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Breast CancerPhase 1/2MoonROSENCT07100106

A Study to Evaluate the Effect of GDC-4198 Alone and in Combination With Giredestrant Versus Abemaciclib and Giredestrant in Participants With Locally Advanced or Metastatic Estrogen Receptor-Positive (ER+), Human Epidermal Growth Factor Receptor-Negative (HER2-) Breast Cancer

A Phase 1/2 study testing GDC-4198, Giredestrant and Abemaciclib in people with Breast Cancer, run by Genentech, Inc. at 77 sites in 10 countries.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
Search all trials

Trial summary

The purpose of this study is to assess the safety of GDC-4198 alone and in combination with giredestrant and also the efficacy of GDC-4198 + giredestrant versus abemaciclib + giredestrant in participants with locally advanced or metastatic ER+, HER2- breast cancer. Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Breast Cancer
What is being tested?
GDC-4198, Giredestrant and Abemaciclib
Type of treatment
Pill or oral medicine
Could I receive a placebo?
No, everyone receives an active treatment
How many people
285 participants
Where
77 sitesin 10 countries
Study dates
7 Oct 2025to 31 Aug 2028
Phase
Phase 1/2
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Histologically and/or cytologically confirmed adenocarcinoma of the breast that is locally advanced or metastatic.
  • Previously documented ER+ and HER2- tumor according to American Society of Clinical Oncology (ASCO)/ College of American Pathologists (CAP) or European Society of Medical Oncology (ESMO) guidelines or any national guidelines with criteria conforming to ASCO/CAP or ESMO guidelines.
  • Disease progression during or after treatment with an approved cyclin-dependent kinase 4/6 (CDK4/6) inhibitor 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 version 1.1 (RECIST v1.1).
  • Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1.
  • Life expectancy >= 6 months.
  • Current participant enrolled in Study RGT-419B_01-101 who is experiencing clinical benefit from GDC-4198, as determined by the investigator, at the time of consent and enrollment in this study.

Who cannot join

  • Advanced, symptomatic, visceral spread that is at risk of life-threatening complications in the short term 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.
  • 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.

Trial locations and contacts

77 sites in 10 countries. Contact the study team or a site near you to ask about taking part.

Reference Study ID Number: GO46021 https://forpatients.roche.com/ No attachments to email below. contact

888-662-6728 (U.S. Only)

global-roche-genentech-trials@gene.com

Fastest response: use the inquiry form. https://www.gene.com/contact-us/submit-medical-inquiry contact

