PRIMARY OBJECTIVES:~I. To determine the safety and tolerability of GDC-0941 when given in combination with cisplatin in patients with androgen receptor-negative (AR-) triple negative (TN) metastatic breast cancer (MBC): assessment of dose limiting toxicities (DLTs) during the first 4 weeks of treatment (cycle 1); determination of the maximally tolerated dose (MTD) and recommended phase II dose of GDC-0941 given in combination with cisplatin. (Phase IB)~II. To evaluate the efficacy, as measured by the overall response rate (ORR), of cisplatin + GDC-0941 versus cisplatin alone in patients with AR- TN MBC. (Phase II)~SECONDARY OBJECTIVES:~I. To determine the clinical benefit rate (CBR) of cisplatin + GDC-0941 in patients with AR- TN MBC.~II. To determine the time to disease progression (TTP) of cisplatin + GDC-0941 versus cisplatin alone in patients with AR- TN MBC.~TERTIARY OBJECTIVES:~I. To characterize pharmacokinetics of GDC-0941 when administered in combination with cisplatin.~II. To explore predictors of response and mechanisms of resistance based on exploratory analysis of tumor tissue obtained through biopsies.~III. To assess the prognostic effects of phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) mutations and phosphatase and tensin homolog (PTEN) loss on TTP and CBR.~OUTLINE: This is a phase I, dose-deescalation study of PI3K inhibitor GDC-0941 followed by a randomized phase II study.~PHASE I: Patients receive cisplatin intravenously (IV) over 1 hour on days 1, 8, and 15 and PI3K inhibitor GDC-0941 orally (PO) once daily (QD) on days 2-6, 9-13, 16-20, and 23-27. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity.~PHASE II: Patients are randomized to 1 of 2 treatment arms.~ARM I: Patients receive cisplatin IV over 1 hour on days 1, 8, and 15. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. Patients may crossover to Arm II upon disease progression.~ARM II: Patients receive cisplatin as in Arm I and PI3K inhibitor GDC-0941 PO QD on days 2-6, 9-13, 16-20, and 23-27. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity.~After completion of study treatment, patients are followed up for 30 days.
This phase I/II trial study evaluates the tolerability and best tolerated dose of the PI3K inhibitor GDC-0941 when given with the chemotherapy cisplatin. This study will also examine how well the combination of GDC-0941 and cisplatin work in treating patients with androgen receptor negative triple negative metastatic breast cancer. Patients will be randomized to receive cisplatin alone or cisplatin with GDC-0941 in the phase II portion. Those receiving cisplatin alone can receive GDC-0941 upon progression of their disease. Cisplatin is a chemotherapy which has been shown to be effective in treating triple negative breast cancer. Preclinical studies show that adding a PI3K inhibitor such as GDC-0941 to cisplatin may be a more effective treatment for breast cancer.