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GDC-0587 and Giredestrant for ER+/HER2- Breast Cancer

This study is testing the safety and effects of a new drug, GDC-0587, by itself and in combination with another drug called Giredestrant. It's for people with locally advanced or metastatic (spread to other parts of the body) estrogen receptor-positive and HER2-negative (ER+/HER2-) breast cancer. You might be able to join if your cancer has progressed after previous treatment with a CDK 4/6 inhibitor. The study will look at side effects (adverse events) and how much of the drugs your body absorbs. The main goals are to see how safe the treatments are and if they cause any dose-limiting toxicities (side effects that are severe enough to stop treatment).

Study design
This is a first-in-human, Phase Ia/Ib study that will gradually increase the drug dose. It plans to enroll 136 participants.
What's involved
You would take GDC-0587 and/or Giredestrant orally according to a schedule. If you are a female of childbearing potential or a male, you would also need to take LHRH agonist therapy starting at least 2 weeks before the study and continue it throughout.
Compensation
Not stated in the trial record.
Follow-up
Your adverse events will be measured from the beginning of the study until 30 days after your last dose of study treatment, which could be up to approximately 18 months.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT07214662

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

Terminated
PHASE1Ages 18+InterventionalTreatment
Genentech, Inc.
~3 participants
Updated 2026-08-21 on ClinicalTrials.gov
What's tested:GDC-0587GiredestrantOmeprazole

At a glance

Recruiting sites
0 of 4 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Percentage of Participants with Adverse Events
Measured over From Baseline to 30 days after final dose of study treatment (Up to approximately to 18 months)
+1 more outcome measured

Conditions

Breast Cancer

Explore related trials

Breast Carcinoma

Where it's being run

4 sites across 4 states
Michigan1
Texas1
Taipei City1
Taiwan1

Study leadership

  • Clinical Trials · STUDY_DIRECTOR · Genentech, Inc.

Who to contact

This trial hasn't published a contact. View it on ClinicalTrials.gov

Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

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
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)

Exclusion

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
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

What this trial measures

  • Percentage of Participants with Adverse EventsFrom Baseline to 30 days after final dose of study treatment (Up to approximately to 18 months)

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

  • Percentage of Participants with Dose-limiting Toxicity (DLTs)Phase 1a: Days 1-28 of Cycle 1; Phase 1b: Days 1-28 of Cycle 1 (Each cycle is 28 days)