Safety, Tolerability, and Pharmacokinetics of Proxalutamide Therapy in Women With Metastatic Breast Cancer

This study is a multi-center, open-label, dose-esclation study. Subjects will be enrolled to the 100mg, 200mg, 300mg, 400mg and 500mg group in turn. Unless DLT was found, the dose esclation will continue. 28 days of DLT observation period is needed after 7-day single dose administration, until disease progression, intolerable toxicities (AEs), or withdrawn consent. After the completion of stage 1, 2 doses for the stage 2 will be determined. In stage 2, patients with AR-positive metastatic breast cancer will be selected to explore the efficacy and safety of proxalutamide, and biomarkers will be explored.