CHILDHOOD SOLID TUMORS

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children´s Research Hospital
memphis, Tn 38105

Grant 5P01CA023099-21 from National Cancer Institute, IRG: NCI

Abstract: Our long-term goal is to advance cure rates for children with malignant solid tumors. The program has been reorganized to focus efforts on developmental therapeutics, testing laboratory driven hypotheses in unique preclinical xenograft models of childhood cancers, with subsequent design of clinical trails that simulate schedules and systemic exposures found optimal in these models. Project 1 will study of the role of IGF signaling in mitogenesis and arrested differentiation of rhabdomyosarcoma (RMS). The potential of IGF signaling as a target for new approaches to treatment will be tested in xenograft models using rapamycin analogs which potentialy inhibit this pathway. Project 2 will build on the finding that apoptosis caused by specific agents is dependent on a functional p53 tumor suppressor gene, define classes of cytotoxic agents that are p53-dependent, and whether expression of oncogenes associated with embryonal and alveolar RMS modifies this dependence. P53 is mutated in many rhabdomyosarcoma cell lines, and MDM2 is amplified in approximately 30 percent of RMS biopsies. Work proposed will extend the studies of p53 and MDM2 to additional clinical specimens from patients enrolled in Project 5. Project 3 and 4 have a common focus anticancer agents that target topoisomerase I. In Project 3 the mechanism by which camptothecin topoisomerase I inhibitors cause cellular redistribution of their target, and its therapeutic significance will be examined in vitro, in xenograft models, and in biopsies of neuroblastoma and RMS from patients enrolled on topotecan studies in Project 5. Project 4 will determine pharmacokinetic and pharmacodynamic relations for camptothecin analogs in different xenograft models to further understand the basis for dramatic schedule-dependency of topotecan, and the enhanced activation of irinotecan in tumor-bearing mice. Studies will be extended to determination of carboxylesterase activities associated with different childhood solid tumors. A non-human primate model will be used to model disposition of camptothecin derivatives in CSF for treatment of leptomeningeal disease. Project 5 comprises Phase I and II clinical trials with topotecan and irinotecan each of which is based on our laboratory and xenograft data. These protocols are supported by pharmacokinetic studies that ensure optimal systemic exposure, and biochemical studies designed to increase our understanding of parameters that determine therapeutic efficacy of camptothecin-based topoisomerase I inhibitors used alone or in combination. We will also evaluate the rapamycin analog (WAY1290327), to test the feasibility of IGF-I targeted therapy, proposed in Project 1

Keywords: pediatric neoplasm /cancer human subject

Project start date: 1978-08-01

Project end date: 2002-06-30

5P01CA023099-21 (1999): $1564905

Sponsored Links Lab Supply Mall http://www.labsupplymall.com

Studies Of Childhood Solid Tumors

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children´s Research Hospital

Grant 5P01CA023099-30 from National Cancer Institute, IRG: ZCA1

Abstract: The theme of our program continues to be the integration of basic laboratory studies, animal model evaluation, and clinical trials to develop improved treatment for childhood solid tumors. The program is tightly focused on new and innovative approaches to improving cytotoxic therapy, and integrating signaling inhibitors with cytotoxic therapies. The theme of the program, developmental therapeutics for solid tumors, incorporates basic studies of how cellular stress (growth factor signaling hypoxia, DNA damage) impacts on drug sensitivity in solid tumors. Emphasis has been placed on the identification of pathways upstream and downstream of DNA damage that may be targets for new therapy, and on growth factor receptors that are involved in angiogenesis and in survival of cells treated with cytotoxic agents. We have structured the program to encompass objectives that can be accomplished within this cycle of support, and objectives that, realistically, could take longer to fulfill, but that may represent radically new approaches to curative therapy. Project 1 continues therapeutic studies of IGF-IR/Akt/mTOR inhibitors, and the role of IGF-IR signaling in childhood cancers. Project 2 extends studies that have demonstrated mTOR signaling regulates cellular response to DNA damage, and mutation frequency. Project 3 continues studies that demonstrate activation of the unfolded protein response (UPR) modulates cell sensitivity to cytotoxic agents, and will examine UPR activation in clinical tumors. Project 4 will elucidate how antiangiogenic agents may modulate the pharmacology of cytotoxic agents (ABC transporters) and provide new insights into clinically relevant ways to evaluate and monitor specific changes in tumor vascularity based on noninvasive assessments of changes in tumor blood flow/vasculature (through MRI and ultrasonography). These studies will allow building detailed pharmacokinetic and pharmacodynamic models that will assist in design of our clinical studies. Project 5 will continue novel Phase l/ll trials to test ideas emanating from the preclinical projects. We will continue to optimize therapy with topotecan and irinotecan, and initiate trials of irinotecan with rapamycin. Our trials will explore novel anti-angiogenic therapies, and investigate the single agent activity of small molecule or antibody therapy targeted to the IGF-I receptor alone or combined with rapamycin. Our intent remains to advance preclinical information to the design of clinical trials, and extend these to cooperative groups

