Periodic Reporting for period 1 - GT-GM1 (Ex vivo gene therapy for GM1-gangliosidosis)
Reporting period: 2020-09-01 to 2022-08-31
GM1 is a genetic disorder that occurs when a person has very low amounts of a vital enzyme, β-galactosidase. The absence of this enzyme affects nerve cells (called neurons) in the brain and spinal cord, components of the central nervous system (CNS). GM1 gangliosidosis involves small compartments within cells called lysosomes. Lysosomes contain various enzymes that break down (or metabolize) larger molecules into smaller components for reuse or recycling elsewhere in the cell. This avoids the buildup of too many of these components within the cell. The absence of a lysosomal enzyme result in the buildup of excess waste in the cells of the impacted organ or system, causing a Lysosomal Storage Disease (LSD). GM1 is a fatal LSD, which causes developmental regression, mobility deterioration, seizures, visual impairment, and neurodegeneration. It currently has no cure or effective treatment.
Each LSD is rare on its own, but collectively LSDs impact a significant number of people, with about 1 in 100,000 to 1 in 200,000 infants born with GM1 gangliosidosis each year. Our project focus on developing effective treatments that are desperately needed for CNS disorders, like GM1 gangliosidosis.
Our therapeutic strategy is based on ex vivo gene therapy (GT), which works by providing a functional copy of the defective gene, in this case the gene encoding the β-galactosidase (GLB1), using a vector that allows the gene to penetrate inside the patient's cells and then express itself. Specific aims of the projects are the development of such therapeutic vector, the investigation of its therapeutic efficacy in vitro, in GM1-patient derived primary cells, and the validation of the whole gene therapy strategy in the murine model of the disease, i.e. mice affected by GM1.
After a work-intensive design and characterization step of a therapeutic vector encoding the human β-galactosidase, we tested its therapeutic potential in vitro. In GM1 patient-derived primary fibroblasts, a single vector copy resulted sufficient to restore the normal level of β-gal activity in this cell-type, and an average of 2 vector copies per cell determined a complete metabolic correction, removing GM1 ganglioside accumulations in few weeks. Preliminary data of β-gal activity in the blood of GM1 mice receiving the gene therapy, indicate a reconstitution of ~12% of the murine enzymatic activity, approximately equivalent to the human physiological level. Overall, considering the promising in vitro data produced in the cellular model of the disease, and the encouraging preliminary results in vivo, we hope and believe this study will generate a proof of concept for a future clinical development of an efficacious ex vivo GT for infantile GM1-gangliosidosis.
Each LSD is rare on its own, but collectively LSDs impact a significant number of people, with about 1 in 100,000 to 1 in 200,000 infants born with GM1 gangliosidosis each year. Our project focus on developing effective treatments that are desperately needed for CNS disorders, like GM1 gangliosidosis.
Our therapeutic strategy is based on ex vivo gene therapy (GT), which works by providing a functional copy of the defective gene, in this case the gene encoding the β-galactosidase (GLB1), using a vector that allows the gene to penetrate inside the patient's cells and then express itself. Specific aims of the projects are the development of such therapeutic vector, the investigation of its therapeutic efficacy in vitro, in GM1-patient derived primary cells, and the validation of the whole gene therapy strategy in the murine model of the disease, i.e. mice affected by GM1.
After a work-intensive design and characterization step of a therapeutic vector encoding the human β-galactosidase, we tested its therapeutic potential in vitro. In GM1 patient-derived primary fibroblasts, a single vector copy resulted sufficient to restore the normal level of β-gal activity in this cell-type, and an average of 2 vector copies per cell determined a complete metabolic correction, removing GM1 ganglioside accumulations in few weeks. Preliminary data of β-gal activity in the blood of GM1 mice receiving the gene therapy, indicate a reconstitution of ~12% of the murine enzymatic activity, approximately equivalent to the human physiological level. Overall, considering the promising in vitro data produced in the cellular model of the disease, and the encouraging preliminary results in vivo, we hope and believe this study will generate a proof of concept for a future clinical development of an efficacious ex vivo GT for infantile GM1-gangliosidosis.
From the beginning of the project, we designed and developed two versions of the therapeutic vector expressing the therapeutic enzyme β-galactosidase alone, or in combination with an additional molecular drug expected to further enhance the efficacy of the therapeutic approach. Then, the two vectors were extensively tested in vitro, in human cell lines and primary GM1-patient derived cells, where they corrected the molecular and biochemical defect. Finally, we are currently testing these vectors, and the whole gene therapy strategy in vivo, mimicking the treatment envisioned for GM1 children in GM1-mice. Preliminary data of β-gal activity in the blood of GM1 mice receiving the gene therapy, indicate a reconstitution of ~12% of the murine enzymatic activity, approximately equivalent to the human physiological level.
These results have been already presented at the two principal society for gene and cell therapy at their annual meeting (European and American Society for Gene and Cell Therapy, ESGCT and ASGCT, respectively) in 2021 and 2022.
We continue to present and discuss these results worldwide at the major scientific conferences of gene therapy and with the Italian and American GM1 patient’s associations, with the aim of finding scientific and financial support for a further development of our therapy towards the clinic.
These results have been already presented at the two principal society for gene and cell therapy at their annual meeting (European and American Society for Gene and Cell Therapy, ESGCT and ASGCT, respectively) in 2021 and 2022.
We continue to present and discuss these results worldwide at the major scientific conferences of gene therapy and with the Italian and American GM1 patient’s associations, with the aim of finding scientific and financial support for a further development of our therapy towards the clinic.
The project represents a significant progress beyond the state of the art, as it represents the first attempt of exploiting a potentially efficacious ex vivo gene therapy for GM1 gangliosidosis. It may serve as a solid proof of principle for a phase I/II clinical trial of ex vivo GT in GM1-gangliosidosis children, and produce significant knowledge on the molecular mechanisms involved in the pathology. If tested efficacious in the murine model of the disease, this GT may progress toward the clinical development, a have an impact on survival and quality of life of the affected patients, and on the burden of care for their families and the health care systems in their countries.