Phase II study of OsciLLation of ER activitY levels through sequential estradiol/anti-estrogen therapies in ER+/HER2- metastatic or advanced breast cancer (POLLY)
Before anti-estrogens such as tamoxifen were developed to treat estrogen receptor
(ER)-positive breast cancer, high-dose estrogen therapies were used. This seems
counterintuitive since anti-estrogens block ER function, while estrogens increase ER
function, but these therapies are effective to similar extents for the treatment of
metastatic ER+ breast cancer. Estrogen therapies are most effective against cancers that
develop resistance to anti-estrogens, likely because such cancers have adapted to grow
without ER function, and restoring ER function (with estrogen) is damaging to the cancer
cells. In some patients with ER+ breast cancer that becomes resistant to anti-estrogens,
treatment with the estrogen 17B-estradiol induces tumor response. Furthermore, when
17B-estradiol-sensitive tumors eventually become resistant to 17B-estradiol, switching back
to anti-estrogen therapy is often effective. These observations suggest that cancers can
alternate between anti-estrogen-sensitive and 17B-estradiol-sensitive states. The
investigators hypothesize that treatment with alternating 17B-estradiol / anti-estrogen
therapies on a defined 8-week / 16-week schedule will more effectively prevent cancer growth
than continuous treatment with either type of therapy in patients with metastatic
anti-estrogen-resistant ER+ breast cancer.
View more details from ClinicalTrials.gov.
For more information about a clinical trial, clinical trial eligibility, or informed consent, contact our research nurses by phone or email:
Please Note: Any eligibility criteria noted are subject to change. Our research nurses can provide you with the most current eligibility and exclusion criteria. Any study involvement to be undertaken must ultimately be determined on an individual basis.