Poster T10 - PATIENT-DERIVED GLIOBLASTOMA MODELS FOR PERSONALIZED MEDICINE: TMZ CHEMORESISTANCE SCREENING

Introduction: Pre-clinical in vitro models using patient-specific glioblastoma (GBM) allow chemotherapeutic drug sensitivity testing for personalized medicine applications. However, reliable models that recapitulate the complex mechanisms of chemoresistance driven by the GBM tumor microenvironment remain to be thoroughly validated in a patient-specific manner, particularly pericyte-induced chemoresistance mediated by the CCL5-CCR5 paracrine axis. Therefore, this study aimed to assess and validate the impact of pericytes on inter- and intra-tumoral TMZ chemoresistance heterogeneity.

Materials and

Methods: Patient-derived GBM cells were isolated from two patients with grade IV tumors. For each patient, GBM cells were isolated from two distinct tumor regions. To evaluate Temozolomide (TMZ) sensitivity, GBM cells (QNS89WT-1C, -1D, -3C, and -3D), cultured with or without primary pericytes (ScienCell, USA), were treated with 0, 200, and 800 µM TMZ for 72 hours. The viability of GBM cells in response to TMZ was measured using cellular metabolic activity (Presto Bleu), viability (immunofluorescence: Live/Dead staining; and flow cytometry: Zombie violet), and cell proliferation (flow cytometry: CFSE).

Results, Conclusions, and Discussions: In mono-culture, 72 hours of TMZ treatment decreased the metabolic activity (Presto Blue) of all GBM cells compared to controls, with 3C cells being most sensitive to TMZ, followed by 3D, 1D, and 1C cells. TMZ treatment decreased the viability (Live/Dead staining) of all GBM cells compared to controls, with 1D and 3D cells demonstrating a 30% decrease in viability, a 17% decrease for 3C cells, and an 8% decrease for 1C cells. Interestingly, the proliferation (CFSE) of 1C, 1D, and 3C cells was reduced by TMZ treatment but increased for 3D cells. In co-culture, the viability and proliferation of all GBM cells were affected by TMZ treatment. The viability of 1C and 3C cells decreased but increased for 1D and 3D cells. Conversely, the proliferation of 1C and 3C increased but reduced for 1D and 3D cells. After 72 hours of TMZ treatment, the results demonstrated pericytes-induced inter- and intra-tumoral TMZ chemoresistance response heterogeneity, but discrepancies in the dose-dependent TMZ response were observed between the different outcome measures used to quantify TMZ sensitivity (Table 1).
This study demonstrated that patient-derived GBM in vitro models can be used to assess pericyte-induced chemoresistance and inter- and intra-tumoral TMZ sensitivity heterogeneity. However, the presence of pericytes and the method used to measure TMZ sensitivity are essential factors to consider for the clinical translation of personalized medicine in treating GBM.

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