Phase II trial of pirfenidone in adults with neurofibromatosis type 1

Schwann cell derived pleiotrophin stimulates fibroblast for proliferation and excessive collagen deposition in plexiform neurofibroma

Neurofibromatosis type 1 associated plexiform neurofibroma (pNF) is characterized by abundant fibroblasts and dense collagen, yet the intricate interactions between tumor-origin cells (Schwann cells) and neurofibroma-associated fibroblasts (NFAFs) remain elusive. Employing single-cell RNA sequencing on human pNF samples, we generated a comprehensive transcriptomics dataset and conducted cell-cell communication analysis to unravel the molecular dynamics between Schwann cells and NFAFs. Our focus centered on the pleiotrophin (PTN)/nucleolin (NCL) axis as a pivotal ligand-receptor pair orchestrating this interaction. Validation of PTN involvement was affirmed through coculture models and recombinant protein experiments. Functional and mechanistic investigations, employing assays such as CCK8, EdU, Western Blot, ELISA, Hydroxyproline Assay, and Human phospho-kinase array, provided critical insights. We employed siRNA or inhibitors to intercept the PTN/NCL/proline-rich Akt substrate of 40 kDa (PRAS40) axis, validating the associated molecular mechanism. Our analysis highlighted a subset of Schwann cells closely linked to collagen deposition, underscoring their significance in pNF development. The PTN/NCL axis emerged as a key mediator of the Schwann cell-NFAF interaction. Furthermore, our study demonstrated that elevated PTN levels enhanced NFAF proliferation and collagen synthesis, either independently or synergistically with TGF-β1 in vitro. Activation of the downstream molecule PRAS40 was noted in NFAFs upon PTN treatment. Crucially, by targeting NCL and PRAS40, we successfully reversed collagen synthesis within NFAFs. In conclusion, our findings unveil the pivotal role of the PTN/NCL/PRAS40 axis in driving pNF development by promoting NFAFs proliferation and function. Targeting this pathway emerges as a potential therapeutic strategy for pNF. This study contributes novel insights into the molecular mechanisms governing pNF pathogenesis.

Management of neurofibromatosis type 1-associated plexiform neurofibromas

Plexiform Neurofibromas (PN) are a common manifestation of the genetic disorder neurofibromatosis type 1 (NF1). These benign nerve sheath tumors often cause significant morbidity, with treatment options limited historically to surgery. There have been tremendous advances over the past two decades in our understanding of PN, and the recent regulatory approvals of the MEK inhibitor selumetinib are reshaping the landscape for PN management. At present, there is no agreed upon PN definition, diagnostic evaluation, surveillance strategy, or clear indications for when to initiate treatment and selection of treatment modality. In this review, we address these questions via consensus recommendations from a panel of multidisciplinary NF1 experts.

Clinical Trials Targeting Neurofibromatoses-associated Tumors: A Systematic Review

Background

There is a paucity of literature that comprehensively analyzes previous and current clinical trials targeting neurofibromatoses-related tumors. This article aims to provide readers with drug development efforts targeting these tumors by analyzing translational and clinical findings.

Methods

This systematic review was written according to the PRISMA guidelines. Inclusion criteria were clinical trials involving patients with neurofibromatosis type 1, type 2, or schwannomatosis that were treated with therapies targeting neurofibromatoses-associated tumors and that were registered on clinicaltrials.gov. In addition, a search was performed in PubMed, Web of Science, Google Scholar, and Embase European for articles fully describing these clinical trials.

Results

A total of 265 clinical trials were registered and screened for eligibility. Ninety-two were included in this systematic review involving approximately 4636 participants. The number of therapies analyzed was more than 50. Drugs under investigation mainly act on the MAPK/ERK and PI3K/AKT/mTOR pathways, tumor microenvironment, or aberrantly over-expressed cell surface receptors. Selumetinib was the most effective medication for treating a neurofibromatosis type 1-associated tumor with approximately 68%–71% partial response for inoperable or progressive plexiform neurofibromas in children 2 years of age and older and bevacizumab for a neurofibromatosis type 2-related tumor with approximately 36%–41% partial response for vestibular schwannomas in patients 12 years of age and older.

Conclusions

This systematic review presents the results of previous clinical investigations and those under development for neurofibromatoses-associated tumors. Clinicians may use this information to strategize patients to appropriate clinical trials.

Plexiform neurofibroma: shedding light on the investigational agents in clinical trials

INTRODUCTION

Neurofibromatosis Type 1 (NF1) is an autosomal dominant genetic condition, which predisposes individuals to the development of plexiform neurofibromas (PN), benign nerve sheath tumors seen in 30-50% of patients with NF1. These tumors may cause significant pain and disfigurement or may compromise organ function. Given the morbidity associated with these tumors, therapeutic options for patients with NF1-related PN are necessary.

AREAS COVERED

We searched the www.clinicaltrials.gov database for 'plexiform neurofibroma.' This article summarizes completed and ongoing trials involving systemic therapies for PN.

EXPERT OPINION

Surgery is the mainstay treatment; however, complete resection is not possible in many cases. Numerous systemic therapies have been evaluated in patients with NF1, with MEK inhibitors (MEKi) showing the greatest efficacy for volumetric reduction and improvement in functional and patient-reported outcomes. The MEKi selumetinib is now FDA approved for the treatment of inoperable, symptomatic PN in pediatric NF1 patients. Questions remain regarding the use of this drug class in terms of when to initiate therapy, overall duration, reduced dosing schedules, and side effect management. Future studies are needed to fully understand the clinical application of MEKi and to evaluate other potential therapies through appropriate trial designs for this potentially devastating, manifestation in NF1.

