Early administration of imatinib mesylate reduces plexiform neurofibroma tumor burden with durable results after drug discontinuation in a mouse model of neurofibromatosis type 1.

BACKGROUND: Neurofibromatosis type 1 (NF1) is a common genetic disorder characterized by plexiform neurofibromas (pNF), which are thought to be congenital tumors that arise in utero and enlarge throughout life. Genetic studies in murine models delineated an indispensable role for the stem cell factor (SCF)/c-kit pathway in pNF initiation and progression. A subsequent phase 2 clinical trial using imatinib mesylate to inhibit SCF/c-kit demonstrated tumor shrinkage in a subset of preexisting pNF; however, imatinib's role on preventing pNF development has yet to be explored. PROCEDURE: We evaluated the effect of imatinib dosed at 10-100 mg/kg/day for 12 weeks to one-month-old Nf1flox/flox ;PostnCre(+) mice, prior to onset of pNF formation. To determine durability of response, we then monitored for pNF growth at later time points, comparing imatinib- with vehicle-treated mice. We assessed gross and histopathological analysis of tumor burden. RESULTS: Imatinib administered preventatively led to a significant decrease in pNF number, even at doses as low as 10 mg/kg/day. Tumor development continued to be significantly inhibited after cessation of imatinib dosed at 50 and 100 mg/kg/day. In the cohort of treated mice that underwent prolonged follow-up, the size of residual tumors was significantly reduced as compared with age-matched littermates that received vehicle control. CONCLUSIONS: Early administration of imatinib inhibits pNF genesis in vivo, and effects are sustained after discontinuation of therapy. These findings may guide clinical use of imatinib in young NF1 patients prior to the substantial development of pNF.

Biome depletion in conjunction with evolutionary mismatches could play a role in the etiology of neurofibromatosis 1.

Neurofibromatosis 1 (NF1) arises de novo in a striking 30-50% of cases, pointing toward an environmental etiology, though none has been clearly identified. The Biome Depletion Theory posits that the absence of mutualistic and commensal organisms within the human body coupled with modern lifestyle alterations may have profoundly deleterious effects, inclusive of immunologic derangement that is thought to result in allergy, atopy, and numerous autoimmune diseases. Biome depletion has been implicated as a factor in the etiology of both multiple sclerosis and autism spectrum disorders; biome reconstitution, i.e. replenishment of the biome with certain keynote species, is being used in the treatment of these and other autoimmune states. Neurofibromatosis 1 has been associated with allergy, various autoimmune states, multiple sclerosis, and autism. Recent research has posited that NF1, multiple sclerosis and autism may all arise from disturbances in the neural crest during gestation. This paper hypothesizes that there is indirect evidence that a highly inflammatory uterine state may precipitate epigenetic changes in vulnerable NF-related genes in the course of fetal development. The etiology of NF1 may lie in the absence of immunomodulation by commensal and mutualistic species once ubiquitously present in the environment, as well as through adoption of a modern lifestyle that contributes to chronic inflammation. Replenishment of helminths and other missing organisms to the human biome prior to conception as well as addressing nutritional status, psychological stress, and environmental exposures may prevent the development of NF1.

Usefulness of screening investigations in neurofibromatosis type 1. A study of 152 patients.

OBJECTIVE: To evaluate the usefulness of screening investigations in patients with neurofibromatosis type 1 (NF1). DESIGN: Clinical and screening data were retrospectively collected from a case series of patients with NF1. Screening investigations included an opthalmologic consultation, chest x-ray film, abdominal ultrasonography, cerebral imaging, and analysis of urinary catecholamine levels. Clinical features and complications of patients with NF1 were compared with those of the Neurofibromatoses Institute Clinical Research Program and of the Southeast Wales study patients. SETTING: Ambulatory care in a referral center. PATIENTS: Between 1988 and 1992, 152 patients classified as having NF1 according to the criteria of the National Institutes of Health Consensus Development Conference Statement were studied. MAIN OUTCOME MEASURE: Complications requiring therapeutic action detected using screening investigations vs clinical examination. RESULTS: Systemic chest x-ray films were taken of 134 patients, and intrathoracic nodules thought to be neurofibromas were discovered in 2 patients. Ninety-three asymptomatic patients had cerebral imaging performed, which showed optic pathway glioma in 12 patients. Abdominal ultrasonography was performed on 62 asymptomatic patients, results of which showed internal neurofibromas in 4 patients. In 2 of these patients, abdominal surgery was performed. Eighty-three patients without hypertension had 24-hour urinary specific catecholamine levels analyzed, which were within the normal range. Clinical features and complications were not different from other large clinical studies. Nearly 400 systematic investigations were performed without clinical orientation, detecting 21 abnormalities. In only 2 cases, these discoveries led to therapeutic action. On the other hand, 22 complications requiring treatment were detected by clinical examination. CONCLUSION: Clinical follow-up seems to be more beneficial than systematic investigations in patients with NF1.

Neurofibromatosis Type I With Pulmonary Involvement / Neurofibromatosis tipo I con afectación pulmonar

No disponible

Prevention and control of neurofibromatosis: memorandum from a joint WHO/NNFF meeting.

Neurofibromatosis (NF) is a serious, common, genetically determined neurological disorder; with a prevalence of about 1:4000 births it affects both sexes and all races and ethnic groups. The two major forms are referred to as NF1 and NF2, as suggested in 1987 by a National Institutes of Health Consensus Development Conference on Neurofibromatosis. In NF1, the disease phenotype is more variable and complex than in NF2. Complications can occur in any of the body systems in tissues of ectodermal, mesodermal and neural tube origin; there is marked variation of disease phenotype even within families. The NF2 gene, in contrast, only seems to be expressed in tissues of ectodermal origin and its expression is more uniform both within and between families. The recent discovery and isolation of the gene responsible for the NF1 mutation has practical applications in the field of molecular genetics which could modify the approaches for diagnosis, treatment and prevention of NF. This Memorandum summarizes the discussions and recommendations of the participants at a joint WHO/National Neurofibromatosis Foundation (NNFF) meeting, held in Jacksonville, Florida, USA, on 27-28 January 1991.