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 A Study of Giredestrant (GDC-9545) in Postmenopausal Women With Stage I-III Operable, Estrogen Receptor-Positive Breast Cancer (NCT03916744), a non-randomized phase 1 study. The primary outcome is Change From Baseline in Tumor Cell Proliferation, as Measured by the Proportion of Nuclei Staining Ki67-Positive at Surgery Relative to Baseline in Pre- and Post-Treatment Tumor Biopsy Samples.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03916744 |
| Phase | Phase 1 |
| Condition | Breast Cancer |
| Allocation | Non-Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 75 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Genentech, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
Postmenopausal women with Stage I-III operable, estrogen receptor-positive, HER2-negative, untreated breast cancer were the intended study population. The primary endpoint was assessed in an efficacy-evaluable population defined by available baseline and post-baseline Ki67 results, no early discontinuation, at least 12 doses, and no more than one modified dose. The registry record reports 10 participants in that population, but the accompanying cohort breakdown is incomplete.
Intervention
Participants received giredestrant in one of three dose cohorts: 10 mg, 30 mg, or 100 mg. The study evaluated the drug during a short preoperative period, with tumor samples assessed at baseline and at surgery. Surgery is also listed as an intervention in the registry record.
Comparator
There was no randomized control group. The study was non-randomized, open-label, and organized in parallel dose cohorts. As a result, the dose groups are not like-for-like randomized comparisons, and differences between them cannot be attributed solely to dose.
Primary question
The primary question was how tumor cell proliferation, measured by the proportion of nuclei staining Ki67-positive, changed from the baseline biopsy to the biopsy taken at surgery on Day 15. The registry record identifies the endpoint and a 95% confidence interval as its dispersion measure, but does not report the numerical endpoint estimate or confidence interval. The size and precision of the observed change therefore cannot be assessed from the registry record.
3. Trial Design
This was a Phase I, multicenter, open-label, preoperative, short-term window study of giredestrant in postmenopausal women with Stage I-III operable, estrogen receptor-positive breast cancer. The registry record describes the intended population as having untreated, HER2-negative disease. The study was non-randomized and used a parallel model, with giredestrant 10 mg, 30 mg, and 100 mg cohorts. The record lists 75 participants enrolled and indicates that the study is completed.
Because treatment allocation was not randomized, the cohorts should not be read as randomized treatment arms. The registry record does not describe a separate untreated or active control group. Nor does it give arm descriptions beyond the dose labels. Participants and investigators were not masked, consistent with the record's open-label designation. These design features make the study useful for describing biologic and safety observations during the preoperative period, but they do not provide a controlled estimate of the effect of giredestrant relative to another treatment.
The primary assessment compared tumor biopsy samples taken before study drug began with samples taken at surgery on Day 15. The primary endpoint was the change in tumor cell proliferation, assessed through Ki67 staining. Other stated aims included pharmacodynamics, pharmacokinetics, safety, and biologic activity. The registry lists surgery as an intervention alongside giredestrant.
The study began on 2019-07-26, had a primary completion date of 2021-05-25, and is recorded as completed. These dates describe the study record and do not establish when any particular participant began or finished treatment. The registry record does not report a sample-size justification, detailed allocation procedure, or additional protocol details that would explain how participants entered the dose cohorts.
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 | Giredestrant 10 mg | Giredestrant 30 mg | Giredestrant 100 mg |
|---|---|---|---|
| STARTED | 17 | 40 | 18 |
| Received at Least One Dose of Study Drug | 17 | 40 | 17 |
| COMPLETED | 17 | 39 | 16 |
| NOT COMPLETED | 0 | 1 | 2 |
Reasons for not completing this period:
| Reason | Giredestrant 10 mg | Giredestrant 30 mg | Giredestrant 100 mg |
|---|---|---|---|
| Withdrawal by Subject | 0 | 1 | 2 |
Analysis population for the primary outcome, as defined in the registry: Efficacy Evaluable Population: all participants who 1) had non-missing baseline and post-baseline Ki67 results available, 2) did not discontinue early from the study, 3) had taken at least 12 doses, and 4) had no more than one modified dose. A total of 10 participants (2 in the 10mg cohort, 5 in the 30mg cohort, and 3 in the 100mg cohort) were excluded from efficacy evaluation for not meeting the criteria.
