However, EGFR FISH for mCRC is undergoing inter-laboratory standardization and to avoid the introduction of confounding elements we elected not to carry out this analysis. Here, we exploited the comprehensive molecular analysis of EGFR downstream Alisol-A effectors to ascertain their role in predicting response/resistance to cetuximab or panitumumab in mCRC. By the concomitant assessment of four molecular alterations, we were able to identify up to 70% of non-responder patients, a result that has never been achieved before. Notably, only three patients with tumors carrying a single alteration were in the subgroup of responders, whereas no others showed any alteration. This suggests that previously reported outliers, very uncommon cases of mCRC with KRAS Polyphyllin-I mutations responding to therapy may be patients harboring only one of these molecular alterations, thus not concurrently deregulating both MAPK and PI3K pathways. Our data indicate that single or multiple mutations of KRAS, BRAF, or PIK3CA unfavorably affect clinical outcome to cetuximab or panitumumab-based therapies; however, the possibility that these molecular alterations could be negative prognostic biomarkers independently from targeted therapies should be taken into account. The RASCAL retrospective study conducted on 2721 CRC patients indicated that the presence of KRAS mutations is associated with a 26% increased risk of fatal outcome. However, conflicting data on the same topic have been recently published. In a phase III trial reported by Karapetis et al., clinical benefit in patients with wild-type KRAS mCRC was found in cetuximab treated patients but not in control patients treated with best supportive care only, thus indicating that the benefit was not due to a prognostic effect of KRAS. Moreover, Roth et al. tested the prognostic value per stage of KRAS and BRAF mutations using CRC tumor samples from the adjuvant PETACC3 trial, and they found no significant effects on relapse-free survival for both mutations, neither in stage II nor in stage III. Studies assessing the impact of other molecular alterations rather than KRAS mutations are limited.