Tumorigenesis in neurofibromatosis type 1: role of the microenvironment

Neurofibromatosis Type 1 (NF1) is one of the most common inherited neurological disorders and predisposes patients to develop benign and malignant tumors. Neurofibromas are NF1-associated benign tumors but can cause substantial discomfort and disfigurement. Numerous studies have shown that neurofibromas arise from the Schwann cell lineage but both preclinical mouse models and clinical trials have demonstrated that the neurofibroma tumor microenvironment contributes significantly to tumorigenesis. This offers the opportunity for targeting new therapeutic vulnerabilities to treat neurofibromas. However, a translational gap exists between deciphering the contribution of the neurofibroma tumor microenvironment and clinically applying this knowledge to treat neurofibromas. Here, we discuss the key cellular and molecular components in the neurofibroma tumor microenvironment that can potentially be targeted therapeutically to advance neurofibroma treatment.

Drug Repurposing, an Attractive Strategy in Pancreatic Cancer Treatment: Preclinical and Clinical Updates

Pancreatic cancer (PC) is one of the deadliest malignancies worldwide, since patients rarely display symptoms until an advanced and unresectable stage of the disease. Current chemotherapy options are unsatisfactory and there is an urgent need for more effective and less toxic drugs to improve the dismal PC therapy. Repurposing of non-oncology drugs in PC treatment represents a very promising therapeutic option and different compounds are currently being considered as candidates for repurposing in the treatment of this tumor. In this review, we provide an update on some of the most promising FDA-approved, non-oncology, repurposed drug candidates that show prominent clinical and preclinical data in pancreatic cancer. We also focus on proposed mechanisms of action and known molecular targets that they modulate in PC. Furthermore, we provide an explorative bioinformatic analysis, which suggests that some of the PC repurposed drug candidates have additional, unexplored, oncology-relevant targets. Finally, we discuss recent developments regarding the immunomodulatory role displayed by some of these drugs, which may expand their potential application in synergy with approved anticancer immunomodulatory agents that are mostly ineffective as single agents in PC.

Targeted genetic and molecular therapies in neurofibromatosis - A review of present therapeutic options and a glimpse into the future

Neurofibromatosis type 1, the most common phakomatoses, can present with a host of signs and symptoms, usually involving the skin and the peripheral nervous system. It is characterized by a mutation in the neurofibromatosis type 1 gene on chromosome 17q11.2 that codes for the protein neurofibromin. Neurofibromin acts as a tumor suppressor gene by inhibiting rat sarcoma (Ras) activity and its deficiency leads to increased Ras activity, cellular proliferation and tumor formation. This review was conducted to analyze the various targeted therapies at the genetic and molecular level employed to manage the tumors and other clinical presentations associated with neurofibromatosis type 1. Twenty-eight studies of treatment modalities for the conditions associated with neurofibromatosis and which involved either targeted gene therapy or molecular level therapies, including the latest advances, were included in this review. Mitogen-activated protein kinase kinase inhibition, mammalian target of Rapamycin inhibition and Tyrosine kinase inhibition, represent some of the newer treatment options in this category. Although there are a number of trials for providing therapeutic options at the genetic and molecular level for the various physical and psychological morbidities associated with neurofibromatosis type 1, most of them are in the preclinical stage. Increased clinical trials of the molecules and gene therapies could significantly help in managing the various chronic and sometimes, life-threatening conditions associated with neurofibromatosis 1 and these will probably represent the preferred treatment direction of the future.

Clinical trial design in neurofibromatosis type 1 as a model for other tumor predisposition syndromes

Up to 10% of all pediatric cancer patients may have an underlying germline mutation which predisposed them to develop a malignancy. With more patients being tested for and diagnosed with genetic tumor predisposition syndromes, there has been improved characterization of their many nonmalignant manifestations. However, designing and implementing clinical trials to treat the nonmalignant tumor and non-tumor manifestations of these syndromes poses many unique challenges. Unlike trials for malignancies where tumor response and survival can be used as straightforward trial endpoints, the nonmalignant manifestations are often chronic, evolve more slowly over time, and may not be immediately life-threatening. Therefore, they will likely require a different approach to both testing and treatment with a focus on more functional and patient-reported outcome trial endpoints. The recent success of treatment trials for the benign tumors plexiform neurofibromas in the tumor predisposition syndrome neurofibromatosis type 1 (NF1) can be used as a model for the development of clinical trials in other tumor predisposition syndromes. In this article, we review the unique challenges associated with targeting the nonmalignant aspects of these conditions as well as some of the lessons learned from the NF1 experience which may be applied to other syndromes in the future.

[Management of cervico-cephalic plexiform neurofibromas: About 35 cases]

OBJECT

Plexiform neurofibroma is a characteristic lesion of Von Recklinghausen's disease. Conservative surgery is the most widely adopted treatment. However, it is very challenging because of its hemorrhagic nature and the infiltrative aspect of the lesions. The aim of this study was to evaluate our management.

PATIENTS AND METHOD

A retrospective study over 16 years was realized and during this period 35 patients with neurofibroma with cervico-facial location were included.

RESULTS

There were 18 men and 17 women with an average age of 23 years (3-50 years). The familial form was found in 9% of patients. Aesthetic discomfort was noted in all patients and functional impairment only occurred in 10% of patients. The NFP was localized at the hemiface in 11 cases, periorbital in 6 cases, naso-labial in 5 cases, scalp in 4 cases, jugal in 4 cases and cervico-chin in 5 cases. Size of the lesions averaged 11.6cm (4-45cm). Eighteen patients (51.4%) were operated including 10 by modeling resection, 05 cervico-facial lifting and 3 complete resections. Complication rate was 28% dominated by disunion wound. The average number of procedures was 1.6 (1 to 5). After 3 years average follow-up, aesthetic et functional results was assessed as good over 75 per cent of patients.

CONCLUSION

Cervico-facial plexiform neurofibromas is challenging. Conservative surgery should be the gold standard and long time follow-up is recommended.

The biology of cutaneous neurofibromas: Consensus recommendations for setting research priorities

OBJECTIVE

A group of experts in dermatology, genetics, neuroscience, and regenerative medicine collaborated to summarize current knowledge on the defined factors contributing to cutaneous neurofibroma (cNF) development and to provide consensus recommendations for future research priorities to gain an improved understanding of the biology of cNF.

