Cetuximab binds to the epidermal growth factor receptor (EGFr) on both normal and tumor cells. EGFr is over-expressed in many colorectal cancers. Cetuximab competitively inhibits the binding of epidermal growth factor (EGF) and TGF alpha, thereby reducing their effects on cell growth and metastatic spread.

Used in the treatment of colorectal cancer, cetuximab binds specifically to the epidermal growth factor receptor (EGFr, HER1, c-ErbB-1) on both normal and tumor cells. EGFr is over-expressed in many colorectal cancers. Cetuximab competitively inhibits the binding of epidermal growth factor (EGF) and other ligands, such as transforming growth factor–alpha. Binding of cetuximab to the EGFr blocks phosphorylation and activation of receptor-associated kinases, resulting in inhibition of cell growth, induction of apoptosis, decreased matrix metalloproteinase secretion and reduced vascular endothelial growth factor production.

Pulmonary Toxicity Interstitial lung disease (ILD) was reported in 3 of 633 (<0.5%) patients with advanced colorectal cancer receiving cetuximab. Interstitial pneumonitis with non-cardiogenic pulmonary edema resulting in death was reported in one case. Two patients had pre-existing fibrotic lung disease and experienced an acute exacerbation of their disease while receiving cetuximab in combination with irinotecan. In the clinical investigational program, an additional case of interstitial pneumonitis was reported in a patient with head and neck cancer treated with cetuximab and cisplatin. The onset of symptoms occurred between the fourth and eleventh doses of treatment in all reported cases.

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