P2.09-28 Prognostic Impact of LKB1 Expression in Advanced Non-Small-Cell Lung Cancer

Abstract

(IHC) clone which has higher sensitivity and specificity (SP384) is available. The aim of this study is to compare these ROS1 antibodies and to interpret with FISH results. Method: Twenty-three patients (fourteen ROS1 FISH-positive, nine ROS1 FISH-negative) were included for this study. The material available for all tumors had been formalinfixed and paraffin-embedded (FFPE). D4D6 clone from Cell Signaling Technology and SP384 clone were provided by Ventana Medical Systems, which were used for ROS1 expression. The staining study was performed according to previously published methodology. ROS1 expression was evaluated by intensity scoring. IHC staining patterns of tumor cells was also interpreted as cytoplasmic or membranous and/or both pattern predominantly. All samples of FISH testing has been performed with LSI ROS1 Break Apart Probe; Abbott Molecular probe. Incompatible cases according to FISH and IHC results AmoyDx gene fusions detection kit testing has been used as confirmatory RT-PCR method. Result: See table. Conclusion:-ROS1 SP384 is more feasible then D4D6 for ROS1 protein evaluation. However, both clones may rarely be incompatible with FISH results.-We recommend that the IHC and FISH study should be done together.-In incompatible cases, the RT-PCR study will be determinant with the FISH study.

Metformin Plus Tyrosine Kinase Inhibitors in Epidermal Growth Factor Receptor–Mutated Non–Small Cell Lung Cancer—Reply

“…Moreover, it is important to highlight that an LKB1 variation is different from the loss of LKB1 protein expression, the latter of which being the alteration we tested. Interestingly, a study in Italy previously identified negative LKB1 expression by immunohistochemistry in 66% (65 of 98) of patients with non–small cell lung cancer (NSCLC), and similarly, a study performed in our population identified this result in 65 of 87 patients (75%) with NSCLC …”