The NF1 gene revisited - from bench to bedside. Oncotarget. 2014;5:5873-5892. [PMID: 25026295 PMCID: PMC4171599 DOI: 10.18632/oncotarget.2194]

Novel insights toward diagnosis and treatment of glioneuronal and neuronal tumors in young adults

Aim: Glioneuronal and neuronal tumors are rare primary central nervous system malignancies with heterogeneous features. Due to the rarity of these malignancies diagnosis and treatment remains a clinical challenge. Methods: Here we performed a narrative review aimed to investigate the principal issues concerning the diagnosis, pathology, and clinical management of glioneuronal tumors. Results: Diagnostic criteria have been recently overturned thanks to a better characterization on a histological and molecular biology level. The study of genomic alterations occurring within these tumors has allowed us to identify potential therapeutic targets including BRAF, FGFR, and PDGFRA. Conclusion: Techniques allowing molecular sequencing DNA methylation assessment of the disease are essential diagnostic tools. Targeting agents should be included in the therapeutic armamentarium after loco-regional treatment failure.

An Update on the Nitrogen Heterocycle Compositions and Properties of U.S. FDA-Approved Pharmaceuticals (2013-2023)

This Perspective is a continuation of our analysis of U.S. FDA-approved small-molecule drugs (1938-2012) containing nitrogen heterocycles. In this study we report drug structure and property analyses of 321 unique new small-molecule drugs approved from January 2013 to December 2023 as well as information about frequency of important heteroatoms such as sulfur and fluorine and key small nitrogen substituents (CN and NO2). The most notable change is an incredible increase in drugs containing at least one nitrogen heterocycle─82%, compared to 59% from preceding decades─as well as a significant increase in the number of nitrogen heterocycles per drug. Pyridine has claimed the #1 high-frequency nitrogen heterocycle occurrence spot from piperidine (#2), with pyrimidine (#5), pyrazole (#6), and morpholine (#9) being the big top 10 climbers. Also notable is high number of fused nitrogen heterocycles, apparently driven largely by newly approved cancer drugs.

A Population Pharmacokinetic Assessment of the Effect of Food on Selumetinib in Patients with Neurofibromatosis Type 1-Related Plexiform Neurofibromas and Healthy Volunteers

Selumetinib is clinically used for pediatric patients with neurofibromatosis type 1 and symptomatic, inoperable plexiform neurofibromas. Until recently, selumetinib had to be taken twice daily, after 2 hours of fasting and followed by 1 hour of fasting, which could be inconvenient. This population analysis evaluated the effect of low- and high-fat meals on the pharmacokinetic (PK) parameters of selumetinib and its active metabolite N-desmethyl selumetinib. The dataset comprised 511 subjects from 15 clinical trials who received ≥1 dose of selumetinib and provided ≥1 measurable postdose concentration of selumetinib and N-desmethyl selumetinib. A 2-compartment model with sequential 0- and 1st-order delayed absorption and 1st-order elimination adequately described selumetinib PK characteristics. A 1-compartment model reasonably described N-desmethyl selumetinib PK characteristics over time simultaneously with selumetinib. Selumetinib geometric mean area under the concentration-time curve ratio (1-sided 90% confidence interval [CI] lower bound) was 76.9% (73.3%) with a low-fat meal and 79.3% (76.3%) with a high-fat meal versus fasting. The lower bound of the 1-sided 90% CI demonstrated a difference of <30% between fed and fasted states. Considering the flat exposure-response relationship within the dose range (20-30 mg/m2), the observed range of exposure, and the variability in the SPRINT trial, this was not considered clinically relevant.

Drug screening on digital microfluidics for cancer precision medicine

Drug screening based on in-vitro primary tumor cell culture has demonstrated potential in personalized cancer diagnosis. However, the limited number of tumor cells, especially from patients with early stage cancer, has hindered the widespread application of this technique. Hence, we developed a digital microfluidic system for drug screening using primary tumor cells and established a working protocol for precision medicine. Smart control logic was developed to increase the throughput of the system and decrease its footprint to parallelly screen three drugs on a 4 × 4 cm2 chip in a device measuring 23 × 16 × 3.5 cm3. We validated this method in an MDA-MB-231 breast cancer xenograft mouse model and liver cancer specimens from patients, demonstrating tumor suppression in mice/patients treated with drugs that were screened to be effective on individual primary tumor cells. Mice treated with drugs screened on-chip as ineffective exhibited similar results to those in the control groups. The effective drug identified through on-chip screening demonstrated consistency with the absence of mutations in their related genes determined via exome sequencing of individual tumors, further validating this protocol. Therefore, this technique and system may promote advances in precision medicine for cancer treatment and, eventually, for any disease.

Nf1 deficiency modulates the stromal environment in the pretumorigenic rat mammary gland

Background

Neurofibromin, coded by the NF1 tumor suppressor gene, is the main negative regulator of the RAS pathway and is frequently mutated in various cancers. Women with Neurofibromatosis Type I (NF1)-a tumor predisposition syndrome caused by a germline NF1 mutation-have an increased risk of developing aggressive breast cancer with poorer prognosis. The mechanism by which NF1 mutations lead to breast cancer tumorigenesis is not well understood. Therefore, the objective of this work was to identify stromal alterations before tumor formation that result in the increased risk and poorer outcome seen among NF1 patients with breast cancer.

Approach

To accurately model the germline monoallelic NF1 mutations in NF1 patients, we utilized an Nf1-deficient rat model with accelerated mammary development before presenting with highly penetrant breast cancer.

