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Palazestrant with Ribociclib for Advanced ER+/HER2- Breast Cancer

This study is testing a new combination of medicines, palazestrant and ribociclib, for people with advanced breast cancer that is estrogen receptor-positive (ER+) and HER2-negative (HER2-). It compares this new combination to a standard treatment, letrozole and ribociclib. The goal is to see if the new combination is more effective and safe. You could be eligible if you are an adult with this type of breast cancer that has spread or is locally advanced, and you haven't had prior systemic anti-cancer treatment for advanced disease. The study will measure how long people live without their cancer getting worse (Progression-Free Survival). The study is currently recruiting about 1,000 participants.

Study design
This is an international, multi-center, randomized, double-blind, active-controlled Phase 3 study. About 1,000 participants will be randomly assigned to one of two treatment groups.
What's involved
Participants will take study medications daily on a 4-week cycle. The specific number of visits or procedures is not detailed in this record.
Compensation
Not stated in the trial record.
Follow-up
Participants will be followed from the date they are randomly assigned until their disease progresses or they pass away, estimated to be up to 3.5 years.

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NCT07085767

Palazestrant in Combination With Ribociclib for the First-line Treatment of ER+/HER2- Advanced Breast Cancer

Recruiting
PHASE3Ages 18+InterventionalTreatment
Olema Pharmaceuticals, Inc.
~1,000 participants
Updated 2026-08-17 on ClinicalTrials.gov
What's tested:PalazestrantLetrozole-matching placeboRibociclibLetrozolePalazestrant matching-placebo

At a glance

Recruiting sites
135 of 181 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Progression-Free Survival (PFS)
Measured over From Date of Randomization until Disease Progression or Death Due to Any Cause (estimated as up to 3.5 years)

Conditions

Breast Cancer
Locally Advanced Breast Cancer
Metastatic Breast Cancer
ER Positive Breast Cancer
HER2 Negative Breast Carcinoma

Explore related trials

Breast Carcinoma

Where it's being run

181 sites across 132 states
California6
Tennessee5
Texas4
Gyeonggi-do4
Seoul4
Madrid4
Virginia3
Victoria3

Study leadership

  • Medical Director, MD · STUDY_DIRECTOR · Olema Pharmaceuticals, Inc.

Who to contact

Olema Pharmaceuticals, Inc.
[email protected]
415-651-7206
Email the study team

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Eligibility criteria

Inclusion

Adult female or male participants.
ER+, HER2- locally advanced or metastatic breast cancer that is not amenable to curative therapy.
Evaluable disease (measurable disease per RECIST 1.1 or bone-only disease).
De novo advanced breast cancer or with disease recurrence occurring after 12 months of completing adjuvant endocrine therapy (with or without CDK4/6 inhibitors)
Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
Adequate hematologic, hepatic, and renal functions.
Female participants can be pre-, peri- or postmenopausal.
Male and pre- or peri-menopausal female participants must be willing to take a GnRH (or LHRH) agonist.

Exclusion

Disease recurrence during adjuvant endocrine therapy
Currently receiving or previously received systemic anti-cancer therapy for ER+, HER2- advanced breast cancer.
Previously received treatment with fulvestrant, elacestrant or an investigational endocrine therapy in any setting.
History of allergic reactions to study treatment.
Any contraindications to letrozole and ribociclib.
Symptomatic central nervous system metastases, carcinomatous meningitis, leptomeningeal disease, or a spinal cord compression that require immediate treatment.

What this trial measures

  • Progression-Free Survival (PFS)From Date of Randomization until Disease Progression or Death Due to Any Cause (estimated as up to 3.5 years)

    To compare PFS, based on a local investigator assessment, between investigational (palazestrant with ribociclib + letrozole-matching placebo) and control (letrozole with ribociclib + palazestrant-matching placebo) arms.