P1.02-003 ROS1 (D4D6) is Reliable for Immunohisochemistry Detecting of ROS1 Fusion Lung Adenocarcinoma in Malignant Pleural Effusion

Abstract

ROS1 fusion is of a low frequency genetic alteration in non-small cell lung cancer (NSCLC). The clinical trial showed that NSCLC patients harboring ROS1 fusion could benefit from crizotinib treatment. Several studies reported that immunohistochemistry (IHC) could be employed as a screening method for detecting ROS1 fusion in tumor tissue using Anti-ROS1(D4D6) antibody. Malignant pleural effusion (MPE) is the common sample type in advanced NSCLC, the reliability of ROS1(D4D6) for detecting ROS1 fusion in MPE cell blocks (CBs) should be explored. Anti-ROS1(D4D6) monoclonal antibody (Cell Signaling Technology, Danvers, USA) IHC testing was performed on 227 formalin fixed paraffin embedded (FFPE) MPE CBs from lung adenocarcinoma patients. RT-PCR using ROS1 fusion gene detection kit (AmoyDx) was performed to detected ROS1 gene fusion as a comfirming test. Some other lung cancer driver genes were also detected in both IHC/RT-PCR ROS1 positive samples, among which EGFR, KRAS, BRAF, PIK3CA and HER2 20 exon mutation was tested by amplification refractory mutation system kits(AmoyDx), ALK and RET fusion was tested by RT-PCR kits(AmoyDx). 4 of 227 MPE samples(1.76%) of lung adenocarcinoma were interpreted as ROS1 fusion-positive cases by IHC staining, and the cytoplasmic and membranous granular positive signals were displayed. Comparison with RT-PCR testing results, 3 of 4 IHC positive cases were verified by RT-PCR, the sensitivity was 100% and specificity of was 99.6%. The clinicopathologic features and other genes status of 3 both IHC/RT-PCR positive patients were showed Table 1. One ROS1 IHC/RT-PCR positive lung adenocarcinoma patient received crizotinib therapy and obtained partial response. ROS1 (D4D6) would be a reliable antibody for screening ROS1 fusion-positive lung adenocarcinoma on FFPE MPE CBs by IHC assay and shows high specificity in the FFPE MPE CBs samples.Table 1Clinicopathologic features and genes status of ROS1 IHC/RT-PCR positive patientsGenderAgeSmokingTTF1/ P63E/k/B/ P/HA/RTherapyEfficacyPFS/Follow-upp1Male55Smoker+/-WTWTcrizotinibPR10m+/alivep2Female60Never+/-WTWTNo1m/DeadP3Male62Never+/-WTWTPEM+CISPR9m+/aliveE/K/B/P/H: EGFR/KRAS/BRAF/PIK3CA/HER-2 20 exon mutation, A/R: ALK/RET fusion, WT: wild type, PEM+CIS: Pemetrexed plus Cisplatin, PR: partial response, m: months Open table in a new tab