METHODS

The group members reviewed published and unpublished data on cNF and related diseases via literature search, defined a set of key topic areas deemed critical in cNF pathogenesis, and developed recommendations in a series of consensus meetings.

RESULTS

Five specific topic areas were identified as being relevant to providing an enhanced understanding of the biology of cNF: (1) defining the human cells of origin; (2) understanding the role of the microenvironment, focusing on neurons, mast cells, and fibroblasts; (3) defining the genetic and molecular differences between the cNFs, focusing on size and number; (4) understanding if sex hormones are critical for cNF development or progression; and (5) identifying challenges in establishing in vitro and in vivo models representing human cNF.

CONCLUSIONS

The complexity of cNF biology stems from its heterogeneity at multiple levels including genetic, spatial involvement, temporal development, and cellular composition. We propose a unified working model for cNF that builds a framework to address the key questions about cNF that, when answered, will provide the necessary understanding of cNF biology to allow meaningful development of therapies.

Activated androgen receptor accelerates angiogenesis in cutaneous neurofibroma by regulating VEGFA transcription

Accumulating evidence has demonstrated the significant progression of cutaneous neurofibroma (cNF) without necrosis during puberty. However, the molecular events involved in this process remain unclear. The alteration of the steroid hormone levels during puberty has led to the investigation of the expression levels of the androgen receptor (AR). A positive correlation between AR expression and microvessel density has been reported in human cNF tissues in combination with enhanced endothelial cell tube formation in vitro. In addition, activated AR signaling can promote neurofibroma cell growth in vivo and in vitro and tube formation in vitro. In the present study, AR was shown to bind directly to the promoter of vascular endothelial growth factor A (VEGFA), a key factor involved in angiogenesis, and to sequentially induce its expression. Furthermore, the AR inhibitor, MDV3100, downregulated VEGFA expression and abolished endothelial cell recruitment and tube formation. Taken collectively, the findings of this study revealed that AR signaling enhanced tumor growth and angiogenesis in cNF by regulating VEGFA transcription. However, whether AR can be regarded a therapeutic target for cNF requires further investigation.

Emerging therapeutic targets for neurofibromatosis type 1

INTRODUCTION

Neurofibromatosis type 1 (NF1) is an autosomal dominantly inherited tumor predisposition syndrome with an incidence of one in 3000-4000 individuals with no currently effective therapies. The NF1 gene encodes neurofibromin, which functions as a negative regulator of RAS. NF1 is a chronic multisystem disorder affecting many different tissues. Due to cell-specific complexities of RAS signaling, therapeutic approaches for NF1 will likely have to focus on a particular tissue and manifestation of the disease. Areas covered: We discuss the multisystem nature of NF1 and the signaling pathways affected due to neurofibromin deficiency. We explore the cell-/tissue-specific molecular and cellular consequences of aberrant RAS signaling in NF1 and speculate on their potential as therapeutic targets for the disease. We discuss recent genomic, transcriptomic, and proteomic studies combined with molecular, cellular, and biochemical analyses which have identified several targets for specific NF1 manifestations. We also consider the possibility of patient-specific gene therapy approaches for NF1. Expert opinion: The emergence of NF1 genotype-phenotype correlations, characterization of cell-specific signaling pathways affected in NF1, identification of novel biomarkers, and the development of sophisticated animal models accurately reflecting human pathology will continue to provide opportunities to develop therapeutic approaches to combat this multisystem disorder.

Targeting GLI Transcription Factors in Cancer

Aberrant activation of hedgehog (Hh) signaling has been observed in a wide variety of tumors and accounts for more than 25% of human cancer deaths. Inhibitors targeting the Hh signal transducer Smoothened (SMO) are widely used and display a good initial efficacy in patients suffering from basal cell carcinoma (BCC); however, a large number of patients relapse. Though SMO mutations may explain acquired therapy resistance, a growing body of evidence suggests that the non-canonical, SMO-independent activation of the Hh pathway in BCC patients can also account for this adverse effect. In this review, we highlight the importance of glioma-associated oncogene (GLI) transcription factors (the main downstream effectors of the canonical and the non-canonical Hh cascade) and their putative role in the regulation of multiple oncogenic signaling pathways. Moreover, we discuss the contribution of the Hh signaling to malignant transformation and propose GLIs as central hubs in tumor signaling networks and thus attractive molecular targets in anti-cancer therapies.

Orbital/Periorbital Plexiform Neurofibromas in Children with Neurofibromatosis Type 1: Multidisciplinary Recommendations for Care

TOPIC

Children and adults with neurofibromatosis type 1 (NF1), a common autosomal dominant condition, manifest a variety of ophthalmologic conditions. Plexiform neurofibromas (PNs) involving the eyelid, orbit, periorbital, and facial structures (orbital-periorbital plexiform neurofibroma [OPPN]) can result in significant visual loss in children. Equally important, OPPNs can cause significant alteration in physical appearance secondary to proptosis, ptosis, and facial disfigurement, leading to social embarrassment and decreased self-esteem.

CLINICAL RELEVANCE

Although NF1 is a relatively common disease in which routine ophthalmologic examinations are required, no formal recommendations for clinical care of children with OPPNs exist. Although medical and surgical interventions have been reported, there are no agreed-on criteria for when OPPNs require therapy and which treatment produces the best outcome.

METHODS

Because a multidisciplinary team of specialists (oculofacial plastics, pediatric ophthalmology, neuro-ophthalmology, medical genetics, and neuro-oncology) direct management decisions, the absence of a uniform outcome measure that represents visual or aesthetic sequelae complicates the design of evidence-based studies and feasible clinical trials.

RESULTS

In September 2013, a multidisciplinary task force, composed of pediatric practitioners from tertiary care centers experienced in caring for children with OPPN, was convened to address the lack of clinical care guidelines for children with OPPN.

