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

NCT ID: NCT07214662

Last Updated: 2026-01-12

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: PHASE1
• Total Enrollment: 136 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2026-01-12
• Study Completion Date: 2029-07-01

Brief 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 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

Study Design

• Allocation Method: NON_RANDOMIZED
• Intervention Model: SEQUENTIAL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Study Groups

Phase Ia: GDC-0587 Monotherapy

Participants will receive GDC-0587 orally.

Group Type: EXPERIMENTAL

GDC-0587

Intervention Type: DRUG

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

Phase Ib: GDC-0587 + Giredestrant Cohort

Participants will receive GDC-0587 and Giredestrant orally.

Group Type: EXPERIMENTAL

GDC-0587

Intervention Type: DRUG

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

Giredestrant

Intervention Type: DRUG

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

Phase Ib: GDC-0587 + Giredestrant Food-Effect and PPI-Effect Cohort

Participants 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.

Group Type: EXPERIMENTAL

GDC-0587

Intervention Type: DRUG

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

Giredestrant

Intervention Type: DRUG

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

Omeprazole

Intervention Type: DRUG

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

Interventions

GDC-0587

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

Intervention Type: DRUG

Giredestrant

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

Intervention Type: DRUG

Omeprazole

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

Intervention Type: DRUG

Other Intervention Names

RO7840736; RGT-587; GDC-9545; RO7197597; RG6171

Eligibility Criteria

Inclusion Criteria

• 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 Criteria

• 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

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Genentech, Inc.

INDUSTRY

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Clinical Trials

Role: STUDY_DIRECTOR

Genentech, Inc.

Locations

START - San Antonio - EDOS

San Antonio, Texas, United States

Site Status: RECRUITING

Countries

United States

Central Contacts

Reference Study ID Number: GO46057 https://forpatients.roche.com/

Role: CONTACT

global-roche-genentech-trials@gene.com

888-662-6728 (U.S. only)

Other Identifiers

GO46057

Identifier Type: -

Identifier Source: org_study_id