Markos Leggas, Ph.D. - US grants

[unreadable] DESCRIPTION (provided by applicant): As a class, the camptothecins have been widely recognized for their therapeutic potential, which for many reasons, including the instability of the lipophilic lactone moiety, has not been fully realized. DB-67 (7-t- butyldimethylsilyl-10-hydroxycamptothecin) is a third generation analog that was engineered to be blood stable and highly potent, on the basis of structure-activity relationship studies. The camptothecins have a labile a-hydroxy-5-lactone ring, which hydrolyzes to yield the negatively charged carboxylate form. Compared to the uncharged lactone, the negatively charged carboxylate is less likely to diffuse into cells and is often considered "inactive." Based on its blood stability and anti-tumor activity, DB-67 was selected by the NCI for development through three cycles of the RAID program. Data from NCI studies and from collaborative efforts revealed impressive in vitro and in vivo anti-tumor activity, particularly in glioma models, but also in melanoma and colon xenograft models. Currently DB-67 formulation and toxicology studies have been completed and clinical grade material is available through the NCI. Based on the extensive formulation, toxicology, and pharmacokinetic profile observed in preclinical models, and its potential to exert a potent anti-tumor effect in humans, we hypothesize that DB-67 will be well-tolerated and efficacious in clinical trials. This grant application outlines the clinical studies and the correlative pharmacokinetic studies that will define DB-67 disposition and toxicity in patients with refractory solid tumors. The following specific aims will be accomplished: 1.1) To estimate the maximum tolerated dose (MTD) and describe the dose limiting toxicities (DLT) of intravenous DB-67 administered once daily for 5 days every 21 days to adults with recurrent or refractory solid tumors in which standard therapies are not effective; 1.2) To characterize the plasma pharmacokinetics of DB-67 and metabolites after intravenous administration and relate DB-67 pharmacokinetics and toxicity. Ultimately, the objective is to use DB-67 as a single agent or in combination with other molecular-targeted therapies or cytotoxics in frontline therapy with the goal to improve overall patient outcome. [unreadable] [unreadable] [unreadable]

ABSTRACT The number of newborns that develop the constellation of drug withdrawal symptoms or Neonatal Abstinence Syndrome (NAS) in the US has increased to epidemic proportions. The pharmacologic treatment of NAS with morphine or methadone is highly concerning as it corresponds with a timeframe of rapid postnatal brain devel- opment. The negative effects of opioids on the developing brain include decreased neurogenesis, synaptogen- esis, and corticogenesis, decreased brain size, and decreased brain volumes in older children with prenatal opiate exposure. Furthermore, response of neonates to treatment is highly variable and limited pharmaco- genetic and metabolic activity data, which can be used to optimize therapy in this population, pose additional challenges in using any drug to treat NAS. Collectively, these issues present a critical need to evaluate and optimize the use of a non-opioid drug for treatment of NAS. The long term goals of our research is to establish the best pharmacological treatment for NAS and determine how pharmacologic treatment of NAS affects long- term developmental outcomes. The objective of this application is to evaluate the effectiveness of clonidine, an ?2 adrenergic receptor agonist, as a treatment for neonates with NAS, in a randomized clinical trial. Our cen- tral hypothesis is that clonidine will effectively treat drug withdrawal manifestations in neonates. Preliminary clinical evidence supports this hypothesis. Clonidine has previously been reported by us and others as a single drug therapy for NAS in small number of infants with relief of withdrawal symptoms and as an effective adjunc- tive treatment, when giving chloral hydrate or morphine. The rationale for the proposed research is that, once we understand how clonidine can be used optimally in the clinic to treat NAS, a safe medication will be availa- ble and it could potentially minimize complications associated increased length-of-stay in the hospital, healthcare costs and the deleterious opiate assaults on the developing brain that continue with postnatal opiate administration. To test our central hypothesis and accomplish the objective of this application we plan to pur- sue the following three specific aims: 1) To determine whether the treatment of NAS with a non-opiate medica- tion, clonidine, will be more effective than morphine. 2) To determine whether treatment of NAS with clonidine will result in better early childhood outcomes than those treated with morphine. 3) To determine how infants with NAS metabolize morphine and clonidine. With respect to expected outcomes, this proposal will provide prospective evidence: a) regarding the potential of clonidine treatment to treat NAS; b) regarding how opioid and non-opioid exposure affect early childhood development; c) regarding factors that influence response to treatment. These results are expected to have an important positive impact, because they have the potential to provide fundamental information regarding the metabolic ontogeny of infants exposed to opioid drugs and, most importantly, to improve the long-term outcomes of children born to addicted mothers.

