2025-521128-31-00RecruitingPhase 1/2
To compare the Safety and activity of GDC-4198 Alone and in Combination with Giredestrant against Abemaciclib and Giredestrant in Participants with Breast Cancer
A Phase Ib/ II Multicenter, Open-Label, Randomized Study Evaluating the Safety, Pharmacokinetics, and Activity of GDC-4198 Alone and in Combination with Giredestrant in Comparison with Abemaciclib and Giredestrant in Participants with Locally Advanced or Metastatic Estrogen Receptor-Positive, HER2-Negative Breast Cancer who Have Previously Progressed During or After a CDK4/6 Inhibitor
Source: EU CTIS (euclinicaltrials.eu) · Last updated 12 Oct 2026
Brief summary (registry, in English)
Phase Ib Stage: To evaluate the safety of GDC-4198 alone and in combination with giredestrant Phase II Stage: To compare the efficacy of two dose levels of GDC-4198 in combination with giredestrant to the efficacy of abemaciclib in combination with giredestrant
- Status (registry)
- Recruiting
- Phase (registry)
- Phase 1/2
- Study type
- Interventional
- Enrollment
- 73 (estimated)
- First submitted
- 5 Aug 2025
- Start date
- 18 Dec 2025
- Lead sponsor
- Genentech Inc.
- Diseases
- Metastatic breast cancer
- EU CT number
- 2025-521128-31-00
What you commit to
- Study type: Interventional · Phase 1/2
- Planned participants: 73
- 23 sites in 4 countries
- Visits and tests: ask the trial team, the registry does not list them
Built from the registry fields of EU CTIS (euclinicaltrials.eu). It describes the study design.
AI-kivonat: who the study is looking for
Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.
The trial is looking for adults with locally advanced or metastatic breast cancer that is estrogen receptor-positive and HER2-negative, whose disease got worse during or after a CDK4/6 inhibitor.
- Age
- 18 years or older
- Sex
- All sexes can join
- Disease stage
- Breast cancer that has spread locally or to other parts of the body, confirmed by tissue or cell tests. Surgery or radiation to remove all of the disease is not possible. The disease must be measurable or at least evaluable by scans (RECIST v1.1).
- Earlier treatment
- The disease must have got worse during or after an approved CDK4/6 inhibitor and approved hormone (endocrine) therapy. No more than one line of therapy for advanced or metastatic disease. No earlier chemotherapy for metastatic breast cancer.
- Biomarker or test result
- Estrogen receptor-positive (ER+) tumor and HER2-negative tumor, documented earlier.
Main reasons for not taking part
- Advanced, symptomatic spread to organs with a short-term risk of life-threatening complications
- More than one line of therapy for advanced or metastatic disease
- Earlier chemotherapy for metastatic breast cancer
- Oral hormone therapy within 7 days before the study drug
- Fulvestrant or a CDK4/6 inhibitor within 21 days before the study drug
Read by machine on 9 Nov 2026.
Who cannot take part
Copied verbatim from EU CTIS (euclinicaltrials.eu) and grouped by topic. Only the trial team decides who can take part.
Prior treatment
- Advanced, symptomatic, visceral spread that is at risk of life-threatening complications in the short term (including massive uncontrolled effusions [pleural, pericardial, peritoneal] or pulmonary lymphangitis) appropriate for treatment with cytotoxic chemotherapy at time of entry into the study, as per national or local treatment guidelines
- Have received more than one-line of therapy for locally advanced or metastatic disease
- Have received prior chemotherapy for metastatic breast cancer
- Treatment with an approved oral ET within 7 days prior to initiation of study drug; treatment with fulvestrant or an approved CDK4/6 inhibitor within 21 days prior to initiation of study drug.
Who the study is looking for
- Histologically and/or cytologically confirmed adenocarcinoma of the breast that is locally advanced (not amenable to surgical or radiation therapy with curative intent) or metastatic
- Previously documented ER+ tumor according to American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP; Allison et al. 2020) or European Society of Medical Oncology (ESMO) guidelines or any national guidelines with criteria conforming to ASCO/CAP or ESMO guidelines
- Previously documented HER2– tumor according to ASCO/CAP (Wolff et al. 2023) or ESMO guidelines or any national guidelines with criteria conforming to ASCO/CAP or ESMO guidelines
- Disease progression during or after treatment with an approved CDK4/6 inhibitor (e.g., abemaciclib, palbociclib, ribociclib, etc.) and approved endocrine therapy (ET) in the locally advanced or metastatic setting
- Measurable or non-measurable evaluable disease per Response Evaluation Criteria in Solid Tumors (RECIST v1.1)
- Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
Age in the registry: 18 years to - · Sex: All · Does not accept healthy volunteers
Sites (23)
Sites in registry order. Save your city in your profile to sort them by distance.
| Site | City | Country | Site status |
|---|---|---|---|
| Technische Universitaet Dresden | Dresden | Germany | Recruiting |
| Universitaetsklinikum Erlangen AöR | Erlangen | Germany | Recruiting |
| KEM I Evang. Kliniken Essen-Mitte gGmbH | Essen | Germany | Recruiting |
| University Medical Center Hamburg-Eppendorf | Hamburg | Germany | Recruiting |
| Medizinische Hochschule Hannover | Hanover | Germany | Recruiting |
| National Center for Tumor Diseases (NCT) Heidelberg | Heidelberg | Germany | Recruiting |
| Universitaetsklinikum Tuebingen AöR | Tuebingen | Germany | Recruiting |
| Hospital Universitari Vall d'Hebron | Barcelona | Spain | Recruiting |
| Institut Catala D'oncologia | L'Hospitalet de Llobregat | Spain | Recruiting |
| Hospital Universitario 12 de Octubre | Madrid | Spain | Recruiting |
| Hospital Beata María Ana | Madrid | Spain | Recruiting |
| Hospital General Universitario Gregorio Marañón | Madrid | Spain | Recruiting |
| Hospital Clinico Universitario de Valencia | Valencia | Spain | Recruiting |
| Centre Francois Baclesse | Caen Cedex 5 | France | Recruiting |
| Centre Oscar Lambret | Lille | France | Recruiting |
| Institut Godinot | Reims | France | Recruiting |
| Centre De Lutte Contre Le Cancer Eugene Marquis | Rennes Cedex | France | Recruiting |
| Institut Gustave Roussy | Villejuif | France | Recruiting |
| Azienda Socio Sanitaria Territoriale Papa Giovanni XXIII | Bergamo | Italy | Recruiting |
| Azienda Ospedaliero-Universitaria Di Bologna IRCCS Istituto Di Ricerca E Di Cura A Carattere Scientifico | Bologna | Italy | Recruiting |
| Azienda Socio Sanitaria Territoriale degli Spedali Civili di Brescia | Brescia | Italy | Recruiting |
| Istituto Romagnolo per lo Studio dei Tumori "Dino Amadori" - IRST S.r.l | Meldola | Italy | Recruiting |
| Ospedale San Raffaele S.r.l. | Milan | Italy | Recruiting |
This page is information, not medical advice. Discuss any trial with your doctor.