Entinostat, Lapatinib Ditosylate and Trastuzumab in Treating Patients With Locally Recurrent or Distant Relapsed Metastatic Breast Cancer Previously Treated With Trastuzumab Only

PRIMARY OBJECTIVES: I. To determine the recommended phase II dose (RP2D) for entinostat in combination with lapatinib (lapatinib ditosylate) in patients whom trastuzumab has failed for human epidermal growth factor receptor 2+ (HER2+) metastatic breast cancer (Phase I). II. To determine the maximum tolerated dose (MTD) for entinostat in combination with lapatinib and trastuzumab in patients whom trastuzumab has failed for HER2+ metastatic breast cancer (Phase I Trastuzumab Cohort). SECONDARY OBJECTIVES: I. To determine the toxicity of combination therapy with entinostat and lapatinib in patients whom trastuzumab has failed for HER2+ metastatic breast cancer (Phase I). II. To determine the toxicity of entinostat in combination with lapatinib and trastuzumab in patients whom trastuzumab has failed for HER2+ metastatic breast cancer (Phase I Trastuzumab Cohort). EXPLORATORY OBJECTIVES: I. Determine whether the 2-drug combination modulates the expression of HER2, phosphorylated HER2 (pHER), epidermal growth factor receptor (EGFR), phosphorylated EGFR (pEGFR), v-akt murine thymoma viral oncogene homolog 1 (Akt), and phosphorylated Akt (pAkt) in breast tumors and/or circulating tumor cells (CTCs). OUTLINE: This is a dose-escalation study of entinostat. Patients receive entinostat orally (PO) on days 1 and 15 and lapatinib tosylate PO on days 1-28. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. Patients in the Phase I trastuzumab cohort also receive maintenance dose of trastuzumab intravenously (IV) over 30-90 minutes every 3 weeks. After completion of study treatment, patients are followed up for 28 days or until toxicities are resolved.