CONCLUSIONS

This consensus statement provides recommendations for ophthalmologic monitoring, outlines treatment indications and forthcoming biologic therapy, and discusses challenges to performing clinical trials in this complicated condition.

Preclinical Evidence for the Use of Sunitinib Malate in the Treatment of Plexiform Neurofibromas

PURPOSE

Plexiform neurofibromas (pNF) are pathognomonic nerve and soft tissue tumors of neurofibromatosis type I (NF1), which are highly resistant to conventional chemotherapy and associated with significant morbidity/mortality. Disruption of aberrant SCF/c-Kit signaling emanating from the pNF microenvironment induced the first ever objective therapeutic responses in a recent phase 2 trial. Sunitinib malate is a potent, highly selective RTK inhibitor with activity against c-Kit, PDGFR, and VEGFR, which have also been implicated in the pathogenesis of these lesions. Here, we evaluate the efficacy of sunitinib malate in a preclinical Krox20;Nf1(flox/-) pNF murine model.

EXPERIMENTAL DESIGN

Proliferation, β-hexosaminidase release (degranulation), and Erk1/2 phosphorylation were assessed in sunitinib treated Nf1(+/-) mast cells and fibroblasts, respectively. Krox20;Nf1(flox/-) mice with established pNF were treated sunitinib or PBS-vehicle control for a duration of 12 weeks. pNF metabolic activity was monitored by serial [(18)F]DG-PET/CT imaging.

RESULTS

Sunitinib suppressed multiple in vitro gain-in-functions of Nf1(+/-) mast cells and fibroblasts and attenuated Erk1/2 phosphorylation. Sunitinib treated Krox20;Nf1(flox/-) mice exhibited significant reductions in pNF size, tumor number, and FDG uptake compared to control mice. Histopathology revealed reduced tumor cellularity and infiltrating mast cells, markedly diminished collagen deposition, and increased cellular apoptosis in sunitinib treated pNF.

CONCLUSIONS

Collectively, these results demonstrate the efficacy of sunitinib in reducing tumor burden in Krox20;Nf1(flox/-) mice. These preclinical findings demonstrate the utility of inhibiting multiple RTKs in pNF and provide insights into the design of future clinical trials.

Translational aspects in targeting the stromal tumour microenvironment: from bench to bedside

Solid tumours comprise, not only malignant cells but also a variety of stromal cells and extracellular matrix proteins. These components interact via an array of signalling pathways to create an adaptable network that may act to promote or suppress cancer progression. To date, the majority of anti-tumour chemotherapeutic agents have principally sought to target the cancer cell. Consequently, resistance develops because of clonal evolution, as a result of selection pressure during tumour expansion. The concept of activating or inhibiting other cell types within the tumour microenvironment is relatively novel and has the advantage of targeting cells which are genetically stable and less likely to develop resistance. This review outlines key players in the stromal tumour microenvironment and discusses potential targeting strategies that may offer therapeutic benefit.

The NF1 gene revisited - from bench to bedside

Neurofibromatosis type 1 (NF1) is a relatively common tumour predisposition syndrome related to germline aberrations of NF1, a tumour suppressor gene. The gene product neurofibromin is a negative regulator of the Ras cellular proliferation pathway, and also exerts tumour suppression via other mechanisms.

Recent next-generation sequencing projects have revealed somatic NF1 aberrations in various sporadic tumours. NF1 plays a critical role in a wide range of tumours. NF1 alterations appear to be associated with resistance to therapy and adverse outcomes in several tumour types.

Identification of a patient's germline or somatic NF1 aberrations can be challenging, as NF1 is one of the largest human genes, with a myriad of possible mutations. Epigenetic factors may also contribute to inadequate levels of neurofibromin in cancer cells.

Clinical trials of NF1-based therapeutic approaches are currently limited. Preclinical studies on neurofibromin-deficient malignancies have mainly been on malignant peripheral nerve sheath tumour cell lines or xenografts derived from NF1 patients. However, the emerging recognition of the role of NF1 in sporadic cancers may lead to the development of NF1-based treatments for other tumour types. Improved understanding of the implications of NF1 aberrations is critical for the development of novel therapeutic strategies.

Phase II trial of pirfenidone in children and young adults with neurofibromatosis type 1 and progressive plexiform neurofibromas

BACKGROUND

Pirfenidone, an oral anti-inflammatory, antifibrotic agent with activity in idiopathic pulmonary fibrosis, may mediate anti-tumor activity in neurofibromatosis type 1 (NF1) and plexiform neurofibromas (PN) by inhibition of fibroblast proliferation and collagen synthesis. The primary objective of this open label, single arm phase II trial was to evaluate the activity of pirfenidone in children and young adults with inoperable PN.

PROCEDURE

Patients (3-21 years) with NF1-related progressive PN received pirfenidone at the previously determined optimal dose (500 mg/m(2) orally, q8h) on a continuous dosing schedule (one cycle = 28 days). Volumetric MRI analysis was used to assess response. Progression was defined as ≥ 20% PN volume increase compared to baseline. Pirfenidone would be considered active if it doubled the median time to progression (TTP) compared to the TTP on the placebo arm of a phase II trial with the farnesyltransferase inhibitor tipifarnib, which used near identical eligibility criteria. Toxicities, objective response rate, and quality of life (QOL) also were evaluated.

RESULTS

Thirty-six patients were enrolled and tolerated pirfenidone well with intermittent nausea and vomiting as the most frequent toxicities. A dose reduction was required in only three patients. The median TTP for pirfenidone was 13.2 months compared to 10.6 months for the placebo control group from the tipifarnib trial (two-tailed P = 0.92; one-tailed P = 0.46). No objective responses were observed.

CONCLUSIONS

Pirfenidone was well tolerated, but did not demonstrate activity as defined in this trial and does not warrant further evaluation in children with NF1 and progressive PN.

