A Study Evaluating the Efficacy and Safety of GDC-9545 Combined With Palbociclib Compared With Letrozole Combined With Palbociclib in Participants With Estrogen Receptor-Positive, HER2-Negative Locally Advanced or Metastatic Breast Cancer
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ClinicalTrials.gov Identifier: NCT04546009 |
Recruitment Status :
Recruiting
First Posted : September 11, 2020
Last Update Posted : February 11, 2021
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Condition or disease | Intervention/treatment | Phase |
---|---|---|
Estrogen Receptor-Positive, HER2-Negative Locally Advanced or Metastatic Breast Cancer | Drug: GDC-9545 Drug: GDC-9545-matched Placebo Drug: Letrozole Drug: Letrozole-matched Placebo Drug: Palbociclib Drug: LHRH Agonist | Phase 3 |
Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 978 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Masking: | Double (Participant, Investigator) |
Primary Purpose: | Treatment |
Official Title: | A Phase III Randomized, Double-Blind, Placebo-Controlled, Multicenter Study Evaluating the Efficacy and Safety of GDC-9545 Combined With Palbociclib Compared With Letrozole Combined With Palbociclib in Patients With Estrogen Receptor-Positive, HER2-Negative Locally Advanced or Metastatic Breast Cancer |
Actual Study Start Date : | October 9, 2020 |
Estimated Primary Completion Date : | April 26, 2024 |
Estimated Study Completion Date : | March 18, 2027 |

Arm | Intervention/treatment |
---|---|
Experimental: GDC-9545 + Letrozole-matched Placebo + Palbociclib |
Drug: GDC-9545
GDC-9545 is taken orally once per day on Days 1-28 of each 28-day treatment cycle.
Other Names:
Drug: Letrozole-matched Placebo Letrozole-matched placebo is taken orally once per day on Days 1-28 of each 28-day treatment cycle. Drug: Palbociclib Palbociclib 125 mg is taken orally once per day on Days 1-21 of each 28-day treatment cycle. Drug: LHRH Agonist Only premenopausal and male participants will receive a luteinizing hormone-releasing hormone (LHRH) agonist on Day 1 of each 28-day treatment cycle. The investigator will determine and supply the appropriate LHRH agonist locally approved for use in breast cancer. |
Active Comparator: Letrozole + GDC-9545-matched Placebo + Palbociclib |
Drug: GDC-9545-matched Placebo
GDC-9545-matched placebo is taken orally once per day on Days 1-28 of each 28-day treatment cycle. Drug: Letrozole Letrozole 2.5 milligrams (mg) is taken orally once per day on Days 1-28 of each 28-day treatment cycle. Drug: Palbociclib Palbociclib 125 mg is taken orally once per day on Days 1-21 of each 28-day treatment cycle. Drug: LHRH Agonist Only premenopausal and male participants will receive a luteinizing hormone-releasing hormone (LHRH) agonist on Day 1 of each 28-day treatment cycle. The investigator will determine and supply the appropriate LHRH agonist locally approved for use in breast cancer. |
- Progression-Free Survival (PFS), as Determined by the Investigator According to RECIST v1.1 [ Time Frame: From randomization to the first occurrence of disease progression or death from any cause, whichever occurs first (up to 78 months) ]
- Overall Survival [ Time Frame: From randomization to death from any cause (up to 78 months) ]
- Objective Response Rate, as Determined by the Investigator According to RECIST v1.1 [ Time Frame: From randomization until disease progression or death (up to 78 months) ]The objective response rate is defined as the percentage of participants with a complete response or partial response on two consecutive occasions at least (≥)4 weeks apart.
- Duration of Response, as Determined by the Investigator According to RECIST v1.1 [ Time Frame: From first occurrence of documented objective response to disease progression or death from any cause, whichever occurs first (up to 78 months) ]
- Clinical Benefit Rate, as Determined by the Investigator According to RECIST v1.1 [ Time Frame: From randomization until disease progression or death (up to 78 months) ]The clinical benefit rate is defined as the percentage of participants with stable disease for ≥24 weeks or a complete response or partial response.
- Time to Deterioration in Pain Level, Defined as the Time to First Documented ≥2-Point Increase from Baseline in the 'Worst Pain' Item from the Brief Pain Inventory-Short Form (BPI-SF) Questionnaire [ Time Frame: From Baseline until treatment discontinuation (up to 78 months) ]
- Time to Deterioration in Pain Presence and Interference, Defined as the Time to First Documented ≥10-Point Increase from Baseline in the EORTC QLQ-C30 Linearly Transformed Pain Scale Score [ Time Frame: From Baseline until treatment discontinuation (up to 78 months) ]EORTC QLQ-C30 = European Organization for Research and Treatment of Cancer Quality-of-Life Questionnaire
- Time to Deterioration in Physical Functioning, Defined as the Time to First Documented ≥10-Point Decrease from Baseline in the EORTC QLQ-C30 Linearly Transformed Physical Functioning Scale Score [ Time Frame: From Baseline until treatment discontinuation (up to 78 months) ]
- Time to Deterioration in Role Functioning, Defined as the Time to First Documented ≥10-Point Decrease from Baseline in the EORTC QLQ-C30 Linearly Transformed Role Functioning Scale Score [ Time Frame: From Baseline until treatment discontinuation (up to 78 months) ]
- Time to Deterioration in Global Health Status and Quality of Life (GHS/QoL), Defined as the Time to First Documented ≥10-Point Decrease from Baseline in the EORTC QLQ-C30 Linearly Transformed GHS/QoL Scale Score [ Time Frame: From Baseline until treatment discontinuation (up to 78 months) ]
- Number of Participants with Adverse Events, Severity Determined According to National Cancer Institute Common Terminology Criteria for Adverse Events, Version 5.0 (NCI-CTCAE v5.0) [ Time Frame: From treatment initiation until 30 days after the final dose of study treatment (up to 78 months) ]
- Number of Participants with Vital Sign Abnormalities Over the Course of the Study [ Time Frame: Baseline, Days 1 and 15 of Cycles 1 and 2, and Day 1 of each cycle thereafter until treatment discontinuation (1 cycle is 28 days) ]Vital signs include respiratory rate, pulse rate, and systolic and diastolic blood pressure while the participant is in a seated position, and temperature.
- Plasma Concentration of GDC-9545 at Specified Timepoints [ Time Frame: Days 1 and 15 of Cycle 1; Day 1 of Cycles 2, 4, 8, and 16 (1 cycle is 28 days) ]
- Plasma Concentration of Palbociclib at Specified Timepoints [ Time Frame: Days 1 and 15 of Cycle 1 (1 cycle is 28 days) ]

