Mark R. Gilbert, M.D. - US grants

Neurotoxicity is a serious dose-limiting complication in the chemotherapeutic treatment of cancer. Existing laboratory models are limited in their ability to determine the mechanism of toxicity, thus hindering efforts to reduce or reverse these often serious complications of treatment. The development of an in vitro model system using cultured dorsal root ganglia (DRG) would allow examination of the effect of neurotoxins, including cancer chemotherapeutic agents, on neurons. Axon cytoskeletal changes are an established mechanism of action of several neurotoxins and it is likely that many neurotoxic drugs also cause primary disruption or secondary alteration of the axon cytoskeleton. The cytoskeleton of cultured DRG neurites has not been fully characterized during normal development or in response to injury. For these studies, molecular biologic, ELISA and histologic techniques will be used to characterize this culture system. The following Specific Aims are proposed: 1. Characterize the neuronal cytoskeleton and cytoskeletal gene expression in cultured dorsal root ganglia and develop methods to promote a maturational changes in vitro. 2. Evaluate the effect of myelination and Schwann cell ensheathment on the neurite cytoskeleton and cytoskeletal gene expression in cultured DRG. 3. Analyze changes in the cytoskeleton of DRG cultures in response to axotomy and compare these changes to the in vivo axotomy model. 4. Investigate models of neurotoxic neuronal injury. This model system will allow the study of the mechanisms of neurotoxicity of varied agents by enabling detailed analysis of toxin induced changes at the molecular and cytoskeletal level. This will facilitate the long term goals of permitting rational development of pharmacological approaches to preventing or reversing neurotoxicity.

Neurotoxicity is a serious dose-limiting complication in the chemotherapeutic treatment of cancer. Existing laboratory models are limited in their ability to determine the mechanism of toxicity, thus hindering efforts to reduce or reverse these often serious complications of treatment. The development of an in vitro model system using cultured dorsal root ganglia (DRG) would allow examination of the effect of neurotoxins, including cancer chemotherapeutic agents, on neurons. Axon cytoskeletal changes are an established mechanism of action of several neurotoxins and it is likely that many neurotoxic drugs also cause primary disruption or secondary alteration of the axon cytoskeleton. The cytoskeleton of cultured DRG neurites has not been fully characterized during normal development or in response to injury. For these studies, molecular biologic, ELISA and histologic techniques will be used to characterize this culture system. The following Specific Aims are proposed: 1. Characterize the neuronal cytoskeleton and cytoskeletal gene expression in cultured dorsal root ganglia and develop methods to promote a maturational changes in vitro. 2. Evaluate the effect of myelination and Schwann cell ensheathment on the neurite cytoskeleton and cytoskeletal gene expression in cultured DRG. 3. Analyze changes in the cytoskeleton of DRG cultures in response to axotomy and compare these changes to the in vivo axotomy model. 4. Investigate models of neurotoxic neuronal injury. This model system will allow the study of the mechanisms of neurotoxicity of varied agents by enabling detailed analysis of toxin induced changes at the molecular and cytoskeletal level. This will facilitate the long term goals of permitting rational development of pharmacological approaches to preventing or reversing neurotoxicity.

Neurotoxicity is a serious dose-limiting complication in the chemotherapeutic treatment of cancer. Existing laboratory models are limited in their ability to determine the mechanism of toxicity, thus hindering efforts to reduce or reverse these often serious complications of treatment. The development of an in vitro model system using cultured dorsal root ganglia (DRG) would allow examination of the effect of neurotoxins, including cancer chemotherapeutic agents, on neurons. Axon cytoskeletal changes are an established mechanism of action of several neurotoxins and it is likely that many neurotoxic drugs also cause primary disruption or secondary alteration of the axon cytoskeleton. The cytoskeleton of cultured DRG neurites has not been fully characterized during normal development or in response to injury. For these studies, molecular biologic, ELISA and histologic techniques will be used to characterize this culture system. The following Specific Aims are proposed: 1. Characterize the neuronal cytoskeleton and cytoskeletal gene expression in cultured dorsal root ganglia and develop methods to promote a maturational changes in vitro. 2. Evaluate the effect of myelination and Schwann cell ensheathment on the neurite cytoskeleton and cytoskeletal gene expression in cultured DRG. 3. Analyze changes in the cytoskeleton of DRG cultures in response to axotomy and compare these changes to the in vivo axotomy model. 4. Investigate models of neurotoxic neuronal injury. This model system will allow the study of the mechanisms of neurotoxicity of varied agents by enabling detailed analysis of toxin induced changes at the molecular and cytoskeletal level. This will facilitate the long term goals of permitting rational development of pharmacological approaches to preventing or reversing neurotoxicity.

The prognosis for patients with malignant brain tumors remains grim despite advances in neurosurgery, radiation treatment, neuroimaging and chemotherapy. Clinical studies are needed to evaluate new treatment approaches. Laboratory research is required to provide the foundation for future therapies. The creation of a consortium, bringing together a multidisciplinary team of clinical and laboratory researchers and pooling the resources of several centers, will facilitate and enhance these needed studies. This proposal describes the resources available at the Pittsburgh Cancer Institute (PCI), University of Pittsburgh, qualifying it for participation in the Central Nervous System Consortium (CNSC). The Central Operations Office/Coordinating Center for this consortium will be at the University Of California, San Francisco. The resources of the PCI, including the Clinical Core Facility and the Tissue Bank, will provide essential support for CNSC-related trials. The PC Brain Tumor Center, with its clinical and laboratory investigators dedicated to advancing the treatment of brain tumor patients, will collaborate with other members of the CNSC to rapidly evaluate new treatments and investigate avenues of translational research. Initial studies will involve evaluating new agents, including taxol and temozolomide, in the treatment of malignant gliomas. Future investigations may include using inhibitors of O6-alkyl guanine DNA transferase to modulate tumor resistance to nitrosoureas, examining other investigational agents, and evaluating new drug delivery systems. Ongoing laboratory studies include exploring modulators of drug resistance, in vitro chemotherapy sensitivity assays, differentiation agents in brain tumor therapy, mechanisms of brain tumor invasiveness, and cytogenetic and molecular correlates of treatment response and prognosis. Advances in these projects will lead to innovative treatments that may be suitable for testing in the CNSC.

