Panitumumab (ABX-EGF) is a monoclonal antibody in phase III trials as third- or fourth-line monotherapy in patients with advanced colorectal cancer who have failed previous fluoropyrimidine, irinotecan and/or oxaliplatin chemotherapy regimens. Panitumumab binds to the epidermal growth factor receptor (EGFR), blocking critical signalling pathways and inhibiting the growth of tumours expressing EGFR. A phase II trial in 148 patients demonstrated partial responses in around 10% of patients and stable disease in a third. Median duration of response was 5.2 months. Median overall time to progression was 2 months, and median overall survival was 7.9 months.