Achieving consensus for clinical trials: the REiNS International Collaboration

The neurofibromatoses (NF)--including neurofibromatosis 1 (NF1), neurofibromatosis 2 (NF2), and schwannomatosis--are related tumor-suppressor syndromes characterized by a predisposition to multiple tumor types and other disease manifestations, which often result in functional disability, reduced quality of life, pain, and, in some cases, malignancy. With increasing knowledge of the biology and pathogenesis of NF, clinical trials with targeted agents directed at NF tumors have become available. Most clinical trials for patients with NF have used designs and endpoints similar to oncology trials. However, differences in the disease manifestations and natural history of NF (compared to cancers) require the development of new designs and endpoints to perform meaningful NF clinical trials. The Response Evaluation in Neurofibromatosis and Schwannomatosis (REiNS) International Collaboration was established in 2011 at the Children's Tumor Foundation meeting to achieve consensus within the NF community about the design of future clinical trials, with a specific emphasis on endpoints. The REiNS Collaboration includes 7 working groups that focus on imaging of tumor response; functional, visual, patient-reported, and neurocognitive outcomes; whole-body MRI; and disease biomarkers. This supplement includes the first series of recommendations by the REiNS Collaboration. The hope is that these recommendations will be used by members of the group and by researchers outside of the REiNS International Collaboration to standardize the measurement of outcomes and thus improve clinical trials for patients with NF. Ultimately, we plan to engage industry partners and national regulatory agencies in this process to facilitate the approval of drugs for patients with NF.

Recommendations for imaging tumor response in neurofibromatosis clinical trials

OBJECTIVE

Neurofibromatosis (NF)-related benign tumors such as plexiform neurofibromas (PN) and vestibular schwannomas (VS) can cause substantial morbidity. Clinical trials directed at these tumors have become available. Due to differences in disease manifestations and the natural history of NF-related tumors, response criteria used for solid cancers (1-dimensional/RECIST [Response Evaluation Criteria in Solid Tumors] and bidimensional/World Health Organization) have limited applicability. No standardized response criteria for benign NF tumors exist. The goal of the Tumor Measurement Working Group of the REiNS (Response Evaluation in Neurofibromatosis and Schwannomatosis) committee is to propose consensus guidelines for the evaluation of imaging response in clinical trials for NF tumors.

METHODS

Currently used imaging endpoints, designs of NF clinical trials, and knowledge of the natural history of NF-related tumors, in particular PN and VS, were reviewed. Consensus recommendations for response evaluation for future studies were developed based on this review and the expertise of group members.

RESULTS

MRI with volumetric analysis is recommended to sensitively and reproducibly evaluate changes in tumor size in clinical trials. Volumetric analysis requires adherence to specific imaging recommendations. A 20% volume change was chosen to indicate a decrease or increase in tumor size. Use of these criteria in future trials will enable meaningful comparison of results across studies.

CONCLUSIONS

The proposed imaging response evaluation guidelines, along with validated clinical outcome measures, will maximize the ability to identify potentially active agents for patients with NF and benign tumors.

Mutation spectrum of NF1 and clinical characteristics in 78 Korean patients with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant disorders in humans. NF1 is caused by mutations of the NF1 gene. Mutation detection is complex owing to the large size of the NF1 gene, the presence of pseudogenes, and the great variety of mutations. Also, few probable genotype-phenotype correlations have been found in NF1. In this study 78 Korean patients from 60 families were screened for NF1 mutations. Mutation analysis of the entire coding region and flanking splice sites was carried out and included the use of a combination of reverse transcription polymerase chain reaction, multiplex ligation probe amplification, or fluorescence in situ hybridization. Mutation spectrum and genotype-phenotype relationship were assessed. Fifty-two distinct NF1 mutations were identified in 60 families. The mutations included 30 single base substitutions (12 missense and 18 nonsense), 11 missplicing mutations, seven small insertion or deletions, and four gross deletions. Sixteen (30.8%) mutations were novel; c.1A>G, c.2033_2034insC, c.2540T>C, c.4537C>T, c.5546G>A, c.6792C>A, and c.6792C>G were recurrently identified. The mutations were evenly distributed across exon 1 through intron 47 of NF1, and no mutational hot spots were found. A genotype-phenotype analysis suggests that there is no clear relationship between specific mutations and clinical features. This analysis revealed a wide spectrum of NF1 mutations in Korean patients. As technologies advance in molecular genetics, the mutation detection rate will increase. Considering that 30.8% of detected mutations were novel, exhaustive mutation analysis of NF1 may be an important tool in early diagnosis and genetic counseling.

Optimizing biologically targeted clinical trials for neurofibromatosis

INTRODUCTION

The neurofibromatoses (neurofibromatosis type 1, NF1 and neurofibromatosis type 2, NF2) comprise the most common inherited conditions in which affected children and adults develop tumors of the central and peripheral nervous system. In this review, the authors discuss how the establishment of the Neurofibromatosis Clinical Trials Consortium (NFCTC) has positively impacted on the design and execution of treatment studies for individuals with NF1 and NF2.

AREAS COVERED

Using an extensive PUBMED search in collaboration with select NFCTC members expert in distinct NF topics, the authors discuss the clinical features of NF1 and NF2, the molecular biology of the NF1 and NF2 genes, the development and application of clinically relevant Nf1 and Nf2 genetically engineered mouse models and the formation of the NFCTC to enable efficient clinical trial design and execution.

EXPERT OPINION

The NFCTC has resulted in a more seamless integration of mouse preclinical and human clinical trials efforts. Leveraging emerging enabling resources, current research is focused on identifying subtypes of tumors in NF1 and NF2 to deliver the most active compounds to the patients most likely to respond to the targeted therapy.

