Open AccessComparison of IHC, FISH and RT-PCR Methods for Detection of ALK Rearrangements in 312 Non-Small Cell Lung Cancer Patients in Taiwan
Author(s) -
YiCheng Wu,
I–Shou Chang,
Chi-Liang Wang,
TaiDi Chen,
YaTing Chen,
Huiping Liu,
Yen Chu,
Ya-Ling Chiu,
Tzu-Hua Wu,
LiHui Chou,
Yirong Chen,
Shiu-Feng Huang
Publication year - 2013
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0070839
Subject(s) - crizotinib , anaplastic lymphoma kinase , kras , lung cancer , fluorescence in situ hybridization , immunohistochemistry , biology , fusion gene , microbiology and biotechnology , cancer research , cancer , pathology , medicine , gene , genetics , immunology , colorectal cancer , malignant pleural effusion , chromosome
Background Recently Echinoderm microtubule-associated protein-like 4- anaplastic lymphoma kinase ( EML4-ALK ) fusion gene has become an important biomarker for ALK tyrosine kinase inhibitor (crizotinib) treatment in NSCLC. However, the best detection method and the significance of EML4-ALK variant types remain uncertain. Methods Reverse transcriptase-polymerase chain reaction (RT-PCR), fluorescence in Situ hybridization (FISH) and Immunohistochemical (IHC) stain were performed on tumor tissues of 312 NSCLC patients for detection of ALK rearrangements. Mutation analyses for EGFR and KRAS genes were also performed. Results Thirteen of the 312 patients (4.17%) had ALK rearrangements detected by RT-PCR. If RT-PCR data was used as the gold standard, FISH tests had a low sensitivity (58.33%), but very good specificity (99.32%). IHC stain had better sensitivity (91.67%) than FISH, but lower specificity (79.52%), when the cut off was IHC2+. All of the 8 patients with high abundance of EML4-ALK positive cells in tumor tissues (assessed by the signal intensities of the RT-PCR product), were also have high expression of ALK protein (IHC3+), and positive for FISH, except one failed in FISH. Variants 3a+3b (4/5, 80%) of EML4-ALK fusion gene were more common to have high abundance of EML4-ALK positive cells in tumor tissues than variant 1 (1/3, 33.3%). Meta-analysis of the published data of 2273 NSCLC patients revealed that variant 3 (23/44, 52.3%) was the most common type in Chinese population, while variant 1 (28/37, 75.7%) was most common in Caucasian. Conclusions Among the three detection methods, RT-PCR could detect not only the presence of EML4-ALK fusion gene and their variant types, but also the abundance of EML4-ALK positive cells in NSCLC tumor tissues. The latter two factors might affect the treatment response to anti-ALK inhibitor. Including RT-PCR as a diagnostic test for ALK inhibitor treatment in the prospective clinical trials is recommended.