Epidermal growth factor receptor truncated form (EGFR truncated form)

A truncated form of the epidermal growth factor receptor (EGFR) is any protein product arising from alternative mRNA splicing, gene deletion, or mutation that lacks all or part of EGFR’s transmembrane or intracellular tyrosine kinase domains. The most notable truncated form is EGFRvIII, a constitutively active mutant resulting from deletion of exons 2–7, found primarily in glioblastoma. EGFRvIII lacks most of the extracellular ligand-binding domain, cannot bind EGF, but signals independently, leading to increased cell proliferation, reduced apoptosis, and strong oncogenic potential. Another class of truncated EGFRs are secreted, soluble forms arising from alternative transcripts, which may act as decoy receptors by binding ligand but failing to signal due to lack of intracellular domains. Truncated EGFR forms are important in cancer biology due to their altered signaling, resistance to standard EGFR-targeted therapies, and utility as biomarkers. They are rarely—if ever—detected in healthy tissue, making them highly tumor-specific but also a therapeutic challenge.

Other names

EGFRvIIIEGFR variant IIITruncated EGFRSecreted EGFR isoformEGFRΔ

EGFR inhibitors (tyrosine kinase inhibitors and monoclonal antibodies) block ligand-binding, kinase activity or dimerization in wild-type EGFR. For truncated forms like EGFRvIII, which lack the ligand-binding domain and are constitutively active, inhibition mechanisms include antibody-drug conjugates, immunotherapy, and approaches targeting mutant-specific epitopes. Cetuximab and similar drugs block extracellular domain; less effective against EGFRvIII. Small molecule TKIs (e.g., erlotinib, gefitinib) inhibit kinase domain; EGFRvIII may be less sensitive due to constant activity.