A New Antibody Recognizing the vIII Mutation of Human Epidermal Growth Factor Receptor

The epidermal growth factor receptor (EGFR) gene is frequently amplified and the receptor overexpressed in different types of human tumors. Furthermore, genomic rearrangements can cause expression of modified receptors, as one frequently occurring truncated form, EGFRvIII. This mutated receptor has previously been described and is formed by a 267-amino acid in-frame deletion and an insertion of a glycine in the fusion junction of the extracellular domain. EGFRvIII is a tumor-specific marker and therefore of interest for diagnostic and therapeutic applications. In this study we report on a new monoclonal antibody (Ua30:2) directed to the mutation site of EGFRvIII. The antibody was generated by immunization of mice with a synthetic peptide corresponding to the mutated sequence of the receptor. The affinity of Ua30:2 was found to be high [K(d) = 45 nM (Biacore) and 80 nM (saturation analysis)]. Immunohistochemistry in tissue sections from human gliomas demonstrated a similar expression pattern for Ua30:2 as for the recently characterized antibodies L8A4 and DH8.3. The antibody binding was EGFRvIII specific with no measurable cross-reactivity to the wild-type receptor, wtEGFR, as analyzed both with displacement analysis, Western blots and immunohistochemistry. The new antibody is a candidate for radioimmunotargeting aiming at diagnostic and therapeutic applications.