Molecular insights to AR antagonist and PI3K inhibitor efficacy in patients with AR+ metastatic triple-negative breast cancer

Preclinical data demonstrating androgen receptor (AR)-positive (AR+) TNBC cells are sensitive to AR antagonists and PI3K inhibition catalyzed an investigator-initiated, multi-institutional phase Ib/II study TBCRC032. The trial investigated the safety and efficacy of the AR-antagonist enzalutamide alone or in combination with the PI3K inhibitor taselisib in patients with metastatic AR+ (≥10%) breast cancer. RNA-seq and DNA-seq was performed on pre-treatment metastatic biopsies from patients enrolled on the trial. Matched pre- and post-treatment specimens were evaluated for changes in RNA expression.