Arm A: panitumumab 6 mg/kg will be administered over 60 minute +/- 15 minutes on day 1 followed by Gemcitabine 1000mg/sqm administered by intravenous infusion as 1-hour infusion on day 1 of each cycle. Oxaliplatin 100mg/sqm will be administered by intravenous infusion as 2-hour infusion on day 2 of each cycle.