Carboplatin, gemcitabine, and mifepristone for advanced breast and recurrent/persistent epithelial ovarian cancer

Preclinical models of glucocorticoid receptor (GR)-positive breast cancer (BC) and ovarian cancer (OC) suggest GR activity inhibits chemotherapy-induced apoptosis, and GR antagonism using mifepristone (Mif) enhances cytotoxicity. We performed a phase I trial combining mifepristone, carboplatin (C), gemcitabine (G).

A standard "3 + 3" dose escalation scheme was used. Objectives were safety and to determine the maximum tolerated dose (MTD) of Mif + CG. CG was administered intravenously on days 1 and 8 of a 21-day cycle, and mifepristone was administered orally the day before and day of chemotherapy.

Thirty-one patients enrolled with a median age of 54 years; the median prior metastatic regimens were one. Twenty-five patients were evaluable for dose-limiting toxicities (DLT) including 16 BC and 9 OC. Dose was de-escalated to dose level (DL) -1 due to 2/4 neutropenia-related DLT's. DLT definition was updated to exclude hematologic DLTs starting at DL-1. The dose  was further de-escalated due to neutropenia, and 2/3, 1/4 and 0/6 patients experienced a DLT at DL-1, DL-2, and DL-3, respectively. At DL-1, prophylactic pegylated granulocyte colony-stimulating factor (G-CSF) was instituted. Dose levels -1 and -2 were expanded to add 3 and 6 patients, respectively, to evaluate tolerability  in dose levels -1a and -2a. There were 3 major responses (1CR, 2PR) at DL1, and 1 CR at DL-1. No responses were observed at lower levels.

The MTD was carboplatin AUC 2  + gemcitabine 600 mg/m² on D1 and 8 with Mif 300 mg D-1 and D1 with pegylated G-CSF administered on day 9 of a 21-day cycle.