Adjunctive albuterol enhances the response to enzyme replacement therapy in late-onset Pompe disease.

As a physician-scientist practicing clinical and biochemical genetics, I am highly motivated to seek improved therapy for my patients with inherited disorders of metabolism. The focus of our research has been the development of gene therapy with adeno-associated virus (AAV) vectors, most recently by genome editing with CRISPR/Cas9. We have developed gene therapy for inherited disorders of metabolism, especially glycogen storage disease (GSD) and phenylketonuria (PKU). 
1) GSD Ia: Glucose-6-phosphatase (G6Pase) deficient animals provide models for developing new therapy for GSD Ia, although early mortality complicates research with both the murine and canine models of GSD Ia. We have prolonged the survival and reversed the biochemical abnormalities in G6Pase-knockout mice and dogs with GSD type Ia, following the administration of AAV8-pseudotyped AAV vectors encoding human G6Pase. More recently, we have performed genome editing to integrate a therapeutic transgene in a safe harbor locus for mice with GSD Ia, permanently correcting G6Pase deficiency in the GSD Ia liver. Finally, we have identified reduced autophagy as an underlying hepatocellular defect that might be treated with pro-autophagic drugs in GSD Ia.
2) GSD II/Pompe disease: Pompe disease is caused by the deficiency of acid-alpha-glucosidase (GAA) in muscle, resulting in the massive accumulation of lysosomal glycogen in striated muscle with accompanying weakness. While enzyme replacement has shown promise in infantile-onset Pompe disease patients, no curative therapy is available. We demonstrated that AAV vector-mediated gene therapy will likely overcome limitations of enzyme replacement therapy, including formation of anti-GAA antibodies and the need for frequent infusions. We demonstrated that liver-restricted expression with an AAV vector prevented antibody responses in GAA-knockout mice by inducing immune tolerance to human GAA. Antibody responses have complicated enzyme replacement therapy for Pompe disease and emphasized a potential advantage of gene therapy for this disorder. The strategy of administering low-dose gene therapy prior to initiation of enzyme replacement therapy, termed immunomodulatory gene therapy, prevented antibody formation and increased efficacy in Pompe disease mice. We are currently conducting a Phase I clinical trial of immunomodulatory gene therapy in adult patients with Pompe disease. Furthermore, we have developed drug therapy to increase the receptor-mediated uptake of GAA in muscle cells, which provides adjunctive therapy to more definitively treat Pompe disease.
3) PKU: In collaboration with researchers at OHSU, we performed an early gene therapy experiment that demonstrated long-term biochemical correction of PKU in mice with an AAV8 vector. PKU is a very significant disorder detected by newborn screening and currently inadequately treated by dietary therapy. Phenylalanine levels in mice were corrected in the blood, and elevated phenylalanine causes mental retardation and birth defects in children born to affected women, and gene therapy for PKU would address an unmet need for therapy in this disorder.

Currently we are developing methods for genome editing that will stably correct the enzyme  deficiency in GSD Ia and in Pompe disease.  Our long-term goal is to develop efficacious genome editing for glycogen storage diseases, which will allow us to treat these conditions early in life with long-term benefits. 

Laura E Case, PT, DPT, MS, PhD, PCS, C/NDT is a board-certified clinical specialist in pediatric physical therapy. She has dedicated her career to teaching, research in childhood-onset neuromusculoskeletal disorders, and to the lifelong treatment of people with childhood-onset neurological and neuromuscular disorders such as cerebral palsy, traumatic brain injury, Duchenne muscular dystrophy, spinal muscular atrophy, Pompe disease, myelodysplasia, juvenile rheumatoid arthritis, and brachial plexus injury.

She has been involved in numerous clinical trials for the treatment of disorders including Pompe disease and other metabolic disorders, cerebral palsy, Duchenne muscular dystrophy, and spinal muscular atrophy. Dr. Case has participated in the development of international guidelines for the management of Duchenne muscular dystrophy, Pompe disease, and other glycogen storage diseases.

She teaches and consults internationally, has worked on a number of Center for Disease Control (CDC) task forces, has served on numerous committees and task forces in the pediatric section of APTA, served two terms as NC State Representative to the APTA Section on Pediatrics, and is a member of the North American Pompe Registry Board of Advisors.

My basic research focus is on neurogenic stem cells and their involvement in brain development and brain tumors. I work in mouse models using inducible in vivo genetic systems, live imaging, and tissue culture, in addition to histological and biochemical methods.
My clinical research interests include neuromuscular diseases. I collaborate with colleagues at Duke on basic and translational research in this area.

As a clinical biochemical geneticist and a director of the Duke Biochemical Genetics laboratory, my research interests are focused on improving laboratory diagnostics for rare inherited disorders of metabolism. I am actively involved in the development of assays using mass spectrometry and other analytical techniques. My current research on biomarkers for lysosomal storage disorders, such as Fabry and Pompe disease and the mucopolysaccharidoses includes monitoring the response to novel therapies in patients. I also have an interest in neurometabolic disorders such as the creatine deficiency syndromes and sulfite oxidase and molybdenum cofactors. These disorders can be diagnosed using liquid chromatography-tandem mass spectrometric assays that measure biomarkers in urine. Guanidinoacetate methyltransferase deficiency is a disorder that can be detected in the newborn period and is amenable to dietary therapy, and is thus a good candidate for newborn screening.

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.

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.