• Incidence of adverse events [ Time Frame: 5 years ]
  An adverse event (AE) is any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medical treatment or procedure that may or may not be considered related to the medical treatment or procedure. All grade 2, 3, 4 or 5 adverse events will be documented and assigned an attribute by treating clinician as to its relationship to treatment. For a given AE, the proportion of patients who report developing a grade 2-5 of this AE are determined. The number of dose reductions per patient and the reasons for the dose reduction are summarized.
• Tumor response rate among those patients with measurable disease [ Time Frame: 5 years ]
  The tumor response rate is defined as the 100% time the number of patients with a CR or PR (as defined by the RECIST criteria) on 2 consecutive evaluations at least 8 weeks apart divided by the total number of eligible patients who began study treatment. A 90% binomial confidence interval is constructed for the true response rate.
• Progression free survival (PFS) distribution [ Time Frame: From randomization to the first of the following events: local, regional, or distant recurrence, second primary disease of death due to any cause, assessed up to 5 years ]
  The distribution of PFS times will be estimated using the method of Kaplan-Meier.
• Overall survival distribution [ Time Frame: From randomization to death due to any cause, assessed up to 5 years ]
  The distribution of survival times are estimated using the method of Kaplan-Meier.
• Changes in phospho-ERbeta, cystatins 1, 2, 4 and 5, phospho-Smad2/3 and Ki-67 [ Time Frame: 5 years ]
  Patients undergo tumor biopsies prior to the start of treatment and at completion of cycle 1 treatment. These specimens will be undergoing immunohistochemistry (IHC) staining with the following antibodies: phosphorylated (phospho)-ERbeta, cystatins 1, 2, 4 and 5, phospho-Smad2/3 and Ki-67. For each of these biomarkers, a times series plot are constructed so that an individual patient's data will be represented using the same color for each of the five graphs. These graphs are visually inspected for trends within each of the graphs (variation between individuals) as well as across the five graphs (profile of biomarker changes within an individual).

• Incidence of adverse events [ Time Frame: 5 years ]
  An adverse event (AE) is any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medical treatment or procedure that may or may not be considered related to the medical treatment or procedure. All grade 2, 3, 4 or 5 adverse events will be documented and assigned an attribute by treating clinician as to its relationship to treatment. For a given AE, the proportion of patients who report developing a grade 2-5 of this AE are determined. The number of dose reductions per patient and the reasons for the dose reduction are summarized.
• Tumor response rate [ Time Frame: 5 years ]
  The tumor response rate is defined as the 100% time the number of patients with a CR or PR (as defined by the RECIST criteria) on 2 consecutive evaluations at least 8 weeks apart divided by the total number of eligible patients who began study treatment. A 90% binomial confidence interval is constructed for the true response rate.
• Progression free survival (PFS) distribution [ Time Frame: From randomization to the first of the following events: local, regional, or distant recurrence, second primary disease of death due to any cause, assessed up to 5 years ]
  The distribution of PFS times will be estimated using the method of Kaplan-Meier.
• Overall survival distribution [ Time Frame: From randomization to death due to any cause, assessed up to 5 years ]
  The distribution of survival times are estimated using the method of Kaplan-Meier.
• Changes in phospho-ERbeta, cystatins 1, 2, 4 and 5, phospho-Smad2/3 and Ki-67 [ Time Frame: 5 years ]
  Patients undergo tumor biopsies prior to the start of treatment and at completion of cycle 1 treatment. These specimens will be undergoing immunohistochemistry (IHC) staining with the following antibodies: phosphorylated (phospho)-ERbeta, cystatins 1, 2, 4 and 5, phospho-Smad2/3 and Ki-67. For each of these biomarkers, a times series plot are constructed so that an individual patient?s data will be represented using the same color for each of the five graphs. These graphs are visually inspected for trends within each of the graphs (variation between individuals) as well as across the five graphs (profile of biomarker changes within an individual).

PRIMARY OBJECTIVE:

I. To assess the anti-tumor activity of estradiol in patients with locally advanced or metastatic triple negative breast cancer (TNBC) that expresses ERbeta (> 25% moderate or strong nuclear staining) and who have prior receipt of taxane and anthracycline based chemotherapy.