77 sites in 10 countries

United States33 sites, 33 recruiting

  • Maryland Oncology Hematology - Annapolis

    Annapolis, Maryland, 21401

    Recruiting

  • Winship Cancer Institute of Emory University

    Atlanta, Georgia, 30322-1013

    Recruiting

  • University of Colorado Cancer Center

    Aurora, Colorado, 80124-5316

    Recruiting

  • Massachusetts General Hospital

    Boston, Massachusetts, 02114

    Recruiting

  • Cleveland Clinic Mercy Hospital

    Canton, Ohio, 44708

    Recruiting

  • Levine Cancer Institute

    Charlotte, North Carolina, 28204

    Recruiting

  • Novant Health Cancer Institute

    Charlotte, North Carolina, 28204

    Recruiting

  • Cleveland Clinic Taussig Cancer Center

    Cleveland, Ohio, 44195-0001

    Recruiting

  • Texas Oncology (Worth) - USOR

    Dallas, Texas, 75246-2003

    Recruiting

  • Barbara Ann Karmanos Cancer Institute

    Detroit, Maine, 48201-2013

    Recruiting

  • City of Hope

    Duarte, California, 91010

    Recruiting

  • New York Cancer & Blood Specialists

    East Patchogue, New York, 11772

    Recruiting

  • Oncology Associates of Oregon, P.C

    Eugene, Oregon, 97401

    Recruiting

  • Penn State Health Milton S. Hershey Medical Center

    Hershey, Pennsylvania, 17033-2360

    Recruiting

  • Clearview Cancer Institute - Huntsville

    Huntsville, Alabama, 35805-2606

    Recruiting

  • City of Hope - Orange County Lennar Foundation Cancer Center

    Irvine, California, 92618

    Recruiting

  • UC San Diego Moores Cancer Center

    La Jolla, California, 92093-1503

    Recruiting

  • Sylvester Comprehensive Cancer Center

    Miami, Florida, 33136-1002

    Recruiting

  • Tennesse Oncology - Mt. Juliet Clinic

    Mount Juliet, Tennessee, 37122

    Recruiting

  • Vanderbilt Breast Center at One Hundred Oaks

    Nashville, Tennessee, 37204-3609

    Recruiting

  • Rutgers Cancer Institute of New Jersey

    New Brunswick, New Jersey, 08901-1914

    Recruiting

  • Virginia Oncology Associates (Norfolk) - USOR

    Norfolk, Virginia, 23502-2800

    Recruiting

  • University of Pennsylvania - Abramson Cancer Center

    Philadelphia, Pennsylvania, 19104

    Recruiting

  • UPMC - Hillman Cancer Center

    Pittsburgh, Pennsylvania, 15213-3108

    Recruiting

  • University of Utah Huntsman Cancer Institute

    Salt Lake City, Utah, 84013

    Recruiting

  • University of California San Diego Medical Center

    San Diego, California, 92103-1911

    Recruiting

  • UCSF Helen Diller Family CCC

    San Francisco, California, 94158

    Recruiting

  • Washington University Siteman Cancer Center

    St Louis, Missouri, 63110-1010

    Recruiting

  • Moffitt Cancer Center

    Tampa, Florida, 33612

    Recruiting

  • Montefiore Einstein Cancer Center

    The Bronx, New York, 10461

    Recruiting

  • University of Arizona Cancer Center

    Tucson, Arizona, 85724-0001

    Recruiting

  • Novant Health Oncology Specialists

    Winston-Salem, North Carolina, 27103-3224

    Recruiting

  • City of Hope® Cancer Center Chicago

    Zion, Illinois, 60099

    Recruiting

Other trials in United States

South Korea7 sites, 7 recruiting

  • Seoul National University Bundang Hospital

    Seongnam-si, 13620

    Recruiting

  • Gangnam Severance Hospital, Yonsei University Health System

    Seoul, Seoul Teugbyeolsi, 6273

    Recruiting

  • Seoul National University Hospital

    Seoul, 03080

    Recruiting

  • Asan Medical Center.

