ERBB2 and neoplasm: Indeed, this study incorporates: (1) in vitro cell death and double-strand break (DSB) quantification assays used to evaluate the combination of trastuzumab and radiation therapy, (2) PET imaging of hypoxia changes during combination HER2-targeted and radiation therapy, and (3) in vivo monitoring of longitudinal tumor changes in targeted therapy plus fractionated radiation in xenograft cell line and patient-derived xenograft (PDX) models.