ERBB2 and neoplasm: Drug response is driven directly by oncogenic receptor expression and mutational burden levels in tumor cells and modulated via various cellular/non‐cellular components of TME, which can regulate drug distribution, penetration, and binding across solid tumors.[30] We performed morphological and molecular characterization of untreated and TZM‐treated HER2 positive human breast (AU565 and XTM) and ovarian and (SKOV‐3) tumor xenografts in mice using H&E staining and immunohistochemistry.