A Phase 2 interventional study of Estradiol in Metastatic Breast Cancer, sponsored by Dartmouth-Hitchcock Medical Center. Recruiting at 1 site in United States. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-05-05.
Sponsored by Dartmouth-Hitchcock Medical Center · Phase 2, Interventional, and Treatment
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
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
12,544 studies on the registry are indexed under Breast Neoplasms; 2,892 are open to participants now.
This study's planned enrollment of 36 is below the median of 72 across 9,303 interventional studies indexed under Breast Neoplasms.
Browse Breast Neoplasms studies →Dartmouth-Hitchcock Medical Center is the lead sponsor of 472 studies on the registry; 68 are open to participants now.
Of its 30 completed or terminated interventional studies of FDA-regulated products, 20 (67%) have results posted.
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Exclusion Criteria:
During the study Treatment Phase with 17b-estradiol, no concurrent anti-cancer therapies are allowed with the following exceptions:
History of any of the following:
Treatment Phase: Patients will be treated with 17b-estradiol until disease progression. At this point, the patient will end protocol therapy
Drug: Estradiol
Estradiol is a therapeutic option for the treatment of advanced ER+ breast cancer
Also known as: Estrace
Clinical Benefit Rate
The clinical benefit rate (complete responses + partial responses + stable disease at 24 weeks) will be ascertained and compared between subjects treated with 17b-estradiol harboring amplified/mutant ESR1 and wild-type ESR1.
Time frame: 12 months
Objective response rate
The objective response rate (complete + partial responses) to the first 8 weeks of treatment with 17b-estradiol will be ascertained and compared between subjects harboring amplified/mutant ESR1 and wild-type ESR1.
Time frame: 8 weeks
Progression-free survival
Progression-free survival with 17b-estradiol treatment will be ascertained and compared between subjects harboring amplified/mutant ESR1 and wild-type ESR1.
Time frame: 12 months
Tumor Metabolic response
Tumor metabolic response will be defined as the best response at any time point per PERCIST. The metabolic response rate (complete + partial metabolic response) will be ascertained and compared between subjects treated with 17b-estradiol harboring amplified/mutant ESR1 and wild-type ESR1.
Time frame: 12 months
Adverse event profiles
The number of participants with treatment-related adverse events as assessed by CTCAE v5.0 will be collected
Time frame: 12 months
Plan to share: No
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