Ewing sarcoma family of tumors (ESFT) is a family of resilient devastating cancers of bone and soft tissue affecting primarily children and young adults. Current highly cytotoxic combination therapy of five drugs provides only 30% overall survival. The aberrant transcription factor EWS-FLI1 present only in tumor cells is the oncogenic driver of EWS. However, transcription factors were believed to be ?undruggable?, until a recent NCI screening found mithramycin (MTM) to act as a potent EWS-FLI1 antagonist. MTM has proven to be too toxic with a narrow therapeutic window and poor pharmacokinetic (PK) properties. Here we propose mechanistic and pharmacology studies of novel MTM analogues (MTM-SA) with significantly reduced toxicity, increased target specificity and greatly improved PK properties. In contrast to other analogues reported elsewhere, which still suffer from poor PK properties, the MTM-SA analogs display superior kinetics and reduced toxicity. The goal of this project is to gain molecular insights into the mode of action of MTM via structural, biochemical and pharmacological studies to generate a highly efficacious and selective anti-ESFT treatment. To aid synthetic efforts in Aim1 and identify analogues with clinical potential, we will perform molecular structure-function level studies in Aim 2 to determine how transcription factor EWS-FLI1 interacts with DNA microsatellite repeats and transcription factor Runx2 (each a necessary interaction for oncogenesis), and how these oncogenic functions are disrupted by MTM-SA. In Aim 3 will assess the in vitro cytotoxicity and target selectivity to identify analogues that will be evaluated in pharmacologic studies that will assess toxicity in humanized liver mice, PK and metabolism, as well as efficacy in xenograft and PDx models of Ewing Sarcoma. The project will be carried out by a team with an established collaboration who have extensive experience in fragment-based drug design and semi-synthetic routes of natural products, X-ray crystallographic, biophysical and molecular biology studies, and pharmacological evaluations. We expect that these structure-function studies will identify a lead-candidate that could enter a clinical trial for the treatment of ESFT.

PROJECT SUMMARY/ABSTRACT ? TRANSLATIONAL CORE We propose to establish a Center of Biomedical Research Excellence (COBRE) in Pharmaceutical Research and Innovation at the University of Kentucky (UK). CPRI will serve as a comprehensive multidisciplinary center focused on translational chemical biology [the nexus of chemical biology (the application of chemical biology principles to develop validated probe/models to advance our understanding of biology) and pharmaceutical science (the application of pharmaceutical principles to advance leads/materials/devices that address unmet clinical needs)]. The COBRE will leverage and develop unique translational chemical biology research support infrastructure/expertise to facilitate junior faculty mentorship and career development, innovative biomedical research probe/tool/model/materials development and validation, and the early advancement of potential ?translatable? assets. Within this context, the CPRI Translational Core will provide key infrastructure and expertise to support experimental studies central to probe/lead/materials discovery. Under the co-direction of Drs. Markos Leggas and Jon Thorson, the Core will support assay design, development, validation and implementation; pilot screening campaigns; a suite of in vitro absorption, distribution, metabolism, excretion and toxicity (ADMET) assays; and first in animal ADMET/pharmacokinetics (PK) studies. Support in the Core will be tailored toward specific COBRE project/pilot needs and screening services will also leverage CPRI-exclusive compound collections (both natural products and synthetics). The Core?s services have been strategically designed to integrate with, and complement, the support provided by the CPRI Computational Core and the CPRI-affiliated COBRE for Molecular Medicine Organic Synthesis Core. Together, CPRI?s corresponding fully integrated research support capabilities and expertise will accelerate innovative, ?translatable? transdisciplinary research and facilitate junior investigator career development.