NCT02188745

ER Reactivation Therapy for Breast Cancer

Phase II Pre-emptive OsciLLation of ER activitY Levels Through Alternation of Estradiol/Anti-estrogen Therapies Prior to Disease Progression in ER+/HER2- Metastatic or Advanced Breast Cancer

• Status: Completed
• Phase: Phase 2
• Study type: Interventional
• Enrollment: 19 (actual)
• Sponsor: Dartmouth-Hitchcock Medical Center · Academic / Other
• Sex: Female
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

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.

Detailed description

Metastatic breast cancer is rarely cured by current therapies. ER+ breast cancers ultimately become resistant to all available anti-estrogens. Response rates to estrogens are similar to those of anti-estrogens in the metastatic setting. Given that ER+ breast cancers are often responsive to anti-estrogens and estrogens, alternating anti-estrogen/estrogen therapies may be more effective than continuous treatment with either type of agent. Anecdotal evidence indicates that such a strategy of alternating therapies is effective in some patients. Preclinical evidence suggests that anti-estrogen-resistant ER+ breast cancers are sensitized to the anti-tumor effects of estrogens. Such cells harbor subpopulations that can ultimately regain the ability to grow in the presence of estrogens, and revert to their anti-estrogen-sensitive state. The investigators will formally test whether alternating 17B-estradiol/anti-estrogen therapies is effective for the management of anti-estrogen-resistant metastatic ER+/HER2- breast cancer, and to identify molecular biomarkers that predict tumor response to 1) 17B-estradiol and 2) alternating 17B-estradiol/anti-estrogen therapies. If successful, this study would present a novel strategy to manage metastatic ER+/HER2- breast cancer by pre-emptively switching therapies prior to disease progression.

Conditions

• Metastatic Breast Cancer

Interventions

Type	Name	Description
DRUG	17B-estradiol	Anti-estrogen
DRUG	Letrozole	Aromatase inhibitors work by blocking estrogen receptors; they stop a key enzyme (called aromatase) from changing other hormones into estrogen. This lowers estrogen levels in the body, taking away the fuel that estrogen receptor-positive breast cancers need to grow.
DRUG	Anastrozole	Aromatase inhibitors work differently from tamoxifen and raloxifene. Instead of blocking the estrogen receptors, they stop a key enzyme (called aromatase) from changing other hormones into estrogen. This lowers estrogen levels in the body, taking away the fuel that estrogen receptor-positive breast cancers need to grow.
DRUG	Exemestane	Aromatase inhibitors work differently from tamoxifen and raloxifene. Instead of blocking the estrogen receptors, they stop a key enzyme (called aromatase) from changing other hormones into estrogen. This lowers estrogen levels in the body, taking away the fuel that estrogen receptor-positive breast cancers need to grow.

Timeline

• Start date: 2016-03-11
• Primary completion: 2024-01-05
• Completion: 2024-07-05
• First posted: 2014-07-14
• Last updated: 2024-07-17

Locations

3 sites across 1 country: United States