Epidermal growth factor receptor variant III and wild-type epidermal growth factor receptor shared conformational epitope (EGFRvIII/wtEGFR shared epitope)

The EGFRvIII extracellular domain – D2C7 shared conformational epitope is a distinct structural motif present on both the mutant Epidermal Growth Factor Receptor variant III (EGFRvIII) and the overexpressed wild-type Epidermal Growth Factor Receptor (wtEGFR). EGFRvIII is a common, tumor-specific mutation in glioblastoma resulting from an in-frame deletion of exons 2 through 7, which creates a novel glycine residue at the junction and leads to constitutive signaling (Bigner et al., 2013). The D2C7 monoclonal antibody was specifically engineered to recognize a conformational epitope that is exposed on both this mutant form and the amplified wild-type receptor, both of which drive tumor progression. This dual-specificity allows for a more comprehensive targeting of the heterogeneous cell populations within malignant gliomas, where both EGFRvIII and wtEGFR are often co-expressed (Desjardins et al., 2021). Therapeutic strategies targeting this epitope include immunotoxins, such as D2C7-IT (a recombinant protein combining the D2C7 scFv with Pseudomonas exotoxin A), and chimeric antigen receptor (CAR) T-cell therapies (Chandramohan et al., 2013). These treatments aim to induce cell death by inhibiting protein synthesis or through direct cellular cytotoxicity, often utilizing convection-enhanced delivery to maximize local concentration within the brain.

Other names

D2C7 epitopeEGFRvIII/wtEGFR dual epitopeD2C7-reactive EGFR epitopeEpidermal growth factor receptor variant III / wild-type epidermal growth factor receptor shared epitope

The D2C7 antibody binds to a shared conformational epitope on the extracellular domain of both EGFRvIII and overexpressed wild-type EGFR. In the case of D2C7-IT, this binding facilitates the internalization of the Pseudomonas exotoxin A (PE38KDEL), which then catalyzes the ADP-ribosylation of elongation factor 2 (EF-2), halting protein synthesis and inducing apoptosis in the target cell (Desjardins et al., 2021). For CAR-T applications, the epitope serves as the docking site for the chimeric receptor, triggering T-cell mediated cytolysis of the tumor cell (Chandramohan et al., 2013).