Wu et al. [16] found a PIK3CA gene copy number gain in 8.7% BC over 92 cases evaluated in their study, an interesting finding since PIK3CA gene amplification has been described as a mechanism of resistance to selective PIK3CA inhibitor in HER2+, PIK3CA mutant breast cancer cell line, KPL-4 [17]. The gene discussed is ERBB2; the disease is breast cancer.