Search

There are very few xenograft models available for the study of esophageal (E) and gastro-esophageal junction (GEJ) cancer. Using a NOD/SCID model, we implanted 90 primary E and GEJ tumors resected from patients and six endoscopic biopsy specimens. Of 69 resected tumors with histologically confirmed viable adenocarcinoma or squamous cell carcinoma, 22 (32%) was engrafted. One of 11 tumors, considered to have had a complete pathological response to neo-adjuvant chemo-radiation, also engrafted. Of the 23 patients whose tumors were engrafted, 65% were male; 30% were early stage while 70% were late stage; 22% received neo-adjuvant chemo-radiation; 61% were GEJ cancers. Engraftment occurred in 18/54 (33%) adenocarcinomas and 5/16 (31%) squamous cell carcinomas. Small endoscopic biopsy tissue had a 50% (3/6) engraftment rate. Of the factors analyzed, pretreatment with chemo-radiation and well/moderate differentiation showed significantly lower correlation with engraftment (P

Introduction: Xenograft models of epithelial malignancies potentially have greater correlation with clinical end points. We implanted 153 primary non–small cell lung carcinomas into non-obese diabetic-severe combined immunodeficient mice to develop primary lung cancer xenografts. Sixty-three xenografts formed. However, in 19 implantations, tumors consisted of a lymphocyte proliferation without a carcinoma component. We further characterized these lymphomas to determine clinicopathological features associated with their formation. Methods: Lymphomas were investigated morphologically and by silver in situ hybridization to determine their species of origin. Characterization both of the xenograft lymphomas and the primary NSCLCs from which they were derived included immunohistochemistry for lymphoma markers and Epstein Barr virus Early RNA (EBER) by in situ hybridization. DNA was profiled using the MassARRAY platform; EML4-ALK translocations and lymphocyte infiltration were assessed in the primary tumor. Lymphoma formation was correlated with patient and primary tumor characteristics and survival. Results: The lymphocytic tumors were EBER positive, human diffuse large B-cell lymphomas (DLBCLs). Significantly more DLBCLs that formed in mice arose in primary lung adenocarcinomas and in epithelial growth factor receptor mutant never smokers. DLBCL formation was not associated with the degree of tumor-infiltrating lymphocytes or EBER-positive lymphocytes in the primary NSCLCs. Patients whose tumors developed DLBCL had longer disease-free survival compared with patients whose tumors formed epithelial xenografts (hazard ratio: 0.44; 95% confidence interval: 0.18 -1.06, Wald p = 0.07), regardless of genotype. Conclusion: We hypothesize that mechanisms involved in the active suppression of viral antigens may also be involved in the suppression of tumor antigens, and may have resulted in the observed favorable clinical outcome.

Background The epidermal growth factor receptor (EGFR) kinase domain T790M (amino acid substitution at position 790 in EGFR from threonine [T] to methionine [M]) mutation in non–small-cell lung cancer (NSCLC) results in resistance to EGFR tyrosine kinase inhibitors (TKIs). We used a patient-derived tumor xenograft (PDX) model containing an EGFR exon 19 deletion/T790M mutation to assess response to the EGFR-directed antibody cetuximab. Changes in the EGFR signaling pathway and ligand expression after treatment were investigated. Methods PDX were randomized into control and treatment arms. Pharmacodynamic studies were performed at 2 and 24 hours and at 4 days after a single administration of cetuximab, erlotinib, or dacomitinib. Changes in the EGFR signaling pathway were assessed using Western blot analysis, and baseline mRNA expression of EGFR ligands using microarray analysis. Relative changes after treatment were assessed using quantitative polymerase chain reaction. Results The xenograft showed a dramatic response to cetuximab. A complete reduction of total EGFR and phosphorylated EGFR occurred after cetuximab treatment. The PDX had increased baseline levels of heparin-binding epidermal growth factor-like growth factor ( HB-EGF ) compared with other PDX models with or without EGFR mutations. Amphiregulin was significantly reduced 2 hours after treatment with cetuximab. Compared with control mice, cetuximab- and EGFR–TKI-treated mice had significantly reduced HB-EGF gene expression at 2 hours, however, by day 4 the level of HB-EGF expression was higher. The effect of cetuximab compared with EGFR TKI on HB-EGF gene expression levels differed significantly at 2 and 24 hours but not at 4 days. Conclusion We showed a dramatic tumor response with cetuximab in an exon 19 deletion/T790M EGFR mutant lung adenocarcinoma PDX model, which suggests a role for the autocrine feedback loop in the mutant EGFR signaling pathway. Further investigation using cetuximab in NSCLC with T790M mutation is warranted.

