Abraxane® With or Without Mifepristone for Advanced, Glucocorticoid Receptor-Positive, Triple-Negative Breast Cancer

This is a randomized, placebo-controlled, double-blind, phase II trial of nab-paclitaxel with or without mifepristone for advanced, glucocorticoid receptor-positive, triple-negative breast cancer. A total of 64 patients will receive nab-paclitaxel. Patients will be randomly assigned to either receive placebo or to receive mifepristone daily on the day prior to and day of each dose of nab-paclitaxel. Patients will be enrolled over 12 months and followed for 12 months following completion of study. To expand and follow up on the investigators understanding of a potential pharmacokinetic (PK) interaction between nab-paclitaxel and mifepristone, investigators will perform PK studies in the first 20 patients enrolled at pre-specified "PK sites".