Preclinical Evaluation Of New Therapies Research Articles

Comparative pathology of experimental pulmonary tuberculosis in animal models.

Research in human tuberculosis (TB) is limited by the availability of human tissues from patients, which is often altered by therapy and treatment. Thus, the use of animal models is a key tool in increasing our understanding of the pathogenesis, disease progression and preclinical evaluation of new therapies and vaccines. The granuloma is the hallmark lesion of pulmonary tuberculosis, regardless of the species or animal model used. Although animal models may not fully replicate all the histopathological characteristics observed in natural, human TB disease, each one brings its own attributes which enable researchers to answer specific questions regarding TB immunopathogenesis. This review delves into the pulmonary pathology induced by Mycobacterium tuberculosis complex (MTBC) bacteria in different animal models (non-human primates, rodents, guinea pigs, rabbits, cattle, goats, and others) and compares how they relate to the pulmonary disease described in humans. Although the described models have demonstrated some histopathological features in common with human pulmonary TB, these data should be considered carefully in the context of this disease. Further research is necessary to establish the most appropriate model for the study of TB, and to carry out a standard characterisation and score of pulmonary lesions.

Delivery of Cardioactive Therapeutics in a Porcine Myocardial Infarction Model.

Myocardial infarction is one of the leading causes of death and disability worldwide, and there is an urgent need for novel cardioprotective or regenerative strategies. An essential component of drug development is determining how a novel therapeutic is to be administered. Physiologically relevant large animal models are of critical importance in assessing the feasibility and efficacy of various therapeutic delivery strategies. Due to their similarities to humans in cardiovascular physiology, coronary vascular anatomy, and heart weight to body weight ratio, swine is one of the preferred species in the preclinical evaluation of new therapies for myocardial infarction. The present protocol describes three methods of administering cardioactive therapeutic agents in a porcine model. After percutaneously induced myocardial infarction, female landrace swine received treatment with novel agents through either: (1) thoracotomy and transepicardial injection, (2) catheter-based transendocardial injection, or (3) intravenous infusion via jugular vein osmotic minipump. The procedures employed for each technique are reproducible, resulting in reliable cardioactive drug delivery. These models can be easily adapted to suit individual study designs, and each of these delivery techniques can be used to investigate a variety of possible interventions. Therefore, these methods are a useful tool for translational scientists pursuing novel biological approaches in cardiac repair following myocardial infarction.

From Cancer to Immune-Mediated Diseases and Tolerance Induction: Lessons Learned From Immune Oncology and Classical Anti-cancer Treatment.

Success in cancer treatment over the last four decades has ranged from improvements in classical drug therapy to immune oncology. Anti-cancer drugs have also often proven beneficial for the treatment of inflammatory and autoimmune diseases. In this review, we report on challenging examples that bridge between treatment of cancer and immune-mediated diseases, addressing mechanisms and experimental models as well as clinical investigations. Patient-derived tumor xenograft (PDX) (humanized) mouse models represent useful tools for preclinical evaluation of new therapies and biomarker identification. However, new developments using human ex vivo approaches modeling cancer, for example in microfluidic human organs-on-chips, promise to identify key molecular, cellular and immunological features of human cancer progression in a fully human setting. Classical drugs which bridge the gap, for instance, include cytotoxic drugs, proteasome inhibitors, PI3K/mTOR inhibitors and metabolic inhibitors. Biologicals developed for cancer therapy have also shown efficacy in the treatment of autoimmune diseases. In immune oncology, redirected chimeric antigen receptor (CAR) T cells have achieved spectacular remissions in refractory B cell leukemia and lymphoma and are currently under development for tolerance induction using cell-based therapies such as CAR Tregs or NK cells. Finally, a brief outline will be given of the lessons learned from bridging cancer and autoimmune diseases as well as tolerance induction.

Imaging of Preclinical Endometrial Cancer Models for Monitoring Tumor Progression and Response to Targeted Therapy.

Endometrial cancer is the most common gynecologic malignancy in industrialized countries. Most patients are cured by surgery; however, about 15% of the patients develop recurrence with limited treatment options. Patient-derived tumor xenograft (PDX) mouse models represent useful tools for preclinical evaluation of new therapies and biomarker identification. Preclinical imaging by magnetic resonance imaging (MRI), positron emission tomography-computed tomography (PET-CT), single-photon emission computed tomography (SPECT) and optical imaging during disease progression enables visualization and quantification of functional tumor characteristics, which may serve as imaging biomarkers guiding targeted therapies. A critical question, however, is whether the in vivo model systems mimic the disease setting in patients to such an extent that the imaging biomarkers may be translatable to the clinic. The primary objective of this review is to give an overview of current and novel preclinical imaging methods relevant for endometrial cancer animal models. Furthermore, we highlight how these advanced imaging methods depict pathogenic mechanisms important for tumor progression that represent potential targets for treatment in endometrial cancer.

