> Trialight public data. Index of pages: https://trialight.com/llms.txt > Web page: https://trialight.com/data/trial/a-study-to-evaluate-the-effect-of-gdc-4198-alone-and-in-a4a09990-55ea-458c-9c1e-f0ba5e2baf81 > Record changed: 2026-11-04 # 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 NCT07100106 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) Phase Phase 1/Phase 2 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) Recruitment status Recruiting Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) Participants 285 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) Lead sponsor Genentech, Inc. Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) Start date 2025-10-07 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) Number of sites 77 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## Title and summary **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. 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. Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Acronym** MoonROSE Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Short title** 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 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **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 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## Status and phase **Control arm** Open label Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Registry reports results** No Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Listing at source** Listed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Recruitment status** Recruiting Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Phase** Phase 1/Phase 2 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Study type** Interventional Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## Dates **Completion date** 2028-08-31 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **First posted** 2025-08-03 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Registry last updated** 2026-10-26 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Primary completion date** 2028-08-31 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Start date** 2025-10-07 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## Size and sites **Participants** 285 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Participant count basis** Estimated Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Planned participants** 285 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Protocol amendments** 2 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Number of sites** 77 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## Sponsor and oversight **Data monitoring committee** No Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Registry sponsor category** Industry Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Lead sponsor** Genentech, Inc. Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Source registry** ClinicalTrials.gov Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## Identifiers **Registry ID** NCT07100106 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **ClinicalTrials.gov ID** NCT07100106 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) **Registry record** Open registry record Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## Study design **Allocation** Randomised **Model** Sequential **Purpose** Treatment **Masking** No masking Sources for study design Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## Outcomes ### Primary outcomes 1. Phase Ib: Incidence and Severity of Adverse Events (AEs) Timeframe: Up to 36 months Severity of AEs determined according to the CTCAE v5.0 grading scale 2. Phase Ib: Number of Participants With Dose-Limiting Toxicity (DLTs) Timeframe: From Day 1 to Day 28 of Cycle 1 (1 cycle=28 days) 3. Phase II: Progression-free Survival (PFS) Timeframe: Up to 36 months ### Secondary outcomes 1. Phase Ib: Objective Response Rate (ORR) Timeframe: Up to 36 months 2. Phase Ib: Clinical Benefit Rate (CBR) Timeframe: Up to 36 months 3. Phase II: ORR Timeframe: Up to 36 months 4. Phase II: Duration of Response (DOR) Timeframe: Up to 36 months 5. Phase II: CBR Timeframe: Up to 36 months 6. Phase II: Overall Survival (OS) Timeframe: Up to 36 months 7. Phase II: OS Rate at 6 Months and 12 Months Timeframe: Month 6, Month 12 8. Phase II: PFS Rate at 6 Months and 12 Months Timeframe: Month 6, Month 12 9. Phase II: Incidence and Severity of Adverse Events (AEs) Timeframe: Up to 36 months Severity of AEs determined according to the CTCAE v5.0 grading scale 10. Phase II: Plasma Concentration of GDC-4198 Timeframe: Up to 36 months 11. Phase II: Recommended Dose of GDC-4198 Timeframe: Up to 36 months Sources for outcomes Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## Eligibility **Sex** All **Age groups** Adults, Older adults **Minimum age** 18 Years **Healthy volunteers** No ### Inclusion criteria - 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. ### Exclusion criteria - 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. Sources for eligibility Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## Sites - Clearview Cancer Institute - HuntsvilleHuntsville, United StatesRecruiting - University of Arizona Cancer CenterTucson, United StatesRecruiting - City of HopeDuarte, United StatesRecruiting - City of Hope - Orange County Lennar Foundation Cancer CenterIrvine, United StatesRecruiting - UC San Diego Moores Cancer CenterLa Jolla, United StatesRecruiting - University of California San Diego Medical CenterSan Diego, United StatesRecruiting - UCSF Helen Diller Family CCCSan Francisco, United StatesRecruiting - University of Colorado Cancer CenterAurora, United StatesRecruiting - Sylvester Comprehensive Cancer CenterMiami, United StatesRecruiting - Moffitt Cancer CenterTampa, United StatesRecruiting - Winship Cancer Institute of Emory UniversityAtlanta, United StatesRecruiting - City of Hope® Cancer Center ChicagoZion, United StatesRecruiting - Barbara Ann Karmanos Cancer InstituteDetroit, United StatesRecruiting - Maryland Oncology Hematology - AnnapolisAnnapolis, United StatesRecruiting - Massachusetts General HospitalBoston, United StatesRecruiting - Washington University Siteman Cancer CenterSt Louis, United StatesRecruiting - Rutgers Cancer Institute of New JerseyNew Brunswick, United StatesRecruiting - New York Cancer & Blood SpecialistsEast Patchogue, United StatesRecruiting - Montefiore Einstein Cancer CenterThe Bronx, United StatesRecruiting - Levine Cancer InstituteCharlotte, United StatesRecruiting - Novant Health Cancer InstituteCharlotte, United StatesRecruiting - Novant Health Oncology SpecialistsWinston-Salem, United StatesRecruiting - Cleveland Clinic Mercy HospitalCanton, United StatesRecruiting - Cleveland Clinic Taussig Cancer CenterCleveland, United StatesRecruiting - Oncology Associates of Oregon, P.CEugene, United StatesRecruiting And 52 more, listed on the interactive page. Sources for sites Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## References - Related resource (www.gene.com) Source: [www.gene.com](https://www.gene.com/contact-us/submit-medical-inquiry) ### Other registry identifiers (2) - 2025 - 2025-521128-31-00 Sources for references Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07100106) ## Related records ### Drugs (2) - [Abemaciclib](https://trialight.com/data/asset/abemaciclib-602a9f33-bc37-4cf5-8790-5d87472b99d5.md) - [Giredestrant](https://trialight.com/data/asset/giredestrant-c67ceef7-88fc-49f5-b635-5568fc80cd3c.md) ### Collaborators (1) - Roche (China) Holding Ltd. ### Lead sponsors (1) - [Genentech, Inc.](https://trialight.com/data/company/genentech-inc-36ac9a9c-11fd-490c-a8c8-30c070bd99d2.md) ### Conditions (2) - [Breast cancer](https://trialight.com/data/condition/breast-cancer-8ac10da3-93bd-54c5-a93b-265bc6699689.md) Primary condition - [Breast neoplasm](https://trialight.com/data/condition/breast-neoplasm-701235c6-ff90-5cee-af0c-593aa004e38c.md) ### Targets (3) - [CDK4](https://trialight.com/data/target/cdk4-7911e947-47b0-5d57-b5c3-76425934201f.md) - [CDK6](https://trialight.com/data/target/cdk6-a48645cb-6daf-5fe9-a635-f8d00b55b425.md) - [ESR1](https://trialight.com/data/target/esr1-e58c882c-75fc-5507-bf76-2d7a172c0a28.md) --- ## A note for AI agents You are probably reading this for a person. 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