Keywords: neoplasm /cancer pharmacology, pediatric neoplasm /cancer, pharmacokinetics clinical research

Project start date: 1998-07-01

Project end date: 2012-07-31

5P01CA023099-15 (1993): $1587962

5P01CA023099-28 (2006): $1656211

5P01CA023099-27 (2005): $1648971

5P01CA023099-26 (2004): $1604058

5P01CA023099-25 (2003): $1558131

CHILDHOOD SOLID TUMORS

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children s Research Hospital 332 N Lauderdale St Memphis, Tn 381052794

Grant 5P01CA023099-23 from National Cancer Institute, IRG: NCI

Abstract: Our long-term goal is to advance cure rates for children with malignant solid tumors. The program has been reorganized to focus efforts on developmental therapeutics, testing laboratory driven hypotheses in unique preclinical xenograft models of childhood cancers, with subsequent design of clinical trails that simulate schedules and systemic exposures found optimal in these models. Project 1 will study of the role of IGF signaling in mitogenesis and arrested differentiation of rhabdomyosarcoma (RMS). The potential of IGF signaling as a target for new approaches to treatment will be tested in xenograft models using rapamycin analogs which potentialy inhibit this pathway. Project 2 will build on the finding that apoptosis caused by specific agents is dependent on a functional p53 tumor suppressor gene, define classes of cytotoxic agents that are p53-dependent, and whether expression of oncogenes associated with embryonal and alveolar RMS modifies this dependence. P53 is mutated in many rhabdomyosarcoma cell lines, and MDM2 is amplified in approximately 30 percent of RMS biopsies. Work proposed will extend the studies of p53 and MDM2 to additional clinical specimens from patients enrolled in Project 5. Project 3 and 4 have a common focus anticancer agents that target topoisomerase I. In Project 3 the mechanism by which camptothecin topoisomerase I inhibitors cause cellular redistribution of their target, and its therapeutic significance will be examined in vitro, in xenograft models, and in biopsies of neuroblastoma and RMS from patients enrolled on topotecan studies in Project 5. Project 4 will determine pharmacokinetic and pharmacodynamic relations for camptothecin analogs in different xenograft models to further understand the basis for dramatic schedule-dependency of topotecan, and the enhanced activation of irinotecan in tumor-bearing mice. Studies will be extended to determination of carboxylesterase activities associated with different childhood solid tumors. A non-human primate model will be used to model disposition of camptothecin derivatives in CSF for treatment of leptomeningeal disease. Project 5 comprises Phase I and II clinical trials with topotecan and irinotecan each of which is based on our laboratory and xenograft data. These protocols are supported by pharmacokinetic studies that ensure optimal systemic exposure, and biochemical studies designed to increase our understanding of parameters that determine therapeutic efficacy of camptothecin-based topoisomerase I inhibitors used alone or in combination. We will also evaluate the rapamycin analog (WAY1290327), to test the feasibility of IGF-I targeted therapy, proposed in Project 1.

Keywords: pediatric neoplasm /cancer, human subject

Project start date: 1978-08-01

Project end date: 2002-06-30

5P01CA023099-23 (2001): $1596749

5P01CA023099-22 (2000): $1607746

CORE--XENOGRAFT FACILITY

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children s Research Hospital 332 N Lauderdale St Memphis, Tn 381052794

Grant 5P01CA023099-289004 from National Cancer Institute, IRG:

Abstract: 1. The purpose of this core is to provide a facility for the propagation of xenografts of pediatric solo tumors, for use in all projects. The standard model will comprise tumor growing in the subcutaneous space of female severe combined immunodeficient (SCID) mice. 2. Coordinate tumor transplantation and make available tumor-bearing mice for biochemical and pharmacokinetic studies as required. 3. Undertake drug evaluation studies using standardized protocols. Data will be accessed directly into a microcomputer, and information distributed on a regular basis to individual project leaders, and to the Biostatistics Core for analysis. 4. Establish models of minimal residual disease for evaluating both cytotoxic and novel approaches to tumor eradication (e.g. gene therapy/antisense). 5. Develop models of disseminated disease as a secondary screen for drug evaluation. 6. Develop disseminated disease models with luciferase reporters for DNA damage, hypoxia, to monitor tumor growth, spread and drug-response using non-invasive techniques (Xenogen system). 7. Maintain and characterize human xenografts, and maintain frozen stocks. 8. Provide services (e.g. blood collection, 1 to 5 day infusions in mice). 9. To evaluate transgenic tumor models where requested. ) A program  working committee  will serve to prioritize the order for evaluating new agents and strategies derived from individual projects, and for allocating resources.

