Studies targeting the androgen receptor (AR) signaling pathway in aromatase inhibitor (AI)-resistant breast cancer are limited.Bicalutamide, one of the commonly used AR inhibitors in prostate cancer, in combination with AI, did not show synergistic activity in patients with estrogen receptor-positive and AI-resistant disease in this phase II, single-arm study.The clinical benefit rate and objective response rate at 6 months were 16.7% and 0%, respectively, and the study was terminated after the first stage.
Furthermore, expression of estrogen receptor (ER) is a high relevant molecular event with key therapeutic implications in breast cancer, and androgen receptor (AR) signaling is involved in the pathogenesis of breast cancer and represents a novel target with crescent importance in this disease.
All nine patients with ESR1 mutations were treated with aromatase inhibitors (AIs) prior to sampling, and the mutations were frequently detected in patients who received AI treatments in the metastatic setting.
Patients with estrogen receptor positive (ER+)/AR+ BC treated with AIs were at increased risk of disease progression compared to ER+/AR+ non-AI treated and ER+/AR- AI treated cases.
To assess the prognostic and predictive value of circulating ESR1 mutation and its kinetics before and after progression on aromatase inhibitor (AI) treatment.
Aromatase inhibitor (AI) treatment is first-line systemic treatment for the majority of postmenopausal breast cancer patients with estrogen receptor (ER)-positive primary tumor.
Androgen receptor (AR) signaling exerts an antiestrogenic, growth-inhibitory influence in normal breast tissue, and this role may be sustained in estrogen receptor α (ERα)-positive luminal breast cancers.
There is emerging evidence that the balance between estrogen receptor-alpha (ER(alpha)) and androgen receptor (AR) signaling is a critical determinant of growth in the normal and malignant breast.