A 16 year-retrospective study of refractory meningiomas: Prognostic factors and systemic treatments.

2085 Background: Meningiomas are the most common brain tumors, with no established standard systemic treatment for refractory cases after surgical and radiotherapeutic interventions. This study aims to identify prognostic factors for overall survival in refractory meningioma and document patient evolution with systemic treatments. Methods: In a retrospective study, we identified patients with meningioma initially followed at CHUM university hospital between 2006 and 2022. Patients with progression after first-line treatment and over 6 months of follow-up were included. The population was divided into two: group 1 received surgery and/or radiotherapy for progression, and group 2 received additional systemic treatments. Survival analysis with Kaplan-Meier curves and group comparisons (Log-Rank, Fisher's Exact Tests) were conducted. Results: A total of750 patients with meningioma were identified. 99 (13%) progressed after first-line treatment. Among them, 70 (9%) were categorized in group 1 and 29 (4%), in group 2. The median follow-up time from diagnosis was 7.5 years. The overall 10-year survival rate was higher in group 1 compared to group 2 (88% vs 62%). Prognostic factors affecting survival were identified as the following: disease progression after second-line treatment, age ≥ 65 years, and grade 2 or 3. When comparing PFS-1 after first-line treatment, they were similar between group 1 and group 2 (mPFS-1: 2.63 vs 3.49 years; p = 0.421). However, PFS-2 after second-line treatment was significantly shorter in group 2 (mPFS-2 : 12.6 vs 2.3 years ; p < 0.001). Age of ≥ 65 years (10-year survival: 57% vs 89%; p < 0.001) and higher grades (10 year survival: 90% grade 1 vs 58% - grade 2 vs 75% - grade 3; p = 0.027) were associated with lower survival rates. The number of lesions (unique or multiple) and localization (supra or infratentorial) of tumors had no significant impact on survival (p=0.257; p = 0.482). Regarding systemic treatments, 7 patients (25%) received Bevacizumab. It was the treatment associated with the longest PFS (mPFS = 22.5 months) when compared to Hydroxyurea (n=18 62%, mPFS = 4 months), Somatostatin (n = 5 17%, mPFS = 8 months), a combination of Hydroxyurea and Somatostatin (n=7 24%, mPFS = 8 months) and Sunitinib (n=3 10%, mPFS = 14 months). For patients discontinuing systemic treatment, median survival was 5 months. Systemic treatments were well-tolerated. Among moderate to severe side effects (grade ≥ 2), we documented bradycardia (Somatostatin, n=1), elevated liver enzymes (Sunitinib, n=1), anemia and neutropenia (Hydroxyurea, n=3) and proteinuria (Bevacizumab, n=1). Conclusions: Prognostic factors for survival in meningioma include age ≥ 65 years, grades 2 and 3, and the occurrence of a second progression. Our study highlights Bevacizumab in systemic treatment strategies which was well tolerated in our patients.