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Benjamin Yang

Targeted Therapy — Erbitux (Part 1)

Erbitux (cetuximab) is a mouse/human chimeric monoclonal antibody drug that targets and inhibits epidermal growth factor receptors (EGFR). It is approved by the U.S. FDA for treating metastatic colorectal cancer (February 12, 2004) and locally advanced or metastatic squamous cell carcinoma of the head and neck (March 1, 2006).

Erbitux is a work of molecular engineering. Roughly one third of the monoclonal antibody drug comes from a mouse antibody — this is the part of the antibody that recognizes and binds to EGFR. The rest comes from a human antibody. The use of human antibody portions is to minimize the probability that the antibody drug could be attacked by the patient’s immune system, as an all-mouse antibody could be perceived as dangerous and could evoke a hostile immune response by the patient.

EGFR is a member of a subfamily of type I receptor tyrosine kinases. Binding of Erbitux to EGFR leads to the inhibition of tumor cell growth, induction of cell death (apoptosis), suppression of cell repair and recovery after chemotherapy or radiation, and other effects. The expression of EGFR is elevated on solid tumor cells of a variety of tissue origins including those from the colon, rectum, and head and neck. It is also expressed on many normal cells such as those in skin and hair follicles.

Erbitux is made by ImClone Systems and marketed by Bristol-Myers Squibb in the U.S. and Merck KGaA in Europe. It had worldwide sales of $417.3 million in the first quarter of 2008.

[Originally written for a company's weekly newsletter. With permission.]

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