[Update on the treatment of RASopathies]. / Actualizacion del tratamiento de las rasopatias.

INTRODUCTION: The term 'RASopathies' covers a series of diseases that present mutations in the genes that code for the proteins of the RAS/MAPK pathway. These diseases include neurofibromatosis type 1, Noonan syndrome, Legius syndrome, LEOPARD syndrome, Costello syndrome and cardiofaciocutaneous syndrome. Involvement of the RAS/MAPK pathway not only increases predisposition to develop tumours, but also determines the presence of phenotypic anomalies and alterations in learning processes. AIM: To review the use of therapeutic strategies with mechanisms that have a selective action on RASopathies. DEVELOPMENT: The fact that the RAS pathway is involved in a third of all neoplasms has led to the development and study of different drugs at this level. Some of these pharmaceutical agents have been tested in RASopathies, mainly in neurofibromatosis type 1. Here we analyse the use of different antitarget treatments: drugs that act on the membrane receptors, such as tyrosine kinase inhibitors, in the mTOR pathway or MEK inhibitors. These latter have shown potential benefits in recent studies conducted on different RASopathies. CONCLUSIONS: Today, thanks to the results from the first studies conducted with MEK inhibitor based mainly on animal models, a number of promising clinical trials are being carried out.

TITLE: Actualizacion del tratamiento de las rasopatias.Introduccion. El termino 'rasopatias' agrupa una serie de enfermedades que presentan mutaciones en genes que codifican las proteinas de la via RAS/MAPK. Estas enfermedades incluyen la neurofibromatosis de tipo 1, el sindrome de Noonan, el sindrome de Legius, el sindrome LEOPARD, el sindrome de Costello y el sindrome cardiofaciocutaneo. La afectacion de la via RAS/MAPK no solo aumenta la predisposicion a desarrollar tumores, sino que tambien determina la presencia de anomalias fenotipicas y alteraciones en los procesos de aprendizaje. Objetivo. Revisar el papel del uso de estrategias terapeuticas con mecanismos de accion selectivo en las rasopatias. Desarrollo. El hecho de que la via RAS participe en un tercio de las neoplasias ha motivado el desarrollo y el estudio de distintos farmacos a este nivel. Algunos de estos farmacos han sido probados en las rasopatias, principalmente en la neurofibromatosis de tipo 1. Analizamos el uso de distintos tratamientos antidiana: farmacos que actuan en los receptores de membrana, como los inhibidores de la tirosincinasa, en la via mTOR o los inhibidores de MEK. Existe un potencial beneficio de estos ultimos en estudios recientes realizados en distintas rasopatias. Conclusiones. Actualmente, gracias a los resultados de los primeros trabajos desarrollados con inhibidor de MEK basados principalmente en modelos animales, se estan realizando multiples ensayos clinicos prometedores.

High-Dose Intravenous Vitamin C Treatment of a Child with Neurofibromatosis Type 1 and Optic Pathway Glioma: A Case Report.

BACKGROUND In neurofibromatosis type 1 (NF1) disease, the loss of the tumor suppressor function of the neurofibromin gene leads to proliferation of neural tumors. In children, the most frequently identified tumor is the optic pathway glioma. CASE REPORT We describe the case of a 5-year-old child who was diagnosed with NF1 and optic pathway tumor onset at the age of 14 months. Because of the tumor progression, chemotherapy with carboplatin and vincristine was prescribed at this early age and continued for one year. As the progression of disease continued after chemotherapy, the child, at the age of 2.8 years, was started on high-dose intravenous vitamin C (IVC) treatment (7-15 grams per week) for 30 months. After 30 months, the results of IVC treatments demonstrated reduction and stabilization of the tumors in the optic chiasm, hypothalamus, and left optic nerve according to radiographic imaging. The right-sided optic nerve mass seen before IVC treatment disappeared by the end of the treatment. CONCLUSIONS This case highlights the positive effects of treating NF1 glioma with IVC. Additional studies are necessary to evaluate the role of high-dose IVC in glioma treatment.

In vitro responses of neurofibroma fibroblasts, mast cells and Schwann cells obtained from patients with neurofibromatosis 1 to 308-nm excimer light and/or vitamin D3.

