ERBB2 and breast cancer: Using plasma samples from BC (HER2+ and TNBC) patients after NAT before surgery, the authors showed that a downregulation of exosomal miR-155 (in both TNBC and HER2+BC subtypes) (p = 0.002) and miR-301 (in HER2+BC patients) (p = 0.002) significantly predicted pCR to NAT.