Corruption of neuroblastoma patient derived xenografts with human T cell lymphoma

BackgroundPatient derived xenografts (PDXs) provide a unique opportunity for investigators to study tumor cell activity, response to therapeutics, and resistance patterns without exposing the human patient to experimental compounds, and thereby play a crucial role in pre-clinical evaluation of new therapies. It has been reported that PDXs may undergo a transformation to lymphoma, most commonly associated with Epstein Barr virus (EBV). If the character of a xenograft becomes compromised and remains undetected, it could have a detrimental impact on the research community as a whole. Our lab has established a number of pediatric solid tumor PDXs which accurately recapitulate the human tumors following several passages. One particular neuroblastoma PDX was noted to grow quickly and with an unusual phenotype, leading us to hypothesize that this PDX had undergone a transformation. MethodsThe PDX in question was investigated with histology, immunohistochemistry (IHC), EBER in situ hybridization, and PCR to determine its identity. ResultsHistology on the tumor revealed a small, round blue cell tumor similar to the original neuroblastoma from which it was derived. IHC staining showed that the tumor was composed of lymphocytes that were CD3 positive, <5% CD4 positive, and CD20 negative. The cells were Epstein Barr virus negative. PCR demonstrated that the tumor was human and not murine in origin. ConclusionThese findings indicate that a human T Cell lymphoma developed in place of this neuroblastoma PDX. Changes in PDX identity such as this one will significantly impact studies utilizing pediatric PDXs and the mechanism by which this occurred warrants further investigation.

Abstract 1038: Xenograft-associated B cell lymphoproliferative disease as a surrogate model to study Epstein-Barr virus (EBV) driven lymphoma of the elderly

Abstract Background: Patient-derived tumor xenografts (PDX) are powerful tools to study cancer biology, cancer genomics and developmental therapeutics. A common problem in the development of PDX models is proliferation of atypical lymphocytes at the implant site, which often overtake or limit the growth of the original tumor. This atypical proliferation has been described as Xenograft-Associated B cell Lymphoproliferative Disease (XABLD) in our PDX models. In this study, we characterized XABLD cases by morphology, immunophenotyping and genomic profiling. We hypothesize that XABLD tumors are morphologically and phenotypically similar to EBV-driven lymphoma of the elderly and may function as a surrogate model for that lymphoma. Materials and Methods: Models were generated from patient tissue collected under NCI Tissue Procurement Protocol (clincialtrials.gov: NCT00900198) and CIRB Tissue Procurement Protocol 9846 for development of models for NCI's Patient-Derived Models Repository (https://pdmr.cancer.gov). Specimens were implanted subcutaneously in NOD/SCID/IL2Rg null (NSG) mice and animal health was monitored throughout the study. Tumors in mice with suspected XABLD were harvested and reviewed by histology and immunohistochemical analysis for CD45, B and T cell markers and EBV status. All samples in this study were classified by the Lymph2Cx NanoString cell of origin assay and transcriptome profiling. Results: XABLD-associated mice had rapidly growing CD45-positive tumors at the implantation site. Histopathological features were consistent with EBV-driven diffuse large B-cell lymphoma (DLBCL) primarily of polymorphous subtype. All XABLD specimens were diffusely positive for CD20 and EBNA, and most cases contained tumor infiltrating CD8-positive T-cells. Out of 42 cases, 36 were PD-L1-positive and 26 were PD-1-positive by IHC. 39 cases exhibited an activated B cell (ABC) phenotype, which is predominant in EBV-positive DLBCL. Conclusion: XABLD development has been seen across multiple patient histologies from both solid tumor and circulating tumor cells tissues of origin. The clinical presentation, morphology and molecular characteristics of XABLD cases were similar to EBV-driven DLBCL. As DLBCL is an aggressive disease with limited treatment options, our early-passage XABLD models may be useful in the preclinical evaluation of new therapies for EBV-positive DLBCL. Grant Support: This project has been funded in part with federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. HHSN261200800001E. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government. Citation Format: Tomas Vilimas, Gloryvee Rivera, Brandie Fullmer, Wiem Lassoued, Lindsay Dutko, William Walsh, Amanda Peach, Corinne Camalier, Li Chen, Rajesh Patidar, Suzanne Borgel, John Carter, Howard Stotler, Raymond Divelbiss, Jesse Stottlemyer, Margaret Defreytas, Michelle M. Gottholm-Ahalt, Michelle A. Crespo-Eugeni, Sean McDermott, Yvonne A. Evrard, Melinda G. Hollingshead, Biswajit Das, Chris Karlovich, Vivekananda Datta, James H. Doroshow, P. Mickey Williams. Xenograft-associated B cell lymphoproliferative disease as a surrogate model to study Epstein-Barr virus (EBV) driven lymphoma of the elderly [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1038.

