Molecular epidemiological study of microtubule-associated protein-like 4-anaplastic lymphoma kinase fusion gene using immunohistochemistry as a cost effective alternative to fluorescence in situ hybridization for Indian patients with adenocarcinoma lung

Abstract

Abstract Background: With fluorescence in situ hybridization (FISH) as the main-stay for the detection of anaplastic lymphoma kinase (ALK) rearrangements, the ALK Break Apart FISH Probe Kit has become a Food and Drug Association-approved companion diagnostic for targeted therapy with the ALK inhibitor crizotinib in lung cancers. The objective of this molecular epidemiological study was to estimate the prevalence of microtubule-associated protein-like 4-ALK (EML4-ALK) fusion gene using immunohistochemistry (IHC) as a cost effective alternative to FISH for Indian patients with nonsmall-cell cancer (NSCC)-adenocarcinoma, favor adenocarcinoma lung and NSCC- Not otherwise specified (NOS). Materials and Methods: Patients with NSCC-adenocarcinoma, favor adenocarcinoma lung, and nonsmall cell lung cancer-NOS histology were considered for this study. Permission was obtained from the Ethics Committee before the start of the study. Clinical characteristics and treatment details were collected from the patient's medical records. IHC analysis was performed using a Ventana automated immunostainer (Benchmark XT). Detection was performed using OptiView DAB Detection and Amplification Kit. Results: A total of 200 NSCC-adenocarcinoma, favour adenocarcinoma and NSCC-NOS patients were included in the study. There were 122 (61%) men and 78 (39%) women with a median age of 57 years. Of the 200 patients, 43 (21.5%) were nonsmokers and 175 (87.5%) had Stage-IV disease at the time of initial diagnosis. 48 (24%) cases were positive for epidermal growth factor receptor mutations, whereas EML4-ALK fusion gene was present in 27 (13.5%) patients. 25 of the 27 patients with ALK positivity received crizotinib therapy. Conclusions: The incidence of EML4-ALK gene fusions (13.5%) in this Indian population is four-fold high than the previous reported incidences and supports the claim of several recent studies that a relatively new ALK clone, 5A4, and D5F3 from Leica/Novocastra and cell signaling technology/Ventana, respectively can accurately identify ALK rearranged lung adenocarcinoma. The inclusion of IHC for the detection of EML4-ALK gene fusions as a low cost alternative seems justified in low resource setting.