Primary and Secondary Endpoints: The primary endpoints for this study are the ratio of geometric means (with:without panitumumab) for AUC of total plasma cisplatin-derived platinum and average concentration at steady sate (Css) of 5-FU measured at cycle 2 at which time panitumumab levels are anticipated to be at steady state. Secondary endpoints are the ratio of geometric means (with:without panitumumab) for 1) Cmax of total plasma cisplatin-derived platinum and 2) Cmax and AUC of free plasma cisplatin-derived platinum measured at cycle 2.