Uncovering Pathogenic Mechanisms of Inflammatory Bowel Disease Using Mouse Models of Crohn's Disease-Like Ileitis: What is the Right Model?

Crohn’s disease and ulcerative colitis, together known as inflammatory bowel disease, are debilitating chronic disorders of unknown cause and cure. Our evolving understanding of these pathologies is enhanced greatly by the use of animal models of intestinal inflammation that allow in vivo mechanistic studies, preclinical evaluation of new therapies, and investigation into the causative factors that underlie disease pathogenesis. Several animal models, most commonly generated in mice, exist for the study of colitis. The appropriateness of their use often can be determined by their mode of generation (ie, chemical induction, T-cell transfer, targeted genetic manipulation, spontaneously occurring, and so forth), the type of investigation (mechanistic studies, pathogenic experiments, preclinical evaluations, and so forth), and the type of inflammation that occurs in the model (acute vs chronic colitis, tissue injury/repair, and so forth). Although most murine models of inflammatory bowel disease develop inflammation in the colon, Crohn’s disease most commonly occurs in the terminal ileum, where a very limited number of mouse models manifest disease. This review discusses appropriate experimental applications for different mouse models of colitis, and highlights the particular utility of 2 highly relevant models of Crohn’s-like ileitis—the spontaneous SAMP1/YitFc inbred mouse strain and the genetically engineered TnfΔAU-rich element/+ mouse model of tumor necrosis factor overexpression, both of which bear strong resemblance to the human condition. Similar to patients with Crohn’s disease, SAMP1/YitFc ileitis develops spontaneously, without chemical, genetic, or immunologic manipulation, making this model particularly relevant for studies aimed at identifying the primary defect underlying the occurrence of Crohn’s ileitis, as well as preclinical testing of novel treatment modalities.

Animal models of inflammatory bowel disease: how useful are they really?

Inflammatory bowel diseases (IBDs) are idiopathic chronic relapsing disorders of the gastrointestinal tract of unknown origin, characterized by heterogeneity and a multifactorial nature of their pathogenesis. Despite the recent improved options for treatment, patients with IBD still have an impaired quality of life, and require hospitalization and surgery. This review examines the contribution of animal models to the understanding and treatment of IBD. During the last decades, a large number of experimental models of intestinal inflammation have been developed. These models have proved to be helpful tools for obtaining new insights in the pathogenesis of the disease and for the preclinical evaluation of new therapies. However, even with the development of many new animal models in recent years, there are still limitations in the study of IBD because of lack of suitable animal models to cover all the requirements of basic research and preclinical studies. There is a need for a better interpretation of the data we obtain from the study of IBD animal models, in order to better understand the underlying pathogenetic mechanisms and improve the quality of the preclinical studies, and to develop more appropriate models to cover the research requirements.

Abstract B141: Predictive value of genetically engineered endogenous mouse models in preclinical therapeutic studies

