P1.13-14 The Molecular Landscape of Lung Adenocarcinomas with Activating EGFR Gene Mutations Determined by Targeted-Sequencing

Abstract

chaperon protein expressed at high levels in cancer cells and involved in folding or stabilization of client proteins essential for cancer cell growth and survival. Ganetespib (STA-9090) is one of the second-generation HSP90 inhibitors with potent anti-tumor effect on NSCLC cells. In this study, we evaluated the anti-tumor effect of ganetespib in EGFR-TKI sensitive and acquired resistance NSCLC cell lines. Method: We treated 4 EGFR-mutant NSCLC cell lines (HCC827, HCC4006, HCC4011 and PC-9), and 5 experimentally established EGFR-TKI (gefitinib) resistance cell lines with ganetespib. The EGFR-TKI resistant mechanism consisted of EGFR T790M second mutation, MET amplification, epithelial-to-mesenchymal transition (EMT) and cancer stem cell-like properties. We determined cell proliferation by MTS assay and calculated the IC50 values. We also performed Western blotting to investigate downstream signaling pathway alterations. Result: The IC50 values in parental NSCLC cell lines ranged from 1.3nM to 15nM, and those in acquired EGFR-TKI resistance NSCLC cell lines ranged from 0.87nM to 25nM, which suggests potent anti-tumor effect of ganetespib. In addition, this effect was observed regardless of the resistant mechanisms, including EMT. Ganetespib effectively suppressed the expression of downstream pathway molecules in all examined cell lines including acquired EGFR-TKI resistance NSCLC cell lines. Also, ganetespib effectively induced apoptosis in parental and acquired EGFR-TKI resistance NSCLC cell lines with EGFR T790M mutation or MET amplification. Conclusion: Ganetespib exhibited potent anti-tumor effect in acquired EGFR-TKI resistance NSCLC cell lines regardless of the resistant mechanisms, suggesting that ganetespib could be a promising therapeutic option in the treatment of NSCLC with acquired EGFR-TKI resistance.Background: The analysis of EGFR activating mutations and ALK rearrangement is a routine procedure in qualification of NSCLC patients for molecularly targeted therapy. Targeted sequencing, as a type of NGS, allows more comprehensive analysis of low-frequency variations in suppressors and oncogenes that are commonly mutated in solid tumors. In the following study we analyzed a molecular landscape of NSCLC patients harboring EGFR activating mutations who response for EGFR TKIs. Method: The studied group included 19 Caucasian patients (7 male and 12 female, median age 65±12 years, 4 current smokers, 12 non-smokers and 3 formersmokers) with lung adenocarcinoma. 12 (63%) deletions in exon 19, 4 (21%) substitutions Leu858Arg in exon 21, 2 (11%) insertions A763_Y764 in exon 20 and 1 (5%) substitution Thr790Met in exon 20 of EGFR gene were detected using real-time PCR technique. Four non-smoking patients (median age 65±12 years) with lung adenocarcinoma and wild-type (wt) of EGFR gene were a control group. The DNA for the analysis was isolated from FFPE tissue or cellblocks and the mutational landscape was evaluated using Illumina's TruSight Tumor 26 panel on miSeq platform (Illumina, USA). Result: The targeted s...