Abstract
Early studies suggest that bevacizumab treatment can result in tumor shrinkage and hearing improvement for some patients with neurofibromatosis type 2 (NF2). The aim of this study was to report extended follow-up in a larger cohort of similarly treated patients. Retrospective study. Tertiary referral center Thirty-one consecutive NF2 patients who received bevacizumab for progressive vestibular schwannomas. Hearing improvement, defined as an improvement in word recognition score above the 95% critical difference compared with baseline, and radiographic response, defined as a 20% or greater decrease in tumor volume compared with baseline. The median age was 26 years (range, 12-73 yr). The median volumetric tumor growth rate before treatment was 64% per year. At the time of analysis, the median duration of treatment was 14 months (range, 6-41 mo) with a total of 47 patient-years of follow-up. A hearing response occurred in 57% (13/23) of evaluable patients and a radiographic response in 55% (17/31) of target vestibular schwannomas. The median time to response was 3 months for both end points. The only clinical or radiographic feature at baseline that correlated with change in tumor volume at 3 months was the mean apparent diffusion coefficient value, a radiologic marker of edema (p = 0.036). Ninety percent of patients had stable or improved hearing after 1 year of treatment and 61% at 3 years; 88% of patients had stable or decreased tumor size after 1 year of treatment and 54% at 3 years. Overall, treatment was well tolerated. Bevacizumab treatment was followed by hearing improvement and tumor shrinkage in more than 50% of progressive vestibular schwannomas in NF2 patients. Stable or improved hearing was retained in the majority of patients.
Highlights
Neurofibromatosis type 2 (NF2) is a hereditary tumor predisposition syndrome caused by mutations in the NF2 tumor suppressor gene
The baseline clinical characteristics of the 31 consecutive patients we treated using bevacizumab for NF2-related vestibular schwannoma are shown in Table 1 and Supplemental Digital Content 1
The results of this study agree with previous estimates of the activity of bevacizumab against progressive vestibular schwannoma in NF2 patients.8;10;23;24 In this larger cohort of 31 patients with 52 vestibular schwannomas and a total of 45 patient-years of follow up, the rates of hearing improvement (54%) and tumor shrinkage (57%) during bevacizumab treatment were similar to an earlier report.[8]
Summary
Neurofibromatosis type 2 (NF2) is a hereditary tumor predisposition syndrome caused by mutations in the NF2 tumor suppressor gene. Individuals with NF2 have a higher likelihood to develop multiple nervous system tumors, including schwannomas, meningiomas, and ependymomas.[1] The hallmark of NF2 is bilateral vestibular schwannomas. These tumors arise from the vestibular portion of cranial nerve VIII; over time, they lead to hearing loss, tinnitus, and imbalance. Most NF2 patients experience complete hearing loss either from tumor progression or after treatment of the tumors with surgery or radiation. Effective treatments are urgently needed for NF2 patients with progressive hearing loss, because hearing loss is associated with impairment in social, emotional, and communication function, and increased depression. 5-7
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