SECONDARY OBJECTIVES:

I. To examine the safety profile of estradiol when administered at a dose of 2 mg three times daily (tid) to women with locally advanced or metastatic TNBC that expresses ERbeta.

II. To examine the changes in phosphorylated (phospho)-ERbeta, cystatins 1, 2, 4 and 5, phospho-Smad2/3 and Ki-67 in tumor biopsies taken before and after the first cycle of treatment.

EXPLORATORY OBJECTIVES:

I. To examine changes in plasma estradiol, serum cytokine and cystatin levels before/after 1 cycle of estradiol.

II. Analyze the global gene expression profiles of paired biopsies prior to and following 1 cycle of therapy.

III. To develop patient derived xenografts (PDX) that are ERalpha negative, HER2 negative and ERbeta positive (Mayo only).

OUTLINE:

Patients receive estradiol orally (PO) TID for days 1-28. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity.

After completion of study treatment, patients are followed up annually for 5 years from study registration.

• Anatomic Stage III Breast Cancer AJCC v8
• Anatomic Stage IIIA Breast Cancer AJCC v8
• Anatomic Stage IIIB Breast Cancer AJCC v8
• Anatomic Stage IIIC Breast Cancer AJCC v8
• Anatomic Stage IV Breast Cancer AJCC v8
• Metastatic Triple-Negative Breast Carcinoma
• Prognostic Stage III Breast Cancer AJCC v8
• Prognostic Stage IIIA Breast Cancer AJCC v8
• Prognostic Stage IIIB Breast Cancer AJCC v8
• Prognostic Stage IIIC Breast Cancer AJCC v8
• Prognostic Stage IV Breast Cancer AJCC v8
• Recurrent Breast Carcinoma

Inclusion Criteria:

• PRE-SCREENING CRITERIA (STEP 0): History of locally advanced or metastatic breast cancer that is ERalpha negative or low (< 10% nuclear staining) and HER2 negative.

  • Note: HER2 negative disease per 2013 American Society of Clinical Oncology/College of American of Pathologists (ASCO/CAP) guidelines, one of the following must apply:

    • 0 or 1+ by immunohistochemistry (IHC) and not amplified by in situ hybridization (ISH);
    • 0 or 1+ by IHC and ISH not done;
    • 2+ by IHC and not amplified by ISH or;
    • IHC not done and not amplified by ISH.

• PRE-SCREENING CRITERIA (STEP 0): =< 2 prior chemotherapy regimens for treatment of metastatic breast cancer.

  • Note: Prior use of monoclonal antibodies targeting PD1, PDL1 is allowed (if administered as monotherapy it is not counted as a chemotherapy regimen).
• PRE-SCREENING CRITERIA (STEP 0): Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
• PRE-SCREENING CRITERIA (STEP 0): Willing to submit a biopsy specimen from locally recurrent or metastatic site (or primary if metastatic site not available) of breast cancer for ERbeta staining to Mayo Clinic Anatomic Pathology.
• PRE-REGISTRATION CRITERIA (STEP 1): Presence of moderate or strong nuclear ERbeta staining in > 25% of cells in specimen submitted during Pre-Screening Step.
• PRE-REGISTRATION CRITERIA (STEP 1): Willing to undergo a standard of care biopsy of locally recurrent or metastatic breast cancer for ERalpha, PR, and HER2 as well as additional research cores.

• PRE-REGISTRATION CRITERIA (STEP 1): Measurable or non-measurable disease as defined by Response Evaluation Criteria in Solid Tumors (RECIST) criteria.

  • Note: The tumor lesion biopsied during the pre-registration period is not considered measurable disease.

• PRE-REGISTRATION CRITERIA (STEP 1): If history of brain metastases must meet the following criteria:

  • Patients with a history of brain metastases are eligible only if they are asymptomatic and have stable disease for >= 3 months, including < 28 days of prior to pre-registration.
  • Not receiving steroids for brain metastases.
• PRE-REGISTRATION CRITERIA (STEP 1): ECOG performance status 0 or 1.
• PRE-REGISTRATION CRITERIA (STEP 1): Prior treatment with paclitaxel and anthracycline (in combination or in separate regimens) either in the adjuvant or metastatic setting,
• PRE-REGISTRATION CRITERIA (STEP 1): =< 2 prior chemotherapy regimens for treatment of metastatic breast cancer. (Note: Prior use of monoclonal antibodies targeting PD1, PDL1 is allowed.)

