A Study of Binimetinib in Children and Adults With NF1 Plexiform Neurofibromas

Overview

About this study

The purpose of this study is to evaluate children ≥ 1 year of age and adults with neurofibromatosis type 1 (NF1) and plexiform neurofibromas treated with the MEK inhibitor, binimetinib. The primary objective is to determine if there is an adequate level of disease responsiveness to binimetinib in children and adults with NF1 and inoperable plexiform neurofibromas. The objective response to binimetinib is defined as ≥ 20% decrease in tumor volume reduction by 12 courses.

Participation eligibility

Participant eligibility includes age, gender, type and stage of disease, and previous treatments or health concerns. Guidelines differ from study to study, and identify who can or cannot participate. If you need assistance understanding the eligibility criteria, please contact the study team.

Inclusion Criteria:

  • Clinical diagnosis of NF1 using the NIH Consensus Conference criteria OR a documented constitutional NF1 mutation.
  • Plexiform neurofibroma(s) that are progressive or causing significant morbidity.
  • Presence of new plexiform neurofibroma on MRI or CT (documented by comparison with prior MRI or CT). 
  • Measurable plexiform neurofibroma(s) amenable to volumetric MRI analysis. Tumors must be at least 3 mL in volume (most PNs 3 cm in longest diameter will meet this criteria). 
  • Patients must be ≥ 18 years of age at the time of enrollment. 
  • Performance Level: Karnofsky or Lansky ≥ 50%. If unable to walk due to paralysis, but in a wheelchair, patients will be considered ambulatory for the purpose of assessing the performance level. 
  • Ability to swallow capsules/tablets.
  • Ability to comply with follow up procedures.
  • The effects of binimetinib on the developing human fetus are unknown. For this reason, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, for the duration of study participation, and 3 months after completion of binimetinib administration. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. 
  • Negative urine or serum β-HCG test (females of childbearing potential only).
  • Prior Therapy: 
    • Patients are eligible if complete resection of a plexiform neurofibroma with acceptable morbidity is not feasible, or if a subject with surgical option refuses surgery; 
    • Patients who underwent surgery for a progressive plexiform neurofibroma will be eligible to enter the study after the surgery, provided the plexiform neurofibroma was incompletely resected and is evaluable by volumetric analysis;
    • Patients previously treated for a plexiform neurofibroma or other tumor/malignancy, but must have fully recovered from the acute toxic effects of all prior chemotherapy or radiotherapy prior to entering this study;
    • Must not have received myelosuppressive chemotherapy within 3 weeks of entry onto this study; 
    • At least 7 days since the completion of therapy with a hematopoietic growth factor that supports platelet, red or white cell number or function; 
    • At least 4 weeks since the completion of therapy with a biologic anti-neoplastic agent. For agents that have known adverse events occurring beyond 14 days after administration, this period must be extended beyond the time during which adverse events are known to occur;
    • Patients must not have received an investigational drug within 4 weeks; 
    • Patients with endocrine deficiencies are allowed to receive physiologic or stress doses of steroids, if necessary; 
    • Radiation ≥ 6 months from involved field radiation to index plexiform neurofibroma(s), ≥ 6 weeks must have elapsed if patient has received radiation to areas outside index plexiform neurofibroma(s). Patients who have received radiation to the orbit at any time are excluded; 
    • At least 3 weeks since undergoing any major surgery and must be recovered from effects of surgery.
  • Organ Function Requirements: 
    • Adequate bone marrow function defined as: 
      • Peripheral absolute neutrophil count (ANC) ≥ 1500/µL;
      • Platelet count ≥ 100,000/µL (transfusion independent, defined as not receiving platelet transfusions for at least 7 days prior to enrollment);
      • Hemoglobin ≥ 10.0 gm/dL without transfusions. 
    • Adequate renal function defined as:
      • Maximum serum creatinine based on age/gender or a creatinine clearance or radioisotope GFR ≥ 70 ml/min/1.73 m².
    • Adequate liver function defined as: 
      • Bilirubin (sum of conjugated + unconjugated) ≤ 1.5 x upper limit of normal (ULN) for age;
      • SGPT (ALT) ≤ 2.5 x upper limit of normal (ULN) for age; 
      • Serum albumin ≥ 2 g/dL.
    • Adequate cardiac function defined as:
      • Left ventricular fractions (LVEF) ≥ 50% as determined by a multigated acquisition (MUGA) scan or echocardiogram;
      • QTc interval ≤ 480 ms.