Results

We identified increased collagen content in Nf1-deficient rat mammary glands before tumor formation that correlated with age of tumor onset. Additionally, gene expression analysis revealed that Nf1-deficient mature adipocytes in the rat mammary gland have increased collagen expression and shifted to a fibroblast and preadipocyte expression profile. This alteration in lineage commitment was also observed with in vitro differentiation, however, flow cytometry analysis did not show a change in mammary adipose-derived mesenchymal stem cell abundance.

Conclusion

Collectively, this study uncovered the previously undescribed role of Nf1 in mammary collagen deposition and regulating adipocyte differentiation. In addition to unraveling the mechanism of tumor formation, further investigation of adipocytes and collagen modifications in preneoplastic mammary glands will create a foundation for developing early detection strategies of breast cancer among NF1 patients.

Visual Deficits and Diagnostic and Therapeutic Strategies for Neurofibromatosis Type 1: Bridging Science and Patient-Centered Care

Neurofibromatosis type 1 (NF1) is an inherited autosomal dominant disorder primarily affecting children and adolescents characterized by multisystemic clinical manifestations. Mutations in neurofibromin, the protein encoded by the Nf1 tumor suppressor gene, result in dysregulation of the RAS/MAPK pathway leading to uncontrolled cell growth and migration. Neurofibromin is highly expressed in several cell lineages including melanocytes, glial cells, neurons, and Schwann cells. Individuals with NF1 possess a genetic predisposition to central nervous system neoplasms, particularly gliomas affecting the visual pathway, known as optic pathway gliomas (OPGs). While OPGs are typically asymptomatic and benign, they can induce visual impairment in some patients. This review provides insight into the spectrum and visual outcomes of NF1, current diagnostic techniques and therapeutic interventions, and explores the influence of NF1-OPGS on visual abnormalities. We focus on recent advancements in preclinical animal models to elucidate the underlying mechanisms of NF1 pathology and therapies targeting NF1-OPGs. Overall, our review highlights the involvement of retinal ganglion cell dysfunction and degeneration in NF1 disease, and the need for further research to transform scientific laboratory discoveries to improved patient outcomes.

Drosophila Contributions towards Understanding Neurofibromatosis 1

Neurofibromatosis 1 (NF1) is a multisymptomatic disorder with highly variable presentations, which include short stature, susceptibility to formation of the characteristic benign tumors known as neurofibromas, intense freckling and skin discoloration, and cognitive deficits, which characterize most children with the condition. Attention deficits and Autism Spectrum manifestations augment the compromised learning presented by most patients, leading to behavioral problems and school failure, while fragmented sleep contributes to chronic fatigue and poor quality of life. Neurofibromin (Nf1) is present ubiquitously during human development and postnatally in most neuronal, oligodendrocyte, and Schwann cells. Evidence largely from animal models including Drosophila suggests that the symptomatic variability may reflect distinct cell-type-specific functions of the protein, which emerge upon its loss, or mutations affecting the different functional domains of the protein. This review summarizes the contributions of Drosophila in modeling multiple NF1 manifestations, addressing hypotheses regarding the cell-type-specific functions of the protein and exploring the molecular pathways affected upon loss of the highly conserved fly homolog dNf1. Collectively, work in this model not only has efficiently and expediently modelled multiple aspects of the condition and increased understanding of its behavioral manifestations, but also has led to pharmaceutical strategies towards their amelioration.

Variation Analysis in Premenopausal and Postmenopausal Breast Cancer Cases

Menopausal status affects the prognoses and consequences of breast cancer. Therefore, this retrospective study aimed to reveal the molecular variation profile differences in breast cancer patients according to their menopausal status, with the hypothesis that the molecular variation profiles will be different at premenopausal and postmenopausal ages. Breast cancer patients (n = 254) who underwent molecular subtyping and QIAseq Human Breast Cancer NGS Panel screening between 2018 and 2022 were evaluated retrospectively. Their menopausal status was defined by age, and those aged 50 years and above were considered postmenopausal. Of the subjects, 58.66% (n = 149) were premenopausal and 41.34% (n = 105) were postmenopausal. The mean age at the time of diagnosis for all patients was 49.31 ± 11.19 years, with respective values of 42.11 ± 5.51 and 59.54 ± 9.01 years for the premenopausal and postmenopausal groups, respectively (p = 0.000). Among premenopausal patients, the percentages of patients in BCa subtypes (luminal A, luminal B-HER2(-), luminal B-HER2(+), HER2 positive, and triple-negative) were determined to be 34.90%, 8.05%, 26.17%, 10.74%, and 20.13%, respectively, while in the postmenopausal group, these values were 39.05%, 16.19%, 24.76%, 6.67%, and 13.33%, respectively (p > 0.05). Considering menopausal status, the distribution of hormone receptors in premenopausal patients was ER(+)/PgR(+) 63.76%, ER(-)/PgR(-) 23.49%, ER(+)/PgR(-) 10.74%, and ER(-)/PgR(+) 2.01%, respectively, while in postmenopausal women, this distribution was observed to be 74.29%, 23.81%, 1.90% and 0.00% in the same order (p = 0.008). The most frequently mutated gene was TP53 in 130 patients (51.18%), followed by PIK3CA in 85 patients (33.46%), BRCA2 and NF1 in 56 patients (22.05%), PTEN in 54 patients (21.26%), and ATR and CHEK2 in 53 patients (20.87%). TP53, PIK3CA, NF1, BRCA2, PTEN, and CHEK2 mutations were more frequently observed in premenopausal patients, while TP53, PIK3CA, BRCA2, BRCA1, and ATR mutations in postmenopausal patients. These findings contribute to a deeper understanding of the underlying causes of breast cancer with respect to menopausal status. This study is the first from Turkey that reflects the molecular subtyping and somatic mutation profiles of breast cancer patients according to menopausal status.