Fibroblasts, mast cells and Schwann cells were isolated from neurofibromas of patients with neurofibromatosis 1, and their responses to 308-nm excimer light irradiation and/or vitamin D3 or an analog (tacalcitol; 1,24-dihydroxyvitamin D3 ) were examined in vitro. Excimer light irradiation (300 mJ/cm(2) ) suppressed the growth of all three cell types. Exposure to 10(-7)  mol/L of 1α,25(OH)2 D3 (VD3 ) or tacalcitol suppressed the growth of fibroblasts and mast cells, but not Schwann cells. These results suggest that the different neurofibroma cell types show different responses to VD3 . A combination of excimer light irradiation and VD3 is necessary to suppress the growth of neurofibroma cells in vivo.

Effect of vitamin D3 treatment on bone density in neurofibromatosis 1 patients: a retrospective clinical study.

OBJECTIVES: We have previously demonstrated reduced bone density and an increased incidence of 25-hydroxy vitamin D3 (25-OH D3) deficiency in adults with neurofibromatosis 1 (NF1) compared to healthy controls. Vitamin D3 is a cheap, safe, and effective supplement in the general population, but its value in NF1 patients has not been demonstrated. This study investigates the therapeutic potential of oral vitamin D3 on bone mineral density (BMD) in NF1 patients with vitamin D3 deficiency. METHODS: We measured serum 25-OH D3, parathyroid hormone, calcium, and bone alkaline phosphatase concentrations, urinary deoxypyridinoline concentrations, and BMD in 35 adults with NF1. Nineteen patients received vitamin D3 supplementation for 2 years, six patients received supplementation for 1 year and 10 patients received no supplementation. Supplementation was administered in a dose that maintained the serum 25-OH D3 level above 30 µg/l. BMD was measured again at 1 and 2 years, and biochemical assessments of bone metabolism were measured at least every half year during therapy. RESULTS: Treated subjects had significantly reduced loss of BMD, as measured by T score at the hip (p=0.011) and lumbar spine (p=0.022). The effect on hip BMD was apparent at 1 year in comparison to baseline (p=0.02) and was greater at 2 years in comparison to measurements at 1 year (p=0.02). CONCLUSIONS: Vitamin D3 supplementation improves BMD in adult NF1 patients. Further studies are needed to elucidate the mechanisms responsible for reduced BMD in NF1 patients.

Preclinical in vivo evaluation of rapamycin in human malignant peripheral nerve sheath explant xenograft.

Neurofibromatosis type 1 (NF1) patients are prone to the development of malignant tumors, the most common being Malignant Peripheral Nerve Sheath Tumor (MPNST). NF1-MPNST patients have an overall poor survival due to systemic metastasis. Currently, the management of MPNSTs includes surgery and radiation; however, conventional chemotherapy is not very effective, underscoring the need for effective biologically-targeted therapies. Recently, the NF1 gene product, neurofibromin, was shown to negatively regulate the phosphoinositide-3-kinase (PI3K)/Protein Kinase-B (Akt)/mammalian Target Of Rapamycin (mTOR) pathway, with loss of neurofibromin expression in established human MPNST cell lines associated with high levels of mTOR activity. We developed and characterized a human NF1-MPNST explant grown subcutaneously in NOD-SCID mice, to evaluate the effect of the mTOR inhibitor rapamycin. We demonstrate that rapamycin significantly inhibited human NF1-MPNST mTOR pathway activation and explant growth in vivo at doses as low as 1.0 mg/kg/day, without systemic toxicities. While rapamycin was effective at reducing NF1-MPNST proliferation and angiogenesis, with decreased CyclinD1 and VEGF respectively, there was no increase in tumor apoptosis. Rapamycin effectively decreased activation of S6 downstream of mTOR, but there was accompanied increased Akt activation. This study demonstrates the therapeutic potential and limitations of rapamycin in NF1-associated, and likely sporadic, MPNSTs.

CAPE (caffeic acid phenethyl ester)-based propolis extract (Bio 30) suppresses the growth of human neurofibromatosis (NF) tumor xenografts in mice.

