Identification of new candidate therapeutic target genes in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is a subgroup of breast cancer that is negative for estrogen and progesterone receptor and ERBB2 protein expression. It is characterized by its aggressive behavior and by the lack of targeted therapies. To identify new therapeutic targets in TNBC, we used real-time quantitative RT-PCR to analyze 63 TNBC samples in terms of their mRNA expression of 26 genes coding for the major proteins currently targeted by drugs used to treat other cancers or undergoing clinical trials in breast cancer. Six of the 26 genes tested (VEGFA, SRC, PARP1, PTK2, RAF1, and FGFR3) were significantly upregulated in 13% to 46% of the TNBCs. None of the 6 genes was specifically upregulated in the TNBCs compared with 3 other classical breast tumor subtypes. No association was observed between overexpression of these 6 genes (except for FGFR3) and PIK3CA mutation status. These results confirm the interest of targeting VEGFA and PARP1 in ongoing clinical trials in TNBC patients and also identify new target genes (SRC, PTK2, RAF1, and FGFR3). Clinical trials could be initiated easily with existing drugs. Our results also suggest that these target genes might serve as predictive biomarkers of the TNBC treatment response.