DESCRIPTION (provided by applicant): Despite advances in neurosurgical techniques, radiation therapy and chemotherapy and the efforts of a dedicated group of investigators, the prognosis for patients with malignant gliomas remains poor. Research at M. D. Anderson and other centers over the past several years has resulted in new treatment approaches, including the use of signal transduction inhibitors and novel gene therapies. Translational efforts are underway to correlate clinical response with specific tumor markers and pharmacokinetic studies. Gene profiling studies are ongoing to discover new potential therapeutic targets and prognostic markers. Continued collaborative research efforts are needed to advance treatments by enhancing accrual to clinical trials that test new treatment modalities and provide the important materials for correlative biologic studies. The North American Brain Tumor Consortium (NABTC) represents a multi-institutional effort to combine the strengths of centers of excellence in brain tumor treatments to rapidly test new therapies while concurrently testing scientific hypotheses that will lead to future discoveries and advances. M. D. Anderson Cancer Center is one of seven NABTC clinical centers. The Pharmacokinetics Center is at the University of Texas, San Antonio. The Coordinating Center for the NABTC is at UCSF and the Data Management Center is at M. D. Anderson Cancer Center. The continued participation in the consortium by the M. D. Anderson Cancer Center represents an opportunity to play a critical role in the advancement of new therapies. New laboratory discoveries in the area of signal transduction modulation and gene therapies are planned for future clinical trials. Novel chemotherapy trials using combinations of agents as well as trial design strategies, such as the factorial designs, are undergoing preliminary testing at M. D. Anderson for future NABTC studies. The infrastructure at M. D. Anderson provides the critical elements to pursue these research objectives. The efforts directed at primary brain tumors represents the multidisciplinary collaborations of members of the Departments of Neuro-Oncology, Neurosurgery, Radiation Oncology, Neuropathology, Neuroradiology and Biostatistics. The institutional efforts at M. D. Anderson as a component of the NABTC will be an integral part of the Cancer Therapy Evaluation Program (CTEP) and the Radiation Research Program (RRP) of the Division of Cancer Treatment. The NABTC continues with the long-term goal of developing more effective treatments for patients with primary brain tumors, particularly malignant gliomas, combining longevity with the quality of survival.

To fulfill the overall aim of this SPORE in Brain Cancer, accelerating the clinical testing of new diagnostic and therapeutic approaches for patients with malignant glioma, we need to facilitate the translation of laboratory findings into the necessary clinical and correlative studies. This is the function of Core D. This Clinical Core will provide the infrastructure so that concepts emanating from the projects can be evaluated for translational suitability, formulated into appropriate clinical protocols and these protocols carried out with the appropriate regulatory oversight, safety and collection of clinical data. This core is a necessary and vital component of the SPORE in Brain Cancer, and will streamline and standardize its interaction with the extensive clinical trials infrastructure of The University of Texas M. D. Anderson Cancer Center (UTMDACC). The specific objectives of the Clinical Core are to provide support and resources for completion of the clinical trials or clinically related aspects of each of the Projects, as well as to serve as a resource for the development of promising laboratory findings into clinical concepts. Accordingly, Objective 1 is to provide infrastructure for protocol administration, including the clinical and regulatory aspects. Objective 2 is to provide expert consultation to augment and facilitate the development of clinical trials from promising laboratory data generated by the Projects.

The Clinical Core will provide the clinical trial infrastructure to support the clinical trial and related translational research that is generated by the four projects that constitute this SPORE application. The components of the Clinical Core leverage the extensive resources and expertise at MD Anderson in clinical and translational research. As the research efforts proposed in the current application represent extensions and expansions of ongoing efforts, the Clinical Core will continue to provide the support and expertise to develop and manage the highly innovative clinical trials that develop from the proposed research efforts. Additionally, recognizing that the scope of clinical trials may encompass from early stage (proof-of principle) studies examining drug/agent delivery and tissue-based efficacy (i.e. pharmacodynamics) to larger, randomized multicenter clinical trials, we have developed a robust web-based clinical trials management software package, the Data Management Initiative (DMI). This system supports state-of-the art tracking of all critical elements of the clinical trial including patient outcomes, adverse events and drug dosing. It contains internal auditing functions thereby limiting resource consuming queries. Furthermore, the DMI has been approved by the FDA for studies containing IND agents and is also approved for registration clinical trials. The Clinical Core will support the specific SPORE projects as described: Project 1: A Phase l/ll study combining the Delta-24 oncolytic virus with temozolomide. Early phase study of evaluating mesenchymal stem cell mediated delivery of Delta-24 into human glioblastoma. Project 2: A Phase I study of combination signal transduction agents followed by a 2-stage multi-arm Bayesian based Adaptive Selection Design clinical trial to test preclinical developed drug combinations. Project 3: No direct Clinical Core support needed for these clinical-molecular studies using outcomes and molecular profiles from large clinical trials. Project 4: A Phase I clinical trial of WPI 066 an oral STAT3 inhibitor with an arm that will evaluate treatment delivery and impact on molecular targets (pharmacokinetics and pharmacodynamics).