NCT05716516

STUDY02001740;22SCH740: Estradiol For ER+ Advanced Breast Cancer (ESTHER)

Phase II Study of Estradiol Therapy to Target ER-Mutant and ER-Wild-Type ER+ Metastatic or Advanced Breast Cancer

• Status: Recruiting
• Phase: Phase 2
• Study type: Interventional
• Enrollment: 36 (estimated)
• Sponsor: Dartmouth-Hitchcock Medical Center · Academic / Other
• Sex: Female
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

Determine whether subjects harboring ESR1-mutant/amplified breast cancer have a higher rate of clinical benefit from 17b-estradiol therapy than subjects with ESR1-wild-type breast cancer

Detailed description

Patients with endocrine-resistant breast cancer are eligible. Treatment Phase: Patients will be treated with 17b-estradiol until disease progression. At this point, the patient will end protocol therapy. Clinical benefit, progression-free survival, objective response, tumor metabolic response, and toxicity will be determined. Observational Phase (optional): After disease progression on 17b-estradiol, patients will be treated at their oncologist's discretion. Clinical benefit, progression-free survival, and objective response will be measured during this line of treatment of physician's choice until another instance of disease progression. In consented subjects who undergo a clinically indicated tumor biopsy of recurrent or metastatic disease prior to the start of 17b-estradiol treatment, when feasible, acquisition of additional tumor tissue is requested for research purposes. Optional: patients will be asked to provide tumor tissue via a research biopsy on Day 3-4 of 17b-estradiol treatment. Archived tumor tissue and clinical-grade tumor and plasma DNA/RNA sequencing results will be used for research purposes. Blood samples will be obtained at baseline, on Day 3-4 of 17b-estradiol therapy (optional), and upon disease progression on 17b-estradiol. Plasma and buffy coat will be extracted and frozen. Tumor tissue and plasma specimens will be analyzed to identify molecular biomarkers predictive of sensitivity/resistance to 17b-estradiol therapy

Conditions

• Metastatic Breast Cancer

Interventions

Type	Name	Description
DRUG	Estradiol	Estradiol is a therapeutic option for the treatment of advanced ER+ breast cancer

Timeline

• Start date: 2023-05-04
• Primary completion: 2027-05-01
• Completion: 2027-05-01
• First posted: 2023-02-08
• Last updated: 2026-01-14

Locations

1 site across 1 country: United States

Regulatory

• FDA-regulated drug study