Trial · NCT05659563

Preoperative Window Opportunity Study With Giredestrant or Tamoxifen in Premenopausal Women With ER+/HER2[-] & Ki67≥10%

NCT05659563, Phase 2, Completed, MedSIR; results first posted 2026-03-19

3 sourcestrials-2026-11-12-0.5.0

Cite this record

ConductScience Library. Preoperative Window Opportunity Study With Giredestrant or Tamoxifen in Premenopausal Women With ER+/HER2[-] & Ki67≥10%. Trials, record NCT05659563. Release trials-2026-11-12-0.5.0, 12 Nov 2026. https://conductscience.org/library/trials/NCT05659563

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Trial

As registered on ClinicalTrials.gov, in the graph's capture of the registry.

Title: Preoperative Window Opportunity Study With Giredestrant or Tamoxifen in Premenopausal Women With ER+/HER2[-] & Ki67≥10%
NCT number: NCT05659563
Status: Completed
Phases: Phase 2
Enrollment: 92 participants, actual
Lead sponsor: MedSIR
Conditions: Breast Cancer, Breast Cancer, Early-Onset
Interventions: Giredestrant, Tamoxifen
First posted: 2022-12-21
Last updated: 2026-03-19
Other registries' IDs: eudract:2022-002166-33
Results first posted: 2026-03-19

Source ClinicalTrials.gov

Registered outcomes6

Each outcome the trial registered, primary first, in ClinicalTrials.gov's words.

List	Outcome	Time frame	Description
Primary	Change in Proliferative Index (Ki67 Expression)	Baseline up to 15 days	To assess changes in tumor cell proliferation as measured by Ki67 expression between baseline and D15 (+1 day) post-treatment tumor biopsy samples by central assessment in patients with centrally confirmed Ki67 ≥10% (Arm A: giredestrant vs Arm B: tamoxifen)
Secondary	Complete Cell Cycle Arrest (CCCA)	Baseline up to 15 days	To measure complete cell cycle arrest in all arms, defined as the percentage of participants with centrally assessed Ki67 scores ≤2.7% stained nuclei upon treatment
Secondary	Changes in Molecular Profiles of Tumor Tissue Samples	Baseline up to 15 days	To analyze gene expression profiles in tumor tissue samples obtained at baseline and after treatment using the HTG EdgeSeq Oncology Biomarker Panel
Secondary	Changes in Expression Levels of Estrogen Receptor and Progesterone Receptor in Tumor Tissue Samples	Baseline up to 15 days	To analyze the expression of estrogen receptor and progesterone receptor in tumor tissue samples obtained at baseline and post-therapy
Other	Changes in Molecular Profiles of Plasma Biomarkers Related to Endocrine Function	Baseline up to 15 days	To compare the expression of blood biomarkers in samples obtained at baseline and post-therapy using a plasma endocrine panel
Other	Incidence and Severity of Adverse Events	Baseline up to 15 days	To evaluate incidence and severity of adverse events, with severity determined in accordance to NCI-CTCAE v.5.0

Source ClinicalTrials.gov

Outcomes6

Each outcome the trial posted results for, in ClinicalTrials.gov's words.

Type	Outcome	Time frame	Population	Units	Measured as
PRIMARY	Change in Proliferative Index (Ki67 Expression)	Baseline up to 15 days	Primary analysis is performed in modified Intentention-to-Treat analysis population	Difference from baseline (%)	MEDIAN
SECONDARY	Complete Cell Cycle Arrest (CCCA)	Baseline up to 15 days	Seconday analysis is performed in the modified Intention-to-Treat analysis population	% patients with CCCA	NUMBER
SECONDARY	Changes in Molecular Profiles of Tumor Tissue Samples	Baseline up to 15 days	Breast cancer intrinsic molecular subtypes were determined using the PAM50 gene expression assay. Tumors are categorized as Luminal A, Luminal B, HER2-enriched, Basal-like, or Normal-like. These subtypes reflect distinct tumor biology and are associated with different prognostic and therapeutic implications.	Participants	COUNT_OF_PARTICIPANTS
SECONDARY	Changes in Expression Levels of Estrogen Receptor and Progesterone Receptor in Tumor Tissue Samples	Baseline up to 15 days	Secondary analysis are performed on modified Intention-to-Treat population analysis	Percentage	MEDIAN
OTHER_PRE_SPECIFIED	Changes in Molecular Profiles of Plasma Biomarkers Related to Endocrine Function	Baseline up to 15 days
OTHER_PRE_SPECIFIED	Incidence and Severity of Adverse Events	Baseline up to 15 days

Source ClinicalTrials.gov

Results by group32

Each measurement the trial posted, group by group, in the words and numbers it posted.

