Epirubicin, oxaliplatin, and capecitabine (EOC) is a standard treatment in advanced esophagogastric cancer. Panitumumab (P) is a fully human, immunoglobulin G2 monoclonal antibody targeting epidermal growth factor receptor. Randomized Trial of EOC +/- Panitumumab for Advanced and Locally Advanced Esophagogastric Cancer (REAL-3) will evaluate whether the addition of P to EOC improves survival in patients with advanced esophagogastric adenocarcinoma and undifferentiated carcinoma. The original design of REAL-3 added P 9 mg/kg to the standard dose of EOC (dose level DL + 1). Due to toxicity, a dose de-escalation was made to EOC + P DL-1 (epirubicin 50 mg/m(2), oxaliplatin130 mg/m(2), capecitabine 1,000 mg/m(2)/d + P 9 mg/kg every 3 weeks). After additional toxicity was observed, the study was amended to include two additional EOC + P dose levels. Using a 3 + 3 design, dose-limiting toxicities (DLTs) were assessed weekly during cycle 1. Patients were randomly assigned 1:1 to EOC +/- P. Between July 2008 and October 2009, 29 patients were randomly selected for standard-dose EOC (n = 13) or EOC + P (n = 16). Five patients were treated at DL + 1, with grade 3 diarrhea in four of five patients by cycle 4. At DL-1, one patient had grade 3 diarrhea and grade 5 infection. Three patients were treated at DL-3, and then six were treated at DL-2, without DLTs. The recommended dose for EOC + P is epirubicin 50 mg/m(2), oxaliplatin 100 mg/m(2), capecitabine 1,000 mg/m(2)/d, and P 9 mg/kg every 3 weeks. This dose has been selected for the ongoing phase II/III REAL-3 study.