Neurofibromatosis

The "neurofibromatoses" are a set of distinct genetic disorders that have in common the occurrence of tumors of the nerve sheath. They include NF1, NF2, and schwannomatosis. All are dominantly inherited with a high rate of new mutation and variable expression. NF1 includes effects on multiple systems of the body. The major NF1-associated tumor is the neurofibroma. In addition, clinical manifestations include bone dysplasia, learning disabilities, and an increased risk of malignancy. NF2 includes schwannomas of multiple cranial and spinal nerves, especially the vestibular nerve, as well as other tumors such as meningiomas and ependymomas. The schwannomatosis phenotype is limited to multiple schwannomas, and usually presents with pain. The genes that underlie each of the disorders are known: NF1 for neurofibromatosis type 1, NF2 for neurofibromatosis type 2, and INI1/SMARCB1 for schwannomatosis. Genetic testing is possible to identify mutations. Insights into pathogenesis are beginning to suggest new treatment strategies, and therapeutic trials with several new forms of treatment are underway.

Therapeutics for childhood neurofibromatosis type 1 and type 2

Neurofibromatosis type 1 (NF1) and type 2 (NF2) are genetically and medically distinct neurocutaneous disorders that are both associated with tumors affecting the central and peripheral nervous systems. NF1 has a frequency of 1 in 3,000, compared with 1 in 30,000 for NF2. Careful surveillance is important for both conditions, to allow early identification and treatment of complications. The most common and important problems in NF1 are cognitive impairment, optic pathway gliomas, plexiform neurofibromas, and orthopaedic issues. Early intervention and tailored educational programs are indicated for learning difficulties. Attention deficit hyperactivity disorder may be amenable to treatment with stimulant medication. A clinical trial is under way to evaluate lovastatin in the treatment of cognitive problems in children with NF1. Chemotherapy with vincristine and carboplatin is the current standard of care for symptomatic optic pathway gliomas, but new agents with improved efficacy are needed. Plexiform neurofibromas may be treated with surgery, but often recur. To date, no medical therapy has proven effective in limiting plexiform neurofibroma growth, but several candidate medications are under consideration in clinical trials. Malignant peripheral nerve sheath tumors may arise in preexisting plexiform neurofibromas, so changes in tumor growth or an increase in pain or focal neurologic deficit should prompt further investigation and early treatment with wide surgical resection, with or without adjuvant chemotherapy or radiotherapy. Specialist surgical intervention may be needed for scoliosis and tibial pseudoarthrosis. In NF2, surgical treatment remains a cornerstone of management for symptomatic progressive vestibular schwannomas, meningiomas, and spinal tumors. Vascular endothelial growth factor inhibitors show promise for the treatment of vestibular schwannomas, with the aim of delaying surgery, and other targeted molecular therapies are becoming available as investigational options. Hearing aids and brainstem and cochlear implants have a role in optimizing functional hearing in some patients. Specialist ophthalmology input should be arranged to monitor for ophthalmologic complications. A coordinated effort is needed to enroll NF1 and NF2 patients in international multicenter clinical trials of promising new pharmacologic agents. Genetic testing is useful for prenatal diagnosis and may be important in understanding individual responses to novel medical therapies in the future. Effective transition to adult services is important, considering the likelihood of further complications in the adult years.

Neuro-oncology of Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder with an incidence of about 1:2500 to 1:3000. It is caused by a germline inactivating mutation of the NF1 gene on chromosome 17. Patients with NF1 are at increased risk of developing a variety of tumors of the peripheral and central nervous system, including neurofibromas, plexiform neurofibromas, malignant peripheral nerve sheath tumors, and low-grade gliomas of the optic nerves and other cerebral structures. Rarely, they develop high-grade gliomas. Although they are rare, these hereditary tumor syndromes involving the nervous system must be recognized in patients and their families, as early diagnosis may alter management and ultimately improve outcome. Additional insight into the molecular mechanisms causing these syndromes and their relationship with the clinical features will allow the development and implementation of screening and prevention strategies for these diseases. Management of these lesions is difficult and requires specific skills and the collaborative work of neurosurgeons, radiation therapists, neurologists, and oncologists. Ideally, patients should be managed in comprehensive centers with specific expertise in the management of patients with NF1. This review describes current and developing therapies for managing the neuro-oncologic manifestations of NF1.

Response of NF1-related plexiform neurofibroma to high-dose carboplatin

Plexiform neurofibromas (PN) are a hallmark of neurofibromatosis type 1 (NF1). These large nerve tumors can be disfiguring and surgery is the only known standard therapy. Surgical intervention may be suboptimal due to the diffuse nature of PN. Here, we present a case in which we describe the use of high-dose carboplatin to treat the patient's testicular seminoma which resulted in the decrease in size of a PN in a patient with NF1.

Pirfenidone: an anti-fibrotic therapy for progressive kidney disease

IMPORTANCE OF THE FIELD

Many chronic diseases of various etiologies lead to fibrosis and organ dysfunction. Despite many advances in medicine in recent years, options to slow the progression of fibrotic diseases have remained limited. The recent availability of pirfenidone, an antifibrotic and anti-inflammatory investigational agent, thus offers a new hope for treating progressive fibrotic diseases.

AREAS COVERED IN THIS REVIEW

This review provides concise review of the available data regarding the mechanism and pharmacokinetics of pirfenidone and preclinical and clinical data regarding efficacy and safety in fibrotic diseases of the kidney. It also reviews results of clinical trials involving pirfenidone in other fibrotic diseases.

WHAT THE READER WILL GAIN

The review will provide in-depth review of pirfenidone with a renal focus.

TAKE HOME MESSAGE

Because many of the available clinical trials have been small and/or uncontrolled, conclusive evidence regarding efficacy and safety of pirfenidone is lacking, particularly in patients with renal or hepatic dysfunction. Larger studies are needed to better understand long-term efficacy and safety of this medication in various patient populations.

