The goal of this clinical trial is to test whether adding preventive intrathecal chemotherapy (thiotepa) to the standard Stupp regimen can lower the risk of leptomeningeal metastasis (LM) and extend survival in patients with newly diagnosed glioblastoma (GBM) whose tumors touch the sub-ventricular zone (SVZ+) or whose surgery accidentally opened the ventricle (VE). The main questions it aims to answer are:
Can six weekly intrathecal injections of thiotepa (10 mg) given during chemoradiotherapy increase the chance of remaining free of LM at one year? Does the approach also prolong overall survival and progression-free survival compared with historical controls? Is the combination safe and well-tolerated in this high-risk population?
Participants will:
Receive maximal safe tumor resection followed by standard radiotherapy (60 Gy/30 fractions) plus daily temozolomide (75 mg/m²).
Begin thiotepa injections (via lumbar puncture or Ommaya reservoir) within 1 week of starting radiotherapy, repeated every 7 days for 6 doses.
Continue standard adjuvant temozolomide (150-200 mg/m² days 1-5/28) for 6 cycles.
Understand that all procedures, toxicities and survival will be tracked for 2 years, with MRI and clinical visits every 4-8 weeks.
Provide CSF and blood samples for exploratory biomarkers that may predict response or resistance.
Age 18-75 years, either sex.
Histologically confirmed newly-diagnosed WHO grade IV glioblastoma with at least one measurable lesion on MRI.
Pre-operative MRI showing tumour in direct contact with the lateral ventricular sub-ventricular zone (SVZ+); OR
Operative record and post-operative imaging documenting an intra-operative cerebro-spinal-fluid leak (ventricular entry, VE).
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.