Use of mutation specific antibodies to detect EGFR status in small biopsy and cytology specimens of lung adenocarcinoma
ABSTRACT EGFR mutation status is the best predictor of response to tyrosine kinase inhibitors (TKIS) in primary lung adenocarcinoma. Approximately 70% of lung cancers are diagnosed in advanced stages where small biopsies and cytological specimens are the only source of material for both diagnosis and mutation testing. Specific antibodies that can detect mutant EGFR protein were evaluated for the detection of EGFR mutation by immunohistochemistry (IHC) in cytology and small biopsy specimens.
Assessment of EGFR mutation status was performed by using antibodies specific to the two major forms of mutant EGFR, exon 21 L858R and exon 19 deletion (15bp). The study was performed in 145 lung adenocarcinomas, including cytology material, core biopsy, and decalcified bone biopsy. Stains were scored as negative (0), 1+ (weak and focal), 2+ (moderate intensity and focal), and 3+ (strong and diffuse). The result of the IHC stains was correlated with mutations status determined by standard molecular methods.
Validation using clinical material showed deletions in exon 19 were detected in 35% and L858R mutation in 17.6% of all cases by standard molecular methods. A cutoff value of 2+ was used as positive by IHC. No wild type cases were immunoreactive. The positive predictive value (PPV) and specificity for both antibodies was 100%. The antibodies performed well in cytology, core biopsies and decalcified bone biopsies.
Immunostaining to detect specific mutant EGFR shows a good correlation with mutation analysis and can be used as a screening method to identify patients for TKI therapy. IHC methodology is potentially useful when molecular analysis is not available and for use in small biopsies when material is too scant for molecular tests. Importantly mutation specific antibodies are useful in determining EGFR status in tissues obtained from bone biopsy as decalcification processes used in molecular based studies often result in DNA degradation hindering mutation detection.
SourceAvailable from: Chunjiao Xia[Show abstract] [Hide abstract]
ABSTRACT: Epidermal growth factor receptor (EGFR) mutation status is the best predictor of patient response to treatments with tyrosine kinase inhibitors in primary lung adenocarcinoma and is typically analyzed by DNA-based techniques, such as direct DNA sequencing and allele-specific PCR. Recently, however, two mutation-specific antibodies against delE746-A750 in exon 19 and L858R in exon 21 have opened the door for a more convenient and more efficient strategy to determine EGFR mutation status. To evaluate the clinical application of a new mutation-specific mouse monoclonal antibody for EGFR (L858R), we performed immunohistochemistry (IHC) studies with tumor samples from primary lung adenocarcinoma in retrospective and validation settings. A total of 215 cases of primary lung adenocarcinoma were examined and compared using a combination of DNA-based techniques (direct DNA sequencing and/or allele-specific PCR) and protein-based IHC. IHC staining was assessed on a 0 to 3+ score scale, and a cutoff value of 2+ was used as positive by IHC. In the retrospective setting, statistical analyses of the data showed that the sensitivity of IHC was 90.9 % and the specificity was 96.8 %. Findings from the validation study demonstrated that the sensitivity and specificity of IHC were 88.2 % and 100 %, respectively. IHC with the novel mutation-specific antibody could be used as a screening method to assess the EGFR L858R mutation status in primary lung adenocarcinoma.Tumor Biology 10/2014; DOI:10.1007/s13277-014-2643-0 · 2.84 Impact Factor
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ABSTRACT: Context .- Immunohistochemistry has become an indispensable ancillary tool for the accurate classification of pleuropulmonary and mediastinal neoplasms necessary for therapeutic decisions and predicting prognostic outcome in the era of personalized medicine. Diagnostic accuracy has significantly improved because of the continuous discoveries of tumor-associated biomarkers and the development of effective immunohistochemical panels. Objective .- To increase the accuracy of diagnosis and classify pleuropulmonary neoplasms through immunohistochemistry. Data Sources .- Literature review, authors' research data, and personal practice experience. Conclusions .- This review article has shown that appropriately selecting immunohistochemical panels enables pathologists to effectively diagnose most primary pleuropulmonary neoplasms and differentiate primary lung tumors from a variety of metastatic tumors to the lung. The discovery of new mutation-specific antibodies identifying a subset of specific gene-arranged lung tumors provides a promising alternative and cost-effective approach to molecular testing. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoiding potential diagnostic errors.Archives of pathology & laboratory medicine 12/2014; 138(12):1611-28. DOI:10.5858/arpa.2014-0092-RA · 2.88 Impact Factor
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ABSTRACT: Background: Various studies have assessed the diagnostic accuracy of EGFR mutation-specific antibodies in non-small cell lung cancer (NSCLC). We performed a meta-analysis of existing data to investigate the diagnostic value of mutation-specific antibodies for detection of EGFR mutations in NSCLC. Methods: We systematically retrieved relevant studies from PubMed, Web of Knowledge, and Google Scholar. Data from studies that met the inclusion criteria were extracted for further exploration of heterogeneity, including calculation of the average sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and analysis of SROC(summary receiver operating characteristic) curves. Results: Fifteen studies met our inclusion criteria. A summary of the meta-analysis of the efficacy of the anti-E746-A750 antibody was as follows: sensitivity, 0.60 (95% CI, 0.55-0.64); specificity, 0.98 (95% CI, 0.97-0.98); PLR, 33.50 (95% CI, 13.96-80.39); NLR, 0.39 (95% CI, 0.30-0.51) and DOR, 111.17 (95% CI, 62.22-198.63). A similar meta-analysis was performed for the anti-L858R antibody with results as follows: sensitivity, 0.76 (95% CI, 0.71-0.79); specificity, 0.96 (95% CI, 0.95-0.97); PLR, 24.42 (95% CI, 11.66-51.17); NLR, 0.22 (95% CI, 0.12-0.39) and DOR, 126.66 (95% CI, 54.60-293.82). Conclusion: Immunohistochemistry alone is sufficient for the detection of EGFR mutations if the result is positive. Molecular-based analyses are necessary only if the anti-E746-A750 antibody results are negative. Immunohistochemistry seems more suitable for clinical screening for EGFR mutations prior to molecular-based analysis.PLoS ONE 09/2014; 9(9):e105940. DOI:10.1371/journal.pone.0105940 · 3.53 Impact Factor