While surgical resection remains the primary treatment approach for symptomatic or growing meningiomas, radiotherapy represents an auspicious alternative in patients with meningiomas not safely amenable to surgery. Biopsies are often omitted in light of potential postoperative neurological deficits, resulting in a lack of histological grading and (molecular) risk stratification. In this prospective explorative biomarker study, extracellular vesicles in the bloodstream will be investigated in patients with macroscopic meningiomas to identify a biomarker for molecular risk stratification and disease monitoring.

In total, 60 patients with meningiomas and an indication of radiotherapy (RT) and macroscopic tumor on the planning MRI will be enrolled. Blood samples will be obtained before the start, during, and after radiotherapy, as well as during clinical follow-up every 6 months. Extracellular vesicles will be isolated from the blood samples, quantified and correlated with the clinical treatment response or progression. Further, nanopore sequencing-based DNA methylation profiles of plasma EV-DNA will be generated for methylation-based meningioma classification.

This study will explore the dynamic of plasma EVs in meningioma patients under/after radiotherapy, with the objective of identifying potential biomarkers of (early) tumor progression. DNA methylation profiling of plasma EVs in meningioma patients may enable molecular risk stratification, facilitating a molecularly-guided clinical management in meningioma patients in the future.

Inclusion Criteria:

• confirmed meningioma (histologically or MRI/DOTATOC-PET CT)
• macroscopic tumor in MRI (either as definitive RT, or following subtotal resection or relapse)
• indication for radiotherapy
• completed wound healing after surgical intervention)
• Alter ≥ 18 Jahre
• Karnofsky Performance Score ≥ 60%
• written informed consent
• ability of subject to understand character and individual consequences of the trial
• adequate contraception for women of childbearing potential

Exclusion Criteria:

• previous or known tumor diseases < 5 years ago
• previous (cerebral) radiotherapy
• simultaneous chemo/immunotherapy
• evidence that the patient cannot adhere to the study protocol (e.g., non-compliance)
• the refusal of patients to participate in the study
• participation in another clinical study or observation period in a competing trial