Lipocalin 2 (LCN2) is a small secreted protein and its elevated expression has been observed in pancreatic as well as other cancer types. LCN2 has been reported to promote resistance to drug-induced apoptosis, enhance invasion through its physical association with matrix metalloproteinase-9, and promote in vivo tumor growth. LCN2 was found to be commonly expressed in patient PDAC samples and its pattern of immunohistochemical staining intensified with increasing severity in high-grade precursor lesions. Downregulation of LCN2 in two pancreatic ductal adenocarcinoma cell lines (BxPC3 and HPAF-II) with high LCN2 expression significantly reduced attachment, invasion, and tumour growth in vivo, but not proliferation or motility. Downregulation of LCN2 in two pancreatic ductal adenocarcinoma cell lines (BxPC3 and HPAF-II) with high expression significantly reduced attachment, invasion, and tumour growth in vivo. In contrast, LCN2 overexpression in PANC1, with low endogenous expression, significantly increased invasion, attachment, and enhanced tumor growth. Suppression of LCN2 in BxPC3 and HPAF-II cells increased their sensitivity to gemcitabine in vitro, and in vivo when BxPC3 was tested. Furthermore, LCN2 promotes expression of VEGF and HIF1A which contribute to enhanced vascularity. These overall results demonstrate that LCN2 plays an important role in the malignant progression of pancreatic ductal carcinoma and is a potential therapeutic target for this disease.

Purpose: Primary tumor xenografts (PTXG) established directly from patients' primary tumors in immunosuppressed animals might represent the spectrum of histologic complexity of lung cancers better than xenografts derived from established cell lines. These models are important in the study of aberrant biological pathways in cancers and as preclinical models for testing new therapeutic agents. However, not all primary tumors engraft when implanted into immunosuppressed mice. We have investigated factors that may influence the ability of primary non–small cell lung cancer (NSCLC) to form xenografts and their association with clinical outcome. Experimental Design: Tumor fragments from patients undergoing curative surgery were implanted into NOD-SCID (nonobese diabetic-severely combined immunodeficient) mice within 24 hours of surgery. Patient characteristics for tumors that engrafted (XG) and did not engraft (no-XG) were compared. Patient tumor DNA was profiled for the presence of 238 known mutations in 19 cancer-associated genes by using the MassARRAY platform. Results: Xenografts were established and passaged successfully from 63 of 157 (40%) implanted NSCLCs. Tumor factors associated with engraftment included squamous histology, poor differentiation, and larger tumor size. Significantly fewer EGFR (epidermal growth factor receptor)-mutated tumors engrafted (P = 0.03); conversely, more K-RAS–mutated tumors engrafted (P = 0.05). In multivariate analysis including age, sex, stage, and mutation, patients with XG tumors had significantly shorter disease-free survival compared with no-XG patients (hazard ratio: 7.0, 95% CI: 3.1–15.81; P < 0.000003). Conclusion: PTXGs closely mirror the histology and molecular profiles of primary tumors and therefore may serve as important preclinical models. Tumors that engraft are biologically more aggressive and may be more representative of cancers with a higher propensity to relapse after surgery. Clin Cancer Res; 17(1); 134–41. ©2010 AACR.

