Natural History and Biology of Skin Neurofibromas in Neurofibromatosis Type 1

This protocol results from a funded 2005 Bench-to-Bedside Award and explores the genetic basis of disease severity in neurofibromatosis type 1 (NF1) and the evaluation of three methods to measure disease progression of dermal neurofibromas. NF1 is a common multisystem genetic disorder associated with the development of benign and malignant tumors, primarily of the nervous system. NF1 is 100% penetrant and features variable expressivity and limited phenotype/genotype correlation. No standard treatment other than surgery exists for most NF1-associated tumors. Many aspects of the natural history of NF1-associated tumors are not fully characterized and require investigation to assess the effects of potential new treatments, in future clinical trials. The development of medical treatments for NF1-associated tumors is an important goal given their morbidity and the lack of non-surgical treatment options. The ability to predict the ultimate severity of disease would have a significant impact on the management and treatment of individuals with NF1. Sorafenib (BAY 43-9006) is a novel, orally bioavailable agent that targets downstream effectors in the Ras signaling pathway (a key dysregulated pathway in NF1). It has thus a strong scientific rationale for evaluation in NF1 related tumors. Dermal neurofibromas occur in nearly every individual with NF1, and are a significant cosmetic problem and a major cause of morbidity. This protocol will 1) quantify the growth of dermal neurofibromas in NF1 with 3 different imaging modalities 2) use an innovative gene expression method to identify genetic modifiers of dermal neurofibroma burden, and 3) evaluate dermal neurofibromas and normal skin for the presence of targets of sorafenib. Successful validation of reliable quantitative imaging methods of dermal neurofibroma growth is a logical prerequisite to subsequent clinical trials with medical treatments, which will evaluate the effect of new agents on the growth rate of dermal neurofibromas. Identification of genetic modifiers may permit prediction of ultimate tumor burden. Evaluation of targets of new agents in dermal neurofibromas will allow for more rationale drug development for NF1. Given the paucity of protocols for adults with NF1 and dermal neurofibromas, this study will likely generate great interest among affected individuals and have rapid accrual.