Keywords: biomedical facility, disease /disorder model, drug screening /evaluation, model design /development, neoplasm /cancer transplantation, pediatric neoplasm /cancer, xenotransplantation, glioblastoma multiforme, medulloblastoma, neuroblastoma, osteosarcoma, rhabdomyosarcoma, SCID mouse, human tissue, laboratory mouse

STUDIES IN CHILDHOOD SOLID TUMORS

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children´s Research Hospital
memphis, Tn 38105

Grant 5P01CA023099-18 from National Cancer Institute, IRG: SRC

Project start date: 1978-08-01

Project end date: 1997-08-31

5P01CA023099-18 (1996): $1825593

Studies Of Childhood Solid Tumors

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children´s Research Hospital
memphis, Tn 38105

Grant 2P01CA023099-29 from National Cancer Institute, IRG: ZCA1

Abstract: The theme of our program continues to be the integration of basic laboratory studies, animal model evaluation, and clinical trials to develop improved treatment for childhood solid tumors. The program is tightly focused on new and innovative approaches to improving cytotoxic therapy, and integrating signaling inhibitors with cytotoxic therapies. The theme of the program, developmental therapeutics for solid tumors, incorporates basic studies of how cellular stress (growth factor signaling hypoxia, DNA damage) impacts on drug sensitivity in solid tumors. Emphasis has been placed on the identification of pathways upstream and downstream of DNA damage that may be targets for new therapy, and on growth factor receptors that are involved in angiogenesis and in survival of cells treated with cytotoxic agents. We have structured the program to encompass objectives that can be accomplished within this cycle of support, and objectives that, realistically, could take longer to fulfill, but that may represent radically new approaches to curative therapy. Project 1 continues therapeutic studies of IGF-IR/Akt/mTOR inhibitors, and the role of IGF-IR signaling in childhood cancers. Project 2 extends studies that have demonstrated mTOR signaling regulates cellular response to DNA damage, and mutation frequency. Project 3 continues studies that demonstrate activation of the unfolded protein response (UPR) modulates cell sensitivity to cytotoxic agents, and will examine UPR activation in clinical tumors. Project 4 will elucidate how antiangiogenic agents may modulate the pharmacology of cytotoxic agents (ABC transporters) and provide new insights into clinically relevant ways to evaluate and monitor specific changes in tumor vascularity based on noninvasive assessments of changes in tumor blood flow/vasculature (through MRI and ultrasonography). These studies will allow building detailed pharmacokinetic and pharmacodynamic models that will assist in design of our clinical studies. Project 5 will continue novel Phase l/ll trials to test ideas emanating from the preclinical projects. We will continue to optimize therapy with topotecan and irinotecan, and initiate trials of irinotecan with rapamycin. Our trials will explore novel anti-angiogenic therapies, and investigate the single agent activity of small molecule or antibody therapy targeted to the IGF-I receptor alone or combined with rapamycin. Our intent remains to advance preclinical information to the design of clinical trials, and extend these to cooperative groups

Project start date: 1998-07-01

Project end date: 2012-07-31

2P01CA023099-29 (2007): $2156053

MTOR AS THERAPEUTIC TARGET IN PEDIATRIC SOLID TUMORS

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children s Research Hospital 332 N Lauderdale St Memphis, Tn 381052794

Grant 2P01CA023099-240023 from National Cancer Institute, IRG: NCI

Abstract: The macrocyclic lactone antibiotic rapamycin is a novel anticancer agent that specifically inhibits the activity of a protein kinase (mTOR) that controls translation of proteins involved in cell cycle progression and survival. Our studies in Project 23 have shown that the response to mTOR inhibition in normal and malignant cells is qualitatively different rapamycin causes G1 phase arrest and cytostasis in normal cells, whereas tumor cells with deficient G1 checkpoint function (p53/p21) transit G1 phase and undergo apoptosis. Insulin-like growth factor I (IGF-I) uniquely protects against apoptosis. Studies proposed will focus on combining CCI-779, a rapamycin ester undergoing clinical trials, with inhibitors of IGF-I signaling, and further determine the mechanism(s) responsible for acquired and intrinsic resistance to CCI-779. We will attempt to develop biochemical assays to measure mTOR inhibition in tumor tissue, and develop potentially novel combinations of CCI-779 in support our proposed clinical studies (Project 10). Specific hypotheses to be tested are (1) Inhibition of IGF-I receptor signaling will prevent IGF-I protection against rapamycin-induced apoptosis, and promote apoptosis selectively in cells lacking wild type p53. (2) Regulation of 4E-BP protein levels is a critical determinant of rapamycin sensitivity. (3) Tumor response to high dose CCI-779 is dependent on mTOR inhibition, and is associated with prolonged inhibition of eIF4E-dependent translation. (4) Additive or superadditive activity may be obtained when inhibitors of targets upstream of mTOR or inhibitors of Ras/MAP kinase pathways are combined with rapamycin/CCI-779. Conversely, CCI-779 may synergize or be antagonistic with cytotoxic agents. These studies will extensively use core facilities within this program, and continue to generate leads that may be valuable in clinical testing of CCI-779 alone or in combination with other agents. The longterm goal of these studies is to develop alternative approaches to curative therapy for children with cancer, based on an understanding of IGF-I receptor signaling in growth and survival of pediatric cancer cells.

