Study of 5-FU, Oxaliplatin, & Lapatinib Combined With Radiation Therapy to Treat HER2 Positive Esophagogastric Cancer

This is an open-label, non-randomized, Phase II study with a lead-in safety cohort. The study will evaluate the combination of 5-Fluorouracil, Oxaliplatin and Lapatinib with radiation therapy as neoadjuvant treatment for patients with previously untreated localized HER2 positive esophagogastric adenocarcinomas. Approximately 12 patients will be enrolled in the lead-in cohort to evaluate the safety of the combination. Following the lead-in cohort, Phase II will commence and up to 30 additional patients may be treated. The starting doses will be administered as follows: 5-FU 225 mg/mg2 continuous intravenous (IV) infusion Days 1 - 42 during XRT; Oxaliplatin 85 mg/m2 Days 1, 15 and 29, given by IV infusion, per institutional standard; Lapatinib Continuous PO daily dosing during XRT (final dose determined during lead-in cohort).