Abstract 1029: The anti-androgen seviteronel sensitizes triple-negative breast cancer to chemotherapy

Abstract Therapeutic strategies that improve survival outcomes for advanced-stage breast cancers have proven a major clinical challenge. Here, we define an androgen receptor (AR) signalling network that governs the maintenance and de novo formation of cancer stem cells in triple-negative breast cancer. In response to chemotherapy, AR activation switches cells into a cancer stem cell state, while AR antagonism suppresses cancer stem cell formation and function. In vivo, we validate that the AR antagonist, seviteronel, significantly improves chemotherapy-mediated inhibition of primary and metastatic tumour growth. Analysing three independent triple-negative breast cancer patient cohorts we identify that cytoplasmic AR expression prognosticates poor survival in treatment-naïve patients and predicts poor response to chemotherapy. Additionally, Phase II clinical trial data demonstrates that seviteronel treatment followed by chemotherapy improved survival outcomes in triple-negative breast cancer patients expressing high cytoplasmic AR levels. Seviteronel combined with chemotherapy represents a promising therapeutic strategy for triple-negative breast cancer patients. Citation Format: Beatriz P. San Juan, Soroor Hediyah-Zadeh, Laura Rangel, Vanina Rodriguez, Heloisa H. Milioli, Felix Kohane, Carley A. Purcell, Therese E. Hickey, Leonard D. Goldstein, John G. Lock, Melissa J. Davis, Christine L. Chaffer. The anti-androgen seviteronel sensitizes triple-negative breast cancer to chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1029.