Molecular classification with NanoString nCounter system in triple-negative breast cancer.

e23198Background: Previous studies have shown that several distinct subtypes identified by gene expression profiling (GEP) consisted of triple-negative breast cancer (TNBC). Compared with the subtypes defined by GEP, we developed molecular classification with NanoString nCounter system in TNBC. Methods: GEP was conducted on 188 FFPE containing chemotherapy-naive TNBC tumors collected at Gangnam Severance Hospital. To select core genes for classification, other 120 samples from public GEP database were used. Correlation between nCounter system and GEP using identical RNA was done. In a part of tumors, BRCA1 methylation, homologous recombination deficiency (HRD) assay, and drug response assay with ATP was comprehensively assessed. Results: To classify TNBC into 4 major subtypes (Basal-like: BL, Luminal androgen receptor: LAR, Mesenchymal: M, and Immune-modulatory: IM) according to the Vanderbilt classification, we selected 110 genes in 220 samples with GEP (100 from Gangnam Severance Hospital and 120 from p...