These HER2+ BC patients can be treated with HER2‐targeted therapies (Slamon et al., 2001); however, a significant fraction of these patients eventually relapse or develop progressive diseases (Rexer & Arteaga, 2012), which has been reported to be associated with alterations in multiple genes including PIK3CA (OMIM 171834), PTEN (OMIM 601728), RB1 (OMIM 614041), TP53 (OMIM 191170), BRCA1 (OMIM 113705), BRCA2 (OMIM 600185), MAP2K4 (OMIM 601335), and MAP3K1 (OMIM 600982; Ahmad, Gupta, Kumar, Varshney, & Raghava, 2014). Here, PIK3CA is linked to breast cancer.