2632 - The Hearing Preservation in Patients with Schwannomatosis after Combined Treatment
Presenter(s)
E. Makashova1, G. Kobyakov1, S. Zolotova1, M. Galkin1, A. V. Golanov2, and V. Strelnikov3; 1Burdenko Neurosurgical Institute, Moscow, Russian Federation, 2GammaKnife, Moscow, Russian Federation, 3Federal State Autonomous Educational Institution of Higher Education «N.I. Pirogov Russian National Research Medical University» of the Ministry of Health of the Russian Federation, Moscow, Russian Federation
Purpose/Objective(s): To evaluate the efficacy and safety of combined bevacizumab and frameless robotic radiosurgery system radiation therapy in preserving hearing, controlling tumor growth, and improving neurological outcomes in patients with NF2-related schwannomatosis, particularly those with poor prognostic features (Holiday Class 2B/3).
Materials/Methods: A cohort of 25 patients with confirmed pathogenic NF2 variants and bilateral vestibular schwannomas (KOOS 3-4 hearing at baseline) underwent a tailored treatment protocol. Bevacizumab was initiated at 7.5 mg/kg every three weeks, with dose escalation to 10 mg/kg every two weeks for tumor progression or reduction to 5 mg/kg for toxicity. Frameless robotic radiosurgery system stereotactic (median marginal dose: 14 Gy) was timed variably: early radiation after two bevacizumab cycles (2 patients), salvage radiation after bevacizumab monotherapy failure (12–24 cycles, 3 patients), or sequential therapy (radiation before/after bevacizumab, 20 patients).
Results: Tumor response was assessed using RANO criteria, hearing via audiometry, and neurological function through ataxia and muscle strength evaluations. Results demonstrated tumor reduction in 36% (9/25) of patients, with local control achieved in all cases. Hearing improved in 68% (17/25) and stabilized in 32% (8/25), while hearing loss occurred in 12% (3/25), exclusively in patients with prior radiation. Neurological function improved universally, with reduced cerebellar ataxia and enhanced muscle strength. Adverse events included menstrual disturbances (20%, 5/25), epistaxis (4%, 1/25), and renal impairment (4%, 1/25), all Grade 1/2. Prognostically, 96% (24/25) were high-risk (Holiday Class 2B/3), with no correlation between mutation type and outcomes.
Conclusion: The combination of bevacizumab and frameless robotic radiosurgery system radiation significantly improved hearing preservation (68% vs. historical 30% with bevacizumab alone) and tumor control in aggressive NF2-related schwannomas, offering a promising strategy for high-risk patients with manageable toxicity.