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Abstract #4793

MS-275 and Letrozole Treatments Inhibit Tumor Growth and Reduce Phosphomonoesters in Triple Negative MDA-MB-231 Tumors

Tariq Shah1, Nguyen Nguyen2, Sara Sukumar2, Zaver M. Bhujwalla1

1JHU ICMIC Program, Russell H Morgan Department of Radiology and Radiological Sciences, Johns Hopkins School of Medicine , Baltimore, MD, United States; 2Breast Cancer Program, Sidney Kimmel Comprehensive Cancer Center , Johns Hopkins School of Medicine, Baltimore, MD, United States

The absence of ER/PR/Her-2/neu receptors in triple negative breast cancers makes them difficult to treat. Histone deacetylase (HDAC) inhibitors have been found to re-express the estrogen receptor (ER). Combining an HDAC inhibitor with hormonal treatment is therefore an attractive choice for triple negative breast cancers. Here we have investigated the effect of the HDAC inhibitor MS-275, the aromatase inhibitor letrozole that suppresses estrogen, and their combination in vivo in a triple negative human breast cancer xenograft using proton and phosphorus MR spectroscopy. We observed a significant reduction of choline metabolites following HDAC inhibition and combined HDAC and aromatase inhibition.