A Phase 1 interventional study of GDC-9545 and Palbociclib in Breast Cancer, sponsored by Genentech, Inc.. Active, not recruiting at 23 sites in 5 countries. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-10.
Sponsored by Genentech, Inc. (part of Hoffmann-La Roche) · Phase 1, Interventional, and Treatment
Among 16 studies testing giredestrant in Breast Neoplasms — 4 open to participants now, 12 under way, 7 of them phase 3. giredestrant · Breast Neoplasms.
Among the 16 studies testing giredestrant in Breast Neoplasms, this one is the 12th largest by enrollment, is the only one that started in 2017, is one of 2 in phase 1, reaches primary completion later than 5 of the 11 other live ones, and was the 1st registered.
14,825 studies on the registry are indexed under Breast Neoplasms; 3,319 are open to participants now.
Browse Breast Neoplasms studies →4 of the 16 studies testing giredestrant in Breast Neoplasms are open now, in 8 countries. Recruiting first, the newest first:
Hoffmann-La Roche · Sites in Canada
Genentech, Inc. · Sites in United States
Hoffmann-La Roche · Sites in United States, Argentina, Brazil and 4 more countries
Fondazione Oncotech · Sites in Italy
By country, each count listing its studies:
No approval found in the FDA or EMA files read. How studies give it is on its page →
Of the 2,400 Breast Neoplasms studies recruiting now, 1,572 (66%) set no upper age limit and 591 (25%) stop at 75 or younger; 103 take children under 18; 214 take healthy volunteers.
This study: 18 Years and older · female · no healthy volunteers.
The full table on the hub →This tab as a report to print or save as PDF → With an account.
On this site’s reading of the record, giredestrant is the treatment under test here. Read study by study →
16 studies; the count open now beside each. This study's row is marked.
First in 2017; this study’s year is marked. 1 started in 2017.
This study's enrollment of 181 is above the median of 72 across 10,896 interventional studies indexed under Breast Neoplasms.
Median enrollment 302 across the 16 interventional studies. Of the 4 that completed or were terminated, 3 (75%) have results posted.
This tab as a report to print or save as PDF → With an account.
12 of 16 have an industry lead sponsor. The 5 most frequent:
Genentech, Inc. is the lead sponsor of 517 studies on the registry; 20 are open to participants now.
Of its 95 completed or terminated interventional studies of FDA-regulated products, 52 (55%) have results posted.
46 studies in Breast Neoplasms by Genentech, Inc.: 3 open now, 6 under way, 2 of them phase 3. Of 36 finished, 17 (47%) have results posted.
Among the 46 studies in Breast Neoplasms by Genentech, Inc., this one is the 12th largest by enrollment of the 34 interventional ones that give a count, is the only one that started in 2017, is one of 13 in phase 1, and was the 37th registered.
Genentech, Inc.’s Breast Neoplasms studies by the year they started, since 2000.
2 of the studies testing giredestrant in Breast Neoplasms that are under way reach primary completion within a year, 0 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT03332797Genentech, Inc.A Study of GDC-9545 Alone or in Combination With Palbociclib and/or Luteinizing Hormone-Releasing Hormone (LHRH) Agonist in Locally Advanced or Metastatic Estrogen Receptor-Positive Breast Cancer | 2027-07-31 |
| NCT07054190Hoffmann-La RocheA Study to Test Inavolisib Treatments in Participants With Early-Stage, PIK3CA-Mutated Breast Cancer | 2027-07-31 |
Among the 16 studies testing giredestrant in Breast Neoplasms, from their registry updates:
Among Genentech, Inc.’s 46 in Breast Neoplasms:
This tab as a report to print or save as PDF → With an account.
