NCT07214662

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

A Phase Ia/Ib Dose-Escalation and Expansion Study Evaluating the Safety, Pharmacokinetics, and Activity of GDC-0587 as a Monotherapy and in Combination With Giredestrant in Patients With Locally Advanced Or Metastatic ER-Positive, HER2-Negative Breast Cancer Who Have Previously Progressed During or After CDK4/6 Inhibitor Therapy

• Status: Recruiting
• Phase: Phase 1
• Study type: Interventional
• Enrollment: 136 (estimated)
• Sponsor: Genentech, Inc. · Industry
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

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

Interventions

Type	Name	Description
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.

Timeline

• Start date: 2026-01-13
• Primary completion: 2030-04-01
• Completion: 2030-04-01
• First posted: 2025-10-09
• Last updated: 2026-04-03

Locations

3 sites across 2 countries: United States, Taiwan

Regulatory

• FDA-regulated drug study