Bevacizumab treatment for vestibular schwannomas in neurofibromatosis type two: report of two cases, including responses after prior gamma knife and vascular endothelial growth factor inhibition therapy

Vestibular schwannomas are the hallmark of neurofibromatosis type two. They are difficult to treat, due to their bilateral presentation and the quest for hearing preservation. Our report describes a new treatment approach in this clinical scenario. We report two cases which confirm that bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor, causes regression of vestibular schwannomas in patients with a previous history of gamma knife radiosurgery or failed treatment with another form of vascular endothelial growth factor targeted therapy. In 2009, Plotkin et al. reported the volumetric response of vestibular schwannomas to bevacizumab treatment, both in untreated patients and in patients previously treated with erlotinib, an epidermal growth factor receptor inhibitor. The presented cases support the use of bevacizumab to treat vestibular schwannomas. Given the extremely slow growth of these tumours, we note the rapidity of volume reduction following bevacizumab therapy.