PIK3CA and breast cancer: In a sub-study of the NeoALTTO phase 3 trial, a randomized, neoadjuvant dual HER2-targeted therapy study in early HER2+ breast cancer patients, Rothé and colleagues [144] found that the presence of PIK3CA and TP53 mutations, before neoadjuvant therapy, was correlated with low pCR (p = 0.0089).