Characterization of somatic mutations in Malaysian luminal breast cancer

80% tumour content) and their matched normal samples were subjected to exome sequencing. We detected a total of 491 somatic from nine pairs of breast tumour-normal samples. PIK3CA is the most frequently mutated gene in our discovery cohort of patients (n=4/9). Kinases and phosphatases were found as the most significantly enriched mutated genes (enrichment score = 3.12), with all nine luminal breast cancer samples harboring at least one non-synonymous mutation in this cluster of genes. This profile suggested that alteration in protein phosphorylation processes is among the key drivers in luminal breast cancer pathogenesis. Interestingly, genes involved in four key druggable cancer pathways, i.e. PI3K/AKT/mTOR, MAPK/ERK, NF-k? and VEGF signalling pathways were found commonly mutated and require validation in a larger cohort. In conclusion, we have successfully profiled the somatic mutations in Malaysian luminal breast cancer and this is the first study conducted in Malaysian patients. These findings revealed the role of multiple gene testing in discovering luminal breast cancer mutational landscape