IGHE and head and neck cancer: However, IgE-mediated reactions have been noted during the very first administration of cetuximab (a chimeric mAb used in the treatment of colorectal, lung, skin, and head and neck cancers) due to pre-existing IgE antibodies directed against an oligosaccharide (i.e., galactose-alpha-1,3-galactose [alpha-gal]) present on this mAb [41, 42].