Exclusion Criteria:

  • Chronic treatment with systemic steroids or another immunosuppressive agent. 
  • Evidence of an active optic glioma or other low-grade glioma, requiring treatment with chemotherapy or radiation therapy. Patients not requiring treatment are eligible for this protocol. 
  • Patients with malignant glioma, malignant peripheral nerve sheath tumor, or other malignancy requiring treatment in the last 12 months. 
  • Patients who have received radiation to the orbit at any time previously.
  • Ophthalmologic conditions: 
    • Current or past history of central serous retinopathy;
    • Current or past history of retinal vein occlusion; 
    • Known intraocular pressure (IOP) > 21 mmHg (or ULN adjusted by age) or uncontrolled glaucoma (irrespective of IOP). Patients with known glaucoma and increased IOP who do not have meaningful vision (light perception only or no light perception) and are not experiencing pain related to the glaucoma, may be eligible after review. Patients with orbital plexiform neurofibromas should have IOP measured prior to enrollment; 
    • Patients with any other significant abnormality on ophthalmic examination will be reviewed for potential eligibility; 
    • Ophthalmological findings secondary to long-standing optic pathway glioma (such as visual loss, optic nerve pallor or strabismus) or long-standing orbito-temporal PN (such as visual loss, strabismus) will NOT be considered a significant abnormality for the purposes of the study. 
  • Uncontrolled arterial hypertension despite medical treatment defined as CTCAE grade 3 or higher. 
  • Impaired cardiovascular function or clinically significant cardiovascular diseases, including: 
    • History of acute coronary syndromes (including myocardial infarction, unstable angina, coronary artery bypass grafting, coronary angioplasty, or stenting) < 6 months prior to screening;
    • Symptomatic chronic heart failure, history or current evidence of clinically significant cardiac arrhythmia and/or conduction abnormality < 6 months prior to screening except atrial fibrillation and paroxysmal supraventricular tachycardia. 
  • Other concurrent severe and/or uncontrolled medical disease, which could compromise participation in the study (e.g. uncontrolled diabetes, uncontrolled hypertension, severe infection, severe malnutrition, chronic liver or renal disease, active upper GI tract ulceration, congestive heart failure, etc.).
  • Subjects who have an uncontrolled infection.
  • Known positive serology for HIV (human immunodeficiency virus), active hepatitis B, and/or active hepatitis C infection. 
  • Impairment of gastrointestinal function or gastrointestinal disease (e.g. ulcerative disease, uncontrolled nausea, vomiting, diarrhea, malabsorption syndrome or small bowel resection).
  • History of Gilbert's syndrome or patients who are known to be homozygous for UGT1A1 (7/7). 
  • Patients who have neuromuscular disorders that are associated with elevated CK (e.g., inflammatory myopathies, muscular dystrophy, amyotrophic lateral sclerosis, spinal muscular atrophy). 
  • Patients who are planning to embark on a new strenuous exercise regimen after first dose of study treatment. NB: muscular activities, such as strenuous exercise, that can result in significant increases in plasma CK levels should be avoided while on binimetinib treatment.
  • History of allergic reactions attributed to compounds of similar chemical or biologic composition to binimetinib. 
  • Women who are pregnant or breastfeeding. - Any other condition that would contraindicate, in the Investigator's judgement, the patient's participation in the clinical study due to safety concerns or compliance with clinical study procedures, e.g. infection/inflammation, intestinal obstruction, unable to swallow medication, social/ psychological issues, etc. 
  • History of noncompliance to medical regimens.
  • Patients unwilling to or unable to comply with the protocol, or who in the opinion of the investigator may not be able to comply with the safety monitoring requirements of the study. 
  • Prior treatment with a MEK inhibitor of any kind.

Participating Mayo Clinic locations

Study statuses change often. Please contact us for help.

Mayo Clinic Location Status Contact

Rochester, Minn.

Mayo Clinic principal investigator

Dusica Babovic-Vuksanovic, M.D.

