Brief Summary
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 advancedat a late stage, far along or metastatic ER+, HER2- breast cancera disease where abnormal cells split without control and spread to other nearby body tissue and/or organs. 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.
Intervention / Treatment
- Drug: GDC-4198
- Drug: Giredestrant
- Drug: Abemaciclib
Inclusion Criteria
- Histologically and/or cytologically confirmed adenocarcinomacancer arising from mucus-producing glands in organs of the breast that is locally advanced or metastatic.
- Previously documented ER+ and HER2- tumor according to American Society of Clinical Oncologythe study, diagnosis and treatment of cancer (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 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