Abstract Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies with an alarming resistance to both chemotherapeutics and targeted therapy approaches. Genetically engineered mouse models (GEMM) of PDAC reflect molecularly and pathophysiologically the carcinogenesis and cancer progression observed in humans, thus being excellent tools for preclinical evaluation of new therapies. To successfully predict and characterize the effect of chemotherapies and targeted approaches in PDAC, we use a complex and highly aggressive GEMM of endogenous PDAC, Ptf1a +/Cre Kras +/LSL-G12D p53Lox/Lox (CKP) mice. To do so, we established a highly usable GEMM-based therapy platform including multi-parametric MR imaging using CKP mice, in which tumors develop within the first 6 weeks of age (Bardeesy et al, 2006). Animals receive a T2w scan on a 3T clinical MRI scanner for detection and staging of solid tumors for study enrolment at defined inclusion criteria (tumour volume 200-400 mm3). Mice get a weekly scan throughout the study until endpoint criteria are met. Upon reaching the endpoint criteria, mice are sacrificed and tumor material is processed for histopathological and RNA/Protein analysis, isolation and culturing of primary tumor cells. Tumors are assessed macro- and microscopically and graded. Proliferation, apoptosis and analysis of respective downstream effectors are characterized. Further comprehensive analysis depending on the respective phenotypical features is then carried out. Primary cell lines are generated for further functional and molecular characterization including but not limited to cell viability, drug sensitivity, expression and methylation profiling. Through this platform, we have successfully been able to target key signaling pathways and to identify promising novel chemotherapeutic and targeted combinations for PDAC. Here we want to highlight the vital need to develop improved preclinical tools to characterize individual tumors throughout the course of treatment. We propose that such a platform is highly relevant and usable for predicting responses to chemotherapeutic and targeted agents. Citation Format: Aayush Gupta, Marija Trajkovic-Arsic, Irina Heid, Nicole Teichman, Evdokia Kalederis, Rickmer Braren, Jens Siveke. Predictive value of genetically engineered endogenous mouse models in preclinical therapeutic studies. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B141.

A Novel Immunocompetent Mouse Model of Pancreatic Cancer with Robust Stroma: a Valuable Tool for Preclinical Evaluation of New Therapies

A valid preclinical tumor model should recapitulate the tumor microenvironment. Immune and stromal components are absent in immunodeficient models of pancreatic cancer. While these components are present in genetically engineered models such as KrasG12D; Trp53R172H; Pdx-1Cre (KPC), immense variability in development of invasive disease makes them unsuitable for evaluation of novel therapies. We have generated a novel mouse model of pancreatic cancer by implanting tumor fragments from KPC mice into the pancreas of wild type mice. Three-millimeter tumor pieces from KPC mice were implanted into the pancreas of C57BL/6J mice. Four to eight weeks later, tumors were harvested, and stromal and immune components were evaluated. The efficacy of Minnelide, a novel compound which has been shown to be effective against pancreatic cancer in a number of preclinical murine models, was evaluated. In our model, consistent tumor growth and metastases were observed. Tumors demonstrated intense desmoplasia and leukocytic infiltration which was comparable to that in the genetically engineered KPC model and significantly more than that observed in KPC tumor-derived cell line implantation model. Minnelide treatment resulted in a significant decrease in the tumor weight and volume. This novel model demonstrates a consistent growth rate and tumor-associated mortality and recapitulates the tumor microenvironment. This convenient model is a valuable tool to evaluate novel therapies.

Preclinical evaluation of new therapies using a novel mouse model of pancreatic cancer which recapitulates the tumor stromal and immune microenvironment

Preclinical evaluation of new therapies using a novel mouse model of pancreatic cancer which recapitulates the tumor stromal and immune microenvironment

Predictive value of genetically engineered endogenous mouse models in preclinical therapeutic studies

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies with an alarming resistance to both chemotherapeutics and targeted therapy approaches. Genetically engineered mouse models (GEMM) of PDAC reflect molecularly and pathophysiologically the carcinogenesis and cancer progression observed in humans, thus being excellent tools for preclinical evaluation of new therapies.

Tracking human multiple myeloma xenografts in NOD-Rag-1/IL-2 receptor gamma chain-null mice with the novel biomarker AKAP-4

BackgroundMultiple myeloma (MM) is a fatal malignancy ranking second in prevalence among hematological tumors. Continuous efforts are being made to develop innovative and more effective treatments. The preclinical evaluation of new therapies relies on the use of murine models of the disease.MethodsHere we describe a new MM animal model in NOD-Rag1null IL2rgnull (NRG) mice that supports the engraftment of cell lines and primary MM cells that can be tracked with the tumor antigen, AKAP-4.ResultsHuman MM cell lines, U266 and H929, and primary MM cells were successfully engrafted in NRG mice after intravenous administration, and were found in the bone marrow, blood and spleen of tumor-challenged animals. The AKAP-4 expression pattern was similar to that of known MM markers, such as paraproteins, CD38 and CD45.ConclusionsWe developed for the first time a murine model allowing for the growth of both MM cell lines and primary cells in multifocal sites, thus mimicking the disease seen in patients. Additionally, we validated the use of AKAP-4 antigen to track tumor growth in vivo and to specifically identify MM cells in mouse tissues. We expect that our model will significantly improve the pre-clinical evaluation of new anti-myeloma therapies.

