Actively Recruiting
A Phase 3 Study Comparing OP-1250 Palazestrant to Standard Endocrine Therapy for ER, HER2- Advanced or Metastatic Breast Cancer After Endocrine and CDK 46 Inhibitor Therapy
Led by Olema Pharmaceuticals, Inc. · Updated on 2026-03-13
510
Participants Needed
233
Research Sites
65 weeks
Total Duration
On this page
AI-Summary
What this Trial Is About
Researchers are evaluating palazestrant OP-1250 compared to standard endocrine therapies for adults with ER-positive, HER2-negative advanced or metastatic breast cancer that has progressed after endocrine therapy combined with a CDK46 inhibitor. This international phase 3 trial aims to assess the safety and effectiveness of palazestrant versus fulvestrant or aromatase inhibitors such as anastrozole, letrozole, or exemestane. Participants are randomly assigned to receive either palazestrant daily on a 28-day cycle at doses of 90 mg or 120 mg during the dose-selection phase, or the standard-of-care endocrine therapy including fulvestrant administered on specific days or one of the aromatase inhibitors given daily on similar cycles. The trial includes an initial dose-selection period with about 120 participants, followed by a larger randomized phase with approximately 390 participants receiving the selected dose of palazestrant or standard treatment. Throughout the study, participants will be monitored for adverse events, dose adjustments, and drug discontinuations up to 16 weeks. Researchers will measure progression-free survival for up to two years and overall survival for up to four years after randomization. Regular assessments will include clinical evaluations and safety monitoring to observe the effects and tolerability of the treatments during the trial.
CONDITIONS
Brief Title
OP-1250 (Palazestrant) vs. Standard of Care for the Treatment of ER+/HER2- Advanced Breast Cancer
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Adult female or male participants
- ER-positive, HER2-negative locally advanced or metastatic breast cancer not suitable for curative treatment
- Evaluable disease including measurable or bone-only disease
- Prior treatment with a CDK4/6 inhibitor combined with endocrine therapy in the advanced setting
- One additional line of endocrine therapy as monotherapy allowed
- Most recent prior endocrine therapy lasted at least 6 months
- Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
- Adequate blood, liver, and kidney function
- Female participants can be pre-, peri-, or postmenopausal
- Male and pre- or peri-menopausal females must agree to take a GnRH or LHRH agonist
You will not qualify if you...
- Symptomatic visceral disease, imminent organ failure, or other reasons making endocrine monotherapy unsuitable
- Prior chemotherapy in the advanced or metastatic setting
- Prior treatment with elacestrant or investigational estrogen receptor-directed therapy
- History of allergic reactions to study treatments
- Contraindications to the selected standard-of-care endocrine therapy per local guidelines
- Symptomatic central nervous system metastases, carcinomatous meningitis, leptomeningeal disease, or spinal cord compression needing immediate treatment
- Significant comorbidities such as serious heart or cerebrovascular disease or gastrointestinal disorders affecting treatment absorption
Research Team
O
Olema Pharmaceuticals, Inc.
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