Colon

Based on earlier studies, cetuximab is now indicated for treatment of patients with advanced colorectal cancer whose tumors do not have a mutation in the KRAS gene.

KRAS is one of a series of genes along a pathway that can lead tumors cells to grow, divide and evade signals that shut the cells down causing their death..

Source: http://scienceblog.com/36535/new-recommendations-issued-for-use-of-cetuximab-in-colon-cancer-therapy/