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.
Ages Eligible for Study: | 18 Years and older (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Inclusion Criteria:
- For women who are premenopausal or perimenopausal or men: treatment with approved LHRH agonist therapy for the duration of study treatment
- Locally advanced (recurrent or progressed) or metastatic adenocarcinoma of the breast, not amenable to treatment with curative intent
- Documented ER-positive tumor and HER2-negative tumor, assessed locally
- No history of systemic anti-cancer therapy for locally advanced (recurrent or progressed) or metastatic disease
- Measurable disease as defined per RECIST v.1.1
- Eastern Cooperative Oncology Group Performance Status 0-1
- Adequate organ function
Exclusion Criteria:
- Disease recurrence during or within 12 months of completing prior neoadjuvant or adjuvant treatment with an aromatase inhibitor (AI)
- Disease recurrence during or within 12 months of completing prior neoadjuvant or adjuvant treatment with any CDK4/6 inhibitor
- Prior treatment with a selective estrogen receptor degrader (SERD)
- Prior treatment with tamoxifen is permitted, provided the patient did not experience disease recurrence within the first 24 months of treatment with tamoxifen
- Treatment with any investigational therapy within 28 days prior to study treatment
- Advanced, symptomatic, visceral spread that is at risk of life-threatening complications
- Known active uncontrolled or symptomatic CNS metastases, carcinomatous meningitis, or leptomeningeal disease
- Active cardiac disease or history of cardiac dysfunction
- Pregnant or breastfeeding

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04546009
Contact: Reference Study ID Number: BO41843 www.roche.com/about_roche/roche_worldwide.htm | 888-662-6728 (U.S. Only) | global-roche-genentech-trials@gene.com |

Study Director: | Clinical Trials | Hoffmann-La Roche |
Responsible Party: | Hoffmann-La Roche |
ClinicalTrials.gov Identifier: | NCT04546009 |
Other Study ID Numbers: |
BO41843 2020-000119-66 ( EudraCT Number ) |
First Posted: | September 11, 2020 Key Record Dates |
Last Update Posted: | February 11, 2021 |
Last Verified: | February 2021 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | Yes |
Plan Description: | Qualified researchers may request access to individual patient level data through the request platform (www.vivli.org). Further details on Roche's criteria for eligible studies are available here (https://vivli.org/ourmember/roche/). For further details on Roche's Global Policy on the Sharing of Clinical Information and how to request access to related clinical study documents, see here (https://www.roche.com/research_and_development/who_we_are_how_we_work/clinical_trials/our_commitment_to_data_sharing.htm). |
Studies a U.S. FDA-regulated Drug Product: | Yes |
Studies a U.S. FDA-regulated Device Product: | No |
Breast Neoplasms Neoplasms by Site Neoplasms Breast Diseases Skin Diseases Letrozole Palbociclib Antineoplastic Agents Aromatase Inhibitors |
Steroid Synthesis Inhibitors Enzyme Inhibitors Molecular Mechanisms of Pharmacological Action Estrogen Antagonists Hormone Antagonists Hormones, Hormone Substitutes, and Hormone Antagonists Physiological Effects of Drugs Protein Kinase Inhibitors |