Home › Trials › NCT06016738

Comparing Palazestrant to Standard Treatments for Advanced Breast Cancer

A Phase 3 Randomized, Open-Label Study of OP-1250 Monotherapy vs Standard of Care for the Treatment of ER+, HER2- Advanced or Metastatic Breast Cancer Following Endocrine and CDK 4/6 Inhibitor Therapy (OPERA-01)

Phase 3 Interventional Olema Pharmaceuticals, Inc. · NCT06016738

This study is testing if a new drug called palazestrant can work better than standard treatments for adults with advanced breast cancer who have not responded well to previous therapies.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment510 (estimated)
Ages18 Years and up
SexAll
SponsorOlema Pharmaceuticals, Inc. Industry-sponsored
Drugs / interventionschemotherapy
Locations233 sites (Tucson, Arizona and 232 other locations)
Trial IDNCT06016738 on ClinicalTrials.gov

What this trial studies

This phase 3 clinical trial evaluates the safety and efficacy of palazestrant (OP-1250) compared to standard-of-care options, such as fulvestrant or aromatase inhibitors, in adults with ER+/HER2- advanced or metastatic breast cancer. Participants must have experienced disease progression after one or two prior lines of endocrine therapy, including a CDK4/6 inhibitor. The trial is international and multicenter, involving randomization of approximately 510 participants to either palazestrant or standard endocrine therapy. The goal is to determine if palazestrant offers a more effective treatment option for this patient population.

Who should consider this trial

Good fit: Ideal candidates are adults with ER+/HER2- advanced or metastatic breast cancer who have progressed on prior endocrine therapy.

Not a fit: Patients with symptomatic visceral disease or those who have previously received chemotherapy in the advanced setting may not benefit from this study.

Why it matters

Potential benefit: If successful, this trial could provide a new effective treatment option for patients with advanced breast cancer who have limited alternatives.

How similar studies have performed: Other studies have shown promise with similar approaches, but the specific use of palazestrant in this context is being evaluated for the first time.

Eligibility criteria

Show full inclusion / exclusion criteria 
Key inclusion criteria:

* Adult female or male participants.
* ER+, HER2- locally advanced or metastatic breast cancer that is not amenable to curative therapy.
* Evaluable disease (measurable disease or bone-only disease).
* Previously received a CDK4/6 inhibitor in combination with an endocrine therapy in the advanced setting. One additional line of ET as a monotherapy is allowed. Duration of the most recent prior ET must be at least 6 months.
* 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.

Key exclusion criteria:

* Symptomatic visceral disease, imminent organ failure, or any other reason that makes the participant ineligible for endocrine monotherapy.
* Previously received chemotherapy in the advanced/metastatic setting.
* Previously received treatment with elacestrant or an investigational estrogen receptor-directed therapy.
* History of allergic reactions to study treatment.
* Any contraindications to the selected standard-of-care endocrine therapy in the local prescribing information.
* Symptomatic central nervous system metastases, carcinomatous meningitis, leptomeningeal disease, or a spinal cord compression that require immediate treatment.
* Clinically significant comorbidities such as significant cardiac or cerebrovascular disease, gastrointestinal disorders that could affect absorption of study treatment.

Where this trial is running

Tucson, Arizona and 232 other locations

+183 more sites — see ClinicalTrials.gov for the full list.

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Breast CancerAdvanced Breast CancerMetastatic Breast CancerER Positive Breast CancerHER2 Negative Breast Carcinoma
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.