Integrating imaging and genomic data for the discovery of distinct glioblastoma subtypes: a joint learning approach

Glioblastoma is a highly heterogeneous disease, with variations observed at both phenotypical and molecular levels. Personalized therapies would be facilitated by non-invasive in vivo approaches for characterizing this heterogeneity. In this study, we developed unsupervised joint machine learning between radiomic and genomic data, thereby identifying distinct glioblastoma subtypes. A retrospective cohort of 571 IDH-wildtype glioblastoma patients were included in the study, and pre-operative multi-parametric MRI scans and targeted next-generation sequencing (NGS) data were collected. L21-norm minimization was used to select a subset of 12 radiomic features from the MRI scans, and 13 key driver genes from the five main signal pathways most affected in glioblastoma were selected from the genomic data. Subtypes were identified using a joint learning approach called Anchor-based Partial Multi-modal Clustering on both radiomic and genomic modalities. Kaplan-Meier analysis identified three distinct glioblastoma subtypes: high-risk, medium-risk, and low-risk, based on overall survival outcome (p < 0.05, log-rank test; Hazard Ratio = 1.64, 95% CI 1.17-2.31, Cox proportional hazard model on high-risk and low-risk subtypes). The three subtypes displayed different phenotypical and molecular characteristics in terms of imaging histogram, co-occurrence of genes, and correlation between the two modalities. Our findings demonstrate the synergistic value of integrated radiomic signatures and molecular characteristics for glioblastoma subtyping. Joint learning on both modalities can aid in better understanding the molecular basis of phenotypical signatures of glioblastoma, and provide insights into the biological underpinnings of tumor formation and progression.

Salivary Duct Carcinoma Arising in the Submandibular Gland in a Patient with Neurofibromatosis Type 1

A 71-year-old man with neurofibromatosis type 1 (NF1) presented to our department with a 1-week history of a painful mass in the left submandibular area. Computed tomography (CT) and magnetic resonance imaging revealed an irregular-shaped tumor with a diameter of 2.0 cm in the left submandibular gland and a metastatic lymph node with a diameter of 1.0 cm adjacent to the tumor. Fluorodeoxyglucose-positron emission tomography/CT revealed increased uptake in the tumor. Fine-needle aspiration cytology revealed atypical cells, suggesting salivary duct carcinoma (SDC). Left neck dissection with resection of the tumor and submandibular gland was performed under general anesthesia. Histologic examination revealed ductal formation with a solid, cystic, cribriform, and papillary structure with intraductal comedonecrosis, diagnosing as SDC originating in the submandibular gland (pT3N1M0 pStage III). Mutational analysis of 160 cancer-related genes by next-generation sequencing (NGS) revealed a germline and frameshift mutation in the NF1 gene (p.R2408Kfs*14) and a somatic and frameshift mutation in the TP53 gene (p.C176Wfs*22). The patient received postoperative radiotherapy to the left neck area at 66 Gy. No evidence of recurrence or metastasis has been observed as of 10 months postoperatively. This is the first reported case of SDC in the submandibular gland in a patient with NF1. The mutational data by NGS may contribute to a better understanding of the oncogenesis of SDC in patients with NF1.

Emerging insights into cephalic neural crest disorders: A single center experience

Objectives

Neural crest cells (NCCs) are transient structures in the fetal life in vertebrates, which develop at the junctional site of the non-neural and neural ectoderm, sharing a common developmental origin for diverse diseases. After Epithelio-mesenchymal (EMT) of the NCCs within the neural tube, delamination of NCCs occurs. After delamination, the transformation of these cells into various cell lineages produces melanocytes, bones, and cartilage of the skull, cells of the enteric and peripheral nervous system. After the conversion, these cells migrate into various locations of the entire body according to the cell lineage. Abnormalities in neural crest (NC) formation and migration result in various malformations and tumors, known as neurocristopathy.

Material and Methods

Herein, this case series describes a single-center experience in cephalic NC disorders over the past 3 years, including 17 cases of varying composition (i.e., vascular, dysgenetic, mixed, and neoplastic forms) involving the brain and occasionally skin, eyes, and face of the patients.

Results

In our study of 17 patients with cephalic NC disease, 6 (35.3%) patients had vascular form, 5 (29.4%) had dysgenetic form, 4 (23.5%) had mixed form, and 2 (11.7%) had neoplastic form. Brain involvement in the form of vascular or parenchyma or both vascular and parenchymal was seen in all of our patients (100%), skin in 6 (35.3%) patients, eye in 2 (11.7%), and face in 1 (5.9%) patient. Treatment was planned according to the various manifestations of the disease.

Conclusion

Neural crest diseases (NCDs) are a rare and under-recognized group of disorders in the literature and may have been under-reported due to a lack of awareness regarding the same. More such reporting may increase the repertoire of these rare disorders such that clinicians can have a high degree of suspicion leading to early detection and timely counseling and also improve preventive strategies and help in developing new drugs for these disorders or prevent them.

Distinctive mesenchymal-like neurofibroma stem cells shape NF1 clinical phenotypes controlled by BDNF microenvironment

BACKGROUND

Neurofibroma type I (NF1) often presents with multiple clinical phenotypes due to mutations of NF1 gene. The aim of this study was to determine the phenotypic and therapeutic relevance of tumor microenvironment in NF1 patients.