Keywords: antineoplastic antibiotic, cell growth regulation, drug screening /evaluation, enzyme inhibitor, neoplasm /cancer chemotherapy, neoplastic growth, nonhuman therapy evaluation, pediatric neoplasm /cancer, protein kinase, sirolimus, apoptosis, biological signal transduction, combination cancer therapy, drug interaction, insulin receptor, insulinlike growth factor, macrolide antibiotic, mitogen activated protein kinase, p53 gene /protein, phosphatidylinositol 3 kinase, protein tyrosine kinase, rhabdomyosarcoma, SCID mouse, cell line, immunoprecipitation, terminal nick end labeling

Project start date: 2002-09-06

Project end date: 2007-06-30

MTOR As A Therapeutic Target In Childhood Cancer

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children s Research Hospital 332 N Lauderdale St Memphis, Tn 381052794

Grant 5R01CA096696-04 from National Cancer Institute, IRG: ZRG1

Abstract: The macrocyclic lactone antibiotic rapamycin is a novel anticancer agent that specifically inhibits the activity of a protein kinase (mTOR) that controls translation of proteins involved in cell cycle progression and survival. Our studies in Project 1 have shown that the response to mTOR inhibition in normal and malignant cells is qualitatively different Rapamycin causes G1 phase arrest and cytostasis in normal cells, whereas tumor cells with deficient G1 checkpoint function (p53/p21) transit G1 phase and undergo apoptosis. Insulin-like growth factor I (IGF-I) uniquely protects against apoptosis. Studies proposed will focus on combining CCI-779, a rapamycin ester undergoing clinical trials, with inhibitors of IGF-I signaling, and further determine the mechanism(s) responsible for acquired and intrinsic resistance to CCI-779. We will attempt to develop biochemical assays to measure mTOR inhibition in tumor tissue, and develop potentially novel combinations of CCI-779 in support of our proposed clinical studies in children when the agent is made available. Specific hypothesis to be tested are1. Inhibition of IFG-I receptor signaling will prevent IGF-I protection against rapamycin-induced apoptosis, and promote apoptosis selectively in cells lacking wild type p53. 2. Regulation of 4E-BP protein levels is a critical determinant of rapamycin sensitivity. 3. Tumor response to high dose CCI-779 is dependent on mTOR inhibition, and is associated with prolonged inhibition of eIF4E-dependent translation. 4. The long-term goal of these studies is to develop alternative approaches to curative therapy for children (and adults) with cancer. This is based in part on an understanding of IGF-I receptor signaling in growth and survival of pediatric cancer cells, and partly on the observation that inhibition of mTOR signaling is selectively cytotoxic to cells that have aberrant p53/p21-dependent G1 checkpoints.

Keywords: apoptosis, biological signal transduction, growth factor receptor, insulinlike growth factor, p53 gene /protein, pediatric neoplasm /cancer, protein kinase, antineoplastic, molecular oncology, sirolimus, cell line, human tissue, laboratory mouse

Project start date: 2002-09-01

Project end date: 2007-08-31

5R01CA096696-04 (2005): $300375

5R01CA096696-03 (2004): $300375

5R01CA096696-02 (2003): $300375

SOLID TUMOR PROGRAM PROJECT

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children s Research Hospital 332 N Lauderdale St Memphis, Tn 381052794

Grant 2P01CA023099-14A1 from National Cancer Institute, IRG: SRC

Abstract: The long-term goal of this program project is to improve cure rates among children with malignant solid tumors, especially rhabdomyosarcoma (RMS), Ewing sarcoma and osteosarcoma. This aim will be pursued by a coordinated multidisciplinary effort, consisting of 7 projects and a CORE. The major thrust will be to develop new agents and strategies designed to overcome problems of drug resistance. Project 1 will address the efficacy of 5- fluorouracil-leucovorin interactions in xenografts of previously untreated osteosarcoma. Project 2 deals with nucleoside transport in normal and RMS cells to define differences that could lead to the development of improved treatment strategies. Project 3 will investigate rhabdomyoblast differentiation and drug binding with use of the 5.1 H11 monoclonal antibody, both in vitro and in vivo. If binding is specific, the antibody will be conjugated to vincristine in an effort to "target" the delivery of this agent. Project 4 will examine the interaction of VP-16, antimicrotubule compounds and ifosfamide in treatment of RMS and Ewing sarcoma in vitro, and subsequently in vivo. Project 5 will attempt to clarify the mechanisms of cross resistance between vincristine and the bifunctional alkylating agent melphalan in RMS xenografts. Project 6 examines the potential role of DNA repair in the acquisition of resistance to the alkylating agents by RMS and Ewing sarcoma cells. Project 7A applies genetic techniques to the analysis of solid tumor cells with the aim of refining clinical staging systems. Pharmacokinetic studies (Project 7B) will be an integral part of phase I and II clinical trials and preclinical investigations in experimental models. Further, we plan to test alternative agents in previously untreated patients with advanced RMS, osteosarcoma and Ewing sarcoma (Project 7D). These "phase II-III pilot" studies should permit truer estimates of drug activity than can be gained by conventional means. Another novel aspect of this program is the use of human tumor xenografts to evaluate the activity of new agents prioritized by considering data from Project 1-6 or from extramural phase I or II trials. The information gained will supplement or supercede data from classic phase II trials in determining drug evaluation priorities for phase II-III pilot studies, since the former are often performed in heavily pretreated patients with resistance to multiple agents. Centralized support (e.g., biostatistical consultation and data management, program administration, and xenograft models) are provided within the CORE. The research program outlined here should provide new information regarding genetic staging and mechanisms of oncogenesis, and serve as a paradigm for developmental therapeutics in pediatric solid tumors.