This study will evaluate the safety, pharmacokinetic (PK), pharmacodynamic (PD) activity, and preliminary anti-tumor activity of GDC-9545 as a single agent and in combination with palbociclib and/or luteinizing hormone-releasing hormone (LHRH) agonist in participants with advanced or metastatic estrogen receptor (ER)-positive (human epidermal growth factor receptor 2 [HER2]-negative) breast cancer.
Inclusion Criteria for Dose Escalation:
Inclusion Criteria for Dose Expansion:
Same criteria as above for Dose Escalation, except for those that only apply to Dose Escalation, plus the following:
Plus the following criteria:
Exclusion Criteria for Dose Escalation:
Exclusion Criteria for Dose Expansion:
Same criteria as above for Dose Escalation, except for those that only apply to Dose Escalation, plus the following criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Histologically or cytologically confirmed
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HER2
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Measurable disease
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adjuvant and neoadjuvant
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Line of therapy
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Relapsed and refractory
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Brain metastases
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Child-Pugh class
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
During dose escalation, postmenopausal participants will be assigned sequentially to escalating doses of GDC-9545, up to the maximum tolerated dose (MTD) or maximum administered dose (MAD).
Drug: GDC-9545
GDC-9545 will be administered to postmenopausal participants, at a dose lower than the MTD or MAD determined in single-agent dose escalation, in combination with the label-recommended dose of palbociclib.
Drug: GDC-9545 · Drug: Palbociclib
GDC-9545 will be administered to postmenopausal participants as a single-agent at a dose that is less than or equal to the MTD/MAD (Dose 1).
Drug: GDC-9545
GDC-9545 will be administered to pre- or perimenopausal participants at a dose that is less than or equal to the MTD/MAD (Dose 1) in combination with an approved LHRH agonist.
Drug: GDC-9545 · Drug: LHRH Agonist
GDC-9545 will be administered to postmenopausal participants as a single-agent at a dose that is less than or equal to the MTD/MAD (Dose 2).
Drug: GDC-9545
GDC-9545 will be administered to pre- or perimenopausal participants at a dose that is less than or equal to the MTD/MAD (Dose 2) in combination with an LHRH agonist.
Drug: GDC-9545 · Drug: LHRH Agonist
GDC-9545 will be administered to postmenopausal participants as a single-agent at a dose that is less than or equal to the MTD/MAD (Dose 3).
Drug: GDC-9545
GDC-9545 will be administered to postmenopausal participants, at a dose that is less than or equal to the MTD/MAD, in combination with the label-recommended dose of palbociclib.
Drug: GDC-9545 · Drug: Palbociclib
GDC-9545 will be administered to pre- or perimenopausal participants, at a dose that is less than or equal to the MTD/MAD, in combination with the label-recommended dose of palbociclib and an approved LHRH agonist.
Drug: GDC-9545 · Drug: Palbociclib · Drug: LHRH Agonist
GDC-9545 will be administered to postmenopausal participants at a pre-defined dose level (Dose 2) as a single agent for 14 days, followed by treatment with either GDC-9545 (Dose 2) plus palbociclib or GDC-9545 (Dose 2) alone for the duration of the study, as determined by the investigator.
Drug: GDC-9545 · Drug: Palbociclib
GDC-9545 will be administered to postmenopausal participants at a pre-defined dose level (Dose 2), in combination with the label-recommended dose of palbociclib.
Drug: GDC-9545 · Drug: Palbociclib
GDC-9545 will be administered at a pre-defined dose level (Dose 3) to postmenopausal participants currently receiving clinical benefit with GDC-0927 or GDC-0810 on Studies GO29656 (NCT02316509) or GO29642 (NCT01823835), respectively, upon completion of their studies.
Drug: GDC-9545
GDC-9545 will be administered orally, once daily, on Days 1-28 of each 28-day cycle, until disease progression, unacceptable toxicity, withdrawal of consent, or study termination.
Also known as: Giredestrant, RO7197597, RG6171
Palbociclib will be administered orally, once daily, at the label-recommended dose of 125 mg on Days 1-21 of each 28-day cycle, until disease progression, unacceptable toxicity, withdrawal of consent, or study termination.
