Abstract 1227: Preserved histological and molecular phenotypes following serial in vivo propagation of patient-derived xenografts of small cell lung cancer
Authors: Owonikoko Taofeek Kunle , Zhang Guojing , Sica Gabriel L. , Kim Hyun S. , Ogee-Nwankwo Onyinye C. , Ramalingam Suresh S. , Rossi Michael R. , Khuri Fadlo R. 
Published: May 2015

Abstract
Background: Limited availability of tissue samples is a major impediment to small cell lung cancer (SCLC) research but patient-derived xenograft (PDX) offers a potential alternative. The high genomic instability of SCLC necessitates the need to establish whether the molecular characteristics of PDXs are preserved across serial propagation in mice.
Method: PDX were raised using biopsy samples from patients with relapsed SCLC under an IRB-approved protocol. Image guided or bronchoscopic biopsies were directly implanted subcutaneously into SCID mice within 60 minutes of collection and without in vitro culture. Tumor growth was monitored and animals were sacrificed while overall tumor size remained &lt;2g. Harvested tumors were immediately re-implanted into a new set of 5 mice for up to 5 generations while freezing remnant tumor samples in liquid nitrogen for future use. Tumor histology was assessed by standard H&E and immunohistochemistry for neuroendocrine markers (NSE, chromogranin and Synaptophysin). Harvested DNA from tumor samples from all generations of PDX using QiAmp DNA Mini Kit was employed for targeted sequencing at greater than 2,000x coverage on the Illumina MiSeq instrument. A 17-gene panel including frequently encountered genetic aberrations in lung cancer (EGFR, KRAS, TP53, STK11, PTEN, NRAS, ERBB2, MET, NF1 and PIK3CA) was used to characterize molecular phenotype of PDX samples. Molecular homogeneity was assessed by comparing the genetic profile of each PDX across all generations. All identified mutations were compared to the COSMIC database.Results: We have successfully raised PDX from 5 of 9 patient biopsies with a lag time from initial implantation to adequate tumor growth ranging between 1.5 and 11 months. Propagation of PDX across generations has been performed for 5 generations (1PDX), 3 generations (2PDXs), 2 generations (2PDXs) and 1 generation (1PDX). There was good preservation of tumor histology assessed by H&E and IHC across generations. Mutations in TP53 gene (c.422G&gt;A[p.Cys141Tyr]; c.913A&gt;T[p.Lys305Ter], c.488A&gt;G[p.Tyr163Cys], c.892G&gt; [p.Glu298Ter]) detected in tumor samples from the first generation mice were preserved across all subsequent generations tested. Additionally, there were no new aberrations detected in this panel of 17 genes when comparing early to later generations of PDX. Conclusions: Despite the high degree of genomic instability expected in SCLC, serially propagated PDX of SCLC maintained histologic and molecular characteristics across many generations. Our finding that original tumor characteristics remain well preserved in PDX supports future use of this resource as reliable platform for translational research in SCLC.Supported through the Georgia Cancer Coalition Distinguished Scholar Award and NIH/NCI 5K23CA164015 grant to TK Owonikoko
Citation Format: Taofeek Kunle Owonikoko, Guojing Zhang, Gabriel L. Sica, Hyun S. Kim, Onyinye C. Ogee-Nwankwo, Suresh S. Ramalingam, Michael R. Rossi, Fadlo R. Khuri. Preserved histological and molecular phenotypes following serial in vivo propagation of patient-derived xenografts of small cell lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1227. doi:10.1158/1538-7445.AM2014-1227