Predicting gefitinib responsiveness in lung cancer by fluorescence in situ hybridization/chromogenic in situ hybridization analysis of EGFR and HER2 in biopsy and cytology specimens

Abstract

In non -small cell lung cancer (NSCLC), epidermal growth factor receptor (EGFR) mutational analysis is an excellent predictor of responsiveness to treatment with tyrosine kinase inhibitors, such as gefitinib. In up to 80% of NSCLCs, cytologic samples or endoscopic biopsies are the only specimens available for molecular analysis, but PCR amplification of DNA from small fixed and paraffinembedded samples may create artifactual mutations. Fluorescence in situ hybridization (FISH) of EGFR and HER2 has been proposed as an alternative method of analysis. This project aimed to determine the optimal scoring method for FISH or chromogenic in situ hybridization (CISH) assays when analyzing small NSCLC samples to predict response. FISH or CISH analysis of EGFR and HER2 genes was done on 42 small samples derived from NSCLC patients treated with gefitinib.

Predictive value of EGFR and HER2 overexpression in advanced non-small-cell lung cancer

“…A role for EGFR and HER2 receptor cooperation is supported by clinical data showing that patients who have an increased HER2 gene copy number and are EGFR positive by FISH or IHC have increased sensitivity to gefitinib with improved RR, DCR, TTP and OS (Table 1) (Cappuzzo et al, 2005b;Daniele et al, 2007). In a clinical study of 102 patients with NSCLC treated with gefitinib, patients who were positive for both EGFR and HER2, as assessed by FISH, had significantly higher objective RRs to gefitinib than did patients with EGFR-negative and/or HER2-negative tumors (54 vs 7%; Po0.001) (Cappuzzo et al, 2005b).…”

“…Another study showed the effectiveness of FISH/ chromogenic in situ hybridization analysis in assessing EGFR and HER2 in histological biopsy and cytological specimens from 42 patients with NSCLC (Daniele et al, 2007). The concurrent gene gain of both EGFR and HER2 was found to be associated with response to gefitinib.…”

Overview of molecular testing in non-small-cell lung cancer: mutational analysis, gene copy number, protein expression and other biomarkers of EGFR for the prediction of response to tyrosine kinase inhibitors

“…Gene/chromosome probes are visualized as dark brown dots, which are counted in parallel sections using standard light microscopy and are converted into the number of nuclear signals per cell. CISH may be useful in samples that are difficult to interpret by fluorescence microscopy because of sample heterogeneity, high autofluorescent background signal or both (Daniele et al, 2007). The main potential drawback of CISH compared with FISH is that most CISH studies have been performed on frozen sections and only a single color can be developed per section, meaning that one is not able to evaluate a control probe for aneusomy.…”

Expression of epidermal growth factor (EGF)/transforming growth factor-α by human lung cancer cells determines their response to EGF receptor tyrosine kinase inhibition in the lungs of mice

“…For this reason, and because preclinical and clinical data suggest that EGFR expression in tumor cells is not a reliable marker in determining the response of NSCLC to EGFR antagonism (17,18), identifying predictive biomarkers of EGFR pathway inhibitor activity is important. Several groups have reported the association of specific mutations in the tyrosine kinase domain of EGFR (19 -22) or a high EGFR gene copy number (23,24) with sensitivity to tyrosine kinase inhibitors. Because these mutations also occur, albeit at a low frequency, in patients who do not have a response to EGFR inhibitors, the sensitivity of NSCLC to this therapy may be caused by additional mechanisms (25,26).…”