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: This is the Intent-to-Treat (ITT) Population, which includes all participants enrolled in the study regardless of whether they received any study drug.
| Characteristic | Unit | Giredestrant 10 mg | Giredestrant 30 mg | Giredestrant 100 mg | Total |
|---|---|---|---|---|---|
| Participants analysed | 17 | 40 | 18 | 75 | |
| Age, Continuous | Years | 63.4 (SD 8.9) | 64.1 (SD 9.4) | 64.1 (SD 7.7) | 63.9 (SD 8.8) |
| Sex: Female, Male: Female | Participants | 17 | 40 | 18 | 75 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 4 | 0 | 4 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 4 | 19 | 6 | 29 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 13 | 17 | 12 | 42 |
| Race/Ethnicity, Customized: Asian | Participants | 0 | 0 | 1 | 1 |
| Race/Ethnicity, Customized: Black or African American | Participants | 0 | 1 | 0 | 1 |
| Race/Ethnicity, Customized: White | Participants | 16 | 38 | 17 | 71 |
| Race/Ethnicity, Customized: Multiple | Participants | 1 | 0 | 0 | 1 |
| Race/Ethnicity, Customized: Unknown | Participants | 0 | 1 | 0 | 1 |
| Eastern Cooperative Oncology Group (ECOG) Performance Status at Baseline: ECOG Performance Status of 0 | Participants | 17 | 36 | 17 | 70 |
| Eastern Cooperative Oncology Group (ECOG) Performance Status at Baseline: ECOG Performance Status of 1 | Participants | 0 | 4 | 0 | 4 |
| Initial Staging of Breast Cancer (Breast Cancer History): Stage I | Participants | 9 | 19 | 10 | 38 |
| Initial Staging of Breast Cancer (Breast Cancer History): Stage II | Participants | 8 | 21 | 7 | 36 |
| Initial Staging of Breast Cancer (Breast Cancer History): Stage III | Participants | 0 | 0 | 1 | 1 |
| Tumor Grade (Breast Cancer History): Grade 1 | Participants | 6 | 13 | 4 | 23 |
| Tumor Grade (Breast Cancer History): Grade 2 | Participants | 9 | 23 | 12 | 44 |
| Tumor Grade (Breast Cancer History): Grade 3 | Participants | 2 | 4 | 2 | 8 |
| Nodal Status (Breast Cancer History): Negative | Participants | 14 | 37 | 17 | 68 |
| Nodal Status (Breast Cancer History): Positive | Participants | 2 | 3 | 1 | 6 |
| Nodal Status (Breast Cancer History): Missing | Participants | 1 | 0 | 0 | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Change From Baseline in Tumor Cell Proliferation, as Measured by the Proportion of Nuclei Staining Ki67-Positive at Surgery Relative to Baseline in Pre- and Post-Treatment Tumor Biopsy Samples, measured over Baseline and Surgery (Day 15).
| Element | Registry entry |
|---|---|
| Result type | Geometric Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | Proportion of Ki67+ nuclei |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint assessed tumor cell proliferation by measuring the proportion of tumor cell nuclei staining positive for Ki67. Ki67 is a marker of cell proliferation; in this study, the endpoint compared a pretreatment tumor biopsy with a biopsy taken at surgery. Baseline was defined as a sample collected before study drug initiation, and the posts-treatment sample was collected at surgery on Day 15. The recorded unit is the proportion of Ki67-positive nuclei, and the endpoint is described as the posts-treatment result relative to baseline.
In general, a biomarker endpoint can provide an early indication of biologic activity within the tissue being studied. It differs from an endpoint that directly measures longer-term clinical outcomes. Changes in a tissue marker may help characterize a drug's biological effects over the study window, but they do not by themselves establish effects on outcomes that were not measured.