METHODS

Tumor stem cells (TSCs) from NF1 were isolated and cultured using fluorescence activated cell sorting (FACS) and colony formation experiments. Then, flow cytometry was used to detect the surface markers, osteogenic and adipogenic differentiation were performed as well. Its tumorigenesis ability was confirmed by subcutaneous tumorigenesis in nude mice. Immunohistochemical staining was performed on neurofibroma tissues from the head and trunk with different phenotypes. The expression of BDNF in neurofibroma tissues was detected by Elisa and immunohistochemical staining. Western Blotting was used to detect the expression of p38 MAPK pathway in TSCs. The effect of BDNF neutralizing antibody on the tumorigenesis of TSCs was observed.

RESULTS

Herein, we advocate that NF1 contain a new subgroup of mesenchymal-like neurofibroma stem cells (MNSCs). Such colony-forming MNSCs preserved self-renewal, multiple differentiation and tumorigenic capabilities. More interestingly, the MNSCs isolated from neurofibroma tissues of the same patient with different phenotypes presented site-specific capabilities. Moreover, different levels of brain-derived neurotrophic factor (BDNF) in neurofibroma tissues can impact the MNSCs by activating the TrkB/p38 MAPK pathway. Systemic administration of BDNF neutralizing antibodies inhibited MNSCs' characteristics.

CONCLUSIONS

We demonstrated that BDNF can modulate MNSCs and thereby controlling different tumor phenotypes between the head and trunk regions. Application of BDNF neutralizing antibodies may inhibit p38 MAPK pathway, therefore providing a promising strategy for managing NF1.

Antiseizure effect of MEK inhibitor in a child with neurofibromatosis type 1-Developmental and epileptic encephalopathy and optic pathway glioma

BACKGROUND

Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder due to a mutation in NF1 gene, resulting in phenotypically heterogeneous systemic manifestations. Patients with NF1 are prone to develop neoplasms of the central nervous system (CNS) and are particularly at risk for optic pathway gliomas (OPG). Epilepsy is another recognized neurologic complication in patients with NF1, with a prevalence estimated between 4% and 14%. Several case reports and early phase clinical trials have demonstrated that the mitogen-activated protein kinase inhibitors (MEKi) are effective in NF1-low-grade gliomas (LGGs), but their influence on seizure activity in humans has not been established.

CASE STUDY

Here, we report a patient with NF1 and developmental and epileptic encephalopathy (DEE) harboring pharmacoresistant tonic seizures, and progressive optic pathway glioma (OPG). By using a MEKi therapy for her OPG, we observed an end to epileptic seizures as well as a significant improvement of interictal EEG abnormalities, despite a lack of tumor reduction.

CONCLUSION

MEK inhibitor therapy should be considered for patients with NF1 and refractory epilepsy.

Direct comparison of the diagnostic accuracy of 2-[18F]-fluoro-2-deoxy-d-glucose PET/CT and MRI for the differentiation of malignant peripheral nerve sheath tumour in neurofibromatosis type I: a meta-analysis

AIM

To compare the diagnostic test of integrated 2-[18F]-fluoro-2-deoxy-d-glucose positron-emission tomography/computed tomography (FDG PET/CT) with that of magnetic resonance imaging (MRI) for the differentiation of malignant peripheral nerve sheath tumours (MPNSTs) in neurofibromatosis type 1 (NF1) patients.

MATERIALS AND METHODS

A systematic search was performed in PubMed and EMBASE (last updated in 30 November 2022). Studies investigating the performance of FDG PET/CT and MRI for differentiation of MPNSTs were eligible for inclusion. Only studies reporting a direct comparison between these imaging methods were considered to establish precise summary estimates in the same setting of patients.

RESULTS

The pooled estimate of sensitivity of FDG PET/CT was 0.99 and a pooled specificity of 0.53. The pooled estimate of sensitivity of MRI was 0.85 and a pooled specificity of 0.85.

CONCLUSION

Analysis of the available studies indicated that FDG PET/CT and MRI had similar diagnostic performances for differentiation of MPNSTs in patients with NF1; however, either technique can be a complement to the other rather than being used singly.

Exploring Perforated Jejunal GIST: A Rare Case Report and Review of Molecular and Clinical Literature

This case report details a rare instance of a perforated jejunal gastrointestinal stromal tumor (GIST) in a 76-year-old female patient. The patient presented with acute abdominal pain and distension without any changes in bowel habits or episodes of nausea and vomiting. Initial diagnostics, including abdominal plain radiography and ultrasonography, were inconclusive; however, a computed tomography (CT) scan revealed pneumoperitoneum and an irregular fluid collection suggestive of small intestine perforations. Surgical intervention uncovered a 35 mm jejunal GIST with a 10 mm perforation. Histopathological examination confirmed a mixed cell type GIST with high malignancy potential, further substantiated by immunohistochemistry markers CD117, DOG1, and vimentin. Molecular analysis illuminated the role of key oncogenes, primarily KIT and PDGFRA mutations, emphasizing the importance of molecular diagnostics in GIST management. Despite the severity of the presentation, the patient's postoperative recovery was favorable, highlighting the effectiveness of prompt surgical and multidisciplinary approaches in managing complex GIST cases.

