4031 Background: Capecitabine is an oral fluoropyrimidine that has demonstrated similar efficacy to 5-FU/LV in the 1st-line treatment of MCRC. Most patients now receive multi-agent chemotherapy and FOLFOX4 has become a popular regimen in this setting. We conducted a phase III study comparing XELOX with FOLFOX4 in patients who had received prior treatment with irinotecan in combination with bolus and/or infusional 5-FU/LV for MCRC. The primary endpoint of the study was time-to-tumor progression (TTP). With 610 patients, this study had 80% power to detect non-inferiority of the XELOX vs. FOLFOX, defined by a progression hazard ratio (HR) of <1.3. Methods: Patients were treated with XELOX (oxaliplatin 130mg/m2 i.v., capecitabine 1,000mg/m2 bid oral x 14 days, q3w) or FOLFOX4 (as described previously). Results: The study recruited 627 patients (the intent-to-treat - ITT - group). Baseline characteristics were well balanced. The primary objective of the study was met with a progression HR of 0.97 for the XELOX...