The registry record identifies a geometric mean and a 95% confidence interval for this endpoint. A geometric mean is a summary suited to data analyzed on a multiplicative scale; it is not the same as an arithmetic average. A confidence interval communicates uncertainty around an estimate, with its width reflecting precision under the analysis used. The numerical estimate and confidence interval are not reported in the registry record, so neither the direction nor the size of the observed change, nor its precision, can be evaluated from the record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central result needed to interpret the primary endpoint is absent from the registry record: it names the Ki67 comparison and its statistical summary but gives no numerical estimate or confidence interval. Consequently, the registry record does not establish whether the average relative Ki67 measurement was lower, higher, or similar at surgery compared with baseline. It also does not allow readers to judge how precise the estimated change was. A confidence interval is useful because it conveys a range of values compatible with the data under the analysis; without its endpoints, that uncertainty cannot be described.
The study is non-randomized and has three giredestrant dose cohorts. These cohorts are not randomized comparisons, and there is no like-for-like control group in the record. Any differences between dose cohorts could reflect differences in the participants or other features of cohort assignment as well as dose. The available record therefore supports describing the study structure and the outcomes it intended to assess, not making a causal comparison between doses or against an alternative treatment.
The safety record reports 74 participants in the all-participants safety group. In that group, 4 participants were recorded as having at least one serious adverse event, 47 as having at least one other adverse event, and 0 deaths. The dose-specific counts are also reported, but these are descriptive counts rather than randomized comparative estimates. The registry lists serious-event terms with percentages, including Breast abscess and Dizziness at 5.9% each, and Mastitis and Breast haematoma at 2.5% each. The record does not provide further context for those listed percentages in the information available.
The study's total enrollment was 75, while the safety group includes 74 participants. The primary efficacy-evaluable population is reported as 10 participants and has eligibility requirements based on biopsy availability, treatment exposure, discontinuation, and dose modification. These different analysis populations answer different descriptive questions and should not be treated as interchangeable.
Overall, the registry supports a careful account of the study design, endpoint definition, analysis-population criteria, and some safety counts. It does not report the primary endpoint estimate, its confidence interval, or a statistical test result. No conclusion about the magnitude or precision of the Ki67 change can be drawn from the registry record.
9. Statistical Methods Explained
The registry record identifies the primary endpoint as a change in tumor cell proliferation, measured by the proportion of nuclei staining Ki67-positive at surgery relative to baseline. It describes the summary as a geometric mean with a 95% confidence interval. It does not report the numerical summary, confidence-interval limits, statistical test, or model used to obtain the result. Those omissions limit interpretation: the endpoint's direction, magnitude, and precision cannot be reconstructed from the endpoint description alone.
What does a geometric mean describe?
In general, a geometric mean summarizes observations on a multiplicative scale. It is often useful when relative changes or ratios are the focus and measurements are positively valued and skewed. Unlike an arithmetic mean, it does not summarize the simple additive average of the observations. For a relative endpoint, the geometric mean can describe a typical proportional pattern across participants. The registry's use of this summary does not reveal the underlying participant-level data or the exact calculation method.
How should a confidence interval be read?
In general, a confidence interval describes statistical uncertainty around an estimate under the assumptions of the analysis. A narrower interval indicates greater precision than a wider interval, while the interval's location relative to a reference value helps assess which values are compatible with the data. The registry record specifies a 95% confidence interval for the primary endpoint but does not report its limits. It is therefore not possible to state whether the estimate was precise or whether the interval included a value representing no relative change.
Why does the design matter?
The study is non-randomized, open-label, and organized into parallel dose cohorts. In general, randomization helps balance measured and unmeasured participant characteristics between groups, whereas non-randomized allocation does not ensure that balance. Without a randomized control group, comparisons among the dose cohorts may be affected by differences in who entered each cohort, as well as by dose. Open-label conduct means treatment assignment was not masked, which can matter for outcomes susceptible to measurement or reporting influences. The primary outcome is a tissue measurement, but the registry record does not describe any blinding of the laboratory assessment.
The preoperative design uses a within-participant baseline and surgery measurement. In general, repeated measurements can control for stable differences between participants because each participant contributes measurements at both times. However, a before-and-after comparison alone does not separate treatment-associated change from other time-related influences. The record does not describe a control group or an analysis that would address such influences.
