TMOD-08. DETAILED GENERATION OF AN ORTHOTOPIC INTRACRANIAL GLIOBLASTOMA (GBM) PATIENT-DERIVED XENOGRAFT (PDX) MODEL FOR PRECLINICAL IMMUNOTHERAPEUTIC STUDIES

Abstract PURPOSE This study aimed to establish an orthotopic intracranial PDX mouse model using cryopreserved GBM tissues expanded in a heterotopic subcutaneous PDX model for immunotherapeutic studies. The model is designed to closely replicate human GBM, enabling the exploration of its pathophysiology and the development of effective immunotherapies for this type of cancer. METHODS Glioblastoma tissues from 16 fresh and cryopreserved samples were used to establish a heterotopic subcutaneous PDX mouse model for tumor expansion. Successful engraftments were then used to create an orthotopic intracranial PDX mouse model. The tumor formation rates and durations were estimated in both models. Tumor fidelity to the original GBM tumors was confirmed through immunohistology (GFAP, P53, and Ki67) and genetic analysis (whole exome sequencing, RNA sequencing, and methylome analysis). The therapeutic effects of immunotherapy (allogenic NK cells) in combination with Avastin and Irinotecan were tested in the orthotopic intracranial PDX model. RESULTS The orthotopic intracranial GBM mouse model achieved 100% engraftment from successful tumor growth in the subcutaneous PDX model. The overall success rate was 81.25% (85.71% for cryopreserved tissues), with a median process duration of 26.5 weeks (19 weeks for the subcutaneous and 7.5 weeks for intracranial establishment). No significant differences in tumor formation were observed within one year for cryopreserved tissue in the subcutaneous model. Molecular and genetic analysis confirmed similar tumor characteristics between the intracranial PDX tumors and the original patient tumors. Additionally, NK cells combined with Avastin and Irinotecan demonstrated efficacy in this model. CONCLUSIONS We successfully established an orthotopic intracranial PDX mouse model using cryopreserved GBM tissues, with no observed differences within one year. These models accurately mirror patients’ tumor characteristics, promising advancements in glioblastoma research and treatment, particularly for immunotherapy studies. Keywords: Glioblastoma (GBM), cryopreserved GBM tissues, patient-derived xenograft (PDX) model, NOD/SCID IL-12Rγnull (NSG) mice