Open for enrollment

Contact information:

Mohamed Ibrahim

(507)284-4115

Ibrahim.Mohamed@mayo.edu

More information

Publications

  • Neurofibromas are the most common manifestations of neurofibromatosis type-1. They occasionally cause pain or progressive loss of function due to nerve compression. Optimal treatment approach is still challenging and the current treatment results are not satisfactory. Four cases of plexiform neurofibromas with various clinical presentations and an addendum to a previously published report on a patient who had relief from pain and/or regression of tumor volume after treatment with interferon-α 2a are presented. Read More on PubMed
  • Sorafenib targets multiple pathways thought to be crucial in growth of plexiform neurofibroma (PN) in children with neurofibromatosis type 1 (NF1). Sorafenib has been tolerated with manageable toxicities in adults and children with refractory cancer. We conducted a separate study in this population. Monitoring long-term toxicities such as effects on growth and obtaining additional pharmacokinetic data were of importance due to the young age and long duration of therapy seen in previous phase I trials in children with NF1. Read More on PubMed
  • Neurofibromatosis type 1 (NF1) is a common autosomal dominant genetic disorder with significant impact on health-related quality of life (HRQOL). Research in understanding the pathogenetic mechanisms of neurofibroma development has led to the use of new clinical trials for the treatment of NF1. One of the most important outcomes of a trial is improvement in quality of life, however, no condition specific HRQOL instrument for NF1 exists. The objective of this study was to develop an NF1 HRQOL instrument as a module of PedsQL™ and to test for its initial feasibility, internal consistency reliability and validity in adults with NF1. Read More on PubMed
  • Neurofibromatosis type 1 (NF1) is a common genetic disease that predisposes 30-50 % of affected individuals to develop plexiform neurofibromas. We found that macrophage infiltration of both mouse and human neurofibromas correlates with disease progression. Macrophages accounted for almost half of neurofibroma cells, leading us to hypothesize that nerve macrophages are inflammatory effectors in neurofibroma development and/or growth. We tested the effects of PLX3397, a dual kit/fms kinase inhibitor that blocks macrophage infiltration, in the Dhh-Cre; Nf1(flox/flox) mouse model of GEM grade I neurofibroma. In mice aged 1-4 months, prior to development of nerve pathology and neurofibroma formation, PLX3397 did not impair tumor initiation and increased tumor volume compared to controls. However, in mice aged 7-9 months, after tumor establishment, a subset of mice demonstrating the largest reductions in macrophages after PLX3397 exhibited cell death and tumor volume regression. Macrophages are likely to provide an initial line of defense against developing tumors. Once tumors are established, they become tumor permissive. Macrophage depletion may result in impaired tumor maintenance and represent a therapeutic strategy for neurofibroma therapy. Read More on PubMed
  • Neurofibromatosis type 1 (NF1) patients develop benign neurofibromas and malignant peripheral nerve sheath tumors (MPNST). These incurable peripheral nerve tumors result from loss of NF1 tumor suppressor gene function, causing hyperactive Ras signaling. Activated Ras controls numerous downstream effectors, but specific pathways mediating the effects of hyperactive Ras in NF1 tumors are unknown. We performed cross-species transcriptome analyses of mouse and human neurofibromas and MPNSTs and identified global negative feedback of genes that regulate Ras/Raf/MEK/ERK signaling in both species. Nonetheless, ERK activation was sustained in mouse and human neurofibromas and MPNST. We used a highly selective pharmacological inhibitor of MEK, PD0325901, to test whether sustained Ras/Raf/MEK/ERK signaling contributes to neurofibroma growth in a neurofibromatosis mouse model (Nf1(fl/fl);Dhh-Cre) or in NF1 patient MPNST cell xenografts. PD0325901 treatment reduced aberrantly proliferating cells in neurofibroma and MPNST, prolonged survival of mice implanted with human MPNST cells, and shrank neurofibromas in more than 80% of mice tested. Our data demonstrate that deregulated Ras/ERK signaling is critical for the growth of NF1 peripheral nerve tumors and provide a strong rationale for testing MEK inhibitors in NF1 clinical trials. Read More on PubMed
