1
L antibodies made also rapidly clear to the clinicians that a reliable predictive factor for outcome was, in fact, lacking [3-7]. The introduction of K-RAS mutational status analysis allowed a reliable selection of resistant patients (i.e. those with mutated K-RAS). However not all K-RAS wildtype cases were also responders to anti-EGFR monoclonal antibodies. This observation made the need for furt