Prophylactic Regimen With Intrathecal Thiotepa in SVZ-positive or Meningeal-risk Glioblastoma

Inclusion Criteria: * Age 18-75 years, either sex. * Histologically confirmed newly-diagnosed WHO grade IV glioblastoma with at least one measurable lesion on MRI. * Must fulfil ONE of the following high-risk imaging/surgical conditions: 1. Pre-operative MRI showing tumour in direct contact with the lateral ventricular sub-ventricular zone (SVZ+); OR 2. Operative record and post-operative imaging documenting an intra-operative cerebro-spinal-fluid leak (ventricular entry, VE). * Eastern Cooperative Oncology Group (ECOG) performance status 0-2 and estimated life expectancy ≥ 3 months. * Neurological symptoms stable for ≥ 7 days before enrollment. * Adequate bone-marrow reserve: neutrophils ≥ 1.5 × 10⁹/L, haemoglobin ≥ 90 g/L, platelets ≥ 75 × 10⁹/L. * Coagulation acceptable: PT/INR and aPTT ≤ 1.5 × upper limit of normal (ULN). Hepatic: total bilirubin ≤ 1.5 × ULN, ALT \& AST ≤ 1.5 × ULN, albumin ≥ 30 g/L. Renal: serum creatinine ≤ 2 × ULN and calculated or 24-h creatinine clearance ≥ 50 mL/min. * Reliable contraception from first dose until 3 months after the last dose for both sexes. Exclusion Criteria: * Pregnant or lactating women. * Active infection requiring intravenous antibiotics within 7 days before study entry, or therapeutic anticoagulation with warfarin. * History of any other malignancy within the previous 5 years (except adequately treated basal-cell carcinoma of skin or cervical carcinoma in-situ). * Known HIV infection, AIDS, immunodeficiency syndromes, or active autoimmune disease needing systemic therapy. * Severe medical, neurological or psychiatric conditions that would preclude compliance with protocol procedures. * Disrupted ventricular drainage catheter or anatomical contraindication preventing safe lumbar puncture or Ommaya reservoir placement. * Uncontrolled chronic illnesses: diabetes, congestive heart failure (NYHA III/IV), hepatic cirrhosis, chronic kidney disease stage ≥ 3b, etc. * Any condition judged by the investigator to increase the risks of intrathecal chemotherapy or to confound toxicity assessment.