A Study of GDC-9545 Alone or in Combination With Palbociclib and/or Luteinizing Hormone-Releasing Hormone (LHRH) Agonist in Locally Advanced or Metastatic Estrogen Receptor-Positive Breast Cancer

NCT03332797 · Status: ACTIVE_NOT_RECRUITING · Phase: PHASE1 · Type: INTERVENTIONAL · Enrollment: 181

Last updated 2026-05-15

No results posted yet for this study

Summary

This study will evaluate the safety, pharmacokinetic (PK), pharmacodynamic (PD) activity, and preliminary anti-tumor activity of GDC-9545 as a single agent and in combination with palbociclib and/or luteinizing hormone-releasing hormone (LHRH) agonist in participants with advanced or metastatic estrogen receptor (ER)-positive (human epidermal growth factor receptor 2 \[HER2\]-negative) breast cancer.

Conditions

Interventions

DRUG

GDC-9545

GDC-9545 will be administered orally, once daily, on Days 1-28 of each 28-day cycle, until disease progression, unacceptable toxicity, withdrawal of consent, or study termination.

DRUG

Palbociclib

Palbociclib will be administered orally, once daily, at the label-recommended dose of 125 mg on Days 1-21 of each 28-day cycle, until disease progression, unacceptable toxicity, withdrawal of consent, or study termination.

DRUG

LHRH Agonist

The LHRH agonist (leuprolide acetate, goserelin acetate, or triptorelin pamoate) will be administered by injection once every 4 weeks on Day 1 of each 28-day cycle, according to the label. The investigator will choose the appropriate LHRH agonist approved for use in breast cancer.

Sponsors & Collaborators

  • Genentech, Inc.

    lead INDUSTRY

Principal Investigators

  • Clinical Trials · Hoffmann-La Roche

Study Design

Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Model
SEQUENTIAL

Eligibility

Min Age
18 Years
Sex
FEMALE
Healthy Volunteers
No

Timeline & Regulatory

Start
2017-11-24
Primary Completion
2027-07-31
Completion
2027-07-31
FDA Drug
Yes

Countries

  • United States
  • Australia
  • South Korea
  • Spain
  • United Kingdom

Study Locations

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Entities

Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT03332797 on ClinicalTrials.gov