    Seoul, 05505

    Recruiting

  • Samsung Medical Center

    Seoul, 06351

    Recruiting

  • Severance Hospital, Yonsei University Health System

    Seoul, 3722

    Recruiting

  • The Catholic University of Korea, Seoul St. Mary's Hospital

    Seoul, 6591

    Recruiting

Other trials in South Korea

Brazil6 sites, 6 recruiting

  • ONCOSITE Centro de Pesquisa Clínica Em Oncologia

    Ijuí, Rio Grande do Sul, 98700-000

    Recruiting

  • Irmandade Da Santa Casa de Misericordia de Porto Alegre

    Porto Alegre, Rio Grande do Sul, 90035-074

    Recruiting

  • Hospital de Clinicas de Porto Alegre (HCPA) - PPDS

    Porto Alegre, Rio Grande do Sul, 90560-030

    Recruiting

  • Hospital do Cancer de Pernambuco - HCP

    Recife, Pernambuco, 50040-000

    Recruiting

  • Instituto Do Câncer Do Estado de São Paulo Octávio Frias de Oliveira - ICESP

    São Paulo, 01246-000

    Recruiting

  • Beneficencia Portuguesa de Sao Paulo

    São Paulo, 01323-001

    Recruiting

Other trials in Brazil

Germany6 sites, 6 recruiting

  • Universitaetsklinikum Carl Gustav Carus an der TU Dresden

    Dresden, 01307

    Recruiting

  • KEM - Evang. Huyssens-Stiftung Essen-Huttrop

    Essen, North Rhine-Westphalia, 45136

    Recruiting

  • Universitatsklinikum Hamburg-Eppendorf

    Hamburg, 20251

    Recruiting

  • Medizinische Hochschule Hannover

    Hanover, Lower Saxony, 30625

    Recruiting

  • Uniklinikum Heidelberg

    Heidelberg, 69120

    Recruiting

  • Universitatsklinikum Tubingen

    Tübingen, Baden-Wurttemberg, 72076

    Recruiting

Other trials in Germany

Spain6 sites, 6 recruiting

  • Instituto de Investigacion Oncologica Vall dHebron (VHIO) - EPON

    Barcelona, 08035

    Recruiting

  • ICO l?Hospitalet ? Hospital Duran i Reynals

    L'Hospitalet de Llobregat, Barcelona, 08908

    Recruiting

  • Hospital Beata Maria Ana

    Madrid, 28007

    Recruiting

  • Hospital General Universitario Gregorio Maranon

    Madrid, 28007

    Recruiting

  • Hospital Universitario 12 de Octubre

    Madrid, 28041

    Recruiting

  • Hospital Clinico Universitario de Valencia

    Valencia, 46010

    Recruiting

Other trials in Spain

China5 sites, 5 recruiting

  • Fujian Cancer Hospital

    Fuzhou, 350014

    Recruiting

  • Shandong Cancer Hospital

    Jinan, SD, 250117

    Recruiting

  • Guangxi Cancer Hospital of Guangxi Medical University

    Nanning, 530201

    Recruiting

  • Fudan University Shanghai Cancer Center - Pudong Campus

    Shanghai, Shanghai Municipality, 201321

    Recruiting

  • Tianjin Medical University Cancer Institute & Hospital

    Tianjin, Tianjin Municipality, 300060

    Recruiting

Other trials in China

France5 sites, 5 recruiting

  • Centre Francois Baclesse

    Caen, 14076

    Recruiting

  • Centre Oscar Lambret

    Lille, 59020

    Recruiting

  • Institut Jean Godinot

    Reims, Champagne-Ardenne, 51100

    Recruiting

  • Centre Eugene Marquis

    Rennes, 35042

    Recruiting

  • Gustave Roussy

    Villejuif, Val-de-Marne, 94805

    Recruiting

Other trials in France

Italy5 sites, 5 recruiting

  • Asst Papa Giovanni XXIII

    Bergamo, Lombardy, 24127

    Recruiting

  • Azienda Ospedaliero Universitaria Di Bologna_Policlinico S Orsola Malpighi-Via Albertoni

    Bologna, Emilia-Romagna, 40138

    Recruiting

  • ASST degli Spedali Civili di Brescia - Spedali Civili di Brescia

    Brescia, Lombardy, 25123

    Recruiting

  • Istituto Romagnolo per lo Studio dei Tumori Dino Amadori - IRST S.r.l - PPDS

    Meldola, Emilia-Romagna, 47014

    Recruiting

  • Ospedale San Raffaele S.r.l. - PPDS

    Milan, Lombardy, 20132

    Recruiting

Other trials in Italy

Australia2 sites, 2 recruiting

  • Cancer Research SA

    Adelaide, South Australia, 5000

    Recruiting

  • St Vincent's Hospital Sydney

    Darlinghurst, New South Wales, 2010

    Recruiting

Other trials in Australia

Canada2 sites, 2 recruiting

  • Princess Margaret Hospital

    Toronto, Ontario, M5G 2M9

    Recruiting

  • BC Cancer Vancouver Centre

    Vancouver, British Columbia, V5Z 4E6

    Recruiting

Other trials in Canada

About this study

Official title: 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

The purpose of this study is to assess the safety of GDC-4198 alone and in combination with giredestrant and also the efficacy of GDC-4198 + giredestrant versus abemaciclib + giredestrant in participants with locally advanced or metastatic ER+, HER2- breast cancer. The study consists of 2 phases: Phase Ib and Phase II. Phase Ib will evaluate the safety and pharmacokinetics (PK) of GDC-4198 alone and in combination with giredestrant. Phase II stage will compare the activity and safety of GDC-4198 and giredestrant with abemaciclib and giredestrant.

Participants from Study RGT-419B_01-101 (NCT05304962) who are experiencing clinical benefit with GDC-4198, as determined by the investigator, may enroll in this study and continue receiving GDC-4198 at their current dose level following closure of Study RGT-419B_01-101.

Conditions
Breast Cancer
Being tested
GDC-4198, Giredestrant, Abemaciclib
Medical subject headings
Breast Neoplasms

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • GDC-4198Drug

    Also called RGT-419B, RO7840734

    GDC-4198 will be administered orally.

  • GiredestrantDrug

    Also called GDC-9545, RO7197597

    Giredestrant will be administered orally.

  • AbemaciclibDrug

    Abemaciclib will be administered orally.

