Transposon Engineered B Cell Therapy for Hunter Syndrome

PROJECT SUMMARY Mucopolysaccharidosis type II (MPS II, Hunter syndrome) is an X-linked recessive lysosomal disease caused by the absence of iduronate-2-sulfatase (IDS), resulting in systemic accumulation of glycosaminoglycan (GAG) storage materials, hepatosplenomegaly, skeletal dysplasias, cardiopulmonary obstruction, progressive neurologic impairment and death by age 12. MPS II is currently treated by enzyme replacement therapy, but these treatments are extraordinarily expensive and do not fully address the physiologic and neurologic manifestations of the disease. Here we propose an entirely novel approach to the treatment of MPS II. Immusoft Corp. is developing genetically engineered autologous human B cells for production of therapeutic proteins upon infusion into patients. Immusoft is using the Sleeping Beauty (SB) transposon system for integrative gene transfer and expression, as developed by Discovery Genomics, Inc. (DGI). In 2016 Immusoft acquired DGI, and here we propose to combine Immusoft’s novel B cell expression platform with the SB transposon technology for the purpose of expressing human IDS from B cells in vivo as an approach to achieve systemic and CNS-directed expression of IDS as a treatment for MPS II. This project is further strengthened by the extensive experience of Immusoft’s investigative team and colleagues at the University of Minnesota in the conduct of preclinical studies and clinical trials of new treatments for lysosomal diseases, including MPS II. For this Phase I study, the Specific Aims are; (i) Correction of IDS deficiency in a murine model of MPS II by adoptive transfer of human B cells genetically engineered to express human IDS using the Sleeping Beauty transposon system. IDS expressing human B cells will be infused into immunodeficient NSG MPS II mice recently established in the laboratory of the PI, evaluating recipient animals for adoptive transfer, expression and distribution of IDS activity, and correction of neurologic and physiologic disease. Treated animals will be evaluated for prevention of neurocognitive deficiency, skeletal defects and metabolic disease as a model for potential effectiveness in the treatment of human MPS II. (ii) Modification of B cells to promote transmigration of the blood-cerebrospinal fluid (CSF)-barrier. Human B cells will be genetically modified with SB transposons encoding CCR6 or CCR7, chemokine receptors that are known to mediate T-cell migration from the blood into the CSF. These transposed B cells will be tested for the ability to cross the blood-CSF-barrier using an in vitro transmigration assay, mimicking conditions at the blood-CSF barrier, and evidence for engineered B cell penetration of the CNS as a cellular vehicle for delivery of therapeutics for neurologic disease, including MPS II. Results from these studies will be directly applicable to the development of a clinical protocol for treatment of human MPS II by infusion of B cells genetically engineered to express human IDS using the SB transposon system.PROJECT NARRATIVE Lysosomal storage disorder MPSII is a rare inherited disease in which patients suffer from skeletal abnormalities, heart and breathing problems, mental retardation and death. While other lysosomal storage diseases can be treated by protein therapy or by bone marrow transplantation, these treatments proved to be incompletely effective for MPSII. It is envisioned in this grant application that one way to treat MPSII would be to restore the missing gene in patients’ white blood cells as a way of providing the missing protein and restoring function in the different organs, including the brain.