The possible mechanism behind cetuximab induced allergies. Cetuximab is a recombinant chimeric epidermal growth factor monoclonal antibody approved for treatment of metastatic colorectal and head and neck cancer [51,59-61]. Infusion reactions with cetuximab are linked to the presence of IgE antibodies directed against the alpha-gal component of the Fab fragment of cetuximab heavy chain [51,85]. Each cetuximab molecule contains two alpha-gal epitopes that can cross-link the high affinity receptor for IgE (FcεRI) on mast cells  leading to mast cell activation and release of hypersensitivity mediators .
Saleh et al. Clinical and Molecular Allergy 2012 10:5 doi:10.1186/1476-7961-10-5