There will be two parts to the study: Part 1, a dose escalation phase, in which the MTD and RP2D will be determined in up to 20 patients with metastatic breast or other specified solid tumors, regardless of receptor status; and Part 2, a dose expansion phase in which a preliminary estimate of efficacy will be made in an expansion group of up to 20 patients with glucocorticoid receptor-positive metastatic TNBC at the RP2D.