Why can over-dispersion matter?
In general, over-dispersion occurs when observed variability is greater than a statistical model assumes. If it is not accounted for, standard errors can be too small and confidence intervals too narrow. This is a general consideration for analyses of variable clinical data; the registry record does not identify an over-dispersion assessment or state that one was relevant to the Ki67 analysis.
What do the event counts communicate?
The safety results are expressed as counts of participants affected in each dose group and in the all-participants safety group. Such counts describe how many participants were recorded with at least one event in the listed categories. They are not, on their own, comparative estimates of risk, and they do not indicate whether an event was caused by treatment. The record separately identifies serious and other adverse events, and reports no deaths in the listed groups. The listed serious-event terms and percentages are descriptive registry entries; they do not provide the full event-level context or a comparative analysis.
Finally, a statistical analysis plan would normally clarify the target estimand, data handling, model, confidence-interval method, and any planned sensitivity analyses. The registry record does not report those details for the primary endpoint. It also lists zero analyses, so no analysis-specific methods or results are available to explain how the primary estimate was calculated. The statistical interpretation must therefore remain limited to the endpoint definition and the descriptive results actually recorded.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 12 outcome measures and records 0 analyses. It names the Ki67 comparison as the primary outcome and lists several safety outcomes, including adverse events, vital signs, hematology, blood chemistry, and coagulation laboratory abnormalities. The record does not report a multiplicity adjustment, a testing hierarchy, or a detailed statistical analysis plan. It is therefore not possible to determine how the study intended to control the chance of false-positive findings across multiple outcomes or comparisons. This matters in general because interpreting many separate statistical tests without a prespecified approach can make isolated findings harder to distinguish from chance variation.
Missing-data handling is not reported in the registry record. For the primary endpoint, the stated efficacy-evaluable population required non-missing baseline and post-baseline Ki67 results, no early discontinuation, at least 12 doses, and no more than one modified dose. The record gives a total of 10 participants in that population, but the cohort breakdown in the description is incomplete. These criteria define who was included in that population; they do not explain how missing measurements were handled in other analyses or whether any sensitivity analysis was used.
The enrollment count is 75, while the all-participants safety group includes 74 participants. The registry record does not explain the difference. The efficacy-evaluable population is smaller and defined by additional eligibility conditions. In general, results can differ across populations because each population includes a different set of participants and may represent a different analysis question. The record does not report a full accounting of participants excluded from each analysis or the reasons for any exclusions.
A sample-size justification and detailed analysis-population plan are not reported in the registry record. Without those details, the rationale for the planned enrollment and the intended handling of incomplete or non-evaluable observations cannot be assessed.
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 |
|---|---|---|---|
| Giredestrant 10 mg | 1 | 17 | 5.9% |
| Giredestrant 30 mg | 2 | 40 | 5.0% |
| Giredestrant 100 mg | 1 | 17 | 5.9% |
| All Participants, Safety: Giredestrant (10, 30, or 100 mg) | 4 | 74 | 5.4% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Giredestrant 10 mg | 0 of 17 |
| Giredestrant 30 mg | 0 of 40 |
| Giredestrant 100 mg | 0 of 17 |
| All Participants, Safety: Giredestrant (10, 30, or 100 mg) | 0 of 74 |
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 |
|---|---|
| Giredestrant 10 mg | 12 of 17 |
| Giredestrant 30 mg | 21 of 40 |
| Giredestrant 100 mg | 14 of 17 |
| All Participants, Safety: Giredestrant (10, 30, or 100 mg) | 47 of 74 |
Most frequent serious adverse event terms
| Event term | Organ system | Giredestrant 10 mg | Giredestrant 30 mg | Giredestrant 100 mg | All Participants, Safety: Giredestrant (10, 30, or 100 mg) |
|---|---|---|---|---|---|