Background: Resistance to small molecule EGFR tyrosine kinase inhibitors (TKIs) is seen in some NSCLC patients with activating EGFR mutations. We evaluated in vivo PDX models for their utility in studying EGFR-targeted drug resistance mechanisms. Methods: Surgically resected early stage NSCLC tumors were implanted into non-obese diabetic severe combined immune deficient (NOD-SCID) mice. Tumors were passaged and expanded in new mouse hosts once the humane endpoint of 1.5 cm maximum diameter was reached. EGFR TKI treatment was initiated at an average tumor volume of 150mm3. Treatments included daily oral gavage with first and second generation EGFR TKIs, and with weekly intraperitoneally administered cetuximab. Results: Of the 55 NSCLC tumors with EGFR activating mutations, only 6 engrafted (11%) and could be propagated beyond the first passage, and 4 have been studied for their responsiveness to EGFR-targeted agents. Model 148, developed from a patient who received pre-operative erlotinib, showed intrinsic pan-resistance to all EGFR-targeted therapies despite having an L858R mutation. The corresponding patient did not respond to erlotinib, relapsed after surgery and did not receive additional TKI therapy. Model 137, with an exon19 E746-A750 deletion, recapitulated the patient's response to gefitinib at relapse; this model was sensitive to first and second generation EGFR TKIs. Model 192 also has the exon19 E746-A750 deletion, however it did not recapitulate the patient's observed sensitivity to erlotinib. Selection for a MET amplified population during engraftment may be the cause for the disparate drug sensitivities. Model 164 has a double exon19 L747-T751 deletion and T790M EGFR mutation. Neither patient nor xenograft responded to erlotinib; the xenograft responded to cetuximab. Resistance developed over time to a second generation EGFR TKI; this resistant phenotype was not stable as each subsequent passage of the ‘resistant’ tumor exhibited the same initial response pattern. Two potential mechanisms for this transient sensitivity are currently being investigated: epigenetic mechanisms and intratumoural mutational heterogeneity. Conclusions: PDX models may provide important insight into biomarkers and mechanisms of resistance to targeted therapies, and provide a means to test novel treatment strategies to improve future treatment efficacies. Citation Format: Erin L. Stewart, Celine Mascaux, Shingo Shakashita, Devang Panchal, Dennis Wang, Ming Li, Nhu-An Pham, Natasha Leighl, Geoffrey Liu, Frances A. Shepherd, Ming-Sound Tsao. Modeling mechanisms of resistance of epidermal growth factor receptor (EGFR) mutations to targeted drugs through patient-derived xenografts (PDX) of non-small cell lung cancer (NSCLC). [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 1184. doi:10.1158/1538-7445.AM2014-1184

Xenografts established directly from patient tumors mirror closely the histology of the primary tumors. Therefore, primary tumor xenografts (PTXG) may serve as important preclinical models to evaluate novel anti-cancer drugs. We previously reported that the ability of resected tumors to engraft in NOD-scid mice is a strong predictor of relapse after surgery and poorer prognosis in NSCLC patients, and thus may represent biologically more aggressive cancers (Clin Cancer Res 2011;17:134-41). Genomic characterization of PTXG would help identify genetic aberrations that drive malignant oncogenic pathways in NSCLC. We characterized the somatic copy number alterations (CNA) of 36 PTGX, consisting of 15 adenocarcinoma (ADC), 18 squamous cell carcinoma (SCC), 2 large cell neuroendocrine carcinoma (LCNEC) and 1 large cell carcinoma (LC), along with 34 patient normal samples as controls using Illumina Omni-1 Quad SNP arrays. The gene expression profiles of the 36 PTGX were analyzed using Illumina Omni-1 Quad HT-12 v4 arrays. Histology-specific recurrent regions of CNA observed in PTGX are concordant with the published and publicly available primary NSCLC CNAs. We identified 1053 genes with somatic copy number gains and 932 genes with somatic copy number losses that distinguish between SCC and ADC. From integrative analysis of mRNA expression and somatic CNAs, we identified 325 genes specific to ADC and 2232 specific to SCC that are well correlated. Gene candidates that are deregulated in ADC include WRN, STK35, SIX1; and genes that are over-expressed in SCC include SOX2, RNF13, WNK1, PIK3CA, TFRC, TP63, PAK2 suggesting there is differential deregulation of signaling pathways between these two subtypes of lung cancer. We have identified candidate gene signatures that distinguish between ADC and SCC from PTXG, suggesting these xenograft models can provide a valuable resource to study cancer biology and preclinical drug target evaluation in vivo. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5069. doi:1538-7445.AM2012-5069

