The pCR rate to anti-HER2 NAC in patients with HER2-positive breast cancer in the HH group was 28% (5/18 cases), which was significantly lower than that in the LH group at 65% (51/79 cases), indicating that tumors in the HH group exhibited a markedly reduced response to HER2-targeted neoadjuvant therapy and resistance to anti-HER2 agents (univariate analysis, p < 0.01) (Figure 2). Here, ERBB2 is linked to breast cancer.