Alglucosidase alfa enzyme replacement therapy as a therapeutic approach for glycogen storage disease type III.

My overall research interests are finding effective treatment for human glycogen storage diseases (GSDs) and other inherited metabolic disorders. My current research focuses on identification of novel therapeutic targets and development of effective therapies for GSD II (Pompe disease), GSD III (Cori disease), and GSD IV (Andersen disease) using cellular and animal disease models. The main therapeutic approaches we are using in our pre-clinical studies include protein/enzyme therapy, AAV-mediated gene therapy, and substrate reduction therapy with small molecule drugs.

1)Development of new non-invasive laboratory diagnostic methods using enzymology and molecular diagnostic techniques for Glycogen Storage Diseases (GSDs) and Lysosomal Storage Diseases (LSDs) like Pompe, Fabry, Gaucher, MPS - for early diagnosis and treatment modalities. Exploration of new high throughput diagnostic platforms with an idea of implementation into New born screening (NBS)of these diseases.

2)Clinical research studies associated with Pompe disease with a goal to improve the diagnosis, current therapies and patient care, with special emphasis on clinical development of Cross Reactive Immunologic Material (CRIM) diagnostic methods and association with underlying pathogenic GAA mutations and clinical correlations.

3) Clinical research studies involving other common LSDs (Fabry, MPSI,II,IVa and VI, Gaucher, Wolman disease and more) focusing on early diagnosis and new born screening.

4)Understanding the hepatocellular adenoma (HCA) and hepatocellular carcinomas (HCC) transformation in GSD I, using paired samples from resected adenomas and adjoining liver tissue. Experiments use SNP and expression microarray analysis, miRNA and CNV analysis in collaboration with other investigators.

5)Pursuing genotype-phenotype correlations for various clinical phenotypes of GSD IX, in order to better understand clinical heterogeneity. Severe phenotypes of GSD IX resulting in liver cirrhosis and Cardiac involvement are of special interest to us, especially their association with the underlying pathogenic mutations.

6)Research on Pompe/Mannose-6-phosphate receptor (M6PR300) double knock out mice to understand the role of M6PR in rhGAA uptake and glycogen clearance and also beta-agonist like Clenbuterol.

Our overall research interests are in translational research. We aim at translating the promise of genomic medicine into clinical reality.

Specific projects at present time include:

1). Identification of novel genes/targets associated with human diseases. This includes susceptibility genes for common multi-factorial diseases and adverse drug reactions. Genetic epidemiology, mouse ENU mutagenesis, bioinformatics and proteomics are some approaches that we use in identification of novel genes associated with the human disease. Genetic markers associated with drug-induced Stevens-Johnson syndrome and other adverse drug reactions have been identified. Prospective studies are in progress to assess the utilization of these markers to prevent the adverse drug reactions. A systematic, genome-wide, phenotype-driven mutagenesis program for gene function studies in the mouse have resulted in the identification of several mouse models of human genetic metabolic diseases. We will continue our research along these lines to identify more novel disease genes/ targets and to increase our understanding of the diseases.

2). Genetics and molecular mechanisms of Stevens-Johnson syndrome. With the identification of HLA-B allele strongly linked to the genetic susceptibility to the drug-induced Stevens-Johnson syndrome, we are investigating how the specific HLA allele mediated the cell toxicity in causing disseminated keratinocyte death.

3). Functional characterization of a novel glucose transporter and its role in diabetes mellitus. We cloned a novel glucose transporter (Glu 10), which is highly expressed in pancreas and liver and is located on a region of a chromosome where a diabetes mellitus type II locus has been mapped. We are currently investigating its role in diabetes by studying mouse models carrying the GLU10 mutations and by direct genetic association study of human patients affected with diabetes.

4). Enzyme and gene therapy and targeting mechanisms of Pompe disease.
Pompe disease is a fatal genetic muscle disorder. As enzyme replacement therapy for Pompe disease moves into clinical reality the fundamental question of how the enzyme targets the heart and skeletal muscle and why some patients respond better than others remain unanswered. We have generated tissue-specific MPR300 knockout mouse model and other animal models to help answer these questions.

RESEARCH INTERESTS

A multidisciplinary approach to care of individuals with genetic disorders in conjunction with clinical and bench research that contributes to:
1) An understanding of the natural history and delineation of long term complications of genetic disorders  with a special focus on liver Glycogen storage disorders, lysosomal disorders with a special focus on Pompe disease, Down syndrome and hypophosphatasia
2) ) The development of new therapies such as AAV gene therapy, enzyme therapy, small molecule and other approaches for genetic disorders through translational research

3) The development and execution of large multicenter trials to confirm safety and efficacy of potential therapies
4) Role of antibodies/immune response in patients on therapeutic proteins and AAV gene therapy

. Glycogen Storage Disease (GSD): We are actively following subjects with all types of Glycogen Storage Disease, with particular emphasis on types I, II, III, IV, VI and IX. The goal of the treatment team is to better determine the clinical phenotype and long term complications of these diseases. Attention to disease manifestations observed in adulthood, such as adenomas and risk for HCC, is of paramount importance in monitoring and treating these chronic illnesses. We are establishing clinical algorithms for managing adenomas, and the overall management of these patients including cardiac, bone, muscle and liver issues. A special focus is biomarker discovery, an Omics approach including metabolomics and immune phenotyping. We are working on AAV gene therapy for several hepatic GSDs

.Lysosomal Storage Disease: The Duke Lysosomal Storage Disease (LSD) treatment center follows and treats patients with Pompe, Gaucher, Fabry, Mucopolysaccharidosis, Niemann Pick, LAL-D and other LSD's. The Duke Metabolism Clinical Research Team is exploring many aspects of enzyme replacement therapy (ERT), including impact on different systems, differential response, and long term effects. Other symptomatic and treatment interventions for this category of diseases are also being explored in the context of clinical care.

. Pompe Disease: The care team has extensive experience in the care of infants and adults with Pompe disease and was instrumental in conducting clinical trials and the bench to bedside work that led to the 2006 FDA approval of alglucosidase alfa, the first treatment for this devastating disease. We are currently focusing on role of antibodies/immune response on patient outcome and role of immune modulation/immune suppression as an adjunct to ERT. Our team is also working on AAV gene therapy for Pompe disease. A focus is on newborn screening (NBS) and understanding the clinical phenotype and management approaches for babies identified via NBS

.  Hypophosphatasia: We follow a large cohort of patients with HPP. The goal is to understand the features of the disease beyond bone disease, development of biomarkers, role of ERT and immune responses in HPP

. Neuromuscular disorders: We are collaborating with neurologists, cardiologists and neuromuscular physicians to serve as a treatment site for clinical trials in these diseases. We are currently involved in trials of DMD and are working closely on setting up collaborations for studies in SMA.