CTNI-72. LONG-TERM EFFICACY AND SAFETY OF BEVACIZUMAB FOR PROGRESSIVE VESTIBULAR SCHWANNOMA IN PATIENTS WITH <i>NF2</i> -RELATED SCHWANNOMATOSIS ( <i>NF2</i> -SWN)

Abstract PURPOSE To determine long-term outcomes for patients with NF2-SWN treated with bevacizumab. METHODS We retrospectively reviewed the records of NF2-SWN patient at Massachusetts General Hospital who received bevacizumab for ≥2 years. Bevacizumab dose was categorized as low (&amp;lt;2.5 mg/kg/week), standard (2.5 mg/kg/week), and high (&amp;gt;2.5 mg/kg/week) and as continuous or intermittent. Tumor volumes were determined from clinically indicated MRI scans. Radiographic response (RR)/progression were defined as ≥20% decrease/increase in volume from baseline MRI, and hearing improvement/decline were defined as word recognition score above/below the 95% critical threshold. Adverse events resulting in treatment holds or discontinuation were recorded. RESULTS Fifty-three patients were included in this review; 35 were excluded primarily due to treatment &amp;lt;2 years. Median age at treatment initiation was 27.1 years (range, 12.0-73.4). During treatment, 98% of patients received standard-dose bevacizumab, 81% received low-dose treatment after standard dose, and 15% received high-dose treatment for dose intensification. Median duration of observation was 9.7 years (range, 2.3-16.7) with median duration of treatment 6.1 years (range, 1.5-16.0). Eighty-one VS and 67 ears were evaluable for response. Fifty-three percent of VS had RR during treatment with 26% in RR at last follow-up; the median time to progression was 4.0 years (95% CI, 2.7-6.5). Sixty-seven percent of VS had hearing improvement during treatment, and 8% had hearing improvement at last follow-up; the median time to hearing decline was 3.7 years (95% CI, 2.5-6.3). Treatment holds and discontinuation due to adverse events occurred in 45% and 11% of patients, respectively. The most common adverse events included proteinuria (70%), treatment-emergent hypertension (55%), epistaxis (30%) impaired wound-healing, arthralgias, and GI upset (all 21%). DISCUSSION Long-term treatment with bevacizumab using flexible dosing that included low, standard, and high doses was well-tolerated and resulted in durable hearing and radiographic responses with a tolerable safety profile in this patient population.