PET Imaging With 89Zr-DFO-Trastuzumab in Esophagogastric Cancer

Inclusion Criteria: * Registered patient at MSKCC * Age ≥18 years * Pathologically or cytologically confirmed metastatic or primary esophagogastric cancer HER2 positive status by FISH or IHC as currently being implemented for patients with esophagogastric cancer. HER2 overexpression and/or amplification as determined by immunohistochemistry (3+) or FISH (≥2.0) * Measurable or evaluable disease, lesions that have not been previously radiated, with clinically indicated imaging evaluation performed within 4 weeks prior to study entry (CT, MRI, FDG PET or bone scan). Patients requiring concurrent radiation treatment are not eligible unless additional lesions that are not being irradiated and are assessable for targeting are present. * Karnofsky Performance Score ≥ 60 * Ability to understand and willingness to sign informed consent * Negative pregnancy test, to be performed on female patients of childbearing potential within 1week before administration of radioactive material. * Life expectancy of at least three (3) months. * Willingness to use birth control while on study. * The patients will be asked to consent to provide access to data obtained from molecular analysis that has been done on archived tumor tissue that will be correlated with 89Zr-DFO-trastuzumab imaging results. * Concurrent therapy will be allowed. Exclusion Criteria: * Inability to lie still for the duration of the scanning procedure. * Patients with known sensitivity or contraindication to any of the component of 89Zr-DFO-trastuzumab (89Zr or Desferroxamine (DFO) or trastuzumab) * Patients who have received trastuzumab must have at least a washout period for trastuzumab of 14 days, this will not apply to 89Zr-DFO-trastuzumab repeat, post treatment assessment where patients may be receiving trastuzumab. * HIV positive or active hepatitis. * History or presence of clinically relevant cardiovascular abnormalities such as uncontrolled hypertension, congestive heart failure NYHA classification of 3, unstable angina or poorly controlled arrhythmia. Myocardial infarction within 6 months prior to study entry * Hematologic * Platelets \<50K/mcL * ANC \<1.0 K/mcL * Hepatic laboratory values * Bilirubin \>2 x ULN (institutional upper limits of normal), with exception of patients with Gilberts disease. AST/ALT \>2.5 x ULN (institutional upper limits of normal); \>5 x ULN if liver metastasis * Renal laboratory values * Estimated GFR (eGFR) \< 30mL/min/1.73m2