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AzTrials

Breast CancerPhase 1NCT07214662

A Study to Evaluate the Safety, Pharmacokinetics, and Activity of GDC-0587 as a Monotherapy and in Combination With Giredestrant in Participants With Locally Advanced or Metastatic Estrogen Receptor-Positive and Human Epidermal Growth Factor Receptor 2-Negative (ER+/HER2-) Breast Cancer

A Phase 1 study testing GDC-0587, Giredestrant and Omeprazole in people with Breast Cancer, run by Genentech, Inc. at 4 sites in 2 countries.

Terminated

Stopped early. The study ended before it was planned to and will not resume.

Official record
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Trial summary

This is a first-in-human, Phase Ia/Ib, dose-escalation and expansion study evaluating the safety, pharmacokinetics, and activity of GDC-0587 (cyclin-dependent kinase-4 [CDK4] inhibitor) as a monotherapy and in combination with giredestrant in participants with locally advanced or metastatic estrogen receptor-positive… Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Breast Cancer
What is being tested?
GDC-0587, Giredestrant and Omeprazole
Type of treatment
Pill or oral medicine
Could I receive a placebo?
No, everyone receives an active treatment
How many people
3 participants
Where
4 sitesin 2 countries
Study dates
13 Jan 2026to 24 Jun 2026
Phase
Phase 1
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Agreement to adhere to the contraception requirements
  • For females of childbearing potential ≤60 years of age and males: treatment with luteinizing hormone-releasing hormone (LHRH) agonist therapy beginning at least 2 weeks prior to Cycle 1, Day 1 and agreement to continue LHRH agonist therapy for the duration of the study
  • Histologically or cytologically confirmed adenocarcinoma of the breast that is locally advanced or metastatic
  • Previously documented ER+ and HER2- tumor according to American Society of Clinical Oncology (ASCO)/ College of American Pathologists (CAP) or European Society of Medical Oncology (ESMO) guidelines or any national guidelines with criteria conforming to ASCO/CAP or ESMO guidelines
  • Disease progression during or following treatment with an approved CDK 4/6 inhibitor, with or without endocrine therapy, in the locally advanced or metastatic setting
  • Measurable, or non-measurable but evaluable, disease per RECIST v1.1
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  • Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
  • Life expectancy ≥6 months
  • Creatinine clearance ≥60 milliliter per minute (mL/min) (calculated through use of the Cockcroft-Gault formula)

Who cannot join

  • Pregnant or breastfeeding, or intention of becoming pregnant during the study
  • Advanced, symptomatic, visceral spread that is at risk of life-threatening complications in the short term appropriate for treatment with cytotoxic chemotherapy at time of entry into the study, as per national or local treatment guidelines
  • Five or more prior lines of systemic therapy in the locally advanced or metastatic setting
  • Treatment with anti-cancer therapies, including investigational therapies, within 28 days or 5 drug elimination half-lives, whichever is shorter, prior to initiation of study drug
  • Treatment with an approved oral endocrine therapy within 7 days prior to initiation of study drug or treatment with fulvestrant or an approved/investigational CDK inhibitor within 21 days prior to initiation of study drug
  • History of Grade ≥3 adverse event attributed to prior CDK inhibitor therapy that resulted in permanent discontinuation of prior CDK inhibitor therapy
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  • Poor peripheral venous access
  • Malabsorption condition or other gastrointestinal (GI) conditions/surgeries that the investigator assesses may significantly interfere with enteral absorption
  • Major surgical procedure within 28 days prior to initiation of study drug
  • Untreated, active CNS metastases
  • Infection requiring systemic (i.e., oral, IV, or intramuscular) antibiotics, chronic infection requiring treatment within 1 year prior to screening, or any evidence of current infection
  • History of malignancy within 3 years prior to screening, except for cancer under investigation in this study
  • Known history of a clinically significant abnormal ECG

Trial locations and contacts

4 sites in 2 countries.

4 sites in 2 countries

United States2 sites

  • START - Midwest - EDOS

    Grand Rapids, Michigan, 49546-7062

  • START - San Antonio - EDOS

    San Antonio, Texas, 78229-3307

Other trials in United States

Taiwan2 sites

  • National Cheng Kung University Hospital

    Tainan, 70403

  • National Taiwan University Hospital

    Taipei, Taipei City, 10002

Other trials in Taiwan

About this study

Official title: A Phase Ia/Ib Dose-Escalation and Expansion Study Evaluating the Safety, Pharmacokinetics, and Activity of GDC-0587 as a Monotherapy and in Combination With Giredestrant in Patients With Locally Advanced Or Metastatic ER-Positive, HER2-Negative Breast Cancer Who Have Previously Progressed During or After CDK4/6 Inhibitor Therapy

This is a first-in-human, Phase Ia/Ib, dose-escalation and expansion study evaluating the safety, pharmacokinetics, and activity of GDC-0587 (cyclin-dependent kinase-4 [CDK4] inhibitor) as a monotherapy and in combination with giredestrant in participants with locally advanced or metastatic estrogen receptor-positive and human epidermal growth factor receptor 2-negative (ER+/HER2-) breast cancer who have previously progressed during or after CDK 4/6 inhibitor therapy.

