Kim and coworkers have reported the results of BioPATH, a non-interventional study evaluating the relationship of molecular biomarkers, such as PIK3CA mutations, PTEN deletion/downregulation, truncated HER2 receptor, and tumor HER2 mRNA levels, to treatment responses in Asian patients with HER2-positive advanced breast cancer that was treated with lapatinib and other HER2-targeted agents [295]. This evidence concerns the gene PTEN and breast cancer.