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Monoclonal antibodies against EGFRvIII are tumor specific and react with breast and lung carcinomas and malignant
C J Wikstrand1, L P Hale, S K Batra
1Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Abstract:
Despite molecular biological advances in understanding human cancers, translation into therapy has been less forthcoming; targeting neoplastic cells still requires that tumor-specific markers, preferably those on the cell surface, be identified. The epidermal growth factor receptor (EGFR) exists in a deletion-mutant form, EGFRvIII, which has been identified by genetic and immunological means in a subset of gliomas and non-small cell lung carcinomas. Specific polyvalent antisera to the extracellular portion of the variant were readily induced, but immunization using a synthetic linear peptide representing the unique EGFRvIII primary sequence has been unsuccessful in mice or macaques. We report here five specific monoclonal antibodies (mAbs) developed through long-term immunization protocols using the EGFRvIII-specific synthetic peptide and the intact variant in different formats that maintained secondary and tertiary conformation. These mAbs identify the EGFRvIII on the cell surface with relatively high affinity (KA range, 0.13 to 2.5 x 10(9) M-1) by live cell Scatchard analysis. These mAbs are specific for EGFRvIII as determined by RIA, ELISA, Western blot, analytical flow cytometry, autophosphorylation, and immunohistochemistry. Isolating specific mAbs enabled us to analyze normal and neoplastic human tissue and establish that EGFRvIII is truly tumor specific for subsets of breast carcinomas and for previously reported non-small cell lung carcinomas and gliomas. Also, this receptor is not expressed by any normal human tissues thus far examined, including elements of the peripheral, central nervous, and lymphoid systems. With mAbs, we identified a higher incidence of EGFRvIII positivity in gliomas than previously described and identified an EGFRvIII-positive subset of breast tumors; also, we observed that the EGFRvIII epitope is not expressed in normal tissues, and we demonstrated the localizing and therapeutic potential of the mAbs for tumors expressing this epitope. Our observations strongly warrant development of this mAb-antigen system as therapy for breast, lung, and central nervous system tumors.
Insights
Researchers developed five specific monoclonal antibodies (mAbs) targeting the EGFRvIII variant. These mAbs are tumor-specific for gliomas, lung, and breast cancers, showing therapeutic potential for these EGFRvIII-expressing tumors.
Area of Science:
- Oncology
- Immunology
- Molecular Biology
Background:
- Targeting neoplastic cells requires tumor-specific markers, preferably on the cell surface.
- The epidermal growth factor receptor variant EGFRvIII is found in gliomas and lung carcinomas.
- Previous attempts to generate antibodies against EGFRvIII using synthetic peptides were unsuccessful.
Purpose of the Study:
- To develop specific monoclonal antibodies (mAbs) against the EGFRvIII variant.
- To confirm the tumor specificity of EGFRvIII in various human cancers.
- To evaluate the therapeutic potential of EGFRvIII-specific mAbs.
Main Methods:
- Long-term immunization protocols using EGFRvIII synthetic peptides and intact variants.
- Live cell Scatchard analysis for antibody affinity.
- Radioimmunoassay (RIA), ELISA, Western blot, flow cytometry, and immunohistochemistry for specificity.
- Analysis of normal and neoplastic human tissues.
Main Results:
- Five specific mAbs targeting EGFRvIII were successfully developed.
- mAbs demonstrated high affinity (KA range, 0.13–2.5 x 10^9 M⁻¹) for EGFRvIII on the cell surface.
- EGFRvIII was confirmed as tumor-specific in gliomas, non-small cell lung carcinomas, and identified in breast carcinomas.
- EGFRvIII is not expressed in any examined normal human tissues.
- EGFRvIII positivity was higher in gliomas than previously reported.
Conclusions:
- The developed mAbs are specific and high-affinity reagents for EGFRvIII.
- EGFRvIII is a tumor-specific antigen for gliomas, lung, and breast cancers.
- The mAb-EGFRvIII system holds significant therapeutic potential for these cancers.