A Pilot Study of Estradiol Followed by Exemestane for Reversing Endocrine Resistance in Postmenopausal Women With Hormone Receptor-Positive Metastatic Breast Cancer. (26th September 2014)

• Record Type: Journal Article
• Authors: Chalasani, Pavani; Stopeck, Alison; Clarke, Kathryn; Livingston, Robert
• Is Part Of: Oncologist. Volume 19:Number 11(2014)
• Page Start: 1127
• Page End: 1128
• Publication Date: 2014-09-26
• Subjects: Oncology -- Periodicals; Tumors -- Periodicals; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Oncology; Tumors; Neoplasms; Electronic journals; Periodicals; Periodicals; 616.994
• DOI: 10.1634/theoncologist.2014-0306
• Languages: English
• ISSNs: 1083-7159

Abstract

Abstract: Background: Endocrine resistance is a frequent complication, and strategies to reverse it are a high research priority for metastatic breast cancer (MBC) that is hormone receptor positive. Preclinical data suggest re-exposure to estrogen induces tumor regression in tamoxifen-resistant tumors. We conducted a pilot study to determine whether short-term estradiol exposure would reverse endocrine resistance and resensitize tumors Methods: Postmenopausal women with estrogen receptor-positive MBC whose disease had progressed after receiving at least one prior endocrine therapy were eligible for the study. Patients were initially treated with 6 mg/day estradiol, and those who had not progressed after 3 months were then switched to exemestane. Results: Thirteen patients were evaluable for toxicity and response. No grade 3 or 4 toxicities were observed. Of the 13 patients who initiated estradiol therapy, 6 patients (46%) had not experienced disease progression at month 3 and were switched to exemestane. On exemestane, disease progression was documented in five patients, with one having stable disease as best response. Median progression-free survival for all patients was 4.8 months (range: 0.6–9.5 months). Conclusion: Treatment with an estrogen prior to resuming antiestrogen treatments was not effective at reversing hormone resistance; however, low-dose estradiol treatment had measurable clinical activity with minimal toxicity and should be considered as a therapeutic option for hormone-refractory MBC.