SBIR-STTR Award

Mucopolysaccharidosis (MPS) Type IIIA, also called Sanfilippo A syndrome, is a genetic disease caused by mutations in the gene encoding the lysosomal enzyme, N-sulfoglucosamine sulfohydrolase (SGSH), also called sulfamidase. Symptoms including neurodegeneration and mental retardation appear during infancy or childhood; and early death occurs due to organ damage in the brain. Enzyme replacement therapy (ERT) cannot treat the brain, since recombinant SGSH does not cross the blood-brain barrier (BBB). Accordingly, clinical trials on the treatment of children with MPSIIIA with intravenous recombinant SGSH have been abandoned. The present work will re-engineer human SGSH to enable transport across the BBB using a molecular Trojan horse technology. A molecular Trojan horse is a genetically engineered peptidomimetic monoclonal antibody (MAb) against an endogenous BBB peptide receptor, such as the human insulin receptor (HIR). The human SGSH is fused to the heavy chain of the HIRMAb to create a new chemical entity, called the HIRMAb-SGSH fusion protein. Feasibility studies with the HIRMAb-SGSH fusion protein were enabled following the cloning of a high producing, stably transfected host cell line. The HIRMAb-SGSH fusion protein retains high SGSH enzyme activity and high binding to the HIR. This phase I SBIR work will further validate the pharmacologic activity of the HIRMAb-SGSH fusion protein in MPSIIIA fibroblasts, using SGSH enzyme activity assays and confocal microscopy. The HIRMAb-SGSH fusion protein penetration of the BBB in vivo will be confirmed in the Rhesus monkey. This work provides the rationale for future phase II studies that provide the bridge to subsequent GMP/GLP work that supports an IND for treatment of MPSIIIA with intravenous HIRMAb-SGSH fusion protein.

Public Health Relevance Statement:


Public Health Relevance:
Mucopolysaccharidosis (MPS) Type IIIA, also called Sanfilippo A syndrome, is a genetic disease caused by mutations in the gene encoding the lysosomal enzyme, N-sulfoglucosamine sulfohydrolase (SGSH), also called sulfamidase. Enzyme replacement therapy cannot treat the brain, since recombinant SGSH does not cross the blood-brain barrier. The present work will re- engineer human SGSH to enable transport across the BBB using a molecular Trojan horse technology.

Project Terms:
Address; Affinity; Animal Testing; Animals; base; Binding (Molecular Function); Biological Assay; Bioreactors; Blood; Blood - brain barrier anatomy; Blood capillaries; Blood Vessels; Brain; brain cell; capillary; Cell Culture Techniques; Cell Line; Cell membrane; Cells; Cessation of life; Chemicals; Child; Childhood; Chimeric Proteins; Chinese Hamster; Chinese Hamster Ovary Cell; Chronic; Clinical Trials; Cloning; Confocal Microscopy; Disease; disease-causing mutation; Dose; Drug Delivery Systems; drug development; Drug Kinetics; Engineering; enzyme activity; enzyme replacement therapy; Enzymes; Evaluation; Feasibility Studies; Fibroblasts; Future; Genes; Genetic Engineering; Hereditary Disease; Human; Human Engineering; human INSR protein; Hyperactive behavior; Immunoglobulin G; In Vitro; in vivo; infancy; Inherited; Insulin Receptor; Intravenous; Intravenous infusion procedures; Label; Macaca mulatta; Medical; Mental Retardation; Methodology; Methods; Modeling; molecular trojan horse; Monoclonal Antibodies; Mucopolysaccharidoses; Mucopolysaccharidosis III; Mutation; Nerve Degeneration; Neuraxis; Neurons; Organ; Ovary; Penetration; Peptide Receptor; Peptide Signal Sequences; peptidomimetics; Peripheral; Pharmaceutical Preparations; Phase; phase 1 study; phase 2 study; Phenotype; Plasma; Primates; Property; Propionates; protein structure; Proteins; public health relevance; Radio; Recombinant Fusion Proteins; Recombinants; Research; response; Rodent; Small Business Innovation Research Grant; Spinal Cord; Symptoms; Syndrome; Teenagers; Time; Toxic effect; Toxicology; Triage; uptake; Work