  • Children with neurofibromatosis type 1 (NF1) are predisposed to juvenile myelomonocytic leukemia (JMML), an aggressive myeloproliferative neoplasm (MPN) that is refractory to conventional chemotherapy. Conditional inactivation of the Nf1 tumor suppressor in hematopoietic cells of mice causes a progressive MPN that accurately models JMML and chronic myelomonocytic leukemia (CMML). We characterized the effects of Nf1 loss on immature hematopoietic populations and investigated treatment with the MEK inhibitor PD0325901 (hereafter called 901). Somatic Nf1 inactivation resulted in a marked expansion of immature and lineage-committed myelo-erythroid progenitors and ineffective erythropoiesis. Treatment with 901 induced a durable drop in leukocyte counts, enhanced erythropoietic function, and markedly reduced spleen sizes in mice with MPN. MEK inhibition also restored a normal pattern of erythroid differentiation and greatly reduced extramedullary hematopoiesis. Remarkably, genetic analysis revealed the persistence of Nf1-deficient hematopoietic cells, indicating that MEK inhibition modulates the proliferation and differentiation of Nf1 mutant cells in vivo rather than eliminating them. These data provide a rationale for performing clinical trials of MEK inhibitors in patients with JMML and CMML. Read More on PubMed
  • Neurofibromatosis type 1 (NF1) is an inherited disease predisposing affected patients to variable numbers of benign neurofibromas. To date there are no effective chemotherapeutic drugs available for this slow growing tumor. Molecularly targeted agents that aim to slow neurofibroma growth are being tested in clinical trials. So preclinical models for testing potential therapies are urgently needed to prioritize drugs for clinical trials of neurofibromas. Read More on PubMed
  • The objectives of this trial were to define the toxicity profile, dose, pharmacokinetics, and pharmacodynamics of the farnesyl transferase (FTase) inhibitor, tipifarnib, in children and adolescents with hematological malignancies. Read More on PubMed
  • Interferon has antiproliferative and antiangiogenic properties. We sought to evaluate preliminary efficacy and determine the recommended phase II dose (RP2D) for pegylated interferon-α-2b (PI) in patients with unresectable progressive or symptomatic plexiform neurofibromas (PN). Read More on PubMed
  • The NF Conference is the largest annual gathering of researchers and clinicians focused on neurofibromatosis and has been convened by the Children's Tumor Foundation for over 20 years. The 2009 NF Conference was held in Portland, Oregon from June 13 to June 16, 2009 and co-chaired by Kathryn North from the University of Sydney and The Children's Hospital at Westmead, Sydney, Australia; and Joseph Kissil from the Wistar Institute, Philadelphia. The Conference included 80 platform presentations in 9 sessions over 4 days; over 100 abstracts presented as posters; and three Keynote presentations. To date, there have been tremendous advances in basic research in the pathogenesis of neurofibromatosis, and more recently in progress toward identifying effective drug therapies and the commencement of neurofibromatosis clinical trials. The NF Conference attendees have significantly increased (doubling from 140 in 2005 to 280 attending in 2009) with a significant increase in attendance of physicians and clinical researchers. Correspondingly the NF Conference scope has expanded to include translational research, clinical trials and clinical management issues while retaining a core of basic research. These themes are reflected in the highlights from the 2009 NF Conference presented here. Read More on PubMed
  • Interactions between tumorigenic cells and their surrounding microenvironment are critical for tumor progression yet remain incompletely understood. Germline mutations in the NF1 tumor suppressor gene cause neurofibromatosis type 1 (NF1), a common genetic disorder characterized by complex tumors called neurofibromas. Genetic studies indicate that biallelic loss of Nf1 is required in the tumorigenic cell of origin in the embryonic Schwann cell lineage. However, in the physiologic state, Schwann cell loss of heterozygosity is not sufficient for neurofibroma formation and Nf1 haploinsufficiency in at least one additional nonneoplastic lineage is required for tumor progression. Here, we establish that Nf1 heterozygosity of bone marrow-derived cells in the tumor microenvironment is sufficient to allow neurofibroma progression in the context of Schwann cell Nf1 deficiency. Further, genetic or pharmacologic attenuation of c-kit signaling in Nf1+/- hematopoietic cells diminishes neurofibroma initiation and progression. Finally, these studies implicate mast cells as critical mediators of tumor initiation. Read More on PubMed
  • Plexiform neurofibroma is a relatively common but potentially devastating manifestation of neurofibromatosis type 1 (NF 1). A substantial number of plexiform neurofibroma causes morbidity. Various treatment modalities are considered to decrease pain. In this paper a case with plexiform neurofibroma causing severe pain and in whom alpha-interferon was used is presented. Read More on PubMed
