1416 A patients-derived glioblastoma tumoroids model to study individual response to chemo-radiation

<h3>Background</h3> Glioblastoma (GBM) is the most common and lethal malignant brain tumor that is highly resistant to chemotherapy and radiation therapy.¹ The high level of heterogeneity within and between tumors is believed to significantly impact tumor progression, limit treatment options, and lead to poor patient outcomes.² An <i>ex vivo</i> system that can recapitulate the phenotypic and molecular heterogeneity of GBM is necessary for the understanding of the biological mechanisms behind the pathogenesis of GBM and drug discovery. <h3>Methods</h3> Using the method described by Jacob et al., 2020,³ we established an <i>in vitro</i> 3D culture system that generates patient-derived glioblastoma tumoroids. The immunofluorescence and confocal imaging were used to investigate the cell populations and histologic features of tumoroids. The bulk RNA-Seq analysis was performed to compare the gene expression profile of the tumoroids. The irradiation and drug treatment were used to evaluate the response of tumoroids derived from different patients. <h3>Results</h3> Our data showed that 3D cultured tumoroids maintained a heterogeneous cell population that includes neural stem cells, macrophages, and T cells within the tumor microenvironment (TME). The tumoroids also exhibited histologic features of parental tumors, such as maintaining hypoxia gradients, a hallmark of GBM. Furthermore, bulk RNA-Seq analysis of parental tumors and corresponding tumoroids revealed that tumoroids retained a high level of similarity with their parental tumors. Specifically, the gene expression profiles associated with GBM were well-maintained in the 3D culture tumoroids compared to the corresponding parental tumors. While the gene expression levels related to immune cell populations within the TME decrease in the 3D tumoroids during culture, particularly after passaging, the immune cell populations were successfully maintained in the tumoroids after 3–4 weeks of culture. This provides a valuable platform for investigating the TME. Notably, GBM tumoroids exhibited diverse responses to chemotherapy and radiation therapy. <h3>Conclusions</h3> The 3D culture system has the potential to be used in preclinical evaluation of chemo-radiation therapy in the treatment of GBM. <h3>Acknowledgements</h3> We appreciate funding from the USFDA 1R01FD007268-01 to Dr. Elias Sayour and Hyundai Hope on Wheels to Dr. John Ligon. <h3>References</h3> Ostrom QT, Gittleman H, Farah P, Ondracek A, Chen Y, Wolinsky Y, Stroup NE, Kruchko C, Barnholtz-Sloan JS. CBTRUS statistical report: primary brain and central nervous system tumors diagnosed in the United States in 2006-2010. <i>Neuro Oncol</i> 2013;<b>15 Suppl 2</b>:ii1–56. 10.1093/neuonc/not151. Sharma P, Aaroe A, Liang J, Puduvalli VK. Tumor microenvironment in glioblastoma: current and emerging concepts. <i>Neurooncol Adv</i> 2023;<b>5</b>:vdad009. 10.1093/noajnl/vdad009. Jacob F, Salinas RD, Zhang DY, Nguyen PTT, Schnoll JG, Wong SZH, Thokala R, Sheikh S, Saxena D, Prokop S, <i>et al</i>. A patient-derived glioblastoma organoid model and biobank recapitulates inter- and intra-tumoral heterogeneity. <i>Cell</i> 2020;<b>180</b>:188–204 e122. 10.1016/j.cell.2019.11.036. <h3>Ethics Approval</h3> Studies approved by IRB202001710. <h3>Consent</h3> Written informed consent was obtained from the patient for publication of this abstract and any accompanying images. A copy of the written consent is available for review by the editor of this journal.