Multigene clinical mutational profiling of breast carcinoma using next-generation sequencing

The advent of next-generation sequencing (NGS) platforms in the realm of clinical molecular diagnostics provides multigene mutational profiling through massively parallel sequencing.

We analyzed 415 breast carcinoma samples from 354 patients using NGS in known hotspots of 46 commonly known cancer-causing genes.

A total of 281 somatic nonsynonymous mutations were detected in 62.1% of patients. TP53 was most frequently mutated (38.8%), followed by PIK3CA (31.7%), AKT1 (6%), and ATM (3.9%), with other mutations detected at a lower frequency. When stratified into clinically relevant therapeutic groups (estrogen receptor [ER]/progesterone receptor [PR]+ human epidermal growth factor receptor 2 [HER2]-, ER/PR+HER2+, ER/PR-HER2+, ER/PR/HER2-), each group showed distinct mutational profiles. The ER/PR+HER2- tumors (n = 132) showed the highest frequency of PIK3CA mutations (38%), while the triple-negative tumors (n = 64) had a significantly higher number of TP53 mutations (62%). Of the 61 patients tested for both primary and metastatic tumors, concordant results were seen in 47 (77%) patients, while 13 patients showed additional mutations in the metastasis.

Our results indicate that breast cancers may harbor potentially actionable mutations for targeted therapeutics. Therefore, NGS-based mutational profiling can provide useful information that can guide targeted cancer therapy.