  • Neurofibromatosis type I (NF1) is a genetic disorder caused by mutations in the NF1 tumor suppressor gene. Neurofibromin is encoded by NF1 and functions as a negative regulator of Ras activity. Somatic mutations in the residual normal NF1 allele within cancers of NF1 patients is consistent with NF1 functioning as a tumor-suppressor. However, the prevalent non-malignant manifestations of NF1, including learning and bone disorders emphasize the importance of dissecting the cellular and biochemical effects of NF1 haploinsufficiency in multiple cell lineages. One of the least studied complications of NF1 involves cardiovascular disorders, including arterial occlusions that result in cerebral and visceral infarcts. NF1 vasculopathy is characterized by vascular smooth muscle cell (VSMC) accumulation in the intima area of vessels resulting in lumen occlusion. We recently showed that Nf1 haploinsufficiency increases VSMC proliferation and migration via hyperactivation of the Ras-Erk pathway, which is a signaling axis directly linked to neointima formation in diverse animal models of vasculopathy. Given this observation, we tested whether heterozygosity of Nf1 would lead to vaso-occlusive disease in genetically engineered mice in vivo. Strikingly, Nf1+/- mice have increased neointima formation, excessive vessel wall cell proliferation and Erk activation after vascular injury in vivo. Further, this effect is directly dependent on a Gleevec sensitive molecular pathway. Therefore, these studies establish an Nf1 model of vasculopathy, which mirrors features of human NF1 vaso-occlusive disease, identifies a potential therapeutic target and provides a platform to further dissect the effect of Nf1 haploinsufficiency in cardiovascular disease. Read More on PubMed
  • Neurofibromatosis type 1 (Nf1) mutation predisposes to benign peripheral nerve (glial) tumors called neurofibromas. The point(s) in development when Nf1 loss promotes neurofibroma formation are unknown. We show that inactivation of Nf1 in the glial lineage in vitro at embryonic day 12.5 + 1, but not earlier (neural crest) or later (mature Schwann cell), results in colony-forming cells capable of multilineage differentiation. In vivo, inactivation of Nf1 using a DhhCre driver beginning at E12.5 elicits plexiform neurofibromas, dermal neurofibromas, and pigmentation. Tumor Schwann cells uniquely show biallelic Nf1 inactivation. Peripheral nerve and tumors contain transiently proliferating Schwann cells that lose axonal contact, providing insight into early neurofibroma formation. We suggest that timing of Nf1 mutation is critical for neurofibroma formation. Read More on PubMed
  • The human disease von Recklinghausen's neurofibromatosis (Nf1) is one of the most common genetic disorders. It is caused by mutations in the NF1 tumor suppressor gene, which encodes a GTPase activating protein (GAP) that negatively regulates p21-RAS signaling. Dermal and plexiform neurofibromas as well as malignant peripheral nerve sheath tumors and other malignant tumors, are significant complications in Nf1. Neurofibromas are complex tumors and composed mainly of abnormal local cells including Schwann cells, endothelial cells, fibroblasts and additionally a large number of infiltrating inflammatory mast cells. Recent work has indicated a role for the microenvironment in plexiform neurofibroma genesis. The emerging evidence points to mast cells as crucial contributors to neurofibroma tumorigenesis. Therefore, further understanding of the molecular interactions between Schwann cells and their environment will provide tools to develop new therapies aimed at delaying or preventing tumor formation in Nf1 patients. Read More on PubMed
  • We aimed to define the dose of pirfenidone in children and adolescents with neurofibromatosis 1 and plexiform neurofibromas that is pharmacokinetically comparable to the active adult dose. Pirfenidone was administered orally on a continuous dosing schedule. The starting dose level was 250 mg/m2/dose. The second dose level (500 mg/m2/dose) corresponded to the adult dose that previously showed activity in sclerosing conditions. A dose was considered pharmacokinetically comparable if the drug exposure in children was <1 standard deviation below the drug exposure in adults treated with 800 mg three times a day. Pharmacokinetic sampling was performed for 24 hours after the first dose. Response to treatment was evaluated using automated volumetric magnetic resonance imaging analysis; quality of life was evaluated using the Impact of Pediatric Illness Scale. Sixteen patients were entered and evaluated for toxicity. Dose-limiting toxicities were observed in 2 of 12 patients receiving 500 mg/m2 three times a day. The plasma pharmacokinetics of pirfenidone were highly variable, but not age dependent. The second dose level was the pharmacokinetically comparable dose and is being used in an ongoing phase II trial of pirfenidone for children with neurofibromatosis 1 and progressive plexiform neurofibroma. Read More on PubMed
  • We performed an open-label phase II trial of oral pirfenidone in 24 patients with neurofibromatosis type 1 (NF1). Tumors were monitored by three-dimensional MRI. At the end of treatment, four patients had a decrease in tumor volume by 15% or more, three had tumor progression, and 17 remained stable. Pirfenidone warrants further investigation in NF1, which has until now lacked an effective control therapy. Read More on PubMed