[Orbitotemporal facial involvement in type 1 neurofibromatosis (NF1)]

Plexiform neurofibromas of the orbit, sometimes extending to the temporal region and the face, are considered to be a rare but devastating and disfiguring complication of neurofibromatosis type 1. The first symptoms appear in infancy and the involvement of the orbit and the face is present in nearly all children after the age of 5. The disease is unilateral in most cases but can exceptionally involve both sides of the face. Progressive deformation of the orbital frame due to the expanding plexiform neurofibroma and buphthalmos occurs in a large proportion of cases. The associated sphenoidal dysplasia, which is thought to be, according to the most recent hypothesis, genetically determined, will inescapably increase the burden to the orbital content, cause pulsating proptosis and will endanger noble structures, finally resulting in loss of vision. Using the Jackson classification, the authors report their personal series of 22 cases (19 operated). Until now, there has been no effective medical treatment for plexiform neurofibroma and surgery remains the standard care for these patients. Controversies remain about the timing of the first operation and today most multidisciplinary teams involving plastic, maxillofacial, ophthalmologic, and neurosurgeons favor early intervention to try to minimize the secondary deformation of the orbital and facial skeleton. A number of cases of plexiform neurofibromas are illustrated within the three Jackson groups and treatment results of the rare elephantiasis neuromatosa cases are presented. Special techniques such as preoperative embolization of heavily vascularized plexiform neurofibroma are also discussed.

Neurooncology of familial cancer syndromes

The majority of tumors of the nervous system are sporadic. However, a subset of patients with tumors and their families are predisposed to developing cancers of the central nervous system and other organs because of a germline mutation. In the last decade, many of the genes responsible for these typically autosomal dominant familial tumor syndromes have been identified. Additionally, our understanding of the mechanisms of carcinogenesis in these syndromes has increased, allowing for more targeted therapies for these patients as well as those with sporadic cancers. Because these patients present a unique set of issues regarding diagnosis and neurooncological management, the most common familial cancer syndromes involving the nervous system are reviewed: neurofibromatosis type 1 and 2; tuberous sclerosis complex; von Hippel Lindau, Li-Fraumeni, Gorlin, and Turcot syndrome.

Neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant, multisystem disorder affecting approximately 1 in 3500 people. Significant advances in the understanding of the pathophysiology of NF1 have been made in the last decade. While no medical therapies for NF1 are currently available, trials are ongoing to discover and test medical treatments for the various manifestations of NF1, primarily plexiform neurofibromas, learning disabilities, and optic pathway gliomas. In addition, mutational analysis has become available on a clinical basis and is useful for diagnostic confirmation in individuals who do not fulfill diagnostic criteria or when a prenatal diagnosis is desired. There are several disorders that may share overlapping features with NF1; in 2007, a disorder with cutaneous findings similar to NF1 was described. This paper addresses the dermatologist's role in diagnosis and management of NF1 and describes the variety of cutaneous and extracutaneous findings in NF1 to which the dermatologist may be exposed.

LEARNING OBJECTIVES

After completing this learning activity, participants should be able to discuss the indications and limitations of genetic testing in neurofibromatosis type 1, distinguish common and uncommon cutaneous findings, and recognize the dermatologist's role in diagnosis and management.

Hearing improvement after bevacizumab in patients with neurofibromatosis type 2

BACKGROUND

Profound hearing loss is a serious complication of neurofibromatosis type 2, a genetic condition associated with bilateral vestibular schwannomas, benign tumors that arise from the eighth cranial nerve. There is no medical treatment for such tumors.

METHODS

We determined the expression pattern of vascular endothelial growth factor (VEGF) and three of its receptors, VEGFR-2, neuropilin-1, and neuropilin-2, in paraffin-embedded samples from 21 vestibular schwannomas associated with neurofibromatosis type 2 and from 22 sporadic schwannomas. Ten consecutive patients with neurofibromatosis type 2 and progressive vestibular schwannomas who were not candidates for standard treatment were treated with bevacizumab, an anti-VEGF monoclonal antibody. An imaging response was defined as a decrease of at least 20% in tumor volume, as compared with baseline. A hearing response was defined as a significant increase in the word-recognition score, as compared with baseline.

RESULTS

VEGF was expressed in 100% of vestibular schwannomas and VEGFR-2 in 32% of tumor vessels on immunohistochemical analysis. Before treatment, the median annual volumetric growth rate for 10 index tumors was 62%. After bevacizumab treatment in the 10 patients, tumors shrank in 9 patients, and 6 patients had an imaging response, which was maintained in 4 patients during 11 to 16 months of follow-up. The median best response to treatment was a volumetric reduction of 26%. Three patients were not eligible for a hearing response; of the remaining seven patients, four had a hearing response, two had stable hearing, and one had progressive hearing loss. There were 21 adverse events of grade 1 or 2.

CONCLUSIONS

VEGF blockade with bevacizumab improved hearing in some, but not all, patients with neurofibromatosis type 2 and was associated with a reduction in the volume of most growing vestibular schwannomas.

Suggested response criteria for phase II antitumor drug studies for neurofibromatosis type 2 related vestibular schwannoma

Neurofibromatosis type 2 (NF2) is a tumor suppressor gene syndrome characterized by multiple schwannomas, especially vestibular schwannomas (VS), and meningiomas. Anticancer drug trials are now being explored, but there are no standardized endpoints in NF2. We review the challenges of NF2 clinical trials and suggest possible response criteria for use in initial phase II studies. We suggest two main response criteria in such trials. Objective radiographic response is defined as a durable 20% or greater reduction in VS volume based on post-contrast T1-weighted MRI images collected with 3 mm or finer cuts through the internal auditory canal. Hearing response is defined as a statistically significant improvement in word recognition scores using 50-word recorded lists in audiology. A possible composite endpoint incorporating both radiographic response and hearing response is outlined. We emphasize pitfalls in response assessment and suggest guidelines to minimize misinterpretations of response. We also identify research goals in NF2 to facilitate future trial conduct, such as identifying the expectations for time to tumor progression and time to measurable hearing loss in untreated NF2-related VS, and the relation of both endpoints to patient prognostic factors (such as age, baseline tumor volume, and measures of disease severity). These data would facilitate future use of endpoints based on stability of tumor size and hearing, which might be more appropriate for testing certain drugs. We encourage adoption of standardized endpoints early in the development of phase II trials for this population to facilitate comparison of results across trials of different agents.

