KRAS and colorectal cancer: Mutations in KRAS have been associated with resistance to everolimus in BTC cell lines,17 and in patients with colorectal cancer who are treated with this agent.25 Sanger sequencing of KRAS (exons 2 and 3) identified only two patients harbouring KRAS mutations, of whom one was the patient with ampullary carcinoma with intestinal differentiation who also harboured a PIK3CA (E545K) mutation.