Lohse, Christine M.

Objective: To synthesize the available evidence on medical therapies investigated for the management of NF2-related vestibular schwannomas (VS). Study design: Systematic review. Setting: Not applicable. Patients: NF2-related VS patients. Interventions: Systemic medical therapies. Main outcome measures: Tumor control and hearing outcomes. Results: Thirty studies met inclusion criteria: 18 investigated bevacizumab, 5 mTOR inhibitors, 5 tyrosine kinase inhibitors (TKIs), and 2 the vascular endothelial growth factor receptor (VEGFR) vaccine. Bevacizumab demonstrated the most consistent activity, with hearing improvement in up to 61% of patients, stable hearing in up to 84%, and tumor response in up to 60% (Level 4 evidence). Outcomes for mTOR inhibitors were variable, with 1 study stopped for futility, while others reported up to 100% hearing and tumor stability (Level 4 evidence). Five different TKIs showed hearing improvement rates ranging from 17 to 60% and tumor responses of 10 to 23.5% (Level 4 evidence). The VEGFR vaccine appeared safe and immunologically active, with radiologic and hearing improvement in one-third of patients (Level 4 evidence). Conclusions: Bevacizumab remains the most studied and clinically active systemic therapy for NF2-related VS, although evidence is largely nonrandomized. Other systemic therapies have demonstrated variable results in terms of hearing outcomes or tumor control. High-quality prospective and randomized controlled trials are needed to clarify efficacy, durability, and comparative effectiveness.