  • This pediatric phase I trial of tipifarnib determined the maximum-tolerated dose (MTD), pharmacokinetics, and pharmacodynamics of tipifarnib in children with refractory solid tumors and neurofibromatosis type 1 (NF1) -related plexiform neurofibromas. Read More on PubMed
  • The RAS proteins control signalling pathways that are key regulators of several aspects of normal cell growth and malignant transformation. They are aberrant in most human tumours due to activating mutations in the RAS genes themselves or to alterations in upstream or downstream signalling components. Rational therapies that target the RAS pathways might inhibit tumour growth, survival and spread. Several of these new therapeutic agents are showing promise in the clinic and many more are being developed. Read More on PubMed
  • Neurofibromatosis 1 is a common autosomal dominant disease reported in approximately 1 in 3000 individuals. Although some features of neurofibromatosis 1, such as café-au-lait spots and Lisch nodules, are clinically silent, neurofibromas cause a significant degree of morbidity, mortality, and cosmetic disfigurement. Childhood through early adulthood is a vulnerable period for the growth of these lesions. Neurofibromas are a heterogeneous group of benign tumors that grow from intraneural and extraneural tissues. These tumors take on different morphology, grow at variable rates, and occur in multiple locations. Symptoms arise as neurofibromas enlarge, compressing and distorting local structures. The unpredictable nature of neurofibromas has a serious impact on the quality of life of patients with neurofibromatosis 1, and their management is challenging for physicians. Surgical removal remains the mainstay of treatment. However, advances in the understanding of the genetics and pathogenesis of neurofibromatosis 1 have led to the development of promising new biologically directed therapies. The purpose of this review is to summarize the defining characteristics, incidence, clinical course, management options, and outcome of neurofibromas in children with neurofibromatosis 1. Read More on PubMed
  • Neurofibromatosis type 1 affects quality of life (QoL) through association with severe complications, impact on cosmetic features, and uncertainty of the effects of the disorder. Read More on PubMed
  • Neurofibromatosis type 1 (NF1) is a common genetic disorder characterized by multiple neurofibromas, peripheral nerve tumors containing mainly Schwann cells and fibroblasts. The NF1 gene encodes neurofibromin, a tumor suppressor postulated to function in part as a Ras GTPase-activating protein. The roles of different cell types and of elevated Ras-GTP in neurofibroma formation are unclear. To determine which neurofibroma cell type has altered Ras-GTP regulation, we developed an immunocytochemical assay for active, GTP-bound Ras. In NIH 3T3 cells, the assay detected overexpressed, constitutively activated K-, N-, and Ha-Ras and insulin-induced endogenous Ras-GTP. In dissociated neurofibroma cells from NF1 patients, Ras-GTP was elevated in Schwann cells but not fibroblasts. Twelve to 62% of tumor Schwann cells showed elevated Ras-GTP, unexpectedly revealing neurofibroma Schwann cell heterogeneity. Increased basal Ras-GTP did not correlate with increased cell proliferation. Normal human Schwann cells, however, did not demonstrate elevated basal Ras activity. Furthermore, compared with cells from wild type littermates, Ras-GTP was elevated in all mouse Nf1(-/-) Schwann cells but never in Nf1(-/-) mouse fibroblasts. Our results indicate that Ras activity is detectably increased in only some neurofibroma Schwann cells and suggest that neurofibromin is not an essential regulator of Ras activity in fibroblasts. Read More on PubMed
  • The NF1 gene encodes neurofibromin, a GTPase-activating protein (GAP) for members of the p21(ras) (Ras) family, which negatively regulates Ras output by accelerating the conversion of active Ras. GTP to inactive Ras.GDP. Analysis of tumors from patients with neurofibromatosis type 1 (NF1) has shown biochemical evidence of hyperactive Ras as well as frequent loss of the normal NF1 allele, consistent with its role as a tumor suppressor gene. Taken together, these data suggest that novel therapeutics directed against components of the Ras signaling cascade might provide effective treatments for certain pathological complications of NF1. Here we summarize data that support a role for hyperactive Ras in NF1 disease, including Ras processing, activation, and down-regulation. We review targets for rational drug design, provide preliminary results, and discuss implications for future studies. Am. J. Med. Genet. (Semin. Med. Genet.) 89:14-22, 1999. Read More on PubMed
  • The gene responsible for the hereditary disease neurofibromatosis type 1 (NF1) has been well characterized as a regulator of Ras protein activity. Many aspects of the disease seem to be caused by misregulation of Ras as a result of NF1 mutation. Other aspects, however, point at functions for the NF1 protein that have yet to be discovered. Read More on PubMed

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CLS-20454894

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