Abstract 2012: Ultra-deep sequencing of circulating free DNA to identify predictive, mutated HSP90 clients in the GALAXY TrialTM (NCT01348126): a randomized phase IIB/III study of ganetespib (STA-9090) in combination with docetaxel versus docetaxel alone in subjects wit

Abstract

Abstract Background: Non-small cell lung cancer is a mosaic, comprising several distinct molecular subtypes driven by somatic mutations in so-called cancer genes. Several of these oncogenic mutations confer dependence on HSP90 e.g. EML4-ALK, BRAF, KRAS, KIT. Inhibition of Hsp90 induces apoptosis and can exploit this dependence. Ganetespib (G) is an Hsp90 inhibitor with single agent activity in molecularly defined disease, including EML4-ALK rearrangement, KRAS mutations, HER2 amplification and BRAF mutations. Circulating free DNA (cfDNA) is present at low levels in plasma of healthy individuals allowing detection of somatic mutations by deep sequencing. The aim of this work was to determine the mutational spectrum of patients enrolled into the GALAXY trial using this liquid biopsy strategy. Methods: We performed a prospective exploratory analysis to identify plasma-borne somatic mutations as predictors of clinical outcome with G in GALAXY, a randomized trial, comparing G + docetaxel (D), to D alone in 2nd line advanced NSCLC patients. Plasma samples were collected from approximately 200 patients with adenocarcinoma at baseline prior to initiation of treatment, and during cycles 1 and 2. cfDNA samples were evaluated using the Ion AmpliSeq™ Cancer Panel on the Ion Torrent |PGM platform to survey 739 amplicons in 46 cancer genes at up to 6000x depth. Results: CfDNA targeted sequence analysis of the first 38 patients revealed multiple concurrent mutations in client proteins including the HSP90 client proteins BRAF, PDGFR and KIT, demonstrating the feasibility of this method. Sequencing of a larger cohort is underway. Longitudinal sampling of plasma has been conducted to monitor temporal evolution of the penetrance of mutations. Summary: Ultra-deep re-sequencing of multiple somatic mutations in circulating cfDNA is feasible, and can potentially enable identification of G sensitive subgroups. This represents a new approach to biomarker discovery in the context of phase II trials. Citation Format: Dean Anthony Fennell, L. Miguel Martins, Iman El-Hariry, Vojo Vukovic, Florentina Teofilovici, Vienna L. Reichert, Jacqui Shaw. Ultra-deep sequencing of circulating free DNA to identify predictive, mutated HSP90 clients in the GALAXY TrialTM (NCT01348126): a randomized phase IIB/III study of ganetespib (STA-9090) in combination with docetaxel versus docetaxel alone in subjects wit [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2012. doi:10.1158/1538-7445.AM2013-2012