Inclusion Criteria:
1. Age ≥18 years at the time of screening
2. Histomolecular diagnosis of IDH-wildtype glioblastoma (as per WHO 2021)
3. Prior treatment with radiotherapy and an alkylating agent
4. Presence of measurable disease on brain MRI, as defined by RANO 2.0 criteria
5. Radiologically confirmed disease progression as per RANO 2.0 criteria
6. Lesion confined to a single focus, with a maximum diameter ≤6 cm, and located in a vascular territory amenable to selective intra-arterial catheterisation as assessed on baseline imaging and confirmed by planning angiography, cone beam CT, and \[99mTc\]Tc-MAA SPECT/CT (where available)
7. Stable neurological status; patients with epilepsy may be included if seizures are controlled on a stable dose of anti-epileptic medication
8. ECOG performance status 0-2
9. Estimated life expectancy of ≥3 months, in the opinion of the investigator
10. Adequate haematologic, renal, hepatic, and coagulation function at screening, defined as:
* Haemoglobin ≥9 g/dL
* Absolute neutrophil count ≥1.5 x 109/L
* Platelet count ≥100 x 109/L
* Serum creatinine ≤1.5 x ULN, or creatinine clearance ≥30 mL/min (Cockcroft-Gault formula)
* Total bilirubin ≤1.5 x ULN (except patients with known Gilbert's syndrome)
* Aspartate aminotransferase (AST) and alanine transaminase (ALT) ≤2.5 x ULN
* International normalized ratio (INR) ≤1.5 x ULN
* Prothrombin time (PT) or activated partial thromboplastin time (aPTT) ≤1.5 x ULN
11. Ability to understand and comply with study requirements and provide written informed consent.
Exclusion Criteria:
1. Multifocal glioma recurrence
2. Tumour located in the posterior fossa or involving/risking critical subcortical structures (e.g. thalamus, hypothalamus, basal ganglia, internal capsule, cerebral peduncle, midbrain, brainstem, or optic pathways)
3. Prior treatment with VEGF inhibitors
4. Prior re-irradiation for progressive or recurrent disease
5. Any local (surgery or radiotherapy) or systemic anti-cancer therapy within 28 days prior to the planned dose of the investigational treatment
6. Concurrent use of any anti-cancer therapies, investigational drugs, or biological agents not specified in the protocol
7. Contraindications to MRI, including but not limited to non-compatible implantable devices or severe claustrophobia
8. Contraindications to catheter-based angiography, including but not limited to known bleeding disorders, significant vascular abnormalities precluding safe access, and severe allergy to contrast agents
9. Pregnancy or breastfeeding. Women of childbearing potential and men with partners of childbearing potential must agree to use effective contraception during the study and for at least 4 months after the last procedure.
10. Any severe or uncontrolled medical condition that, in the investigator's judgement, would pose an unacceptable risk to the patient or interfere with protocol compliance
11. Cognitive or psychiatric conditions that would limit the ability to provide informed consent or adhere to study procedures
12. Known hypersensitivity or allergy to 90Y-resin microspheres or any component of the investigational product
