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 now · Phase 1/Phase 2

Conditions studied: Breast Cancer

In brief

The purpose of this study is to assess the safety of GDC-4198 alone and in combination with giredestrant and also the efficacy of GDC-4198 + giredestrant versus abemaciclib + giredestrant in participants with locally advanced or metastatic ER+, HER2- breast cancer. The study consists of 2 phases: Phase Ib and Phase II. Phase Ib will evaluate the safety and pharmacokinetics (PK) of GDC-4198 alone and in combination with giredestrant. Phase II stage will compare the activity and safety of GDC-4198 and giredestrant with abemaciclib and giredestrant.

Key facts

Study ID

NCT07100106

Run by

Genentech, Inc.

People needed

285

Starts

2025-10-07

Expected to finish

2028-08-31

Last updated by the study team

2026-07-13

Who can join

Age: 18 and older. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• 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.

You may not qualify if…

• 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.

Where it is running

• City of Hope - Orange County Lennar Foundation Cancer Center — Irvine, California, United States (enrolling)
• UC San Diego Moores Cancer Center — La Jolla, California, United States (enrolling)
• UCSF Helen Diller Family CCC — San Francisco, California, United States (enrolling)
• Sylvester Comprehensive Cancer Center — Miami, Florida, United States (enrolling)
• Moffitt Cancer Center — Tampa, Florida, United States (enrolling)
• Winship Cancer Institute of Emory University — Atlanta, Georgia, United States (enrolling)
• City of Hope® Cancer Center Chicago — Zion, Illinois, United States (enrolling)
• Barbara Ann Karmanos Cancer Institute — Detroit, Maine, United States (enrolling)
• Washington University Siteman Cancer Center — St Louis, Missouri, United States (enrolling)
• Rutgers Cancer Institute of New Jersey — New Brunswick, New Jersey, United States (enrolling)
• New York Cancer & Blood Specialists — East Patchogue, New York, United States (enrolling)
• Levine Cancer Institute — Charlotte, North Carolina, United States (enrolling)
• Novant Health Cancer Institute — Charlotte, North Carolina, United States (enrolling)
• University of Pennsylvania - Abramson Cancer Center — Philadelphia, Pennsylvania, United States (enrolling)
• UPMC - Hillman Cancer Center — Pittsburgh, Pennsylvania, United States (enrolling)
• Vanderbilt Breast Center at One Hundred Oaks — Nashville, Tennessee, United States (enrolling)
• Texas Oncology (Worth) - USOR — Dallas, Texas, United States (enrolling)
• University of Utah Huntsman Cancer Institute — Salt Lake City, Utah, United States (enrolling)
• Virginia Oncology Associates (Norfolk) - USOR — Norfolk, Virginia, United States (enrolling)
• St Vincent's Hospital Sydney — Darlinghurst, New South Wales, Australia (enrolling)
• Cancer Research SA — Adelaide, South Australia, Australia (enrolling)
• Hospital do Cancer de Pernambuco - HCP — Recife, Pernambuco, Brazil (enrolling)
• ONCOSITE Centro de Pesquisa Clínica Em Oncologia — Ijuí, Rio Grande do Sul, Brazil (enrolling)
• Irmandade Da Santa Casa de Misericordia de Porto Alegre — Porto Alegre, Rio Grande do Sul, Brazil (enrolling)
• City of Hope — Duarte, California, United States (enrolling)

Full record on ClinicalTrials.gov

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