At a glance
- What the study gets you
- Access to the study treatment being tested
- Type of study
- Interventional (receives a drug or procedure)
- Time in hospital
- In-person visits at study sites — visit count not specified by the sponsor
- Drug or intervention
- Palazestrant (drug), Letrozole-matching placebo (drug), Ribociclib (drug), Letrozole (drug)
- How long the study runs
- Study runs about 74 months (dates as stated)
- About the drug or intervention
- Palazestrant — drug: Participants will be treated with palazestrant 90 mg once daily on a 4-week (28-day) cycle. · Letrozole-matching placebo — drug: Participants will be treated with letrozole-matching placebo once daily on a 4-week (28 day) cycle · Ribociclib — drug: Participants will be treated with ribociclib 600 mg once daily on Days 1-21 of a 4-week (28 day) cycle. · Letrozole — drug: Participants will be treated with letrozole 2.5 mg once daily on a 4-week (28-day) cycle · Palazestrant matching-placebo — drug: Participants will be treated with palazestrant-matching placebo once daily on a 4-week (28-day) cycle
- Patient visit burden
- Not specified by the sponsor
- Type of study
- Testing a treatment
- Ages
- 18 Years and over
- Who
- All
- Number of participants
- 1,000
- Started
- 2025-11-03
- Last checked
- 2026-09
Plain English Summary
What is this study?
- • Testing a new treatment for breast cancer
- • Phase3 - 1,000 participants
- • This phase 3 clinical trial compares the efficacy and safety of palazestrant with ribociclib to letrozole and ribociclib in women and men who have not received prior systemic anti-cancer treatment for advanced breast cancer
Who can take part?
- • Ages 18 Years and over
- • Diagnosed with breast cancer
Where?
- • Brighton - Clinical Trial Site
- • London - Clinical Trial Site
- • London - Clinical Trial Site
- • Taunton - Clinical Trial Site
- • +2 more UK sites
This is a simplified summary. Always discuss with your doctor before making any decisions.
About This Trial
This phase 3 clinical trial compares the efficacy and safety of palazestrant with ribociclib to letrozole and ribociclib in women and men who have not received prior systemic anti-cancer treatment for advanced breast cancer.
More detail
This is an international, multicenter, randomized, double-blind, active-controlled, phase 3 clinical trial. The purpose of this trial is to compare the efficacy and safety of palazestrant in combination with ribociclib +letrozole -matching placebo (Arm A: investigational arm) with letrozole in combination with ribociclib + palazestrant-matching placebo (Arm B: control arm). This trial is seeking adult participants with ER+, HER2- advanced breast cancer who have not received prior systemic anti-cancer treatment for advanced disease. Approximately 1,000 participants will be randomized in a 1:1 ratio to one of the two study arms.
How this trial compares with your answers
Answer 2 more questions to improve match
What we know so far
Still need:
- • Tell us your age for better matching
- • Tell us your sex for better matching
Preliminary match based on your answers. Full eligibility requires on-site assessment including medical history, physical exam, and lab tests. This does not guarantee enrolment.
Eligibility at a Glance
Key info
- Age: 18 Years and over
- Who can join: All genders
Biomarkers mentioned
What the study is looking for
- ✓Adult female or male participants.
- ✓ER+, HER2- that has grown locally or that has spread breast cancer that is not amenable to curative therapy.
- ✓Evaluable disease (cancer that can be measured on scans 1.1 or bone-only disease).
- ✓De novo advanced breast cancer or with disease recurrence occurring after 12 months of completing after surgery endocrine...
- ✓activity scale (ECOG) performance status of 0 or 1.
Who cannot take part
- ✗Disease recurrence during after surgery 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.
See the full criteria
Where Is This Study? (6 UK sites)
Clinical Trial Site
Brighton BN2 5BE, United Kingdom
Clinical Trial Site
London WC1E 6AG, United Kingdom
Clinical Trial Site
London EC1M 6BQ, United Kingdom
Clinical Trial Site
Taunton TA1 5DA, United Kingdom
Clinical Trial Site
Guildford GU2 7XX, United Kingdom
Clinical Trial Site
Cardiff CF14 2TL, United Kingdom
How to Get in Touch
Olema Pharmaceuticals, Inc.
Sponsor contactCONTACT