Neurologic orphan diseases: Emerging innovations and role for genetic treatments

Orphan diseases are rare diseases that affect less than 200000 individuals within the United States. Most orphan diseases are of neurologic and genetic origin. With the current advances in technology, more funding has been devoted to developing therapeutic agents for patients with these conditions. In our review, we highlight emerging options for patients with neurologic orphan diseases, specifically including diseases resulting in muscular deterioration, epilepsy, seizures, neurodegenerative movement disorders, inhibited cognitive development, neuron deterioration, and tumors. After extensive literature review, gene therapy offers a promising route for the treatment of neurologic orphan diseases. The use of clustered regularly interspaced palindromic repeats/Cas9 has demonstrated positive results in experiments investigating its role in several diseases. Additionally, the use of adeno-associated viral vectors has shown improvement in survival, motor function, and developmental milestones, while also demonstrating reversal of sensory ataxia and cardiomyopathy in Friedreich ataxia patients. Antisense oligonucleotides have also been used in some neurologic orphan diseases with positive outcomes. Mammalian target of rapamycin inhibitors are currently being investigated and have reduced abnormal cell growth, proliferation, and angiogenesis. Emerging innovations and the role of genetic treatments open a new window of opportunity for the treatment of neurologic orphan diseases.

Minimal intervention for neurofibromatosis type I manifestations: A case report

INTRODUCTION AND IMPORTANCE

Neurofibromatosis type I (NF1, OMIM: 162200) is a benign, autosomal dominant, tumorigenic predisposing syndrome with variable manifestations. Both neurofibromatosis and soft tissue sarcomas are associated with the formation of hematomas. Moreover, skeletal manifestations of NF1 include focal or generalized forms and expansive or infiltrative growth types.

CASE PRESENTATION

A 19-year-old NF1 female patient presented with an expanding post-traumatic facial hematoma that resembled a soft-tissue tumor at initial presentation. A congenital neck mass was noted ipsilateral to her craniofacial skeletal deformities. Multiple imaging modalities were used to aid diagnosis, and urgent surgical intervention of the expanding facial lesion was performed. Her neck lesion and skeletal deformities were monitored, and her recovery was uneventful at 1-year follow-up, with no progression.

CLINICAL DISCUSSION

A palpable, non-pulsatile soft tissue mass is a common clinical presentation with a diverse differential diagnosis. Despite the low incidence of post-traumatic vascular injuries and lesions in the maxillofacial region, neurofibromatosis-associated vasculopathy remains an underestimated and serious manifestation of NF1. The reported zygomatic arch deformity is believed to be unique. However, the NF1 tumor-associated skeletal malformations are not linearly related.

CONCLUSION

NF1 is a multisystem disorder necessitating an early multidisciplinary team approach. Minimal intervention can help convert an emergent operation into an urgent one and preclude the need for major surgery. The case illustrated a rare example of simultaneous affection of soft tissue and jaw bones in NF1 patients.

The Contribution of Oxidative Stress to NF1-Altered Tumors

The neurofibromatosis-1 gene (NF1) was initially characterized because its germline mutation is responsible for an inherited syndromic disease predisposing tumor development, in particular neurofibromas but also various malignancies. Recently, large-scale tumor sequencing efforts have demonstrated NF1 as one of the most frequently mutated genes in human cancer, being mutated in approximately 5-10% of all tumors, especially in malignant peripheral nerve sheath tumors and different skin tumors. NF1 acts as a tumor suppressor gene that encodes neurofibromin, a large protein that controls neoplastic transformation through several molecular mechanisms. On the other hand, neurofibromin loss due to NF1 biallelic inactivation induces tumorigenic hyperactivation of Ras and mTOR signaling pathways. Moreover, neurofibromin controls actin cytoskeleton structure and the metaphase-anaphase transition. Consequently, neurofibromin deficiency favors cell mobility and proliferation as well as chromosomal instability and aneuploidy, respectively. Growing evidence supports the role of oxidative stress in NF1-related tumorigenesis. Neurofibromin loss induces oxidative stress both directly and through Ras and mTOR signaling activation. Notably, innovative therapeutic approaches explore drug combinations that further increase reactive oxygen species to boost the oxidative unbalance of NF1-altered cancer cells. In our paper, we review NF1-related tumors and their pathogenesis, highlighting the twofold contribution of oxidative stress, both tumorigenic and therapeutic.

Proteogenomic Approaches for the Identification of NF1/Neurofibromin-depleted Estrogen Receptor-positive Breast Cancers for Targeted Treatment

NF1 is a key tumor suppressor that represses both RAS and estrogen receptor-α (ER) signaling in breast cancer. Blocking both pathways by fulvestrant (F), a selective ER degrader, together with binimetinib (B), a MEK inhibitor, promotes tumor regression in NF1-depleted ER⁺ models. We aimed to establish approaches to determine how NF1 protein levels impact B+F treatment response to improve our ability to identify B+F sensitive tumors. We examined a panel of ER⁺ patient-derived xenograft (PDX) models by DNA and mRNA sequencing and found that more than half of these models carried an NF1 shallow deletion and generally have low mRNA levels. Consistent with RAS and ER activation, RET and MEK levels in NF1-depleted tumors were elevated when profiled by mass spectrometry (MS) after kinase inhibitor bead pulldown. MS showed that NF1 can also directly and selectively bind to palbociclib-conjugated beads, aiding quantification. An IHC assay was also established to measure NF1, but the MS-based approach was more quantitative. Combined IHC and MS analysis defined a threshold of NF1 protein loss in ER⁺ breast PDX, below which tumors regressed upon treatment with B+F. These results suggest that we now have a MS-verified NF1 IHC assay that can be used for patient selection as a complement to somatic genomic analysis.