Conditions
Breast Cancer
Being tested
GDC-0587, Giredestrant, Omeprazole
Medical subject headings
Breast Neoplasms

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • GDC-0587Drug

    Also called RO7840736, RGT-587

    Participants will receive GDC-0587 orally as per the schedule in the protocol.

  • GiredestrantDrug

    Also called GDC-9545, RO7197597, RG6171

    Participants will receive Giredestrant orally as per the schedule in the protocol.

  • OmeprazoleDrug

    Participants will receive Omeprazole orally as per the schedule in the protocol.

Study groups in NCT07214662
Study groupRoleWhat they receive
Phase Ia: GDC-0587 MonotherapyExperimentalParticipants will receive GDC-0587 orally.
Receives: Drug: GDC-0587
Phase Ib: GDC-0587 + Giredestrant CohortExperimentalParticipants will receive GDC-0587 and Giredestrant orally.
Receives: Drug: GDC-0587; Drug: Giredestrant
Phase Ib: GDC-0587 + Giredestrant Food-Effect and PPI-Effect CohortExperimentalParticipants will receive GDC-0587 and Giredestrant orally and also receive omeprazole for evaluating the effects of a proton pump inhibitor (PPI) and food on GDC-0587.
Receives: Drug: GDC-0587; Drug: Giredestrant; Drug: Omeprazole

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Percentage of Participants with Adverse Events

    Measured by reporting the incidence and severity using the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) v5.0 grading scale.

    Measured: From Baseline to 30 days after final dose of study treatment (Up to approximately to 18 months)

  2. Percentage of Participants with Dose-limiting Toxicity (DLTs)

    Measured: Phase 1a: Days 1-28 of Cycle 1; Phase 1b: Days 1-28 of Cycle 1 (Each cycle is 28 days)

Secondary outcomes (6)

  1. Percentage of Participants With Objective Response Rate (ORR) of Complete Response (CR) or Partial Response (PR) According to Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST v1.1)

    Measured: Up to approximately to 18 months

  2. Plasma Concentration of GDC-0587 as a Monotherapy and in Combination With Giredestrant

    Measured: Phase 1a: Cycle 1 (Day 1, 2 15, 16), Cycle 2, 3, 5, 7, 9, 11 (Day 1); Phase 1b: Cycle 1 (Day 1, 2 15, 16), Cycle 2, 3, 5, 7, 9, 11 (Day 1) (Each cycle is 28 days)

  3. Plasma Concentration of GDC-0587 with Giredestrant Under Fasted and Fed Conditions

    Measured: Part 1b: Cycle 1 (Day 1, 2, 4), Cycle 2, 3, 5, 7, 9 and 11 (Day 1) (Each cycle is 28 days)

  4. Plasma Concentration of GDC-0587 with Giredestrant Following Multiple-dose Administration, Either Alone or in Combination With Omeprazole

    Measured: Part 1b: Cycle 1 (Day 11, 12, 20 and 21) (Each cycle is 28 days)

  5. Recommended Phase II Dose (RP2D) of GDC-0587

    Measured: Up to approximately to 18 months

  6. Recommended Phase II Dose (RP2D) of GDC-0587 in Combination with Giredestrant

    Measured: Up to approximately to 18 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted9 Oct 2025
  2. Study start13 Jan 2026
  3. Primary completion24 Jun 2026
  4. Study completion24 Jun 2026

Why it stopped: The trial was terminated due to sponsor decision.

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1
Primary purpose
Treatment
Allocation
Non-randomised
Intervention model
Sequential
Masking
None (open label)
Enrolment
3 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07214662
Sponsor's protocol ID
GO46057
Status last verified
Aug 2026
First submitted
3 Oct 2025
Last updated
21 Aug 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing GDC-0587, Giredestrant and Omeprazole in people with Breast Cancer, run by Genentech, Inc. at 4 sites in 2 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 9 inclusion and 13 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: stopped early, as of the sponsor's last update on 21 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 4 sites in United States, Taiwan. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study was stopped early (reason given: The trial was terminated due to sponsor decision.). Results are not available in the source record.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Percentage of Participants with Adverse Events (time frame: From Baseline to 30 days after final dose of study treatment (Up to approximately to 18 months)). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07214662.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 21 Aug 2026.

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