NCT07867262Not yet recruitingPhase 1
A Study to Evaluate the Effects of GDC-4198 in Combination With Letrozole, Fulvestrant, or Giredestrant in Participants With Locally Advanced or Metastatic Hormone Receptor-Positive, HER2-Negatve Breast Cancer
A Phase Ib, Multicenter, Open-Label Study Evaluating the Safety, Pharmacokinetics, and Activity of GDC-4198 in Combination With Letrozole, Fulvestrant, or Giredestrant in Patients With Locally Advanced or Metastatic Hormone Receptor-Positive, HER2-Negative Breast Cancer Who Are Sensitive or Resistant to Endocrine Therapy
Source: ClinicalTrials.gov · Last updated 9 Oct 2026
Brief summary (registry, in English)
The study will evaluate the safety, pharmacokinetics, and preliminary activity of GDC-4198 when given in combination with endocrine therapy (ET) (letrozole, fulvestrant, or giredestrant) as first-line treatment to participants with locally advanced or metastatic Hormone receptor (HR)-positive, Human epidermal growth factor receptor-2 (HER2)-negative breast cancer
- Status (registry)
- Not yet recruiting
- Phase (registry)
- Phase 1
- Study type
- Interventional
- Enrollment
- 165 (estimated)
- First submitted
- 5 Oct 2026
- Start date
- 15 Dec 2026
- Primary completion date
- 15 Aug 2030
- Lead sponsor
- Genentech, Inc.
- Diseases
- Metastatic breast cancer
- NCT number
- NCT07867262
- EU CT number
- 2026-525266-22-00
What you commit to
- Study type: Interventional · Phase 1
- Planned participants: 165
- From 15 Dec 2026 to the primary completion date, 15 Aug 2030
- No sites listed in no country
- Visits and tests: ask the trial team, the registry does not list them
Built from the registry fields of ClinicalTrials.gov. It describes the study, not your situation.
Who cannot take part
Copied verbatim from ClinicalTrials.gov and grouped by topic. Only the trial team decides who can take part.
Prior treatment
- Advanced, symptomatic, visceral spread at the time of study entry that is at risk of life-threating complications and for which treatment with cytotoxic chemotherapy is considered appropriate per local treatment guidelines.
Other illness
- History of systemic anti-cancer therapy for unresectable locally advanced breast cancer or metastatic breast cancer.
- 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.
Other
- Symptomatic, untreated, or actively progressing CNS metastases.
Who the study is looking for
- Histologically or cytologically confirmed adenocarcinoma of the breast that is locally advanced or metastatic and HER2-negative disease.
- Disease documented HER2-negative tumor according to American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines or documented ER-positive tumor according to ASCO/CAP guidelines.
- Measurable and/or non-measurable disease per Response Evaluation Criteria in Solid Tumors, Version 1.1 (RECIST v1.1) (including bone-only disease).
- For females \<= 60 years of age who are not in a postmenopausal state and males: initiation of treatment with luteinizing hormone-releasing hormone (LHRH) agonist therapy prior to initiation of study treatment according to clinical practice for the selected agent (preferably at least 14 days prior to initiation of study treatment), and agreement to continue LHRH agonist therapy for the duration of the study. LHRH agonist therapy may be discontinued in women \> 60 years of age.
- Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1.
- Life expectancy \>= 6 months.
- Participants with Endocrine therapy (ET)-resistant disease and ET-sensitive disease as defined in the protocol.
Age in the registry: 18 years to - · Sex: All · Does not accept healthy volunteers
This page is information, not medical advice. Discuss any trial with your doctor.