Significance

A major challenge for targeting the consequence of tumor suppressor disruption is the accurate assessment of protein functional inactivation. NF1 can repress both RAS and ER signaling, and a ComboMATCH trial is underway to treat the patients with binimetinib and fulvestrant. Herein we report a MS-verified NF1 IHC assay that can determine a threshold for NF1 loss to predict treatment response. These approaches may be used to identify and expand the eligible patient population.

Dermatologic Manifestations of Neurofibromatosis Type 1 and Emerging Treatments

Neurofibromatosis type 1 (NF1) is an autosomal dominant tumor predisposition syndrome that increases one's risk for both benign and malignant tumors. NF1 affects every organ in the body, but the most distinctive symptoms that are often the most bothersome to patients are the cutaneous manifestations, which can be unsightly, cause pain or pruritus, and have limited therapeutic options. In an effort to increase awareness of lesser-known dermatologic associations and to promote multidisciplinary care, we conducted a narrative review to shed light on dermatologic associations of NF1 as well as emerging treatment options. Topics covered include cutaneous neurofibromas, plexiform neurofibromas, diffuse neurofibromas, distinct nodular lesions, malignant peripheral nerve sheath tumors, glomus tumors, juvenile xanthogranulomas, skin cancer, and cutaneous T-cell lymphoma.

Role of SEC14-like phosphatidylinositol transfer proteins in membrane identity and dynamics

Membrane identity and dynamic processes, that act at membrane sites, provide important cues for regulating transport, signal transduction and communication across membranes. There are still numerous open questions as to how membrane identity changes and the dynamic processes acting at the surface of membranes are regulated in diverse eukaryotes in particular plants and which roles are being played by protein interaction complexes composed of peripheral and integral membrane proteins. One class of peripheral membrane proteins conserved across eukaryotes comprises the SEC14-like phosphatidylinositol transfer proteins (SEC14L-PITPs). These proteins share a SEC14 domain that contributes to membrane identity and fulfills regulatory functions in membrane trafficking by its ability to sense, bind, transport and exchange lipophilic substances between membranes, such as phosphoinositides and diverse other lipophilic substances. SEC14L-PITPs can occur as single-domain SEC14-only proteins in all investigated organisms or with a modular domain structure as multi-domain proteins in animals and streptophytes (comprising charales and land plants). Here, we present an overview on the functional roles of SEC14L-PITPs, with a special focus on the multi-domain SEC14L-PITPs of the SEC14-nodulin and SEC14-GOLD group (PATELLINs, PATLs in plants). This indicates that SEC14L-PITPs play diverse roles from membrane trafficking to organism fitness in plants. We concentrate on the structure of SEC14L-PITPs, their ability to not only bind phospholipids but also other lipophilic ligands, and their ability to regulate complex cellular responses through interacting with proteins at membrane sites.

The therapeutic potential of neurofibromin signaling pathways and binding partners

Neurofibromin controls many cell processes, such as growth, learning, and memory. If neurofibromin is not working properly, it can lead to health problems, including issues with the nervous, skeletal, and cardiovascular systems and cancer. This review examines neurofibromin's binding partners, signaling pathways and potential therapeutic targets. In addition, it summarizes the different post-translational modifications that can affect neurofibromin's interactions with other molecules. It is essential to investigate the molecular mechanisms that underlie neurofibromin variants in order to provide with functional connections between neurofibromin and its associated proteins for possible therapeutic targets based on its biological function.

Exploiting metabolic vulnerabilities in breast cancers with NF1 loss

Auf der Maur et al.¹ identify neurofibromin 1 (NF1) loss as a mechanism of resistance to PI3K inhibitor in breast cancer cells. NF1 loss leads to enhanced glycolysis, which may be targeted with the antioxidant N-acetyl cysteine (NAC).

N-acetylcysteine overcomes NF1 loss-driven resistance to PI3Kα inhibition in breast cancer

A genome-wide PiggyBac transposon-mediated screen and a resistance screen in a PIK3CA^H1047R-mutated murine tumor model reveal NF1 loss in mammary tumors resistant to the phosphatidylinositol 3-kinase α (PI3Kα)-selective inhibitor alpelisib. Depletion of NF1 in PIK3CA^H1047R breast cancer cell lines and a patient-derived organoid model shows that NF1 loss reduces sensitivity to PI3Kα inhibition and correlates with enhanced glycolysis and lower levels of reactive oxygen species (ROS). Unexpectedly, the antioxidant N-acetylcysteine (NAC) sensitizes NF1 knockout cells to PI3Kα inhibition and reverts their glycolytic phenotype. Global phospho-proteomics indicates that combination with NAC enhances the inhibitory effect of alpelisib on mTOR signaling. In public datasets of human breast cancer, we find that NF1 is frequently mutated and that such mutations are enriched in metastases, an indication for which use of PI3Kα inhibitors has been approved. Our results raise the attractive possibility of combining PI3Kα inhibition with NAC supplementation, especially in patients with drug-resistant metastases associated with NF1 loss.

Lymphomas in patients with neurofibromatosis type 1 (NF1): another malignancy in the NF1 syndrome?