Study groups in NCT07100106
Study groupRoleWhat they receive
Phase Ib: Dose-Finding StageExperimentalParticipants will receive GDC-4198 as monotherapy and in combination with giredestrant, 30 milligrams (mg), orally, daily, as per a pre-defined dosing regimen during each cycle until unacceptable toxicity or disease progression and/or loss of clinical benefit. (1 cycle=28 days). Participants from study RGT-419B_01-101 will continue receiving GDC-4198 at their current dose level following closure of study RGT-419B_01-101.
Receives: Drug: GDC-4198; Drug: Giredestrant
Phase II: Arm AExperimentalParticipants will receive GDC-4198, higher dose, in combination with giredestrant, 30 mg, orally, daily, as per a pre-defined dosing regimen during each cycle until unacceptable toxicity or disease progression and/or loss of clinical benefit. (1 cycle=28 days).
Receives: Drug: GDC-4198; Drug: Giredestrant
Phase II: Arm BExperimentalParticipants will receive GDC-4198, lower dose, in combination with giredestrant, 30 mg, orally, daily, as per a pre-defined dosing regimen during each cycle until unacceptable toxicity or disease progression and/or loss of clinical benefit. (1 cycle=28 days).
Receives: Drug: GDC-4198; Drug: Giredestrant
Phase II: Arm CExperimentalParticipants will receive abemaciclib, 150 mg twice daily, in combination with giredestrant, 30 mg, orally, daily, as per a pre-defined dosing regimen during each cycle until unacceptable toxicity or disease progression and/or loss of clinical benefit. (1 cycle=28 days).
Receives: Drug: Giredestrant; Drug: Abemaciclib

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Phase Ib: Incidence and Severity of Adverse Events (AEs)

    Severity of AEs determined according to the CTCAE v5.0 grading scale

    Measured: Up to 36 months

  2. Phase Ib: Number of Participants With Dose-Limiting Toxicity (DLTs)

    Measured: From Day 1 to Day 28 of Cycle 1 (1 cycle=28 days)

  3. Phase II: Progression-free Survival (PFS)

    Measured: Up to 36 months

Secondary outcomes (11)

  1. Phase Ib: Objective Response Rate (ORR)

    Measured: Up to 36 months

  2. Phase Ib: Clinical Benefit Rate (CBR)

    Measured: Up to 36 months

  3. Phase II: ORR

    Measured: Up to 36 months

  4. Phase II: Duration of Response (DOR)

    Measured: Up to 36 months

  5. Phase II: CBR

    Measured: Up to 36 months

  6. Phase II: Overall Survival (OS)

    Measured: Up to 36 months

  7. Phase II: OS Rate at 6 Months and 12 Months

    Measured: Month 6, Month 12

  8. Phase II: PFS Rate at 6 Months and 12 Months

    Measured: Month 6, Month 12

  9. Phase II: Incidence and Severity of Adverse Events (AEs)

    Severity of AEs determined according to the CTCAE v5.0 grading scale

    Measured: Up to 36 months

  10. Phase II: Plasma Concentration of GDC-4198

    Measured: Up to 36 months

  11. Phase II: Recommended Dose of GDC-4198

    Measured: Up to 36 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted3 Aug 2025
  2. Study start7 Oct 2025
  3. Primary completion31 Aug 2028 (estimated)
  4. Study completion31 Aug 2028 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1/2
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Sequential
Masking
None (open label)
Enrolment
285 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07100106
Sponsor's protocol ID
GO46021
Other IDs
2025-521128-31-00, 2025
Acronym
MoonROSE
Status last verified
Oct 2026
First submitted
31 Jul 2025
Last updated
26 Oct 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: For eligible studies, qualified researchers may request access to individual patient level clinical data. See Roche's commitment to transparency of clinical study information here: https://go.roche.com/data\_sharing

Questions about this trial

What is this clinical trial studying?

A Phase 1/2 study testing GDC-4198, Giredestrant and Abemaciclib in people with Breast Cancer, run by Genentech, Inc. at 77 sites in 10 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 7 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 26 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 77 sites in United States, South Korea, Brazil, Germany, Spain and 5 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this combined phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Reference Study ID Number: GO46021 https://forpatients.roche.com/ No attachments to email below. (888-662-6728 (U.S. Only), global-roche-genentech-trials@gene.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Phase Ib: Incidence and Severity of Adverse Events (AEs) (time frame: Up to 36 months). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07100106.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 26 Oct 2026.

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