Patterns of mutation enrichment in metastatic triple-negative breast cancer.

Abstract

e12596 Background: Triple-Negative breast cancer (TNBC) is a group of heterogeneous tumors with aggressive biology. The purpose of this research was to evaluate enrichment patterns of genomic alterations in metastatic TNBC (mTNBC). Methods: We retrieved genomic data (mutations and copy number variation) from 550 primaries TNBC (pTNBC) from the projects METABRIC and TCGA and 58 mTNBC from the projects “Mutational Profile of Metastatic Breast Cancers” and “The metastatic Breast Cancer Project”. Differences in the proportions of mutations between primary vs. metastatic tumors were evaluated by the Chisquare test and the percentage of enrichment in mTNBC was estimated. Pvalues were adjusted for multiple testing with the Benjamini-Hochberg method with and a FDR < 0.05. In addition we conducted an analysis of the hallmarks of cancers enriched in mTNBC. Results: In total, mutations in eight genes were significantly enriched in mTNBC after correcting for multiple testing. These genes included TTN, HMCN1, RELN, PKHD1L1, DMD, FRAS1 and RYR3. In the other hand, only amplification of RPS6KB2 was enriched in mTNBC. Deletions were enriched more frequently in the genes TET1, RHOA, EPHA5, SET, KCNJ5, ABCG4, NKX3-1, SDHB, IGF2, BRCA1, among others. The hallmark of “genetic instability and mutation” was over represented while the hallmark “activating immune destruction” was the least represented between the enriched genetic alterations in mTNBC. Conclusions: Despite the study limitations, we identified that deletions are the aberrations more commonly enriched in mTNBC while some biological processes could be targetable in order to improve the therapeutic opportunities in TNBC.