Non-small cell lung carcinoma (NSCLC) is a major, lethal cancer worldwide. Various molecular and cellular abnormalities are found in NSCLC, and an established theme is the alteration of protein phosphotyrosine (pY), as exemplified by elevated epidermal growth factor receptor (EGFR) activity recognized in a subset of NSCLC. In order to gain a broad perspective of pY-mediated signaling networks in NSCLC, mass spectrometry was used to analyze pY-containing peptides affinity purified from protease-digested xenograft tumors. Seventeen tumors representing the major NSCLC subtypes adenocarcinoma (ADC) and squamous cell carcinoma (SCC) were characterized. The major classes of pY proteins detected were cytoskeletal, protein kinases, and adhesion proteins. Pathways and cellular functions enriched in the data set included focal adhesion, adherens junction, and ErbB signaling. Five receptor tyrosine kinases (RTKs) were detected, with EGFR and EPHA2 most prevalent. Src-family kinases (YES, LYN, FRK and LCK) and focal adhesion kinase (FAK) comprised the majority of non-receptor tyrosine kinases measured. Analysis of individual pY sites on 14 tyrosine kinases indicates their activation by kinase domain activation loop phosphorylation, but also revealed additional pY sites suggestive of regulation by trafficking/endocytosis and inter- and intra-molecular protein-protein interactions involving, for example, SH2 and SH3 domains, and extra-kinase domain regions. Analysis of tumors based on protein-pY suggested subtypes distinguished by their activated tyrosine kinase networks. Genetic analysis of 3 tumors that displayed EGFR-associated phospho-proteome signatures confirmed that they carried either EGFR activating mutations (in two ADCs) or increased gene copy number (in one SCC). Western blot analysis of protein pY confirmed different patterns of cellular protein pY among the tumor phospho-types in agreement with the phospho-proteomic analysis. Quantification of kinase and substrate pY sites, according to their integrated extracted ion currents, revealed a set of phosphorylations that constituted a molecular signature that differentiated between the ADC and SCC subtypes. In summary, quantitative phospho-proteomic profiling of NSCLC tumors is feasible and may have utility in the categorization of individual tumors according to their networks of activated tyrosine kinases and substrates. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4805. doi:1538-7445.AM2012-4805

Background: Dysregulated Notch signalling has been implicated in a variety of cancers. R is a potent and selective inhibitor of -secretase, a key enzyme in Notch signalling. Phase I data demonstrated R to be tolerable but PK profile revealed auto-induction with repeated dosing at high doses (Tolcher et al. ASCO 2010). The primary aim of this study is to determine the optimal regimen of R using alternative dosing schedules. Its secondary aim is to establish mouse XG from tumor biopsies to enable correlative biomarker research. Methods: Pts with advanced solid tumors were enrolled in one of 6 different schedules and starting doses of R. Serial PK samples were collected on Day 1 and at steady state. Mandatory pre and post treatment tumor biopsies were procured if medically safe and implanted subcutaneously into NOD-SCID mice for propagation in up to 4 serial generations. Tumor DNA from second XG passage was analyzed using the Sequenom OncoCarta Panel v1.0 (SOCP). Results: To date, 24 pts have been enrolled. PK data are available for 21 pts, summarized in Table 1. The maximum tolerable dose for schedules C-F has not been reached. Commonest adverse events (AE) of all grades with at least possible attribution to R were fatigue (n=14), nausea (13), hypophosphatemia (11), anorexia (9) and diarrhoea (8). Grade 3/4 AEs consisted of hypophosphatemia (n=2), lymphopenia (2), vomiting (1) and QTc prolongation (1). Data on engraftment are available from biopsies of 18 pts (18 pre and 16 post treatment samples). Primary tumor sites included gastrointestinal (n=6), breast (4), melanoma (2), ovarian (2), pancreatic (1), neuroendocrine (1), parotid (1) and lung cancers (1). In pre treatment biopsies, the rate of initial engraftment was 12/18 (67%); while in post treatment biopsies, the rate of initial engraftment was 14/16 (88%). Further passages (2nd and 3rd) from viable engrafted cancers demonstrated a 100% engraftment rate. The SOCP analyses were carried out in 9 different XG models with mutations detected in 4 (KRAS [n=3] and BRAF mutations), all of which were from metastatic colon cancers. Conclusions: Preliminary PK evaluation demonstrated auto-induction of R in schedules A and B (concordant with prior data), but to a lesser degree in schedules C, D & E. It is unclear whether this observation was due to the lower administered doses of R or the alternative schedules employed. This study demonstrated the ability to generate mouse XG models from different tumor histologies using core biopsies, with a mean engraftment rate of 78% at first implantation. We also confirmed the feasibility of detecting point mutations in cancers using SOCP platform on XG specimens. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B50.