25P Breast cancers with heterogeneous HER2 amplification show a diverse distribution of ‘driver’ and ‘passenger’ somatic mutations and copy number variations

Abstract

Invasive breast cancers with HER2 gene amplification are associated with poor outcome. Heterogeneous HER2 amplification has been observed in up to 41% of breast cancers, depending upon its definition. Carcinogenesis is driven by intra-tumour heterogeneity. Molecular diversity enables cancer cells to circumvent specific targeted treatment. In this study, we compared the genetic differences between admixed HER2-positive and HER2-negative breast cancer components. This in-depth analysis investigated the heterogeneity in their somatic mutational landscape.