Abstract 4813: Comparative activity profiling of tyrosine kinase inhibitors (TKIs) against exon 20 insertions and the wild-type form of epidermal growth factor receptor (EGFR)
Authors: Ward Richard A. , Bianco Ambra , Colclough Nicola , Cross Darren , Cuomo Emanuela M. , Finlay M. Raymond V. , Fitzek Martina , Floc’h Nicolas , Gagrica Sladjana , Hammond Beverley , Martin Matthew J. , McKerrecher Darren , O’Neill Daniel J. , Orme Jonathan P. , Smith Paul D. , Staniszewska Anna D. , Urosevic Jelena , Whalley Nicky , Yates James W. 
Published: August 2019

Abstract
Exon 20 insertions (Ex20Ins) have been identified in approximately 5% of epidermal growth factor receptor (EGFR)-mutated lung tumours in patients presenting with non-small cell lung cancer (NSCLC). Several small molecule tyrosine kinase inhibitors (TKIs) have been reported to have pre-clinical activity against such insertions including afatinib, poziotinib, osimertinib, nazartinib, AP32788/TAK-788 and TAS6417. However, there remains a lack of approved treatments for patients with Ex20Ins with early approved EGFR agents appearing to be ineffective in this setting. Poziotinib, osimertinib and AP32788/TAK-788 are undergoing clinical evaluation in patients whose tumours carry Ex20Ins and in some cases clinical responses have been reported giving hope that such insertions can be targeted by small molecules. There is however a need for comparable data across such compounds that would enable understanding of the relative activity of these compounds between Ex20Ins and the wild-type form of EGFR. As many of the Exon 20 insertions are not part of the ATP binding pocket achieving selectivity over wild type EGFR is highly challenging and may limit the clinical utility of agents due to dose limiting EGFR wild-type driven toxicity.
A selection of TKIs were profiled for Ex20Ins and wild-type EGFR activity using biochemical, in vitro cellular phosphorylation and proliferation assays. This has enabled us to differentiate the Ex20Ins versus wild-type EGFR selectivity profiles of a range of pre-clinical, clinical and proprietary compounds. As part of this evaluation we utilized a CRISPR CAS9 approach in H2073 EGFR wild-type NSCLC cell line, where we have established cellular disease models against the most prevalent insertions including D770-N771insSVD (22%). Finally, we will show anti-tumour efficacy data for a selection of these inhibitors along with a potential combination approach of osimertinib and cetuximab.
EGFR D770-N771InsSVD cell phospho IC50 (µM)EGFR WT (H2073) cell phospho IC50 (µM)Fold-EGFR WT margin (cell)afatinib0.0060.00330.5osimertinib0.0940.414.4poziotinib0.00340.00351TAS64170.0230.0672.9AZ62810.0972.223
Citation Format: Richard A. Ward, Ambra Bianco, Nicola Colclough, Darren Cross, Emanuela M. Cuomo, M. Raymond V. Finlay, Martina Fitzek, Nicolas Floc’h, Sladjana Gagrica, Beverley Hammond, Matthew J. Martin, Darren McKerrecher, Daniel J. O’Neill, Jonathan P. Orme, Paul D. Smith, Anna D. Staniszewska, Jelena Urosevic, Nicky Whalley, James W. Yates. Comparative activity profiling of tyrosine kinase inhibitors (TKIs) against exon 20 insertions and the wild-type form of epidermal growth factor receptor (EGFR) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4813.