The goal of the clinical trial is to assess the presence of circulating tumor cells (CTCs) in the blood and/or cerebrospinal fluid (CSF) of patients with aggressive recurrent meningiomas.

Meningiomas are the most common intracranial tumours. In 80% of cases, they are benign (grade I) and have an indolent growth profile. These tumours are monitored radiologically and clinically using magnetic resonance imaging (MRI), or treated by surgical excision, with good results. However, 20% of them manifest as more aggressive tumours, leading to significant morbidity, either due to symptoms related to their natural history or complications related to treatment. These aggressive meningiomas represent a challenge both in terms of prognosis assessment and treatment selection.

Meningiomas are generally diagnosed using a CT or MRI scan of the brain or spinal cord with contrast injection. However, a definitive diagnosis remains dependent on histopathology, which is used to decide on the treatment sequence.

Recently, liquid biopsy has proven useful in the diagnosis and monitoring of many cancerous conditions. However, no studies have been conducted on the presence of circulating tumour cells (CTCs) in meningiomas. Although these tumours are intracranial, they develop outside the blood-brain barrier, so it is likely that cells are detectable in the blood and cerebrospinal fluid (CSF).

The use of blood markers could enable non-invasive confirmation of the diagnosis when a meningioma is detected by imaging, as well as assessment of the risk of recurrence in the post-operative period.

The BIOLIMEN-1 study is a pilot study aimed at developing and validating this concept.

Inclusion Criteria:

• Over 18 years of age
• Operated on for a grade 2 or 3 meningioma at Montpellier University Hospital between 2015 and 2024
• Tumour expressing SSTR2A on the initial surgical specimen
• Clinical and/or radiological recurrence as determined by MRI imaging (progression of a residual lesion OR appearance of a new lesion consistent with a meningioma at the surgical site or elsewhere)

Exclusion Criteria:

• Other active ongoing cancer
• Contraindications to lumbar puncture:
• Intracranial hypertension with meningioma exerting a mass effect and obstruction of the cerebrospinal fluid (CSF) pathway/risk of trans-tentorial or amygdalar herniation
• Blood clotting disorder with risk of haematoma at the puncture site (anticoagulant treatment at therapeutic dose or antiplatelet therapy, thrombocytopenia or thrombopathy)
• Infection at the puncture site
• Pregnant or breastfeeding women (Article L.1121-5 of the French Public Health Code)
• Persons deprived of their liberty by judicial or administrative decision (Article L.1121-6 of the French Public Health Code)
• Persons who are subject to legal protection measures or who are unable to express their consent (guardianship, curatorship, judicial protection; Article L.1121-8 of the French Public Health Code)
• Not affiliated with a social security scheme or beneficiary of such a scheme (Article L.1121-8-1 of the French Public Health Code)
• Persons participating in another study that includes an ongoing exclusion period (Article L.1121-12 of the French Public Health Code)
• Failure to obtain written informed consent