations, and multiplicity procedure are not reported in the registry record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("GRF6019", "Placebo")
n      <- c(18, 8)
events <- c(8, 3)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  GRF6019  18  8  44.4  21.5  69.2  24.6  66.3  24.4  66.5
ARM  Placebo  8  3  37.5  8.5  75.5  13.7  69.4  13.7  70.1

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists six secondary outcomes: the Mini-Mental State Examination score, Severe Impairment Battery total score, activities of daily living for severe Alzheimer disease, clinical global impression of change with caregiver input, and two neuropsychiatric inventory measures. The record identifies eight outcome measures overall, but it contains no analysis entries. The listed outcomes therefore indicate what was intended for assessment, not which results were observed or how they compared between arms.

When a study assesses multiple outcomes, statistical multiplicity can arise because repeated testing increases the chance of at least one apparently notable result by chance. A statistical plan may identify a primary outcome, define a testing sequence, or adjust inference across outcomes. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or any secondary-outcome results. It is not possible to determine whether or how multiplicity was addressed.

Missing-data handling is also not reported in the registry record. The primary safety population is described as all subjects who received any amount of study treatment, but the record does not explain how incomplete follow-up, unavailable event information, or missing secondary-outcome measurements were handled. The stated safety population should not be assumed to resolve those questions.

The registry identifies the treatment-emergent adverse-event endpoint and its timeframe, but it does not provide a detailed statistical analysis plan. The analysis populations for secondary outcomes, models, covariate adjustments, and sensitivity analyses are not reported in the registry record. Without those details and the missing analyses, secondary-outcome interpretation and the robustness of any comparison cannot be evaluated.

12. 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 non-serious adverse event terms

The serious-adverse-event summary records 0 serious events among 18 participants at risk in the GRF6019 arm and 0 among 8 participants at risk in the placebo arm. It also records 0 deaths in each arm. These are the serious-event and death counts reported for the study’s safety groups.

These values are distinct from the primary endpoint counts. The primary endpoint records 8 participants with at least one treatment-emergent adverse event in the GRF6019 arm and 3 in the placebo arm. A participant can have a treatment-emergent adverse event that is not classified as serious; therefore, nonzero overall event counts can coexist with zero serious-event counts.

Zero recorded serious events means none were reported in these arms during the observed study period. It does not establish that the risk is absent, nor does it characterize events beyond the observed timeframe. The registry record does not list serious adverse-event terms. The counts should be read as descriptive safety information, not as a precise comparative estimate.

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

The result means that the registry record reports 8 participants with at least one treatment-emergent adverse event in the GRF6019 arm and 3 in the placebo arm during the 5-week timeframe. The arm denominators are 18 and 8. Separately, the serious-adverse-event summary reports 0 serious events and 0 deaths in each arm. These are the posted descriptive counts.

The result does not establish that GRF6019 caused or prevented an event. A treatment-emergent event is one recorded after treatment begins; the endpoint description does not say that every event was judged treatment-related. The counts also do not describe event duration, severity, recurrence, or the specific terms and system-organ-class groupings. Those details are not reported in the registry record.

The record does not report an estimable two-arm comparison for the binary endpoint. It therefore does not provide a confidence interval or an inferential result that would show how compatible the data are with different comparative effects. The observed counts should not be converted into a claim that the treatments are equivalent or that one is safer.

Nor do the posted results answer the cognitive-benefit question mentioned in the study summary. Although cognitive and other secondary outcomes are listed, no analyses are reported in the registry record. The safety counts cannot stand in for results on cognition, daily function, global change, or neuropsychiatric symptoms.

The study offers a limited descriptive record of adverse-event counts in randomized arms over a defined follow-up period. It does not settle longer-term safety, characterize rare events, or establish a comparative clinical effect. A careful reading keeps the observed counts separate from causal interpretation, statistical precision, and outcomes for which no results are posted.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of how a registry can contain useful descriptive safety counts without enough information for a comparative conclusion. The primary endpoint is framed at the participant level, and the record reports both event counts and arm denominators. Those details make the basic result interpretable while still leaving its precision and comparative meaning unresolved.

The study also illustrates why a zero count for serious events should not be treated as proof of no risk. The record reports 0 serious events and 0 deaths in each arm, while the broader treatment-emergent adverse-event endpoint has nonzero counts. Understanding which safety definition is being discussed matters: serious events and any treatment-emergent event are not interchangeable outcomes.

Randomization and masking are important design features, but they do not substitute for reporting the analysis. The registry record identifies randomized allocation and masking, yet does not provide the planned statistical methods, a confidence interval, or an estimable two-arm result for the primary binary endpoint. This distinction helps separate the design’s potential protections against bias from the evidence actually available for interpretation.

The listed secondary measures raise a further statistical issue. Multiple outcomes can create multiplicity concerns, and missing results make it impossible to assess the planned outcome hierarchy or the pattern across measures. Statistical transparency requires not only naming outcomes but also reporting analyses and explaining how incomplete data and multiple comparisons were handled.

For clinical researchers, the key lesson is to distinguish descriptive counts from effect estimates, and outcome listings from reported results. This record supports a narrow account of observed safety events, while highlighting how analysis and uncertainty reporting are needed for broader conclusions.

15. 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 primary endpoint covers a 5-week timeframe, which limits what can be said about events occurring later. The posted arm denominators are 18 for GRF6019 and 8 for placebo. Counts from these groups provide limited information about uncommon events, and the registry record does not report an estimable comparative effect or its precision.

The primary result is a participant count for at least one treatment-emergent adverse event. It does not show the number of event episodes, recurrence within participants, event duration, severity distribution, or event-term breakdown. Although the endpoint description refers to MedDRA preferred terms and System Organ Class groupings, those details are not reported in the registry record. Serious adverse events and deaths are separately recorded as zero in each arm, but the record does not list serious-event terms.

The record does not report the statistical analysis plan, randomization procedure, allocation concealment, or the specific roles included in masking. It also does not explain missing-data handling, multiplicity procedures, or whether any sensitivity analyses were planned. The registry lists secondary outcomes but no analysis entries, limiting assessment beyond the primary safety counts.

Finally, treatment-emergent events are not necessarily treatment-related events. The posted counts alone do not establish causation, comparative safety, or equivalence. The registry record also does not provide enough information to assess longer-term outcomes or to draw conclusions about cognitive benefit from the listed secondary measures.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study to Assess the Safety of GRF6019 Infusions in Subjects With Severe Alzheimer's Disease — NCT03765762.
• Registry record last updated 2021-01-27; status last verified 2019-05.
• Results first posted 2021-01-27.
• 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.

19. Record Summary

The registry record describes a randomized, triple-masked, parallel-group Phase 2 study of intravenous GRF6019 versus placebo in participants with severe Alzheimer disease. Both arms had a stated schedule of 250 mL daily for 5 consecutive days. The primary safety endpoint was the number of participants with at least one treatment-emergent adverse event over 5 weeks.

The posted counts are 8 participants with an event among 18 in the GRF6019 arm and 3 among 8 in the placebo arm. Serious-event and death counts are 0 in each arm. The registry record does not provide an estimable two-arm comparison, analysis entries for the listed secondary outcomes, or details on missing-data and multiplicity methods. The results support descriptive reporting, not a firm comparative conclusion.