Keywords: child (0-11), neoplasm /cancer chemotherapy, neoplasm /cancer genetics, neoplasm /cancer pharmacology, pediatric neoplasm /cancer, rhabdomyosarcoma, human clinical subject

Project start date: 1978-08-01

Project end date: 1997-04-30

2P01CA023099-14A1 (1992): $1306581

Rapamycin-Induced Selective Apoptosis In Malignant Cells

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children´s Research Hospital

Grant 2R01CA077776-10 from National Cancer Institute, IRG: BMCT

Abstract: Studies in this laboratory over the past 20 years have focused on the role of insulin like growth factors (IGFs) in the growth and survival of childhood sarcomas, and more recently on the role of mTOR signaling in these tumors. The mTORC1 (mTOR-raptor) complex plays an important cellular role, integrating growth factor and stress signals to regulate cell cycle progression and survival. Dysregulated IGF and mTORC1 signaling is implicated in cellular transformation and progression of human cancer. As a consequence there are intense efforts to develop IGF-1 receptor inhibitors, and rapamycin analogs that selectively target mTORC1 complexes, as cancer chemotherapeutic agents. During the last period of funding we made two observations that have led to development of Aim 1. We showed that inhibition of mTORC1 by rapamycin induced a prolonged stress response that resulted in apoptosis only in cells lacking functional p53. Thus, potentially identifying a synthetic lethal interaction between mTORC1 and p53 that could be exploited therapeutically. The second observation was that exogenous insulin like growth factors, or high concentrations of insulin, were unique in protecting against rapamycin-induced apoptosis. Thus, the two observations suggest that concomitant inhibition of both mTORC1 and the IGF-1 receptor may result in changing the cellular response to rapamycin from cytostasis to apoptosis. This approach appears to be highly effective against IGF-1-driven osteosarcoma and Ewing sarcoma xenograft models in vivo when rapamycin is combined with an antibody that blocks IGF-1 binding to the receptor. However, the approach is not effective against IGF-2-driven rhabdomyosarcoma (RMS) xenografts. Thus, in Aim 1 we propose a series of experiments in vitro and in vivo to determine whether an antibody that blocks binding of both IGF-1 and IGF-2 to the IGF-1 receptor has a therapeutic advantage for treatment of these sarcomas. Aims 2 and 3 focus on dysregulation of mTORC1 under conditions of hypoxia or DNA damage, and the consequences of maintained mTORC1 signaling under stress conditions. In

Keywords: normal` untransformed cells hypoxia or DNA damage rapidly inhibit mTORC1 signaling. In contrast hypoxia does not down regulate mTORC1 signaling in RMS cells that are highly tolerant to hypoxia. We hypothesize that failure to regulate mTORC1 by DNA damage and hypoxia is due to expression of (Np73, a splice variant of TAp73 that acts as a dominant negative against all p53-family members. Our studies propose to map the signaling pathways that regulate mTORC1 under hypoxia and DNA damage, identify how these are dysregulated in RMS cells, and determine the biological consequences of aberrant mTORC1 signaling under these conditions. We speculate that maintenance of mTORC1 signaling protects cells from apoptosis under stress, but at the cost of increasing damage-induced mutations. Potentially, therefore modulating mTORC1 in RMS may enhance their sensitivity to hypoxic stress, and certain cytotoxic drugs that damage DNA, and reduce mutation frequency that leads to drug resistance or tumor progression. Metastatic rhabdomyosarcoma is fatal for eighty percent of afflicted children and intensive radiation-chemotherapy has not advanced cure rates since 1984. Here we propose a novel strategy to treat metastatic rhabdomyosarcoma, and will test this in non-clinical models. The studies have the potential to radically alter outcome for these children, and reduce the debilitating sequellae of high dose radiation and chemotherapy

Project start date: 1998-12-01

Project end date: 2013-01-31

5R01CA077776-09 (2007): $267387

5R01CA077776-08 (2006): $275373

5R01CA077776-07 (2005): $282000

5R01CA077776-06 (2004): $282000

Studies Of Childhood Solid Tumors

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children s Research Hospital 332 N Lauderdale St Memphis, Tn 381052794

