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A Study of GDC-4198 and Giredestrant for ER+, HER2- Breast Cancer

This study is testing new ways to treat locally advanced or metastatic breast cancer that is Estrogen Receptor-positive (ER+) and Human Epidermal Growth Factor Receptor-negative (HER2-). Researchers are looking at the safety of GDC-4198 alone and in combination with giredestrant. They are also comparing the effectiveness of GDC-4198 plus giredestrant against abemaciclib plus giredestrant. To join, you must have this specific type of breast cancer, confirmed by a biopsy. The study will measure how many side effects occur and how long people live without their cancer getting worse (progression-free survival). The study plans to enroll 285 participants, but its current recruitment status is unclear.

Study design
This study has two parts: Phase Ib will look at safety, and Phase II will compare the new treatment combination to an existing one. It plans to enroll 285 participants.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
Participants will be followed for up to 36 months to assess progression-free survival and adverse events.

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

NCT07100106

A Study to Evaluate the Effect of GDC-4198 Alone and in Combination With Giredestrant Versus Abemaciclib and Giredestrant in Participants With Locally Advanced or Metastatic Estrogen Receptor-Positive (ER+), Human Epidermal Growth Factor Receptor-Negative (HER2-) Breast Cancer

Recruiting
PHASE1Ages 18+InterventionalTreatment
Genentech, Inc.
~285 participants
Updated 2026-08-10 on ClinicalTrials.gov
What's tested:GDC-4198GiredestrantAbemaciclib

At a glance

Recruiting sites
61 of 61 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Phase Ib: Incidence and Severity of Adverse Events (AEs)
Measured over Up to 36 months
+2 more outcomes measured

Conditions

Breast Cancer

Explore related trials

Breast Carcinoma

Where it's being run

61 sites across 37 states
South Korea6
California5
Spain5
Pennsylvania3
Rio Grande do Sul3
France3
Florida2
New York2

Study leadership

  • Clinical Trials · STUDY_DIRECTOR · Hoffmann-La Roche

Who to contact

Reference Study ID Number: GO46021 https://forpatients.roche.com/ No attachments to email below.
[email protected]
888-662-6728 (U.S. Only)
Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

Histologically and/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 after treatment with an approved cyclin-dependent kinase 4/6 (CDK4/6) inhibitor and approved endocrine therapy (ET) in the locally advanced or metastatic setting.
Measurable or non-measurable evaluable, disease per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1).
Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1.
Life expectancy \>= 6 months.

Exclusion

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.
Have received more than one-line of therapy for locally advanced or metastatic disease.
Have received prior chemotherapy for metastatic breast cancer.
Treatment with an approved oral ET within 7 days prior to initiation of study drug; treatment with fulvestrant or an approved CDK4/6 inhibitor within 21 days prior to initiation of study drug.
Malabsorption condition or other gastrointestinal (GI) conditions/surgeries that the investigator assesses may significantly interfere with enteral absorption
History of malignancy within 3 years prior to screening, except for cancer under investigation in this study and malignancies with a negligible risk of metastasis or death.
Known allergy or hypersensitivity to any component of the study treatments.

What this trial measures

  • Phase Ib: Incidence and Severity of Adverse Events (AEs)Up to 36 months

    Severity of AEs determined according to the CTCAE v5.0 grading scale

  • Phase Ib: Number of Participants With Dose-Limiting Toxicity (DLTs)From Day 1 to Day 28 of Cycle 1 (1 cycle=28 days)
  • Phase II: Progression-free Survival (PFS)Up to 36 months