PIK3CA and neoplasm: In addition, the occurrence of drug resistance of TNBC is associated with tumor heterogeneity with genomic alterations in the tumor suppressor genes or oncogenic drivers (e.g., BRCA1/BRCA2, RB1, TP53, Phosphoinositide 3-kinases (PI3K)/Phosphatase and tensin homolog (PTEN), PIK3CA) and the complexity of the tumor microenvironment (TME) [7,8].