The LHRH agonist (leuprolide acetate, goserelin acetate, or triptorelin pamoate) will be administered by injection once every 4 weeks on Day 1 of each 28-day cycle, according to the label. The investigator will choose the appropriate LHRH agonist approved for use in breast cancer.
Number of Participants with Adverse Events by Severity, According to National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0 (NCI-CTCAE v4.0)
Time frame: From Baseline until 28 days after the last dose of study treatment (up to 84 months)
Dose Escalation: Maximum Tolerated Dose (MTD) or Maximum Administered Dose (MAD) of GDC-9545 When Administered as a Single Agent or in Combination with Palbociclib
Time frame: Days -7 to 28 of Cycle 1
Dose Escalation: Number of Participants with Dose-Limiting Toxicities When GDC-9545 is Administered as a Single Agent or in Combination with Palbociclib
Time frame: Days -7 to 28 of Cycle 1
Change from Baseline in Systolic Blood Pressure Over Time
Time frame: Baseline and at each treatment cycle (1 cycle is 28 days) through to 28 days after the last dose of study treatment
Change from Baseline in Diastolic Blood Pressure Over Time
Time frame: Baseline and at each treatment cycle (1 cycle is 28 days) through to 28 days after the last dose of study treatment
Change from Baseline in Body Temperature Over Time
Time frame: Baseline and at each treatment cycle (1 cycle is 28 days) through to 28 days after the last dose of study treatment
Change from Baseline in Pulse Rate Over Time
Time frame: Baseline and at each treatment cycle (1 cycle is 28 days) through to 28 days after the last dose of study treatment
Change from Baseline in Respiration Rate Over Time
Time frame: Baseline and at each treatment cycle (1 cycle is 28 days) through to 28 days after the last dose of study treatment
Change from Baseline in Electrocardiogram (ECG) Results Over Time: Heart Rate
Time frame: Baseline and at predefined intervals from Cycle 1 and at each subsequent cycle (1 cycle is 28 days) through to the last dose of study treatment
Change from Baseline in ECG Results Over Time: PR Duration
Time frame: Baseline and at predefined intervals from Cycle 1 and at each subsequent cycle (1 cycle is 28 days) through to the last dose of study treatment
Change from Baseline in ECG Results Over Time: QRS Duration
Time frame: Baseline and at predefined intervals from Cycle 1 and at each subsequent cycle (1 cycle is 28 days) through to the last dose of study treatment
Change from Baseline in ECG Results Over Time: QT Duration
Time frame: Baseline and at predefined intervals from Cycle 1 and at each subsequent cycle (1 cycle is 28 days) through to the last dose of study treatment
Change from Baseline in ECG Results Over Time: QTcF Duration
Time frame: Baseline and at predefined intervals from Cycle 1 and at each subsequent cycle (1 cycle is 28 days) through to the last dose of study treatment
Change from Baseline in ECG Results Over Time: RR Duration
Time frame: Baseline and at predefined intervals from Cycle 1 and at each subsequent cycle (1 cycle is 28 days) through to the last dose of study treatment
Number of Participants with Clinical Laboratory Abnormalities in Hematology Tests by Highest Grade According to NCI-CTCAE v4.0
Laboratory parameters for hematology will be measured and compared with a standard reference range. Values outside of the standard reference range are considered abnormalities. Not every laboratory abnormality qualifies as an adverse event. A laboratory test result will be reported as an adverse event if it meets any of the following criteria: is accompanied by clinical symptoms; results in a change in study treatment, a medical intervention, or a change in concomitant therapy; or is clinically significant in the investigator's judgment.
