Introduction

Schwannomas, meningiomas and ependymomas are tumours of the nervous system which occur sporadically or as part of the hereditary disease neurofibromatosis type 2 (NF2). Mutations in neurofibromin 2/NF2 gene cause all NF2-related schwannomas, meningiomas and ependymomas, 77% sporadic schwannomas, 60% sporadic meningiomas and 30% sporadic ependymomas.1 Schwannomas are the hallmark of NF2 and develop in all patients with NF2. Current treatments for NF2-related tumours are surgery or radiosurgery. Radiation may induce additional mutations and formation of secondary tumours in NF2 whereas surgery has limited use in patients with high tumour load or tumours located at the sites where resection would cause neurological complications.2 Avastin is effective but only in a fraction of patients.2 Published consensus recommendations suggest that the development of effective therapies for NF2 is urgent, with great potential for clinical progress.2

Platelet-derived growth factor receptor β (PDGFRβ) is overexpressed and activated in human primary schwannoma cells leading to increased proliferation.3 Using orally available, Food and Drug Administration (FDA)-approved cRAF/VEGFR-2/PDGFRβ inhibitor, sorafenib, this was successfully inhibited in vitro.3

Here we report an open-label, phase 0, single-agent trial (EudraCT: 2011-001789-16, REC: 11/LO/0771) testing sorafenib in patients with NF2 with the aim to determine whether molecular target inhibition occurs with oral sorafenib in patients with NF2 and whether target inhibition in plasma with oral sorafenib in patients with NF2 can act as a biomarker.