Background: Optimal combination of monoclonal antibody (anti-VEGF vs. anti-EGFR antibody) with standard chemotherapy as first-line treatment in patients (pts) with RAS (KRAS/NRAS) wild-type metastatic colorectal cancer (mCRC) remains controversial. FIRE-3 study demonstrated a significant improvement in overall survival (OS) with anti-EGFR over bevacizumab in pts with KRAS exon 2 wild type mCRC, while CALGB 80405 study did not. PARADIGM study is designed to compare panitumumab vs. bevacizumab combined with mFOLFOX6 in pts with RAS wild-type chemotherapy-naive mCRC. Methods: Eligible pts are aged 20-79 years with ECOG performance status (PS) 0-1 and histologically/cytologically confirmed RAS wild-type mCRC. 800 pts will be randomly assigned in a 1:1 ratio to mFOLFOX6 plus panitumumab or bevacizumab, and stratified according to institution, age (20-64 vs. 65-79 years), and liver metastases (present vs. absent). Each treatment regimen includes oxaliplatin 85 mg/m², l-leucovorin 200 mg/m², 5-fluorouracil (5-FU) iv 400 mg/m² at day 1, 5-FU civ 2400 mg/m² at day 1-3, and either panitumumab 6 mg/kg or bevacizumab 5 mg/kg at day 1 every two weeks. The primary endpoint is the OS; the study was designed to detect the OS hazard ratio of 0.76, with a one-sided type I error of 0.025 and 80% power. Secondary efficacy endpoints include progression-free survival, response rate, duration of response, and curative resection rate. One interim analysis is planned for the OS when approximately 70% of the targeted 570 events has been observed. Exploratory endpoint is to investigate possible biomarkers including oncogenic mutations using tumor tissue and circulating tumor DNA (Study ID: NCT02394834). As of August 2015, 21 pts have been randomized and recruitment is ongoing. Clinical trial information: NCT02394795