Abstract 2796: Patient-derived xenograft models reveal a subset of clinically relevant squamous non-small cell lung cancers that respond to targeted EGFR inhibition.
Authors: Cranston Aaron , Mckenzie Andrew , Mallinder Phil , Jiang Simon , Moakes Kerry , Yin Yinfei , Reece-Smith Alex , Grabowska Anna , Page Martin , Kumari Rajendra 
Published: August 2014

Abstract
BACKGROUND: Non-small cell lung cancer (NSCLC) accounts for 85% of lung cancer cases, carries a poor prognosis and remains an area of high unmet need. Despite recent advances in treating NSCLC adenocarcinomas with targeted epidermal growth factor receptor (EGFR) kinase inhibitors, few advances have been made in the treatment of squamous cell carcinoma (SCC), which accounts for 25% of NSCLC. Although the incidence of EGFR mutations in SCC is low, a retrospective clinical study of erlotinib in SCC suggested that a proportion of SCC patients would benefit from treatment with an EGFR inhibitor (Tseng et al., 2012).
METHODS: NSCLC samples obtained from untreated patients undergoing surgery were collected with ethical consent, disaggregated and implanted subcutaneously in MF-1 nude mice (Harlan UK) admixed with a human stromal cell component to generate patient-derived xenograft (PDX) models (LION PDX models). Tumour material was diagnosed on the basis of operative histology and immunohistochemistry (IHC) used to confirm histological subtype. IHC was also used to evaluate EGFR expression and tumours characterised for mutations in p53, LKB1, EGFR and K-RAS by direct DNA sequencing. Patient-derived xenografts were maintained in vivo and study cohorts of mice dosed when tumours reached 100-200mm3 with either erlotinib or gefitinib or vehicle placebo. Response to treatment was evaluated by tumour growth inhibition and waterfall plots.
RESULTS: We have identified a subset of tumours with squamous histology in our LION panel of patient-derived NSCLC xenografts that respond to treatment with a targeted EGFR inhibitor. Four out of 11 SCC models tested (36%) responded to treatment with either erlotinib or gefitinib with greater than 50% growth inhibition and two SCC models responded with ∼30% growth inhibition. Responses correlated well with EGFR expression. Work to characterise a further 8 LION SCC PDX models is also underway.
CONCLUSIONS: These data support the proposition that a significant subset of NSCLC patients with squamous histology may benefit from treatment with targeted EGFR inhibitors. Our LION SCC models could be valuable for biomarker studies to identify the basis of the EGFR inhibitor responder subset and for evaluating new agents in a more clinically relevant setting.
Citation Format: Aaron Cranston, Andrew Mckenzie, Phil Mallinder, Simon Jiang, Kerry Moakes, Yinfei Yin, Alex Reece-Smith, Anna Grabowska, Martin Page, Rajendra Kumari. Patient-derived xenograft models reveal a subset of clinically relevant squamous non-small cell lung cancers that respond to targeted EGFR inhibition. [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 2796. doi:10.1158/1538-7445.AM2013-2796