Oncolytic virus (OV) treatment may offer a new treatment option for the aggressive brain tumor glioblastoma. Clinical trials testing oncolytic viruses in this patient group have shown promising results, with patients achieving impressive long-term clinical responses. However, the number of responders to each OV remains low. This is thought to arise from the large heterogeneity of these tumors, both in terms of molecular make-up and their immune-suppressive microenvironment, leading to variability in responses. An approach that may improve response rates is the personalized utilization of oncolytic viruses against Glioblastoma (GBM), based on specific tumor- or patient-related characteristics. In this review, we discuss potential biomarkers for response to different OVs as well as emerging ex vivo assays that in the future may enable selection of optimal OV for a specific patient and design of stratified clinical OV trials for GBM.

Background and Objective: Access to high-quality patient-derived brain tumor tissues is instrumental for translational neuro-oncology research. Glioblastoma tumor material resected by ultrasonic aspiration (UA) during surgery offers an abundant source of material; however, it is generally not used for research experiments. We hypothesize that UA-derived tumor tissue represents a source of tissue that accurately reflects the immune infiltrates of glioblastomas. Methods: In this study, we have utilized UA-derived tissue and performed a head-to-head comparison with paired resection tissue from the vital tumor core of the same patient. A combination of 16 fluorochrome-conjugated antibodies was designed to identify tumor-infiltrating T, B, and NK lymphocytes and characterize the TILs by spectral flow cytometry. Furthermore, a 5-plex panel was designed to spatially characterize the T cells, macrophages, and tumor cells on the paired UA and resection tissues. Results: UA-obtained cells exhibited a comparable yield and viability, as well as an abundance of tumor-infiltrating T, B, and NK lymphocytes compared to resection sample-derived cells. Importantly, we observed that there is a high concordance with respect to expression intensities of immune checkpoints by T cells in both types of tissue samples. Conclusions: These findings underscore the feasibility and reliability of utilizing the immune infiltrates from ultrasonic aspiration-acquired glioblastoma tissue.

Oncolytic virus (OV) clinical trials have demonstrated remarkable efficacy in subsets of patients with glioblastoma (GBM). However, the lack of tools to predict this response hinders the advancement of a more personalized application of OV therapy. In this study, we characterize an ex vivo co-culture system designed to examine the immune response to OV infection of patient-derived GBM neurospheres in the presence of autologous peripheral blood mononuclear cells (PBMCs). Co-culture conditions were optimized to retain viability and functionality of both tumor cells and PBMCs, effectively recapitulating the well-recognized immunosuppressive effects of GBM. Following OV infection, we observed elevated secretion of pro-inflammatory cytokines and chemokines, including interferon γ, tumor necrosis factor α, CXCL9, and CXCL10, and marked changes in immune cell activation markers. Importantly, OV treatment induced unique patient-specific immune responses. In summary, our co-culture platform presents an avenue for personalized screening of viro-immunotherapies in GBM, offering promise as a potential tool for future patient stratification in OV therapy.