Neurofibromatosis type 1 (NF1) is an autosomal dominant multisystem syndrome caused by mutations in the neurofibromin 1 (NF1) gene that encodes for the protein neurofibromin acting as a tumour suppressor. Neurofibromin functions primarily as a GTPase-activating protein for the Ras family of oncogenes, which activates many signalling pathways for cell proliferation and differentiation; without neurofibromin, Ras is constitutively activated, thereby turning on many downstream signalling pathways related to oncogenesis. Patients with NF1 have a well known predisposition for certain types of malignancies including malignant peripheral nerve sheath tumours, gliomas, and breast cancers, as well as a potential association of NF1 with lymphoproliferative disorders such as lymphomas. In this article, we review the pathophysiology and tumourigenesis of NF1, previously reported cases of cutaneous lymphomas in NF1 patients along with our case demonstration of a NF1-associated scalp B-cell lymphoma, and NF1-associated extra cutaneous lymphomas. The diagnosis of lymphomas particularly cutaneous lymphomas may be difficult in NF1 patients as they often have skin lesions and/or cutaneous/subcutaneous nodules or tumours like neurofibromas, which raises the possibility of underdiagnosed cutaneous lymphomas in NF1 patients. We also comprehensively discuss the association between NF1 and lymphomas. In summary, most studies support a potential association between NF1 and lymphomas. Further investigation is needed to clarify the association between NF1 and lymphomas in order to bring clinical awareness of possibly underdiagnosed NF1-associated lymphomas and individualised management of NF1 patients to practice.

French cohort of children and adolescents with neurofibromatosis type 1 and symptomatic inoperable plexiform neurofibromas: CASSIOPEA study

Surgery is a treatment option for neurofibromatosis type 1 (NF1)-related plexiform neurofibromas (PN), but complete resection is often not feasible. Real-world studies are warranted to understand disease burden, progression, and need for medical treatment in patients with inoperable PN. CASSIOPEA was a retrospective study of French pediatric patients (aged ≥3 to <18 years) presenting at a national multidisciplinary team (MDT) review with NF1 and ≥1 symptomatic, inoperable PN. Medical records were reviewed from the time of MDT review and over a follow-up period of up to 2 years. Primary objectives were to describe patient characteristics and target PN-associated therapy patterns. A secondary objective was evolution of target PN-related morbidities. Patients with prior, ongoing, or MDT recommendation of mitogen-activated protein kinase kinase (MEK) inhibitor treatment were excluded. Overall, 78 target PN were identified in 76 patients. At MDT review, median age was 8.4 years, with approximately 30% of patients aged 3-6 years. Target PN were primarily internal (77.3%), and 43.2% were progressive. Target PN location was evenly distributed. 34 target PN had documented MDT recommendations; of these, a majority (76.5%) were for non-medication management, including surveillance. At least one follow-up visit was recorded for 74 target PN. Despite initially being considered inoperable, 12.3% of patients underwent surgery for target PN. At MDT review, most (98.7%) target PN were associated with ≥1 morbidity, primarily pain (61.5%) and deformity (24.4%); severe morbidities were identified in 10.3%. Of 74 target PN with follow-up data, 89.2% were associated with ≥1 morbidity, primarily pain (60.8%) and deformity (25.7%). Of 45 target PN associated with pain, pain improved in 26.7%, was stable in 44.4%, and deteriorated in 28.9%. Deformity improved in 15.8% and remained stable in 84.2% of 19 target PN associated with deformity. None deteriorated. In this real-world study in France, NF1-PN disease burden was considerable, and a considerable proportion of patients were very young. Most patients received only supportive care without medication for target PN management. Target PN-related morbidities were frequent, heterogeneous, and generally did not improve during follow-up. These data highlight the importance of effective treatments that target PN progression and improve disease burden.

Perineum Spindle Cell Sarcoma in Neurofibromatosis Type 1

Soft tissue neoplasm is common among patients with neurofibromatosis type 1 (NF-1). We present a case of a middle-aged woman with NF-1 who presented with a painless, insidiously increasing perineal mass for the past eight months. She underwent colonoscopy, computed tomography staging, magnetic resonance imaging of the pelvis, core-needle biopsy, and later wide local excision of left perineum swelling. Histopathological examination showed a high-grade spindle cell sarcoma, which is a rare association among NF-1. Spindle cell sarcoma is a group of malignant soft tissue tumors with locally destructive growth with spindle-shaped neoplastic cells. The solitary spindle cell sarcoma of the perineum is rare, and wide local resection with a clear margin is the only treatment at present-the scarcely available evidence limiting the use of adjuvant chemotherapy, immunotherapy, and radiotherapy.

Predicting IHC staining classes of NF1 using features in the hematoxylin channel

Immunohistochemistry (IHC) highlights specific cell types in tissues and traditionally involves antibody staining together with a hematoxylin counterstain. The intensity and pattern of hematoxylin staining differs between cell types and reveals morphological characteristics of cells. Here, we propose that features in the hematoxylin stain can be used to predict IHC labels, such as Neurofibromin (encoded by the gene NF1). The dataset consists of 7.2 million cells from benign and kidney cancer cores in a tissue microarray. Morphology and hematoxylin (H&M) features defined within QuPath are subjected to a clustering analysis in CytoMap. H&M features are also used to train 4 different XGBoost models to predict high, low, and negative NF1 stain classes in benign renal tubules, clear cell (ccRCC), papillary (PRCC), and chromophobe (ChRCC) renal carcinoma. The prediction accuracies of NF1 staining classes in benign, ccRCC, ChRCC, and PRCC range between 70% and 90% with areas under the precision recall curve PRAUC_NF1-high = 0.82+0.12, PRAUC_NF1-low = 0.62+0.25, and PRAUC_NF1-negative = 0.83+0.16. The most important feature for predicting the NF1 class involves the minimum cellular hematoxylin staining intensity. Together, these results demonstrate the feasibility to predict NF1 expression solely from features in hematoxylin staining using open source software. Since the hematoxylin features can be obtained from regular H&E and IHC slides, the proposed workflow has broad applicability.

