(Z)-Endoxifen for the Treatment of Premenopausal Women With ER+/HER2- Breast Cancer
Status:
Not yet recruiting
Trial end date:
2025-07-01
Target enrollment:
Participant gender:
Summary
This open-label research study is studying (Z)-endoxifen as a possible treatment for
pre-menopausal (still having periods) women with ER+/HER2- breast cancer. This study includes
a pharmacokinetic part (PK, how the drug works in your body) and a treatment part. The
primary purpose of the study is to see how (Z)-endoxifen works on tumor cell growth by taking
a biopsy after 4 weeks of treatment to measure Ki-67. Ki-67 is a cancer marker that indicates
how well the treatments work to slow cancer cell growth. Overall, this study will help
determine if (Z)-endoxifen can effectively treat premenopausal women with ER+/HER2- breast
cancer without the need for monthly injections of goserelin which is a medication given to
block the ovaries from making estrogen (also called ovarian suppression). Studies have shown
harmful long-term effects of ovarian suppression in premenopausal women.
The PK part of the study will be enrolled first, enrolling about 6 study participants who
will all receive oral once daily (Z)-endoxifen treatment. This part of the study will help
select the dose of (Z)-endoxifen to use in the treatment part by measuring the levels of
(Z)-endoxifen in the blood stream and determine how long it takes for the body to remove it.
About 160 study participants will be enrolled in the treatment part. The treatment part will
help to determine how oral once daily (Z)-endoxifen, when taken by itself, compares to oral
once daily exemestane (a medication that decreases the amount of estrogen in the body, also
known as an aromatase inhibitor) and monthly injections of goserelin. Exemestane and
goserelin taken together is a standard treatment regimen for premenopausal patients with
ER+/HER2- breast cancer. Study participants are randomly assigned to treatment with an equal
(50/50) chance to be assigned to (Z)-endoxifen or standard treatment.
Study participation is up to 24 weeks of treatment followed by surgery.