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Supplementary Figures S1-S6 from Acquired Resistance to the Mutant-Selective EGFR Inhibitor AZD9291 Is Associated with Increased Dependence on RAS Signaling in Preclinical Models

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posted on 2023-03-30, 23:05 authored by Catherine A. Eberlein, Daniel Stetson, Aleksandra A. Markovets, Katherine J. Al-Kadhimi, Zhongwu Lai, Paul R. Fisher, Catherine B. Meador, Paula Spitzler, Eiki Ichihara, Sarah J. Ross, Miika J. Ahdesmaki, Ambar Ahmed, Laura E. Ratcliffe, Elizabeth L. Christey O'Brien, Claire H. Barnes, Henry Brown, Paul D. Smith, Jonathan R. Dry, Garry Beran, Kenneth S. Thress, Brian Dougherty, William Pao, Darren A.E. Cross

Supplementary Figures S1-S6. Comparison of genetic alterations across multiple populations resistant to AZD9291 and other EGFR TKIs (S1); Treatment of resistant populations with AZD9291 (S2); Detection and Validation of a novel NRAS E63K mutation (S3); Lysates were prepared from parental PC9 and resistant populations analysed for levels of total and phosphorylated ERK, NRAS and KRAS by western blot (S4); The novel NRAS E63K mutation is an activating mutation that when expressed enhances resistance to cell growth inhibition by gefitinib or AZD9291 in EGFRm cell lines (S5); In vitro combination of AZD9291 with selumetinib induces more profound phenotype inhibition (S6).

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ARTICLE ABSTRACT

Resistance to targeted EGFR inhibitors is likely to develop in EGFR-mutant lung cancers. Early identification of innate or acquired resistance mechanisms to these agents is essential to direct development of future therapies. We describe the detection of heterogeneous mechanisms of resistance within populations of EGFR-mutant cells (PC9 and/or NCI-H1975) with acquired resistance to current and newly developed EGFR tyrosine kinase inhibitors, including AZD9291. We report the detection of NRAS mutations, including a novel E63K mutation, and a gain of copy number of WT NRAS or WT KRAS in cell populations resistant to gefitinib, afatinib, WZ4002, or AZD9291. Compared with parental cells, a number of resistant cell populations were more sensitive to inhibition by the MEK inhibitor selumetinib (AZD6244; ARRY-142886) when treated in combination with the originating EGFR inhibitor. In vitro, a combination of AZD9291 with selumetinib prevented emergence of resistance in PC9 cells and delayed resistance in NCI-H1975 cells. In vivo, concomitant dosing of AZD9291 with selumetinib caused regression of AZD9291-resistant tumors in an EGFRm/T790M transgenic model. Our data support the use of a combination of AZD9291 with a MEK inhibitor to delay or prevent resistance to AZD9291 in EGFRm and/or EGFRm/T790M tumors. Furthermore, these findings suggest that NRAS modifications in tumor samples from patients who have progressed on current or EGFR inhibitors in development may support subsequent treatment with a combination of EGFR and MEK inhibition. Cancer Res; 75(12); 2489–500. ©2015 AACR.

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