ERBB2 and breast cancer: This assumption was supported by the clinical observation that in one study the incidence of PIK3CA/AKT1/PTEN alterations was generally similar in primary breast cancer and TNBC metastasis samples[67] (some temporal discordance between PIK3CA sequence in primary vs. metastasis in a small fraction of hormone receptor positive, HER2-negative breast cancers, notwithstanding[68,69]).