Immunohistochemistry to detect EGFR mutation and ALK gene rearrangement in NSCLC bronchoscopic specimens.

Abstract

e19135 Background: The discovery of the E746-A750 and L858R antibodies for mutated epidermal growth factor receptor (EGFR) and the D5F3 antibody for the product of the rearranged anaplastic lymphoma kinase (ALK) gene enables immunohistochemistry(IHC) to be applied to the identification of lung cancer. This study aimed to explore the effectiveness of IHC in small specimens and compare it with standard methods. Methods: We collected bronchoscopic specimens of lung adenocarcinoma that were confirmed by pathology; gathered clinical information, including the basic characteristics of patients, staging and differentiation of the tumor, and the amount and proportion of tumor cells; identified mutant EGFR with E746-A750del and L858R antibodies and rearranged ALK with D5F3 antibody (Cell Signaling Technology, USA); and compared their sensitivity and specificity with standard methods. Results: We collected 92 patients¡&hibar; bronchoscopic specimens. All specimens were successfully detected by the Scorpions-ARMS method£€and exon 19 deletion occurred in 15 specimens (16.3%), and exon 21 L858R mutation in 15 specimens (16.3%). In EGFR-IHC, the positive rates of E746-A750del and L858R were 17.8% (16/92) and 21.4% (19/92), respectively. The sensitivity and specificity of E746-A750del (with Scorpions-amplification refractory mutation system (ARMS) as the standard) were 73.3% (11/15) and 93.3% (70/75), respectively, and those of L858R were 93.3% (14/15) and 93.2% (69/74). Neither method was significantly worse than Scorpions-ARMS (p£½1.000 for E746-A750del, p£½0.219 for L858R). FISH detected 6 positive and 71 negative specimens for ALK rearrangement; the other 15 could not be evaluated for various different reasons. In ALK-IHC, the positive rate was 7.8% (6/77; 13 could not be evaluated). The sensitivity and specificity of D5F3 were 50% (3/6) and 100% (71/71), respectively. ALK-IHC showed no difference with the standard method of fluorescence in situ hybridization (FISH). Conclusions: IHC with E746-A750del and L858R antibodies is an economical and convenient method for EGFR mutation detection in small specimens of NSCLC, as is D5F3 monoclonal antibody for ALK-IHC, especially for the primary screening.