Following the morphological and molecular characterization of untreated and TZM‐treated HER2‐positive human breast and ovarian tumor xenografts, we measured non‐invasively the level of TZM‐HER2 engagement in AU565 and SKOV‐3 tumor xenografts (Protocols P‐1a and P‐1b; Figure S3, Supporting Information).16 The gene discussed is ERBB2; the disease is ovarian neoplasm.