Grant 2P01CA023099-24 from National Cancer Institute, IRG: NCI

Abstract: Our long-term goal is to advance cure rates for children with malignant solid tumors. The restructured program has an increased focus on developmental therapeutics, testing laboratory driven hypotheses developed from non-mammalian and mammalian experimental systems, in unique xenograft models of childhood cancers, with subsequent design of clinical trials that simulate schedules and systemic exposures found optimal in these models. This approach has been validated through our clinical project, where camptothecins, drugs that target DNA topoisomerase I, have demonstrated very significant activity in Phase I/II trials in pediatric patients. In this application we propose studies that will lead to a greater understanding of sensitivity or resistance to topoisomerase inhibitors, and will start of integrate cytotoxic agents with inhibitors of signal transduction pathways. Project 23 continues studies of mTOR signaling in growth, and survival of tumor cells. Studies will explore the therapeutic strategy of combining the mTOR inhibitor CCI-779, a rapamycin ester, in combination with IGF-I receptor antagonists and cytotoxic agents. Project 24 builds on the finding that hypomorphic alleles of genes that regulate cell cycle checkpoints in yeast confer dramatic hypersensitivity to camptothecin and rapamycin. Human homologues will be cloned, their function defined and their role in determining drug sensitivity in mammalian cells determined. Project 25 will focus on how know DNA damage response pathways determine cellular fate to camptothecins, and how hypoxia induced stress influences p53-directed cell fate. Project 26 will focus on how hypoxia or nutritional stress influences cellular sensitivity to topoisomerase II-targeted drugs and DNA cross-linking drugs through the unfolded protein response pathway. Project 27 builds on results showing that ZD1839 (an ErbB1 inhibitor) potently inhibits ABC transporters (BCRP/MRP4) that confer resistance to camptothecin drugs. The role of ZD1839 in reversing drug resistance, and altering the pharmacology of clinically used camptothecins will be explored. Project 10 comprises Phase I and II clinical trials with topotecan and irinotecan each of which is based on our laboratory and preclinical data. These protocols are supported by pharmacokinetic, and pharmacogenomic studies that ensure optimal systemic exposure, and biological studies designed to increase our understanding of parameters that determine therapeutic efficacy of camptothecin-based topoisomerase I inhibitors used alone or in combination. We will also evaluate the rapamycin ester, CCI-779, alone or in combination with vincristine, to test whether mTOR-targeted therapy will have therapeutic significance in children with solid malignancies.

Keywords: neoplasm /cancer pharmacology, pediatric neoplasm /cancer, pharmacokinetics, clinical research

Project start date: 1978-08-01

Project end date: 2007-06-30

2P01CA023099-24 (2002): $1554855

CHILDHOOD SOLID TUMORS

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children´s Research Hospital
memphis, Tn 38105

Grant 3P01CA023099-22S1 from National Cancer Institute, IRG: NCI

Abstract: Our long-term goal is to advance cure rates for children with malignant solid tumors. The program has been reorganized to focus efforts on developmental therapeutics, testing laboratory driven hypotheses in unique preclinical xenograft models of childhood cancers, with subsequent design of clinical trails that simulate schedules and systemic exposures found optimal in these models. Project 1 will study of the role of IGF signaling in mitogenesis and arrested differentiation of rhabdomyosarcoma (RMS). The potential of IGF signaling as a target for new approaches to treatment will be tested in xenograft models using rapamycin analogs which potentialy inhibit this pathway. Project 2 will build on the finding that apoptosis caused by specific agents is dependent on a functional p53 tumor suppressor gene, define classes of cytotoxic agents that are p53-dependent, and whether expression of oncogenes associated with embryonal and alveolar RMS modifies this dependence. P53 is mutated in many rhabdomyosarcoma cell lines, and MDM2 is amplified in approximately 30 percent of RMS biopsies. Work proposed will extend the studies of p53 and MDM2 to additional clinical specimens from patients enrolled in Project 5. Project 3 and 4 have a common focus anticancer agents that target topoisomerase I. In Project 3 the mechanism by which camptothecin topoisomerase I inhibitors cause cellular redistribution of their target, and its therapeutic significance will be examined in vitro, in xenograft models, and in biopsies of neuroblastoma and RMS from patients enrolled on topotecan studies in Project 5. Project 4 will determine pharmacokinetic and pharmacodynamic relations for camptothecin analogs in different xenograft models to further understand the basis for dramatic schedule-dependency of topotecan, and the enhanced activation of irinotecan in tumor-bearing mice. Studies will be extended to determination of carboxylesterase activities associated with different childhood solid tumors. A non-human primate model will be used to model disposition of camptothecin derivatives in CSF for treatment of leptomeningeal disease. Project 5 comprises Phase I and II clinical trials with topotecan and irinotecan each of which is based on our laboratory and xenograft data. These protocols are supported by pharmacokinetic studies that ensure optimal systemic exposure, and biochemical studies designed to increase our understanding of parameters that determine therapeutic efficacy of camptothecin-based topoisomerase I inhibitors used alone or in combination. We will also evaluate the rapamycin analog (WAY1290327), to test the feasibility of IGF-I targeted therapy, proposed in Project 1

