ERBB2 and neoplasm: Stromal TILs, which by definition are tumor-adjacent, increased modestly after 14–21 days of HER2-targeted therapy (from 9.9% to 12.7%, two-sided paired t-test p = 0.034), and, in the 14 tumors with non-zero cellularity samples both pre-treatment and at time of surgery, were stable after combination chemotherapy and HER2-targeted therapy (8.5% vs 9.5%, two-sided paired t-test p = 0.70), consistent with continued immune infiltration occurring where the tumor was present.