| Breast abscess | Infections and infestations | 1 of 17 | 0 of 40 | 0 of 17 | 1 of 74 |
| Mastitis | Infections and infestations | 0 of 17 | 1 of 40 | 0 of 17 | 1 of 74 |
| Dizziness | Nervous system disorders | 0 of 17 | 0 of 40 | 1 of 17 | 1 of 74 |
| Breast haematoma | Reproductive system and breast disorders | 0 of 17 | 1 of 40 | 0 of 17 | 1 of 74 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Giredestrant 10 mg | Giredestrant 30 mg | Giredestrant 100 mg | All Participants, Safety: Giredestrant (10, 30, or 100 mg) |
|---|---|---|---|---|---|
| Nausea | Gastrointestinal disorders | 3 of 17 | 5 of 40 | 1 of 17 | 9 of 74 |
| Fatigue | General disorders | 2 of 17 | 1 of 40 | 5 of 17 | 8 of 74 |
| Procedural pain | Injury, poisoning and procedural complications | 2 of 17 | 1 of 40 | 3 of 17 | 6 of 74 |
| Dizziness | Nervous system disorders | 1 of 17 | 4 of 40 | 1 of 17 | 6 of 74 |
| Hot flush | Vascular disorders | 2 of 17 | 3 of 40 | 1 of 17 | 6 of 74 |
| Seroma | Injury, poisoning and procedural complications | 2 of 17 | 1 of 40 | 2 of 17 | 5 of 74 |
| Headache | Nervous system disorders | 1 of 17 | 3 of 40 | 1 of 17 | 5 of 74 |
| Vomiting | Gastrointestinal disorders | 1 of 17 | 2 of 40 | 1 of 17 | 4 of 74 |
| Asthenia | General disorders | 0 of 17 | 3 of 40 | 1 of 17 | 4 of 74 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 0 of 17 | 3 of 40 | 1 of 17 | 4 of 74 |
Serious events with the highest arm-level rate: breast abscess (5.9%), dizziness (5.9%), mastitis (2.5%), breast haematoma (2.5%).
The safety record reports counts separately for the 10 mg, 30 mg, and 100 mg cohorts, as well as for all participants receiving giredestrant. In the dose cohorts, the numbers of participants at risk for serious adverse events were 17, 40, and 17, respectively; the corresponding numbers affected were 1, 2, and 1. For the all-participants safety group, 74 participants were at risk and 4 were affected. The record reports 0 deaths in each listed group.
For other adverse events, the numbers at risk were 17, 40, and 17 across the dose cohorts, with 12, 21, and 14 participants affected, respectively. In the all-participants safety group, 74 were at risk and 47 were affected. These are participant counts: the record describes participants with at least one event, not the total number of event occurrences. The counts do not establish whether events were caused by giredestrant or permit a randomized comparison between doses.
The registry lists Breast abscess and Dizziness at 5.9% each, and Mastitis and Breast haematoma at 2.5% each, among the serious-event terms. These listed percentages should be read as the record reports them; further denominator or event-level context is not reported in the registry record. The counts and terms describe the recorded safety experience and should not be taken as estimates of comparative safety against a control group.
12. What the Result Does, and Does Not, Mean
The study provides a description of a Phase I, non-randomized evaluation of giredestrant in a short preoperative window and identifies tumor Ki67 change as its primary biologic endpoint. It also records safety outcomes across three dose cohorts. The intended primary assessment compares Ki67 staining in tumor samples collected before treatment with staining in samples collected at surgery on Day 15. This endpoint can characterize a tissue-level biologic measurement over the study period.
The registry record does not report the numerical primary endpoint result or its 95% confidence interval. Accordingly, it does not show how large the observed change was, which direction it took, or how precisely it was estimated. The endpoint description alone cannot substitute for those missing results. The record also does not report a statistical test result that could be used to assess evidence against a specified null hypothesis.
The study was not randomized and did not include a like-for-like control group in the record. Its dose cohorts therefore cannot be interpreted as a controlled comparison, and differences between them cannot be attributed to dose alone. In general, a before-and-after biomarker assessment can describe change over time, but without a control group it cannot by itself distinguish a treatment-related change from other explanations.
The safety counts give a descriptive account of participants with serious and other adverse events and report no deaths in the listed groups. These counts do not establish causation and do not provide a comparative estimate against another treatment. The reported adverse-event terms and percentages add descriptive information, but the registry record does not provide additional context that would support broader comparisons.
