Efficacy and Safety of Bevacizumab for Vestibular Schwannoma in Neurofibromatosis Type 2: A Systematic Review and Meta-analysis of Treatment Outcomes

Background: Individual evidence suggests that the antiangiogenic agent bevacizumab may control vestibular schwannoma (VS) growth and promote hearing preservation in patients with neurofibromatosis type 2 (NF2). However, such metadata has yet to be consolidated, as well as its side-effect profile yet to be fully understood. Our aim was to pool systematically identified metadata in the literature and substantiate the clinical efficacy and safety of bevacizumab with respect to radiographic tumor response, hearing, and treatment outcomes.

Methods: Searches of 7 electronic databases from inception to March 2019 were conducted following PRISMA guidelines. Articles were screened against prespecified criteria. The incidence of outcomes was then extracted and pooled by random-effects meta-analysis of proportions.

Results: Eight articles reporting 161 NF2 patients with 196 assessable VS met all criteria. Radiographic response to bevacizumab was partial regression in 41% (95% CI, 31–51%), no change in 47% (95% CI, 39–55%), and tumor progression in 7% (95% CI, 1–15%). In patients with assessable audiometric data, bevacizumab treatment resulted in hearing improvement in 20% (95% CI, 9–33%), stability in 69% (95% CI, 51–85%), and additional loss in 6% (95% CI, 1–15%) Serious bevacizumab toxicity was observed in 17% (95% CI, 10–26%). Subsequent surgical intervention was required in 11% (95% CI, 2–20%).

Conclusion: Bevacizumab may arrest both tumor progression and hearing loss in select NF2 patients presenting with VS lesions. However, a considerable proportion of patients are anticipated to experience serious adverse events; correspondingly, judicious use of bevacizumab for symptomatic management of VS in NF2 is recommended.