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Published on: August 14, 2018
Molecular diagnosis of activating EGFR mutations in non-small cell lung cancer using mutation-specific antibodies for
Akihiko Kawahara1, Chizuko Yamamoto, Kazutaka Nakashima
1Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Japan.
Purpose:
Therapeutic responses of non-small cell lung carcinoma (NSCLC) to epidermal growth factor receptor (EGFR)-targeted drugs, such as gefitinib and erlotinib, are closely associated with activating EGFR mutations. The most common mutations are delE746-A750 in exon 19 and L858R in exon 21, accounting for approximately 90% of all EGFR mutations. Recently, EGFR mutation-specific antibodies were developed and did well in immunohistochemical analysis, giving a sensitivity of approximately 90%. We have investigated whether this method detects activating EGFR mutations with sensitivity comparable with direct DNA sequencing, which is used to detect these mutations in NSCLC.
Experimental Design:
We used antibodies specific for the E746-A750 deletion mutation in exon 19 and the L858R point mutation in exon 21 in Western blot analysis and immunohistochemistry to determine the presence of these mutations in NSCLC cell lines. We also examined these EGFR mutations in NSCLC tumor samples from 60 patients by immunohistochemically and direct DNA sequencing.
Results:
We were able to identify EGFR mutations in NSCLC tumor samples immunohistochemically with a sensitivity of 79% using the anti-delE746-A750 antibody and 83% using the anti-L858R antibody. Additional DNA sequencing markedly improved the sensitivity obtained by immunohistochemistry.
Conclusions:
This simple and rapid assay for detecting EGFR mutations, even in the small bronchial biopsies obtained in stage IV NSCLC patients, will be useful for diagnosing responsiveness to EGFR-targeted drugs in patients with NSCLC. Combining this with DNA sequencing is recommended for the development of improved personalized EGFR-targeted therapeutics.
Insights
Immunohistochemistry using EGFR mutation-specific antibodies can detect common mutations in non-small cell lung cancer (NSCLC). Combining this assay with DNA sequencing improves diagnostic sensitivity for targeted therapies.
Area of Science:
- Oncology
- Molecular Biology
- Pathology
Background:
- Therapeutic responses in non-small cell lung cancer (NSCLC) to epidermal growth factor receptor (EGFR)-targeted drugs correlate with specific EGFR mutations.
- The delE746-A750 deletion and L858R point mutation in EGFR account for about 90% of all EGFR mutations in NSCLC.
- EGFR mutation-specific antibodies have shown promise in immunohistochemical analysis for detecting these mutations.
Purpose of the Study:
- To evaluate the sensitivity of EGFR mutation-specific antibodies in immunohistochemistry for detecting common activating EGFR mutations (delE746-A750 and L858R) in NSCLC.
- To compare the diagnostic sensitivity of this antibody-based method with direct DNA sequencing.
- To assess the utility of this method for diagnosing responsiveness to EGFR-targeted drugs.
Main Methods:
- Utilized antibodies specific for the EGFR delE746-A750 deletion and L858R mutation.
- Applied Western blot and immunohistochemistry to analyze NSCLC cell lines and tumor samples.
- Examined 60 NSCLC patient tumor samples using both immunohistochemistry and direct DNA sequencing.
Main Results:
- Immunohistochemistry detected EGFR mutations with 79% sensitivity for the anti-delE746-A750 antibody and 83% sensitivity for the anti-L858R antibody.
- The combination of immunohistochemistry with additional DNA sequencing significantly enhanced the overall sensitivity for mutation detection.
- EGFR mutation-specific antibodies demonstrated potential for identifying targetable mutations in NSCLC.
Conclusions:
- A simple and rapid immunohistochemical assay using EGFR mutation-specific antibodies can aid in diagnosing drug responsiveness in NSCLC patients.
- This method is particularly useful for analyzing small bronchial biopsies from stage IV NSCLC patients.
- Combining immunohistochemistry with DNA sequencing is recommended for optimizing personalized EGFR-targeted therapeutics.