Dysfunction of the NF1 gene coding a RAS GAP is the major cause of neurofibromatosis type 1 (NF1), whereas neurofibromatosis type 2 (NF2) is caused primarily by dysfunction of the NF2 gene product called merlin that inhibits directly PAK1, an oncogenic Rac/CDC42-dependent Ser/Thr kinase. It was demonstrated previously that PAK1 is essential for the growth of both NF1 and NF2 tumors. Thus, several anti-PAK1 drugs, including FK228 and CEP-1347, are being developed for the treatment of NF tumors. However, so far no effective NF therapeutic is available on the market. Since propolis, a very safe healthcare product from bee hives, contains anticancer ingredients called CAPE (caffeic acid phenethyl ester) or ARC (artepillin C), depending on the source, both of which block the oncogenic PAK1 signaling pathways, its potential therapeutic effect on NF tumors was explored in vivo. Here it is demonstrated that Bio 30, a CAPE-rich water-miscible extract of New Zealand (NZ) propolis suppressed completely the growth of a human NF1 cancer called MPNST (malignant peripheral nerve sheath tumor) and caused an almost complete regression of human NF2 tumor (Schwannoma), both grafted in nude mice. Although CAPE alone has never been used clinically, due to its poor bioavailability/water-solubility, Bio 30 contains plenty of lipids which solubilize CAPE, and also includes several other anticancer ingredients that seem to act synergistically with CAPE. Thus, it would be worth testing clinically to see if Bio 30 and other CAPE-rich propolis are useful for the treatment of NF patients.

Sichuan pepper extracts block the PAK1/cyclin D1 pathway and the growth of NF1-deficient cancer xenograft in mice.

There is increasing evidence that more than 70% of cancers including pancreatic, breast and prostate cancers as well as neurofibromatosis (NF) are highly addicted to abnormal activation of the Ser/Thr kinase PAK1 for their growth. So far FK228 is the most potent among the HDAC (histone deacetylase) inhibitors that block the activation of both PAK1 and another kinase AKT, downstream of PI-3 kinase. However, FK228 is still in clinical trials (phase 2) for a variety of cancers (but not for NF as yet), and not available for most cancer/NF patients. Thus, we have been exploring an alternative which is already in the market, and therefore immediately useful for the treatment of those desperate cancer/NF patients. Here we provide the first evidence that extracts of Chinese/ Japanese peppercorns (Zanthoxyli Fructus) from the plant Zanthoxylum piperitum called "Hua Jiao"/"Sansho", block selectively the key kinase PAK1, leading to the downregulation of cyclin D1. Unlike FK228, these extracts do not inhibit AKT activation at the concentrations that block either cancer growth or PAK1 activation. The Chinese pepper extract selectively inhibits the growth of NF1-deficient malignant peripheral nerve sheath tumor (MPNST) cells, without affecting the growth of normal fibroblasts, and suppresses the growth of NF1-deficient human breast cancer (MDA-MB-231) xenograft in mice. Our data suggest that these peppercorn extracts would be potentially useful for the treatment of PAK1-dependent NF such as MPNST, in addition to a variety of PAK1-dependent cancers including breast cancers.

Plexiform neurofibromas in NF1: toward biologic-based therapy.

Neurofibromatosis type 1 (NF1) is one of the most common neurogenetic diseases affecting adults and children. Neurofibromas are one of the most common of the protean manifestations of NF1. Plexiform neurofibromas, which will frequently cause cosmetic abnormalities, pain, and neurologic deficits, are composed of "neoplastic" Schwann cells accompanied by other participating cellular and noncellular components. There is increasing evidence that loss of NF1 expression in neoplastic Schwann cells is associated with elevated levels of activated RAS, supporting the notion that the NF1 gene product, neurofibromin, acts as a growth regulator by inhibiting ras growth-promoting activity. In addition, there is increasing evidence that other cooperating events, which may be under cytokine modulation, are important for neurofibroma development and growth. Treatment of plexiform neurofibromas has been empiric, with surgery being the primary option for those with progressive lesions causing a major degree of morbidity. The efficacy of alternative treatment approaches, including the use of antihistamines, maturation agents, and antiangiogenic drugs, has been questionable. More recently, biologic-based therapeutic approaches, using drugs that target the molecular genetic underpinnings of plexiform neurofibromas or cytokines believed important in tumor growth, have been initiated. Evaluation of such trials is hindered by the unpredictable natural history of plexiform neurofibromas and difficulties in determining objective response in tumors that are notoriously large and irregular in shape. Innovative neuroimaging techniques and the incorporation of quality-of-life scales may be helpful in evaluation of therapeutic interventions. The ability to design more rational therapies for NF1-associated neurofibromas is heavily predicated on an improved understanding of the molecular and cellular biology of the cells involved in neurofibroma formation and growth.