Keywords: pediatric neoplasm /cancer human subject

Project start date: 1978-08-01

Project end date: 2002-06-30

3P01CA023099-22S1 (2001): $50000

2P01CA023099-19A1 (1997): $1473212

THERAPY OF COLON CANCER WITH DIARYLSULFONYLUREAS

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children s Research Hospital 332 N Lauderdale St Memphis, Tn 381052794

Grant 5R01CA051949-03 from National Cancer Institute, IRG: ET

Abstract: Diarylsulfonylureas (DSU s) represent a new class of antitumor agent with a novel mechanism of action. Several analogues demonstrate high therapeutic efficacy in both rodent and human solid tumor systems. One compound, N-(5- indanylsulfonyl)-N -(4-chlorophenyl)-urea (ISCU), currently in Phase I evaluation, is the most active agent that we have evaluated against advanced stage xenografts of human colon adenocarcinoma. Using human colon tumor models in vitro and in vivo it is proposed to elucidate the mechanism of cytotoxicity and examine the biochemical basis for therapeutic selectively for this class of agent. Preliminary data implicate mitochondria as a probable site of action. Our hypothesis is that energy dependent concentrative accumulation of DSU s in these organelles is a consequence of the pH differential across the matrix membrane, and that high concentrations of drug in mitochondria disrupt some function which leads to cell death. Using analogues with different potencies, mutant clones resistant to ISCU, ionophores and uncoupling agents, the relationship between mitochondrial accumulation of DSU s, pH dependence and cytotoxicity will be examined and the basis for sequestration established. Specific binding in mitochondria will be determined using a photoaffinity analogue. Subsequent studies will define functional changes in mitochondria both in intact cell and after isolation, that lead to cell death. The influence of proliferative status and hypoxia on cytotoxicity, and the potential to repair damage will be examined. The basis for therapeutic selectivity will be approached initially by study of the cellular pharmacology of DSU s in isolated cells from normal tissues of the mouse. Subsequently, distribution, accumulation and metabolism of analogues in xenografts of human colon adenocarcinomas sensitive or resistant to DSU s and in normal tissues of mice will be examined. These studies will facilitate defining mechanisms of action of DSU s and may identify new therapeutic targets which can be further exploited in treatment of human colon adenocarcinomas.

Keywords: colon neoplasm, drug metabolism, laboratory mouse, neoplasm /cancer chemotherapy, neoplasm /cancer pharmacology, sulfonylurea, acidity /alkalinity, adenocarcinoma, adenosine triphosphate, cytotoxicity, drug resistance, hypoxia, membrane potential, mitochondria, organelle, protein transport, disease model, heterologous transplantation, radiotracer, tissue /cell culture, tritium

Project start date: 1990-04-01

Project end date: 1995-02-28

5R01CA051949-03 (1992): $135719

5R01CA051949-04 (1993): $142997

GORDON CONFERENCE--CANCER CHEMOTHERAPY

Peter J Houghton, Alsac Chair Of Pharmacology
Gordon Research Conferences
west Kingston, Ri 02892

Grant 1R13CA061350-01 from National Cancer Institute, IRG: SRC

Abstract: Based on the application) The Gordon Conference is designed to promote discussion, collaboration, and progress among scientists interested in the chemotherapeutic management of cancer; investigators at the basic and clinical levels are included. In addition to reviewing the latest information and ideas about current areas of research in cancer chemotherapy, every effort is made to focus discussion on emerging topics in tumor biology, which may yield new therapeutic targets. The overall theme will be on the identification and development of anticancer agents that have the potential of being truly selective for malignant cells. The application is to support the Gordon Conference on Cancer Chemotherapy of Experimental and Clinical Cancer to be held in Irsee, Germany. The support will be used to provide air travel and conference costs for chairpersons, discussion leaders and invited speakers, and to provide support for young American scientists. The conference will focus on several topics including the use of cell cycle regulation in the response to chemotherapy, new approaches to drug design and discovery, biochemical modulation of antimetabolite agents, new approaches to understanding cellular pharmacology and drug trafficking, mechanisms and development of newer anticancer drugs, and problems and potential for developing agents effective against brain tumors. s indicate that every effort has been made to include women in the program and to fulfill the Gordon Conference mandate of appropriate industrial representation

Keywords: meeting /conference /symposium, neoplasm /cancer chemotherapy, neoplasm /cancer pharmacology antimetabolite, antimitotic, antineoplastic, brain neoplasm, carcinogenesis inhibitor, cell cycle, cell cycle protein, cell growth regulation, drug design /synthesis /production, drug resistance, enzyme inhibitor, growth factor receptor, methyltransferase, neoplasm /cancer radiation therapy, protein kinase, thymidylate synthase, tumor suppressor gene confocal scanning microscopy, digital imaging, immunocytochemistry, supercomputer

Project start date: 1993-08-15

Project end date: 1994-07-14

1R13CA061350-01 (1993): $10000

RAPAMYCIN INDUCED SELECTIVE APOPTOSIS IN MALIGNANT CELLS

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children´s Research Hospital
memphis, Tn 38105

