Patients will receive in addition to standard histology analysis also the PDC- based drug screening.

Patients will receive in addition to standard histology analysis also the PDC- based drug screening. The PDC-based drug screening will be performed only in accordance with the approved Performance Study Plan on subjects who have signed an informed consent form. Execution of the PDC-based drug screening is limited to the approved study investigators. Based on the results of the PDC-based drug screening, a molecular tumor board will formulate a personalized treatment approach. The personalized treatment recommendation will be communicated to the patient. Application of adjuvant

/ maintenance therapy will be evaluated to evaluate the proportion of patients scheduled for a reduced course of radio(-chemo)therapy fit enough to receive at least one day of systemic therapy.

Inclusion Criteria:

• ECOG performance status 0-2
• Newly diagnosed glioblastoma, IDH-wildtype - according to the 2021 WHO classification of Tumors of the Central Nervous System
• Unmethylated MGMT promotor per local assessment
• Successful PDC establishment and PDCs available for drug screening - based on inclusion in one of the following studies: (EK Nrs. (a) Medical University of Graz: 32-650 ex 19/20; (b) Medical University of Vienna: 1407/2021; (c) Karl Landsteiner University of Health Sciences: GS1-EK-4/823-2022; (d) Kepler University Hospital Linz: 1323/2022; (e) Medical University of Innsbruck 1003/2023) and follow-up ethics covering the establishment of an Austrian GlioBank (EK Nrs. (a) Medical University of Graz: 36-253 ex 23/24; (b) Medical University of Vienna: 2186/2023; (c) Karl Landsteiner University of Health Sciences: GS3-EK-1/211-2024; (d) Kepler University Hospital Linz: 1002/2024; (e) Medical University of Innsbruck 1095/2024)
• Scheduled short-course radiotherapy with or without concomitant temozolomide
• Written informed consent
• No exclusion criteria

Exclusion Criteria:

• Current participation in another therapeutic clinical trial.
• Patients with a concurrent malignancy or malignancy within five years of study enrolment except for carcinoma in situ of the cervix, non-melanoma skin carcinoma or stage I uterine cancer within the last 3 years.
• Pregnant or lactating women.
• Current known infection with hepatitis B virus (HBV), or hepatitis C virus (HCV). Patients with past HBV infection or resolved HBV infection are eligible. Patients positive for anti-HCV antibody are eligible only if polymerase chain reaction (PCR) is negative for HCV RNA.
• Known human immunodeficiency virus (HIV) infection that is not well controlled. All of the following criteria are required to define an HIV infection that is well controlled: undetectable viral RNA, CD4+ count ≥350 cells/mm3, no history of AIDS-defining opportunistic infection within the past 12 months, and stable for at least 4 weeks on the same anti-HIV medications (meaning there are no expected further changes in that time to the number or type of antiretroviral drugs in the regimen). If an HIV infection meets the above criteria, monitoring of viral RNA load and CD4+ count is recommended.
• Participants who are unable or unwilling to comply with the requirements of the protocol as assessed by the investigator.