Outcome	Group	Category	Value	Spread	Units
Change in Proliferative Index (Ki67 Expression)	Arm A		-14.5	95% Confidence Interval -17.5 to -13.0	Difference from baseline (%)
Change in Proliferative Index (Ki67 Expression)	Arm B		-10.0	95% Confidence Interval -13.0 to -7.0	Difference from baseline (%)
Complete Cell Cycle Arrest (CCCA)	Arm A		17.5	95% Confidence Interval 7.3 to 32.8	% patients with CCCA
Complete Cell Cycle Arrest (CCCA)	Arm B		4.5	95% Confidence Interval 0.6 to 15.5	% patients with CCCA
Changes in Molecular Profiles of Tumor Tissue Samples	Arm A	Baseline / Luminal A	9		Participants
Changes in Molecular Profiles of Tumor Tissue Samples	Arm B	Baseline / Luminal A	5		Participants
Changes in Molecular Profiles of Tumor Tissue Samples	Arm A	Baseline / Luminal B	12		Participants
Changes in Molecular Profiles of Tumor Tissue Samples	Arm B	Baseline / Luminal B	14		Participants
Changes in Molecular Profiles of Tumor Tissue Samples	Arm A	Baseline / Basal	6		Participants
Changes in Molecular Profiles of Tumor Tissue Samples	Arm B	Baseline / Basal	8		Participants

1 to 10 of 32Source ClinicalTrials.gov

See all 32 results by group

Participant flow6

How many started, completed or left each group, period by period.

Period	Milestone	Group	Participants
Overall Study	STARTED	Arm A	46
Overall Study	STARTED	Arm B	46
Overall Study	COMPLETED	Arm A	42
Overall Study	COMPLETED	Arm B	44
Overall Study	NOT COMPLETED	Arm A	4
Overall Study	NOT COMPLETED	Arm B	2

Source ClinicalTrials.gov

Adverse events38

Each adverse event the trial posted, group by group: the participants affected out of those at risk.

Type	Event	Organ system	Group	Affected	At risk	Events
other	Dizziness	Nervous system disorders	Arm A	1	42	1
other	Dizziness	Nervous system disorders	Arm B	0	44	0
other	Fatigue	General disorders and administration site conditions	Arm A	3	42	3
other	Fatigue	General disorders and administration site conditions	Arm B	4	44	4
other	Vulvovaginal dryness	Reproductive system and breast disorders	Arm A	1	42	1
other	Vulvovaginal dryness	Reproductive system and breast disorders	Arm B	0	44	0
other	Abdominal pain	Gastrointestinal disorders	Arm A	0	42	0
other	Abdominal pain	Gastrointestinal disorders	Arm B	1	44	1
other	Arthralgia	Musculoskeletal and connective tissue disorders	Arm A	4	42	4
other	Arthralgia	Musculoskeletal and connective tissue disorders	Arm B	3	44	3

1 to 10 of 38Source ClinicalTrials.gov

See all 38 adverse events

Adverse event totals6

The totals the trial posted for each group.

Total	Group	Affected	At risk
Total, all-cause mortality	Arm A	0	42
Total, all-cause mortality	Arm B	0	44
Total, other adverse events	Arm A	13	42
Total, other adverse events	Arm B	11	44
Total, serious adverse events	Arm A	0	42
Total, serious adverse events	Arm B	0	44

Source ClinicalTrials.gov

Papers0

The papers the trial lists on ClinicalTrials.gov.

None in this release.

Grants0

The grants NIH RePORTER links to the trial, newest funded first: NIH's, and some of AHRQ's, CDC's, FDA's and VA's. Each shows its title, principal investigators, organization and funder in its newest year.

None in this release.

Trial comparisons2

Comparisons of the trial's two groups, calculated by ConductScience from the counts it posted.

Comparison	Source
Arm A vs Arm B: deaths from any cause	Trial comparisons
Arm A vs Arm B: serious adverse events	Trial comparisons

Tests0

The ConductCognition tests this trial's registered outcomes name, as ScienceGraph matched them in trial-tests-2026-11-12-0.2.1.

None in this release.

Data dates

The day each source was copied for this release.

ClinicalTrials.gov: 2026-11-12; ClinicalTrials.gov
Results, from AACT: 2026-03-23; AACT
NIH grant links: 2026-11-13; NIH RePORTER

Sources 3

ClinicalTrials.gov's posted results, through CTTI's AACTFreely available. Acknowledgement requested
ClinicalTrials.govNo license stated
NIH RePORTER's clinical studies and project filesPublic domain

Each source's terms

ClinicalTrials.gov's posted results, through CTTI's AACTClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299
ClinicalTrials.govnone stated
NIH RePORTER's clinical studies and project filesPublic domain (NIH RePORTER)

ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.

For software

Read this trial from software.

The record and each of its lists are JSON, twenty rows a page. No key.

GET https://conductscience.org/api/trials/v1/NCT05659563

GET https://conductscience.org/api/trials/v1/NCT05659563/results?page=2

API reference For AI assistants