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

PHASE1Not yet recruitingINTERVENTIONAL

Enrollment

136

Participants

Timeline

Start Date

November 1, 2025

Primary Completion Date

July 1, 2029

Study Completion Date

July 1, 2029

Conditions

Breast Cancer

Interventions

DRUG

GDC-0587

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

DRUG

Giredestrant

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

DRUG

Omeprazole

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