Neurofibromatosis type 1 revisited

Neurofibromatosis type 1 (NF1) is an autosomal dominant condition with a worldwide incidence of approximately 1 per 2500 to 3000 individuals. Caused by a germ-line-inactivating mutation in the NF1 gene on chromosome 17, the disease is associated with increased morbidity and mortality. In the past several years, significant progress has been made in standardizing management of the major clinical features of neurofibromatosis type 1. Moreover, improved understanding of how the neurofibromatosis type 1 protein, neurofibromin, regulates cell growth recently provided insight into the pathogenesis of the disease and has led to the development of new therapies. In this review, we describe the clinical manifestations, recent molecular and genetic findings, and current and developing therapies for managing clinical problems associated with neurofibromatosis type 1.

Pharmacokinetics and clinical effects of pirfenidone administered intravenously in horses

OBJECTIVE

To characterize the plasma pharmacokinetics and clinical effects of pirfenidone administered IV in healthy horses.

ANIMALS

6 adult horses.

PROCEDURES

A 15 mg/kg dose of pirfenidone was administered IV over 5 minutes. Physical variables were recorded and blood samples collected prior to infusion; 2.5 minutes after beginning infusion; at the end of infusion; and at 3, 6, 9, 12, 15, 20, 25, 30, 40, 50, 60, 75, and 90 minutes and 2, 2.5, 3, 4, 6, 8, 12, and 24 hours after completion of infusion. Plasma concentrations of pirfenidone and its metabolites were determined.

RESULTS

Mild clinical effects, including tachycardia and muscle fasciculations, were observed during drug administration but stopped at the end of the infusion. Pirfenidone and 2 metabolites, hydroxypirfenidone and carboxypirfenidone, were detected by the end of the 5-minute infusion. Mean peak plasma concentration of pirfenidone was 182.5 micromol/L, detected at the end of the infusion. Mean peak plasma concentrations of hydroxypirfenidone and carboxypirfenidone were 1.07 and 3.4 micromol/L, respectively, at 40 minutes after infusion. No parent drug or metabolites were detected at 24 hours. Distribution of pirfenidone best fit a 2-compartment model, and the drug had mean +/- SEM elimination half-life of 86.0 +/- 4.7 minutes, mean body clearance of 6.54 +/- 0.45 mL/kg/min, and apparent volume of distribution at steady state of 0.791 +/- 0.056 L/kg.

CONCLUSIONS AND CLINICAL RELEVANCE

Intravenous administration of pirfenidone was tolerated with transient adverse affects during infusion, and drug clearance was rapid.

Management of plexiform neurofibroma with interferon alpha

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.

Pirfenidone: a novel potential therapeutic agent in the management of chronic allograft rejection

Chronic allograft dysfunction is a leading cause of allograft failure, morbidity, and mortality after solid organ transplantation. The pathogenesis of chronic allograft failure has a final common pathway leading to organ fibrosis. Pirfenidone is an effective and novel antifibrotic agent with anti-inflammatory properties. Clinical use of the agent has been tested in a number of nontransplant recipients and has a favorable safety profile based on available clinical data. Building on these observations and findings, and considering the role of fibrosis in chronic allograft rejection, pirfenidone was initially investigated as adjunct therapy in a rat heterotopic tracheal transplantation model. This led to several studies confirming that pirfenidone may well be worth considering for further investigation. This paper reviews the possibility of using pirfenidone in clinical transplantation management.

Experimental therapeutic approaches to peripheral nerve tumors

✓Discovery that the Schwann cell is the primary cell type responsible for both the neurofibroma as well as the schwannoma has proven to represent a crucial milestone in understanding the pathogenesis of peripheral nerve tumor development. This information and related findings have served as a nidus for research aimed at more fully characterizing this family of conditions. Recent discoveries in the laboratory have clarified an understanding of the molecular mechanisms underlying the pathogenesis of benign peripheral nerve tumors. Similarly, the mechanisms whereby idiopathic and syndromic (NF1- andNF2-associated) nerve sheath tumors progress to malignancy are being elucidated. This detailed understanding of the molecular pathogenesis of peripheral nerve tumors provides the information necessary to create a new generation of therapies tailored specifically to the prevention, cessation, or reversal of pathological conditions at the fundamental level of dysfunction. The authors review the data that have helped to elucidate the molecular pathogenesis of this category of conditions, explore the current progress toward exploitation of these findings, and discuss potential therapeutic avenues for future research.

Phase I trial of pirfenidone in children with neurofibromatosis 1 and plexiform neurofibromas

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.

Pirfenidone inhibits TGF-beta expression in malignant glioma cells

Due to its immunosuppressive properties, the cytokine transforming growth factor (TGF)-beta has become a promising target in the experimental treatment of human malignant gliomas. Here, we report that the antifibrotic drug 5-methyl-1-phenyl-2-(1H)-pyridone (pirfenidone, PFD) elicits growth-inhibitory effects and reduces TGF-beta2 protein levels in human glioma cell lines. This reduction in TGF-beta2 is biologically relevant since PFD treatment reduces the growth inhibition of TGF-beta-sensitive CCL-64 cells mediated by conditioned media of glioma cells. The downregulation of TGF-beta is mediated at multiple levels. PFD leads to a reduction of TGF-beta2 mRNA levels and of the mature TGF-beta2 protein due to decreased expression and direct inhibition of the TGF-beta pro-protein convertase furin. In addition, PFD reduces the protein levels of the matrix metalloproteinase (MMP)-11, a TGF-beta target gene and furin substrate involved in carcinogenesis. These data define PFD or PFD-related agents as promising agents for human cancers associated with enhanced TGF-beta activity.