Moreover, it could be argued that multi-gene classifiers incorporating the expression status of AREG/EREG will be informative of Ctx responsiveness in wt KRAS mCRC but not in EGFR-dependent carcinomas with either intact KRAS signalling (e.g., head and neck SCC (HNSCC)) or cases in which KRAS mutations do not predict a clinical benefit from Ctx (e.g., (NSCLC)) (Mehra et al, 2008; Ettinger, 2010; Vincenzi et al, 2010). This evidence concerns the gene KRAS and head and neck squamous cell carcinoma.