Not all antibodies are equal.

The epidermal growth factor receptor (EGFR) has been validated as a therapeutic target in several human tumors, including colorectal cancer (CRC).(1,2) Occupancy of the EGFR with ligand can activate the RAS/RAF/MAPK, STAT, and PI3K/AKT signaling pathways. These pathways modulate cellular proliferation, adhesion, angiogenesis, migration, and survival.(3) Anti-EGFR targeted antibodies, such as cetuximab and panitumumab, have shown response and disease stabilization rates of approximately 10% and 30%, respectively, when administered as monotherapy in CRC.(1,4) EGFR expression is used for patient selection for these studies. However, clinical results have suggested that the level of EGFR expression as measured by immunohistochemistry may not predict clinical benefit.(4,5)