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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.

Introduction: Phosphatase and tensin homolog (PTEN) has been established as a tumor suppressor gene with an important role in regulating the phosphatidylinositol-3-kinase/AKT antiapoptotic and survival pathway. The prognostic role of PTEN in non–small-cell lung carcinoma has not been evaluated completely in the context of other molecular information. Methods: Tissue microarrays containing 152 resected non–small-cell lung cancer specimens were used to investigate PTEN and p53 by immunohistochemistry and PTEN by fluorescence in situ hybridization. DNA was isolated and subjected to mutational profiling using the Sequenom Oncocarta v1.0 panel. Clinicopathological features were correlated with PTEN expression, gene copy number, and mutation status. Results: PTEN staining was absent in 63 (41.4%) of the cases. Significantly more squamous cell carcinomas compared with adeno carcinomas demonstrated loss of (negative) PTEN staining (26 of 44 [59%] versus 32 of 94 [34%]; p = 0.009). PTEN gene copy deletion was present in only seven of 124 evaluable cases (5.6%); all deleted cases were immunohistochemistry negative. In univariate and multivariate (MV) analyses adjusted for sex, age, histology, and stage, loss of PTEN protein expression was associated with significantly shorter disease-free survival (MV hazard ratio: 1.78, 95% confidence interval: 1.01–3.14, p = 0.048), whereas no significant associations were seen with p53 or KRAS and epidermal growth factor receptor (EGFR) mutation status. Importantly, the prognostic value of absent PTEN staining was limited to adenocarcinomas, with MV diseasefree survival hazard ratio of 2.68 (95% confidence interval: 1.35– 5.32, p = 0.005), whereas no such association was seen in squamous cell carcinomas. Conclusion: Absence of PTEN protein expression is an independent prognostic marker in early-stage resected lung adenocarcinoma.

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.