Thus, the record documents the study's question, design, endpoint definition, and selected safety findings. It does not establish a clinical benefit, answer a comparative treatment question, or provide enough information to judge the magnitude and precision of the primary biomarker result. Those conclusions would require evidence beyond the numerical results recorded.
13. Why This Trial Matters Statistically
Statistically, this trial illustrates the difference between a clearly defined endpoint and a result that can be fully interpreted. The registry specifies the tissue marker, the sampling times, the relative baseline comparison, and the intended summary as a geometric mean with a 95% confidence interval. Those details identify what the study sought to measure. But without the numerical estimate and interval, readers cannot assess the endpoint's direction, size, or precision. An endpoint definition is essential, but it is not a substitute for reporting the estimate and its uncertainty.
The preoperative window design also highlights how biomarker studies can address an early biologic question distinct from a clinical outcome question. A tissue measurement collected before and after treatment can describe change during that interval. In general, the absence of randomization and a control group limits the ability to attribute that change to treatment. The dose cohorts are descriptive groups, not randomized comparisons. This distinction is important when interpreting any apparent pattern across doses.
The record also makes analysis populations consequential. Enrollment is recorded as 75, the safety population includes 74, and the efficacy-evaluable population includes 10 under specific criteria. These populations have different definitions and purposes. Readers need those definitions to understand who contributes to each result, while a complete accounting helps assess how selection into an analysis could affect interpretation.
Finally, the safety data show why counts must be read in context. Counts of participants affected describe the recorded experience but do not establish causation or provide controlled comparisons. The absence of a primary numerical estimate and the limited analysis details also show why transparent reporting of statistical methods, missing-data handling, and uncertainty is necessary for a complete interpretation of a clinical trial.
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.
Several features limit what can be concluded from this registry record. Most directly, the numerical result for the primary Ki67 endpoint and its 95% confidence interval are not reported. The record therefore does not allow assessment of the estimated change or its precision. The registry also lists 0 analyses and does not describe the statistical model, test, confidence-interval method, or analysis plan for the primary endpoint.
The study is non-randomized and has no like-for-like control comparison in the record. Its 10 mg, 30 mg, and 100 mg cohorts should not be treated as randomized arms. Differences among them could reflect factors other than dose, and the record does not provide an allocation procedure that would allow those differences to be evaluated.
The primary endpoint population is defined by availability of Ki67 results, study completion, treatment exposure, and dose modification. The record reports 10 participants in that population, but its cohort breakdown is incomplete. It does not explain the difference between the enrollment count of 75 and the safety population of 74, nor does it provide a full accounting of missing or excluded participants. Missing-data methods and sensitivity analyses are not reported.
The endpoint is a biomarker measured between baseline and surgery on Day 15, rather than a reported longer-term clinical outcome. The study description includes pharmacodynamics, pharmacokinetics, safety, and biologic activity, but the record does not include numerical results for the primary endpoint. Open-label conduct and the absence of a control group further limit comparative interpretation. A sample-size justification, detailed multiplicity approach, and further information about the listed serious-event percentages are also not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study of Giredestrant (GDC-9545) in Postmenopausal Women With Stage I-III Operable, Estrogen Receptor-Positive Breast Cancer — NCT03916744.
- Registry record last updated 2023-03-10; status last verified 2023-03.
- Results first posted 2023-03-10.
- 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
NCT03916744 is a completed Phase I, multicenter, open-label, non-randomized preoperative study of giredestrant in postmenopausal women with Stage I-III operable, estrogen receptor-positive breast cancer. The registry describes the intended population as untreated and HER2-negative. The study enrolled 75 participants and used parallel cohorts receiving giredestrant 10 mg, 30 mg, or 100 mg.
The primary endpoint assessed the proportion of Ki67-positive tumor nuclei at surgery relative to baseline. The registry identifies a geometric mean and 95% confidence interval but does not report the numerical primary result. It records 74 participants in the safety group and 10 in the efficacy-evaluable population. Safety entries include serious and other adverse-event counts and 0 deaths in the listed groups. The study was not randomized, so its dose cohorts do not constitute controlled comparisons.