AR and breast cancer: In addition, preclinical results provide a strong rationale for using AR as a biomarker for selecting TNBC patients for clinical trials, which would investigate the efficacy of therapeutic combinations that simultaneously target AR and PI3K. For instance, one clinical trial Phase 1 (NCT03207529) evaluates alpelisib + enzalutamide in AR-positive and PTEN-positive metastatic BC [55].