Type IIIA Mucopolysaccharidosis (MPS), also known as Sanfilippo A syndrome, is a genetic disease that affects the lysosomal enzyme, N-sulfoglucosamine sulfohydrolase (SGSH), also called sulfamidase. Consequently, patients with MPS-IIIA develop extensive lysosomal storage product accumulation in the brain. Children born with MPS- IIIA develop multiple brain disorders including mental retardation and hydrocephalus. The current therapy for lysosomal storage disorders is Enzyme Replacement Therapy (ERT) with the recombinant human enzyme. However, ERT will not treat the brain of MPS- IIIA, because SGSH does not cross the blood-brain barrier (BBB). The present work will continue work on the development of a new treatment of the brain of MPS- IIIA, which is a genetically engineered biopharmaceutical fusion protein named AGT-184. The SGSH is genetically fused to a BBB molecular Trojan horse, which is a genetically engineered peptidomimetic monoclonal antibody (MAb) against an endogenous BBB peptide receptor, the human insulin receptor (HIR). The human SGSH is fused to the heavy chain of the HIRMAb to create a new chemical entity, called the HIRMAb- SGSH fusion protein. Phase I studies show the HIRMAb-SGSH fusion protein could be engineered and expressed by stably transfected host cells. The fusion protein retained high affinity binding to the HIR and retained high SGSH enzyme activity. The proposed phase II work will develop a manufacturing plan that can be replicated for future GMP manufacturing. The AGT-184 produced in phase II will be evaluated for safety, toxicology and pharmacokinetics in a Rhesus monkey dose-finding study. The completion of this work will enable entry of the AGT-184 drug development program into GLP toxicology and GMP manufacturing required for submission of an IND to begin treatment of the brain in patients with MPS- IIIA.

Public Health Relevance Statement:


Public Health Relevance:
Mucopolysacchridosis Type IIIA, or Sanfilippo A Syndrome, is an inherited condition where patients develop severe brain abnormalities, owing to the genetic defect in the gene encoding the lysosomal enzyme, N-sulfoglucosamine sulfohydrolase (SGSH). Enzyme replacement therapy (ERT) is not effective for the brain, because the SGSH does not cross the blood-brain barrier (BBB). This research will develop a new treatment for the brain in patients with MPSIIIA, which involves the re-engineering of human SGSH as an IgG fusion protein that crosses the human BBB.

Project Terms:
Active Biological Transport; Adult; Affect; Affinity; Affinity Chromatography; Anions; Antibodies; Autopsy; Binding (Molecular Function); Biochemical; Biological Products; Bioreactors; Blood; Blood - brain barrier anatomy; Brain; brain cell; Brain Diseases; Cations; Cell membrane; Cells; Cerebrospinal Fluid; Chemicals; Child; Chimeric Proteins; Chinese Hamster; Chinese Hamster Ovary Cell; Chromatography; Clinical Trials; Development; Disease; Dose; Drug Delivery Systems; drug development; Drug Kinetics; Engineering; enzyme activity; enzyme replacement therapy; Enzyme-Linked Immunosorbent Assay; Enzymes; Exhibits; Fibroblasts; Filtration; Future; Genes; Genetic Engineering; Growth; Hereditary Disease; Histology; Human; Human Engineering; human INSR protein; Hydrocephalus; Immunoglobulin G; in vivo; Inherited; Insulin Receptor; Intravenous; Macaca mulatta; Measures; Mediating; Membrane; Mental Retardation; molecular trojan horse; Monoclonal Antibodies; Mucopolysaccharidoses; Mucopolysaccharidosis III; Mutate; Mutation; Names; nano; Neuraxis; Neurons; Organ; Ovary; Patients; Peptide Receptor; peptidomimetics; Perfusion; Peripheral; Pharmaceutical Preparations; Phase; phase 1 study; Plasma; Primates; Process; Production; programs; Progress Reports; Protein Binding; Proteins; public health relevance; receptor; Recombinants; Research; Safety; Small Business Innovation Research Grant; Structure; Syndrome; Temperature; Testing; Toxicology; uptake; Validation; Work