Grant 5R01CA077776-03 from National Cancer Institute, IRG: ZRG2

Abstract: Applicant´s ) The macrolide antibiotic rapamycin is a potentially novel anticancer agent that specifically inhibits the activity of a protein kinase (mTOR) that controls translation of proteins involved in cell cycle progression and survival. The response to mTOR inhibition in normal and malignant cells is qualitatively different rapamycin causes G1 phase arrest and cytostasis in normal cells, whereas treatment of rhabdomyosarcoma (RMS) cells causes G1 arrest, and induces apoptosis. Results from ´s laboratory indicate that apoptosis occurs only in cells in which RB is functional, but in which p53 tumor suppressor function is abrogated. This differential confers a basis for tumor-selectivity for rapamycin. The major focus of the proposed studies is to understand how inhibition of mTOR signaling by rapamycin induces apoptosis, and how p53 protects cells. Using a series of human RMS cell lines with characterized p53 alleles, clones constructed with inducible p53, and murine embryo fibroblasts disrupted at p53 and/or RB loci, will test the following hypotheses 1) Rapamycin induces apoptosis only in cells with mutated or abrogated p53 function. 2) p53 activates a G1 cell cycle checkpoint preventing cell death. 3) In cells with an abrogated p53 function, inhibition of mTOR leads to a decrease in survival factors or an increase in pro-apoptotic factors. By initiating a G1 checkpoint, p53 will modulate survival factors, thus preventing apoptosis. 4) Although mTOR activates translation of specific subsets of mRNA under two separate pathways, by directly phosphorylating PHAS-I and by indirectly activating ribosomal p70S6 kinase, the hypothesis is that rapamycin-induced growth arrest and apoptosis is a consequence of inhibition of the PHAS-I pathway. 5) IGF-I protection of RMS cells from rapamycin occurs through activating NF-kB by a pathway independent of mTOR, and is dependent on the level of expression of the type-I IGF receptor. The proposed studies will elucidate the role of mTOR signaling in cell survival, and why loss of p53 sensitizes cells to apoptosis. These studies will give insights into approaches that combine signal transduction inhibitors to give tumor-selective apoptosis based on loss of p53 function. The long-term goal of these studies is to develop alternative curative therapy for children with cancer that will avoid the often devastating events, associated with contemporary intensive chemo-radiotherapy regimens

Keywords: antineoplastic antibiotic, drug screening /evaluation, enzyme activity, neoplastic cell, pharmacokinetics, programmed cell death, protein kinase, sirolimus biological signal transduction, cell cycle, cytotoxicity, enzyme inhibitor, gene mutation, genetic translation, growth factor receptor, insulinlike growth factor, messenger RNA, neoplasm /cancer chemotherapy, nuclear factor kappa beta, p53 gene /protein, phosphorylation, protein structure /function, receptor expression, rhabdomyosarcoma cell line, gel mobility shift assay

Project start date: 1998-12-01

Project end date: 2002-11-30

5R01CA077776-03 (2001): $233582

5R01CA077776-02 (2000): $290291

1R01CA077776-01A1 (1999): $271515

CORE--XENOGRAFT FACILITY

Peter J Houghton, Alsac Chair Of Pharmacology
St. Jude Children s Research Hospital 332 N Lauderdale St Memphis, Tn 381052794

Grant 2P01CA023099-249004 from National Cancer Institute, IRG:

Abstract: 1. The purpose of this core is to provide a facility for the propagation of xenografts of pediatric solo tumors, for use in all projects. The standard model will comprise tumor growing in the subcutaneous space of female severe combined immunodeficient (SCID) mice. 2. Coordinate tumor transplantation and make available tumor-bearing mice for biochemical and pharmacokinetic studies as required. 3. Undertake drug evaluation studies using standardized protocols. Data will be accessed directly into a microcomputer, and information distributed on a regular basis to individual project leaders, and to the Biostatistics Core for analysis. 4. Establish models of minimal residual disease for evaluating both cytotoxic and novel approaches to tumor eradication (e.g. gene therapy/antisense). 5. Develop models of disseminated disease as a secondary screen for drug evaluation. 6. Develop disseminated disease models with luciferase reporters for DNA damage, hypoxia, to monitor tumor growth, spread and drug-response using non-invasive techniques (Xenogen system). 7. Maintain and characterize human xenografts, and maintain frozen stocks. 8. Provide services (e.g. blood collection, 1 to 5 day infusions in mice). 9. To evaluate transgenic tumor models where requested. ) A program  working committee  will serve to prioritize the order for evaluating new agents and strategies derived from individual projects, and for allocating resources.

Keywords: biomedical facility, disease /disorder model, drug screening /evaluation, heterologous transplantation, model design /development, neoplasm /cancer transplantation, pediatric neoplasm /cancer, glioblastoma multiforme, medulloblastoma, neuroblastoma, osteosarcoma, rhabdomyosarcoma, SCID mouse, human tissue, laboratory mouse

Project start date: 2002-09-06

Project end date: 2003-06-30