Identifying and Targeting Sporadic Oncogenic Genetic Aberrations in Mouse Models of Triple Negative Breast Cancer

Triple negative breast cancers (TNBC) are genetically characterized by aberrations in TP53 and a low rate of activating point mutations in common oncogenes, rendering it challenging in applying targeted therapies. We performed whole exome sequencing (WES) and RNAseq to identify somatic genetic alterations in mouse models of TNBCs driven by loss of Tp53 alone or in combination with Brca1. Amplifications or translocations that resulted in elevated oncoprotein expressions or oncoprotein-containing fusions, respectively, were identified in 52% of the tumors evaluated. While the spectrum of sporadic genetic alterations was diverse, they had in common the ability to activate the MAPK/PI3K pathways. Importantly, we demonstrated that approved or experimental drugs efficiently induce tumor regression specifically in tumors harboring somatic aberrations of the drug target. Our study suggests that the combination of WES and RNAseq on human TNBC will lead to the identification of actionable therapeutic targets for precision medicine guided TNBC treatment.