Actively Recruiting
(Z)-Endoxifen for the Treatment of Premenopausal Women With ER+/HER2- Breast Cancer
Led by Atossa Therapeutics, Inc. · Updated on 2025-10-30
87
Participants Needed
15
Research Sites
215 weeks
Total Duration
On this page
Sponsors
A
Atossa Therapeutics, Inc.
Lead Sponsor
I
InClin
Collaborating Sponsor
AI-Summary
What this Trial Is About
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.
CONDITIONS
Official Title
(Z)-Endoxifen for the Treatment of Premenopausal Women With ER+/HER2- Breast Cancer
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Female sex assigned at birth (female to male transgender individuals without hormonal therapy may be considered)
- Age 18 years or older
- Not lactating, pregnant, or planning pregnancy within next year and agrees to prevent pregnancy during and 9 months after treatment
- Must use at least one non-hormonal highly effective contraception method during study participation
- Premenopausal status defined by menstruation or plasma estradiol levels
- Pathologic confirmation of strongly estrogen receptor positive (ER+; ER 267% or Allred Score 6-8)
- ECOG Performance Status 0 to 2
- Nottingham Grade 1 or 2
- HER2-negative breast cancer confirmed by standard guidelines
- Clinical T2 or T3 invasive breast cancer (AJCC 8th edition)
- Clinical N0 or N1 invasive breast cancer (AJCC 8th edition)
- MRI performed within 35 days of registration
- Provided written informed consent and understands trial purpose and risks
- Willing to provide blood and breast tissue samples for research
You will not qualify if you...
- Bilateral invasive breast cancer or inflammatory breast cancer
- Prior breast cancer diagnosis or treatment, or other active malignancy within past 2 years (exceptions apply)
- Uncontrolled illnesses including infections requiring certain treatments, symptomatic heart failure, unstable angina, uncontrolled arrhythmias, hypertension, or diabetes (HbA1c >7%)
- Marked QT/QTc prolongation within 28 days prior to registration
- Known cataracts or retinopathy
- History of deep vein thrombosis or pulmonary embolism
- Known activated protein C resistance
- End stage kidney disease requiring dialysis
- Laboratory abnormalities: high bilirubin, elevated liver enzymes, low platelet count, low hemoglobin
- Use of hormonal therapies including birth control or hormone replacement within 1 week of registration
- Allergy to study drugs or components
- Participation in another investigational trial within 6 months
- Known metastatic disease
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Trial Site Locations
Total: 15 locations
1
Mayo Clinic Arizona
Phoenix, Arizona, United States, 85054
Actively Recruiting
2
University of Arizona
Tucson, Arizona, United States, 85719
Actively Recruiting
3
California Research Institute
Los Angeles, California, United States, 90027
Actively Recruiting
4
Mayo Clinic Florida
Jacksonville, Florida, United States, 32224
Actively Recruiting
5
Northwestern University
Chicago, Illinois, United States, 60611
Actively Recruiting
6
St. Elizabeth Healthcare
Edgewood, Kentucky, United States, 41017
Actively Recruiting
7
Henry Ford Cancer Institute
Detroit, Michigan, United States, 48202
Actively Recruiting
8
Mayo Clinic Rochester
Rochester, Minnesota, United States, 55905
Actively Recruiting
9
Washington University School of Medicine
St Louis, Missouri, United States, 63110
Actively Recruiting
10
Avera Cancer Institute
Sioux Falls, South Dakota, United States, 57105
Actively Recruiting
11
Vanderbilt Ingram Cancer Center
Nashville, Tennessee, United States, 37204
Actively Recruiting
12
Baylor University
Houston, Texas, United States, 77054
Actively Recruiting
13
Tranquility Research
Webster, Texas, United States, 77598
Withdrawn
14
Bon Secours Cancer Institute
Midlothian, Virginia, United States, 23114
Actively Recruiting
15
Fred Hutchinson Cancer Center
Seattle, Washington, United States, 98109
Actively Recruiting
Research Team
H
Hayley Erickson
CONTACT
How is the study designed?
Study Type
INTERVENTIONAL
Masking
NONE
Allocation
NON_RANDOMIZED
Model
PARALLEL
Primary Purpose
TREATMENT
Number of Arms
4
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