(Z)-Endoxifen for the Treatment of Premenopausal Women With ER+/HER2- Breast Cancer (NCT05607004)
🩺 Plain-English Summary (8th-Grade Level)
This open-label research study is studying (Z)-endoxifen as a possible treatment for pre-menopausal women with ER+/HER2- breast cancer. (Z)-endoxifen belongs to a group of drugs called selective estrogen receptor modulators or "SERM", which help block estrogen from attaching to cancer cells. This study has two parts: a pharmacokinetic part and a treatment part. The PK part (how the body processes the drug) will enroll about 18 participants. All participants will take (Z)-endoxifen capsules daily. Twelve participants will be randomly assigned (50/50 chance) to take (Z)-endoxifen alone or (Z)-endoxifen with a monthly injection of goserelin a drug that temporarily stops the ovaries from making estrogen. This part will help determine the best dose of (Z)-endoxifen by measuring the drug levels in the blood and how long the body takes to remove it. The Treatment Cohort has been simplified to a single study arm (Z)-endoxifen + goserelin. Up to 20 participants will be enrolled that have a baseline Ki-67 ≤ 10% and 45 participants will be enrolled that have a baseline Ki-67\>10%. A key goal of the study is to see if (Z)-endoxifen can slow down or stop tumor growth as measured by a reduction in Ki-67 levels. Tumor tissue samples will be taken by breast biopsy after about 4 weeks of treatment to check levels of this biomarker. If the tumor shows signs of response, participants can continue treatment for up to 24 weeks or until they have surgery. Study participation is up to 6 months (24 weeks of treatment) followed by surgery and a one-month follow up visit.
Who can join: To join this study, participants generally need to meet the listed inclusion criteria (16 items) and avoid the listed exclusions (28 items).
Location: Mayo Clinic Arizona — Phoenix, Arizona
📋 "Do I Qualify?" — 1-Minute Self Screener
Instant ChecklistCheck every box below. If you can check all of them, you may meet the study's basic screening requirements (final eligibility is confirmed by the site team).
Usually NOT eligible if any of the following apply:
- Exclusion Criteria:
- Bilateral invasive breast cancer; Inflammatory breast cancer defined as clinically significant erythema of the breast and/or documented dermal lymphatic invasion or bilateral invasive breast cancer (patients with pre-malignant disease or DCIS/LCIS in contralateral breast are eligible)
- Prior diagnosis or treatment for breast cancer, including carcinoma in situ, or history of any other active malignancy within the past 2 years prior to study entry with the exception of:
- Adequately treated in situ carcinoma of the cervix uteri
- Adequately treated basal cell carcinoma or localized squamous cell carcinoma of the skin
- Any other malignancy with a life expectancy of less than 2 years
- Any uncontrolled intercurrent illness including, but not limited to:
- Ongoing or active infection requiring systemic treatment with strong inhibitors/inducers of CYP450 enzymes (including bacterial infection, fungal infection, or detectable viral infection).
- Symptomatic congestive heart failure,
- Unstable angina pectoris,
- Uncontrolled symptomatic cardiac arrhythmias
- Uncontrolled hypertension
🔍 Extracted verbatim from the official NIH eligibility criteria. Always confirm with the study coordinator.
📍 All Participating Trial Locations (14 Sites)
- Mayo Clinic Arizona — Phoenix, Arizona
- University of Arizona — Tucson, Arizona
- California Research Institute — Los Angeles, California
- Mayo Clinic Florida — Jacksonville, Florida
- Northwestern University — Chicago, Illinois
- St. Elizabeth Healthcare — Edgewood, Kentucky
- Henry Ford Cancer Institute — Detroit, Michigan
- Mayo Clinic Rochester — Rochester, Minnesota
- Washington University School of Medicine — St Louis, Missouri
- Avera Cancer Institute — Sioux Falls, South Dakota
- Vanderbilt Ingram Cancer Center — Nashville, Tennessee
- Baylor University — Houston, Texas
- Bon Secours Cancer Institute — Midlothian, Virginia
- Fred Hutchinson Cancer Center — Seattle, Washington
💰 Cost, Insurance & Patient Rights
- 100% Free Items: The investigational treatment and protocol-required procedures are supplied at zero cost by the sponsor.
- Routine Patient Care: Under federal law (ACA § 2709) and many state statutes, routine care costs are covered during participation.
- Voluntary Participation: You may withdraw at any time without affecting your standard medical care.