3. Wild-type RAS tumor no mutation in exon 2 [codon 12/13], exon 3 [codon 59/61] and exon 4 [codon 117/146] of both KRAS and NRAS genes (local assessment, performed either on primary tumor or metastasis), In exceptional circumstances, RAS mutational status (KRAS and NRAS) can be pending at time of randomization, provided it is obtained within the first two cycles of first line therapy