ERBB2 and breast carcinoma: Representative immunofluorescence and immunohistochemical staining of HER2+ tumor-infiltrated immune cells in HER2+ breast cancer tissues are shown in Figures 4A and B. The correlation between trogocytosed-HER2+ immune cells and patient response was analyzed; we found that patients with a high degree of HER2-trogocytosis had a significantly greater probability of achieving a pCR with PST consisting of 3–4 courses of FEC100 followed by 12 courses of paclitaxel and trastuzumab than patients with a low level of HER2-trogocytosis (P = 0.023; Figure 4C).