Evolution of Mouse Models for Studying CNS Cancer: a Decade of Progress

The first Mouse Models for Human Cancer Consortium (MMHCC) meeting for human nervous system cancer convened in New York City in November of 2000, with the proceedings of that meeting subsequently reported in Oncogene (1).The emphasis of the first meeting was on the comparative pathology of mouse models and corresponding human tumors. Recommendations from the meeting included the need to recapitulate human CNS tumor gene alterations in mouse model tumors, a need for increased emphasis on the molecular characterization of mouse model tumors for establishing consistency with corresponding human tumors, and the need to utilize mouse models in the preclinical evaluation of new therapies for treating CNS cancer. As indicated in the report ofthe 5th MMHCC meeting for nervous system cancer (Montreal, November 2010) in the current issue of Neuro-Oncology (2), these recommendations have proven influential, as most mouse models for CNS cancer are now 1) based on gene alterations suspected ofdriving corresponding human tumor development; 2) routinely subjected to extensive molecular characterization; and 3) are experiencingincreased use for therapeutic hypothesis testing.In addition, the sophistication of current models has increased substantially, with many utilizing information regarding potential cell of origin to regulate the expression or inactivation of genes in precursor cells thought to give rise to corresponding human tumors. Perhaps unforeseen at the 2000 MMHCC meeting was the revitalization of xenograft models for studying CNS cancer, which has been driven by the growing appreciation that histopathologically defined classes of CNS cancer, such as glioblastoma, consist of multiple distinct tumor subtypes, many of which can be propagated as xenografts, and the understanding that individual tumors are composed of distinct subpopulations of cells with distinct biologic properties.As a result of such understanding, human tumor xenografts, established either by direct transplantation from surgical specimens or by transplantation from primary cultures of surgical specimens, are viewed as model systems in their own right. Currently available genetically engineered mouse(GEM) models and human tumor xenografts now allow for detailed investigation of tumor initiation, progression, and response to therapy and have provided investigators with a resource armamentarium for the in-depthstudy of the molecular, cellular, and tumor biology of CNS cancer.It will be of interest to follow the progress during the next 10 years, as GEM modelers will undoubtedly utilize the rapidly growing base of information regarding developmental regulation of gene expression to further refine models for appropriate temporal, spatial, and cellular recapitulation of corresponding human tumor development.

Abstract 395: Rapid engraftment of human primary acute leukemic cells in NOD/SCID mice by intrasplenic inoculation: a robust human primary leukemia (Hukemia) model for preclinical evaluation of new therapies

Abstract The ability to engraft human leukemia cells directly from patient samples into immunodeficient rodents such as NOD/SCID mice would be uniquely valuable in preclinical prioritization of novel therapies for future clinical trial. The aim of this study was to develop an animal model for human acute leukemia in which the kinetics, characteristics and chemosensitivity of leukemia can be sequentially monitored in individual immunodeficient mouse model. Continuous xenografts from 28 acute myeloid leukemia (AML) patients and 18 acute lymphoblastic leukemia (ALL) patients with AML-ETO, CBFβ/MYH11, TAL/SIL1, MLL/AF4 fusion genes were established in NOD/SCID mice by intrasplenic inoculation of human leukemic cells from born marrow. Progression of leukemia was monitored throughout the development of disease by determination of immunophenotyping and karyotyping of the engraftment tumor cells. Chemosensitivity and in vivo efficacy to standard of care therapies were screened in xenografts from both AML and ALL patients. Genetic lesions and special surface markers in different passages of cells in recipient mice were also examined by gene array and FACS analysis. Intrasplenic inoculation of leukemia cells significantly enhanced the engraftment rate and expedited disease development when compared with I.V. route. Relative to engrafted human primary cells, negligible changes in growth rates, chromosomal aberrations and immunophenotype were observed at second, third and fourth passages. The in vivo sensitivity of xenografts to standard of care correlated significantly with clinical course and patient outcome. We have also uncovered key molecular events and serum immunoassay biomarkers which correlate with the efficacy and potency of the drugs for AML and ALL models. The biologic and genetic characteristics and patterns of chemosensitivity of xenografts from acute leukemia patients accurately reflect the clinical disease. The efficient engraftment and rapid expansion of the leukemia within NOD/SCID mice affords a robust model for the preclinical evaluation of new therapies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 395.

