10000- ET-1 STEM CELL-BASED GENE THERAPY FOR MALIGNANT GLIOMA USING GENOME-EDITED HUMAN INDUCED PLURIPOTENT STEM CELLS

Abstract Malignant glioma is the most aggressive primary brain tumor with dismal prognosis, characterized by diffuse infiltration into the normal brain parenchyma. Invasive glioma stem cells (GSCs) are thought to be an underlying cause of therapeutic resistance and tumor recurrence. Therefore, development of new therapeutic modalities is urgently needed. We demonstrated that human induced pluripotent stem cells (iPSCs)-derived neural stem cells (NSCs) possess the higher tumor-tropic migratory capacity than mesenchymal stem cells. Therefore, we established the concept of suicide gene therapy using iPSCs-derived NSCs as a cellular delivery vehicle for the treatment of malignant glioma. We first used a lentiviral vector for transduction of the yeast cytosine deaminase (yCD)- uracil phosphoribosyl transferase (UPRT) suicide gene into iPSCs, because of the high efficacy and safety. However, lentiviral vectors integrated randomly into the host genome, raising concerns about insertional mutagenesis, oncogene activation, and transgene silencing. In order to improve safety and to achieve stable transgene expression, yCD-UPRT was inserted into a housekeeping gene locus (ACTB) in iPSCs using CRISPR/Cas9-mediated genome editing, resulting in a significantly better anti-tumor effect for human glioma and glioma stem xenograft mice than temozolomide (standard chemotherapy). In the near future, NSCs derived from clinical grade human iPSCs with yCD-UPRT are established. Quality, safety and efficacy is evaluated, leading to obtain preclinical proof of concept. We prepare for the investigator initiated clinical trial.