Under construction – not a live service
Sign in
Taking people in ThailandPhase 3

Tests palazestrant with ribociclib in adults with advanced ER-positive breast cancer

Tests palazestrant with ribociclib against letrozole with ribociclib in adults with advanced breast cancer.

Key facts

Who runs it
Olema Pharmaceuticals, Inc.
Where
Ban Phaeo, Bangkok, Chiang Mai, Dusit, and Hat Yai, ThailandSee the 5 sitesAlso in 22 other countries, 197 sites
Registry title
Palazestrant in Combination With Ribociclib for the First-line Treatment of ER+/HER2- Advanced Breast Cancer
Status
Recruiting
Phase
Phase 3
People taking part
1,000 people, planned
Started
3 Nov 2025
Expected to end
Jan 2032
Type of study
Interventional, 2 groupsOne group gets an existing treatment, for comparison.
Treatments tested
  • Palazestrant
  • Letrozole-matching placebo
  • Ribociclib
  • Letrozole
  • Palazestrant matching-placebo
Record updated
23 September 2026

Who can take part

AI summary

From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.

The trial is looking for women and men with ER+, HER2- breast cancer that has spread or cannot be cured by local treatment, and who have not yet had treatment for advanced disease.

Age
18 years or older.
Sex
Women and men can join.
Disease stage
ER+, HER2- locally advanced or metastatic breast cancer that cannot be treated with treatment meant to remove all of the disease. The disease must be measurable, or be in the bones only. It must be present from the start, or have come back more than 12 months after finishing hormone treatment given after surgery.
Earlier treatment
No earlier anti-cancer drug treatment for ER+, HER2- advanced breast cancer. No earlier fulvestrant, elacestrant or experimental hormone therapy.
Biomarker or test result
ER-positive and HER2-negative tumour.

Main reasons for not taking part

  • Cancer came back during hormone treatment given after surgery
  • Earlier drug treatment for advanced ER+, HER2- breast cancer
  • Earlier fulvestrant, elacestrant or experimental hormone therapy
  • Allergic reaction to study treatment, or any reason not to take letrozole and ribociclib
  • Cancer in the brain or spinal cord area that causes symptoms and needs treatment right away

The registry criteria, word for word

Show all 14 criteriaShow less

Who can take part

  • 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

Who cannot take part

  • 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
  • Disease recurrence during adjuvant endocrine therapy
  • History of allergic reactions to study treatment
  • Symptomatic central nervous system metastases, carcinomatous meningitis, leptomeningeal disease, or a spinal cord compression that require immediate treatment
  • Any contraindications to letrozole and ribociclib

Check if you might fit

Answer for yourself. This is not a decision: only the study team can say whether you can take part.

  • What did the tests on your tumour show about hormone receptors and the HER2 protein?
  • Have you already had any medicine for your cancer after it spread or became advanced?
  • Have you had chemotherapy for cancer that has spread or is advanced?

Where in Thailand

Also in 22 other countries, 197 sites

  • Ban Phaeo, Changwat Samut SakhonHospital not named in the registryContact: Olema Pharmaceuticals, Inc.Taking people
  • BangkokHospital not named in the registryContact: Olema Pharmaceuticals, Inc.Taking people
  • Chiang MaiHospital not named in the registryContact: Olema Pharmaceuticals, Inc.Taking people
  • Dusit, BangkokHospital not named in the registryContact: Olema Pharmaceuticals, Inc.Taking people
  • Hat Yai, Changwat SongkhlaHospital not named in the registryContact: Olema Pharmaceuticals, Inc.Taking people

About the trial

What the trial wants to find out

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.

The 2 groups in the trial

  • PalazestrantTreatment being tested

    Participants will receive palazestrant, ribociclib and letrozole-matching placebo

    Treatment: Palazestrant, Letrozole-matching placebo, and Ribociclib

  • LetrozoleExisting treatment, for comparison

    Participants will receive letrozole, ribociclib and palazestrant-matching placebo

    Treatment: Ribociclib, Letrozole, and Palazestrant matching-placebo

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record → Contacts and Locations

Print a page for my doctor

Data and sources

Registry record
Listed on ClinicalTrials.gov and on the EU's official list of trials (CTIS).
Official title
A Phase 3 Randomized, Double-Blind, Active-Controlled Study of Palazestrant With Ribociclib Versus Letrozole With Ribociclib for the First-Line Treatment of ER+, HER2- Advanced Breast Cancer (OPERA-02)
Plain-language title
Tests palazestrant with ribociclib in adults with advanced ER-positive breast cancerGenerated from the registry record. The registry title is the official one.
AI summary
From the trial's eligibility criteria. Read by machine on 12 November 2026.
Fit questions
Built from NCT07085767, who can take part
Record updated
23 September 2026