Abstract 1341: Endocrine deprivation therapy increases the sensitivity of breast cancer cells to T cell-mediated lysis independently of estrogen receptor or androgen receptor status

Estrogen deprivation therapy has been used as the first line adjuvant hormonal therapy for breast cancer for over 20 years. Tamoxifen, the first drug discovered to inhibit estrogen receptor signaling, is used to treat premenopausal women with estrogen receptor positive tumors. Although tamoxifen can be therapeutic in most women with estrogen receptor positive tumors, some women do not respond and others eventually develop resistance. In addition, tamoxifen has minimal effect on the growth of estrogen receptor negative tumors, including triple negative breast cancer, which has the poorest prognosis. Furthermore, prolonged administration of estrogen deprivation therapy can increase a patient's risk of developing secondary uterine/endometrial cancer, stroke and pulmonary embolism. As breast tumors develop resistant to estrogen deprivation therapy, in some cases, they can switch from estrogen to androgen-dependent growth. Recent studies have shown that enzalutamide, an androgen receptor signaling inhibitor, can reduce the growth of breast tumor cells regardless of their estrogen receptor status. We sought to determine if tamoxifen or enzalutamide could increase the sensitivity of breast tumor cells to T cell-mediated lysis, which would improve their therapeutic value by increasing the number of patients that could derive benefit from these therapies and possibly reducing the duration of treatment required for clinical benefit. We have observed that endocrine deprivation therapy, ...

Source: Cancer Research - August 2, 2015 Category: Cancer & Oncology Authors: Kwilas, A. R., Ardiani, A., Gameiro, S. R., Hodge, J. W. Tags: Immunology Source Type: research