Time frame: Baseline, Cycle 1, and at each subsequent cycle (1 cycle is 28 days) or at every other cycle starting from Cycle 3 (Cohort X only), up to 28 days after the last dose of study treatment
Number of Participants with Clinical Laboratory Abnormalities in Blood Chemistry Tests by Highest Grade According to NCI-CTCAE v4.0
Laboratory parameters for blood chemistry will be measured and compared with a standard reference range. Values outside of the standard reference range are considered abnormalities. Not every laboratory abnormality qualifies as an adverse event. A laboratory test result will be reported as an adverse event if it meets any of the following criteria: is accompanied by clinical symptoms; results in a change in study treatment, a medical intervention, or a change in concomitant therapy; or is clinically significant in the investigator's judgment.
Time frame: Baseline, Cycle 1, and at each subsequent cycle (1 cycle is 28 days) or at every other cycle starting from Cycle 3 (Cohort X only), up to 28 days after the last dose of study treatment
Number of Participants with Clinical Laboratory Abnormalities in Urinalysis Tests by Highest Grade According to NCI-CTCAE v4.0
Laboratory parameters for urinalysis will be measured and compared with a standard reference range. Values outside of the standard reference range are considered abnormalities. Not every laboratory abnormality qualifies as an adverse event. A laboratory test result will be reported as an adverse event if it meets any of the following criteria: is accompanied by clinical symptoms; results in a change in study treatment, a medical intervention, or a change in concomitant therapy; or is clinically significant in the investigator's judgment.
Time frame: Baseline, Cycle 3, and at every other cycle (1 cycle is 28 days) up to 28 days after the last dose of study treatment
Plasma Concentration of GDC-9545 Over Time
Time frame: At predefined intervals from Cycle 1, Day -7 (Single-Agent Dose Escalation and A1-A5 only) or Cycle 1, Day 1 (B0, B1, and B2) to Cycle 4, Day 1 (1 cycle is 28 days) and at study completion; Cycle 1, Days -7 or 8 (C1 only); Cycle 1, Day 8 (C2 only)
Plasma Concentration of Palbociclib Over Time
Time frame: At predefined intervals from Cycle 1, Day 1 to Cycle 4, Day 1 (1 cycle is 28 days) and at study completion (B0, B1, and B2 only); Cycle 1, Day 8 (C2 only)
Plasma Concentration of LHRH Over Time
Time frame: At predefined intervals from Cycle 1, Day 1 to Cycle 4, Day 1 (1 cycle is 28 days) and at study completion (B2 only)
Percentage of Participants with Objective Response
Objective response is defined as a complete response or partial response on two consecutive occasions ≥4 weeks apart, as determined by the investigator according to Response Evaluation Criteria In Solid Tumors version 1.1 (RECIST v1.1).
Time frame: For all cohorts, except for Cohort X: Baseline and every 8 weeks from Cycle 1, Day 1 until end of study treatment (up to 84 months)
Clinical Benefit Rate
Clinical benefit rate is defined as the percentage of participants achieving either of the following: confirmed complete response or partial response (as determined by the investigator according to RECIST v1.1); or the first occurrence of progressive disease after 24 weeks of study treatment.
Time frame: For all cohorts, except for Cohort X: Baseline and every 8 weeks from Cycle 1, Day 1 until end of study treatment (up to 84 months)
Duration of Response
Time frame: For all cohorts, except for Cohort X: From the first occurrence of a documented objective response until first observation of disease progression or death from any cause on study, whichever occurs first (up to 84 months)
Plan to share: No
Started Nov 2017 (actual). Primary completion is estimated for Jul 2027, 116 months after the start.
Of 388 industry-sponsored phase 1 interventional studies under Breast Neoplasms, half reached primary completion within 39 months of starting (the median), counting those still running; a quarter within 22 and three quarters within 56. This study's planned 116 months is above that.
Counting every sponsor, half of 759 studies reached it within 44 months; a quarter within 25 and three quarters within 66.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is active, not recruiting, as verified in Nov 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
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Studies of the drug tested here: Giredestrant