Icotinib Study for Patients With Neurofibromatosis Type 2 (NF2) and NF2-Related Tumors

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. The hallmark of NF2 is bilateral vestibular schwannomas. Historically, 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 with increased depression. Previous studies of NF2 patients treated with Erlotinib suggested that inhibition of epidermal growth factor receptor (EGFR) could result in hearing improvement and reduction in tumor size. Much evidence implicates human epidermal growth factor (HER) receptors in vestibular schwannoma growth.Some studies have demonstrated that Merlin, the NF2 gene protein product, controls surface availability of the EGFR, ErbB2, and ErbB3 receptors in human and Drosophila models. Besides, cell culture models of mouse embryo fibroblasts (MEFs) support the role of EGFR in NF2-associated tumorigenesis. Nf2-deficient cells in culture lack contact-dependent inhibition of growth and continue to grow in confluent cultures. This effect appears to be mediated by EGFR signaling. Treatment of Nf2-deficient cells with EGFR inhibitors such as gefitinib can restore contact-dependent inhibition, suggesting that this class of drugs might be useful for NF2 patients with progressive vestibular schwannomas. In this way, Icotinib can inhibit the nutrition of the tumor and decrease the tumor's growth and metastasis. Based on these studies, we perform this clinical trial to known the treatment effect and tolerability of Icotinib on NF2.