US Clinical Trial NCT03941730

Therapeutic Targeting of ER Beta in Triple Negative Breast Cancer  May 6, 2019

PRIMARY OBJECTIVES:

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) thrice daily (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.

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