New Challenges for Intervertebral Disc Treatment Using Regenerative Medicine

The development of tissue engineering therapies for the intervertebral disc is challenging due to ambiguities of disease and pain mechanisms in patients, and lack of consensus on preclinical models for safety and efficacy testing. Although the issues associated with model selection for studying orthopedic diseases or treatments have been discussed often, the multifaceted challenges associated with developing intervertebral disc tissue engineering therapies require special discussion. This review covers topics relevant to the clinical translation of tissue-engineered technologies: (1) the unmet clinical need, (2) appropriate models for safety and efficacy testing, (3) the need for standardized model systems, and (4) the translational pathways leading to a clinical trial. For preclinical evaluation of new therapies, we recommend establishing biologic plausibility of efficacy and safety using models of increasing complexity, starting with cell culture, small animals (rats and rabbits), and then large animals (goat and minipig) that more closely mimic nutritional, biomechanical, and surgical realities of human application. The use of standardized and reproducible experimental procedures and outcome measures is critical for judging relative efficacy. Finally, success will hinge on carefully designed clinical trials with well-defined patient selection criteria, gold-standard controls, and objective outcome metrics to assess performance in the early postoperative period.

Valproic Acid Prolongs Survival Time of Severe Combined Immunodeficient Mice Bearing Intracerebellar Orthotopic Medulloblastoma Xenografts

To develop novel orthotopic xenograft models of medulloblastoma in severe combined immunodeficient mice and to evaluate the in vivo antitumor efficacy of valproic acid. Orthotopic xenografts were developed by injecting 10(3) to 10(5) tumor cells from four medulloblastoma cell lines (D283-MED, DAOY, MHH-MED-1, and MEB-MED-8A) into the right cerebellum of severe combined immunodeficient mice. Animals were then examined for reproducibility of tumorigenicity, cell number-survival time relationship, and histopathologic features. Tumor growth was monitored in vivo by serially sectioning the xenograft brains at 2, 4, 6, and 8 weeks postinjection. Valproic acid treatment, administered at 600 microg/h for 2 weeks via s.c. osmotic minipumps, was initiated 2 weeks after injection of 10(5) medulloblastoma cells, and treated and untreated animals were monitored for differences in survival. Changes in histone acetylation, proliferation, apoptosis, differentiation, and angiogenesis in xenografts were also evaluated. Tumorigenicity was maintained at 100% in D283-MED, DAOY, and MHH-MED-1 cell lines. These cerebellar xenografts displayed histologic features and immunohistochemical profiles (microtubule-associated protein 2, glial fibrillary acidic protein, and vimentin) similar to human medulloblastomas. Animal survival time was inversely correlated with injected tumor cell number. Treatment with valproic acid prolonged survival time in two (D283-MED and MHH-MED-1) of the three models and was associated with induction of histone hyperacetylation, inhibition of proliferation and angiogenesis, and enhancement of apoptosis and differentiation. We have developed intracerebellar orthotopic models that closely recapitulated the biological features of human medulloblastomas and characterized their in vivo growth characteristics. Valproic acid treatment of these xenografts showed potent in vivo anti-medulloblastoma activity. These xenograft models should facilitate the understanding of medulloblastoma pathogenesis and future preclinical evaluation of new therapies against medulloblastoma.

Characterization of childhood acute lymphoblastic leukemia xenograft models for the preclinical evaluation of new therapies

AbstractContinuous xenografts from 10 children with acute lymphoblastic leukemia (ALL) were established in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. Relative to primary engrafted cells, negligible changes in growth rates and immunophenotype were observed at second and third passage. Analysis of clonal antigen receptor gene rearrangements in 2 xenografts from patients at diagnosis showed that the pattern of clonal variation observed following tertiary transplantation in mice exactly reflected that in bone marrow samples at the time of clinical relapse. Patients experienced diverse treatment outcomes, including 5 who died of disease (median, 13 months; range, 11-76 months, from date of diagnosis), and 5 who remain alive (median, 103 months; range, 56-131 months, following diagnosis). When stratified according to patient outcome, the in vivo sensitivity of xenografts to vincristine and dexamethasone, but not methotrexate, differed significantly (P = .028, P = .029, and P = .56, respectively). The in vitro sensitivity of xenografts to dexamethasone, but not vincristine, correlated significantly with in vivo responses and patient outcome. This study shows, for the first time, that the biologic and genetic characteristics, and patterns of chemosensitivity, of childhood ALL xenografts accurately reflect the clinical disease. As such, they provide powerful experimental models to prioritize new therapeutic strategies for future clinical trials.