Clinical Significance of Liquid Biopsy in Brain Tumor Patients: a 5-ALA Guided Approach

Clinical Significance of Liquid Biopsy in Brain Tumor Patients: a 5-ALA Guided Approach

Glioblastoma (GBM) is the most common and lethal primary brain tumor. Identifying blood biomarkers that reflect the tumor's status is a major unmet need for optimal clinical management. 5-ALA (5-Aminolevulinic Acid) administration leads to the accumulation of fluorescent Protoporphyrin IX (PpIX) in GBM cells, allowing identification during surgery. This project aims to leverage 5-ALA induced fluorescence to maximize the informational power of plasma liquid biopsy as a tool for diagnosis, post-treatment follow-up, and as a prognostic tool in patients with GBM.

This is a prospective observational study. Patients with suspected brain tumors requiring 5-ALA fluorescence-guided surgery will be enrolled. Samples of plasma, serum, and urine will be collected at a minimum of two timepoints: once before 5-ALA administration (baseline, T1) and again 12 hours after administration (T2), when PpIX levels are expected to be highest. All sample collection and processing will occur in low-light conditions to prevent PpIX degradation. Samples will be stored at -80°C. Fluorometric analysis (Perkin Elmer Wallac 1420 Victor2 Microplate Reader) will be performed to measure PpIX fluorescence. Additionally, each patient will undergo a pre-operative MRI as per routine care to measure tumor volume, which will be correlated with fluorescence data.

Inclusion Criteria:

• Inclusion Criteria (Glioblastoma Patients):
• Patient aged 18 years or older
• Diagnosis of supratentorial glioblastoma at its first occurrence (Grade 4, WHO 2021), confirmed through histological analysis, in a brain area that is accessible for surgical removal.
• Ability of the patient to give informed consent.
• Suitability for surgery with fluorescence guidance using 5-ALA.

Inclusion Criteria (Other Brain Tumors):

• Patient aged 18 years or older
• Ability of the patient to give informed consent.
• Suitability for surgery with fluorescence guidance using 5-ALA.

Exclusion Criteria:

Exclusion Criteria (Glioblastoma Patients):

• Presence of other systemic tumors.
• Known allergic sensitivity or contraindications to gadolinium.
• Contraindications to MRI, such as the presence of non-compatible implanted devices.
• Significantly compromised renal function (eGFR <30 ml/min/1.73 m²), and/or patients undergoing dialysis.
• Conditions that contraindicate surgery with fluorescence guidance using 5-ALA.

Exclusion Criteria (Other Brain Tumors):

• Patients suffering from systemic tumors (besides the primary of the brain metastasis).
• Individuals with known allergies or adverse reactions to gadolinium.
• Individuals with contraindications for MRI, including those with implants not compatible with the procedure.
• Individuals with significantly reduced kidney function (eGFR < 30 ml/min/1.73 m²), or those undergoing dialysis.