As shown in Fig. 6A and B, a significantly higher frequency of CD44v6/CD36 + stem-like cells was found in biopsies from HER2 + BC patients who did not achieve pCR (pCR No patients) after neoadjuvant treatment with trastuzumab-based therapy than in biopsies from pCR Yes patients, providing striking clinical evidence corroborating our observations in all of our tested 2D and 3D HER2 + BC cell models and in mice. This evidence concerns the gene ERBB2 and breast cancer.