• PRE-REGISTRATION CRITERIA (STEP 1): Women must be postmenopausal.

  • NOTE: Postmenopausal status is verified by:

    • Prior bilateral surgical oophorectomy, or
    • Age >= 60 years, or
    • Age < 60 years with no menses for > 1 year with follicle stimulating hormone (FSH) and estradiol levels within postmenopausal range, according to institutional standard.
• PRE-REGISTRATION CRITERIA (STEP 1): Able to swallow oral medications.

• PRE-REGISTRATION CRITERIA (STEP 1): Willingness to stop use of strong inducers or inhibitors of CYP3A4 prior to registration.

  • NOTE: Use of strong inducers or inhibitors is allowed during pre-registration as long as patient will complete course prior to registration.

• REGISTRATION CRITERIA (STEP 2): Histologic confirmation, from local lab that tumor is ERalpha negative (< 1% nuclear staining), and HER2 negative.

  • Note: HER2 negative disease per 2013 ASCO/CAP guidelines, one of the following must apply:

    • 0 or 1+ by immunohistochemistry (IHC) and not amplified by in situ hybridization (ISH);
    • 0 or 1+ by IHC and ISH not done;
    • 2+ by IHC and not amplified by ISH or;
    • IHC not done and not amplified by ISH.
• REGISTRATION CRITERIA (STEP 2): Hemoglobin >= 8 g/dL (=< 14 days prior to registration).
• REGISTRATION CRITERIA (STEP 2): Platelet count >= 75,000/mm^3 (=< 14 days prior to registration).
• REGISTRATION CRITERIA (STEP 2): Creatinine =< 1.5 x upper limit of normal (ULN) (=< 14 days prior to registration).
• REGISTRATION CRITERIA (STEP 2): Total bilirubin =< 1.5 x ULN (=< 14 days prior to registration).

• REGISTRATION CRITERIA (STEP 2): Aspartate aminotransferase/serum glutamic-oxaloacetic transaminase (AST/SGOT) 2.5 x ULN (=< 14 days prior to registration).

  • For patients with liver metastasis =< 5 x ULN.

Exclusion Criteria:

• PRE-REGISTRATION CRITERIA: Uncontrolled intercurrent illness including, but not limited to:

  • Ongoing or active infection.
  • Symptomatic congestive heart failure.
  • Unstable angina pectoris.
  • Uncontrolled symptomatic cardiac arrhythmia.
  • Uncontrolled hypertension (defined as blood pressure > 160/90).

• PRE-REGISTRATION CRITERIA: Deep vein thrombosis / pulmonary embolism (DVT/PE) =< 12 months prior to pre-registration.

  • Note: Patients who are on anticoagulant therapy for maintenance are eligible as long as the DVT and/or PE occurred > 6 months prior to pre-registration, and there is no evidence for active thrombosis (either DVT or PE).
• PRE-REGISTRATION CRITERIA: Stroke =< 6 months prior to pre-registration.
• PRE-REGISTRATION CRITERIA: Two or more episodes of DVT and/or PE =< 5 years prior to pre-registration.
• PRE-REGISTRATION CRITERIA: Abnormal uterine bleeding =< 6 months prior to pre-registration
• PRE-REGISTRATION CRITERIA: History of coagulopathy.

• PRE-REGISTRATION CRITERIA: Other active second malignancy other than non-melanoma skin cancers within 3 years prior to pre-registration.

  • NOTE: A second malignancy is not considered active if all treatment for that malignancy is completed and the patient has been disease-free for >= 3 years prior to pre-registration.

• REGISTRATION CRITERIA: None of the following therapies are allowed =< 14 days prior to registration.

  • Chemotherapy.
  • Immunotherapy.
  • Biologic therapy.
  • Hormonal therapy.
  • Monoclonal antibodies.
  • Anti-HER2 or other "targeted" (e.g. mTOR) therapy.
  • Note: Any adverse events derived from these therapies must be =< grade 2 prior to starting study therapy (exceptions for alopecia).