Personalized matched targeted therapy in advanced pancreatic cancer: a pilot cohort analysis

Despite progress, 2-year pancreatic cancer survival remains dismal. We evaluated a biomarker-driven, combination/N-of-one strategy in 18 patients (advanced/metastatic pancreatic cancer) (from Molecular Tumor Board). Targeted agents administered/patient = 2.5 (median) (range, 1-4); first-line therapy (N = 5); second line, (N = 13). Comparing patients (high versus low degrees of matching) (matching score ≥50% versus <50%; reflecting number of alterations matched to targeted agents divided by number of pathogenic alterations), survival was significantly longer (hazard ratio [HR] 0.24 (95% confidence interval [CI], 0.078-0.76, P = 0.016); clinical benefit rates (CBR) (stable disease ≥6 months/partial/complete response) trended higher (45.5 vs 0.0%, P = 0.10); progression-free survival, HR, 95% CI, 0.36 (0.12-1.10) (p = 0.075). First versus ≥2nd-line therapy had higher CBRs (80.0 vs 7.7%, P = 0.008). No grade 3-4 toxicities occurred. The longest responder achieved partial remission (17.5 months) by co-targeting MEK and CDK4/6 alterations (chemotherapy-free). Therefore, genomically matched targeted agent combinations were active in these advanced pancreatic cancers. Larger prospective trials are warranted.

Melanoma and Glioblastoma-Not a Serendipitous Association

Recently, we came across a patient with malignant melanoma and primary glioblastoma. Given this, we parsed the literature to ascertain the relationship, if any, between these 2 malignancies. We begin with a brief overview of melanoma and glioma in isolation followed by a chronologic overview of case reports and epidemiologic studies documenting both neoplasms. This is followed by studies detailing genetic abnormalities common to both malignancies with a view to identifying unifying genetic targets for therapeutic strategies as well as to explore the possibility of a putative association and an inherited cancer susceptibility trait. From a scientific perspective, we believe we have provided evidence favoring an association between melanoma and glioma. Future studies that include documentation of additional cases, as well as a detailed molecular analyses, will lend credence to our hypothesis that the co-occurrence of these 2 conditions is likely not serendipitous.

Identification of Germinal Neurofibromin Hotspots

Neurofibromin is engaged in many cellular processes and when the proper protein functioning is impaired, it causes neurofibromatosis type 1 (NF1), one of the most common inherited neurological disorders. Recent advances in sequencing and screening of the NF1 gene have increased the number of detected variants. However, the correlation of these variants with the clinic remains poorly understood. In this study, we analyzed 4610 germinal NF1 variants annotated in ClinVar and determined on exon level the mutational spectrum and potential pathogenic regions. Then, a binomial and sliding windows test using 783 benign and 938 pathogenic NF1 variants were analyzed against functional and structural regions of neurofibromin. The distribution of synonymous, missense, and frameshift variants are statistically significant in certain regions of neurofibromin suggesting that the type of variant and its associated phenotype may depend on protein disorder. Indeed, there is a negative correlation between the pathogenic fraction prediction and the disorder data, suggesting that the higher an intrinsically disordered region is, the lower the pathogenic fraction is and vice versa. Most pathogenic variants are associated to NF1 and our analysis suggests that GRD, CSRD, TBD, and Armadillo1 domains are hotspots in neurofibromin. Knowledge about NF1 genotype–phenotype correlations can provide prognostic guidance and aid in organ-specific surveillance.

Efficacy and Safety of Trametinib in Neurofibromatosis Type 1-Associated Plexiform Neurofibroma and Low-Grade Glioma: A Systematic Review and Meta-Analysis

Trametinib has been used in neurofibromatosis type 1 (NF1) patients, especially those with unresectable nerve tumors, but no systematic review based on the latest studies has been published. We conducted this meta-analysis to evaluate the effectiveness and safety of trametinib in treating NF1-related nerve tumors. Original articles reporting the efficacy and safety of trametinib in NF1 patents were identified in PubMed, EMBASE, and Web of Science up to 1 June 2022. Using R software and the ‘meta’ package, the objective response rates (ORRs) and disease control rates (DCRs) were calculated to evaluate the efficacy, and the pooled proportion of adverse events (AEs) was calculated. The Grading of Recommendations, Assessment, Development and Evaluation system was used to assess the quality of evidence. Eight studies involving 92 patients were included, which had a very low to moderate quality of evidence. The pooled ORR was 45.3% (95% CI: 28.9–62.1%, I² = 0%), and the DCR was 99.8% (95% CI: 95.5–100%, I² = 0%). The most common AEs was paronychia, with a pooled rate of 60.7% (95% CI: 48.8–72.7%, I² = 0%). Our results indicate the satisfactory ability to stabilize tumor progression but a more limited ability to shrink tumors of trametinib in NF1-related nerve tumors. The safety profile of trametinib is satisfactory.

Synthetic Approaches to the New Drugs Approved During 2020

New drugs introduced to the market are privileged structures that have affinities for biological targets implicated in human diseases and conditions. These new chemical entities (NCEs), particularly small molecules and antibody-drug conjugates (ADCs), provide insight into molecular recognition and simultaneously function as leads for the design of future medicines. This Review is part of a continuing series presenting the most likely process-scale synthetic approaches to 44 new chemical entities approved for the first time anywhere in the world during 2020.

Total-Body Irradiation Is Associated With Increased Incidence of Mesenchymal Neoplasia in a Radiation Late Effects Cohort of Rhesus Macaques (Macaca mulatta)

PURPOSE

Cancer is a severe delayed effect of acute radiation exposure. Total-body irradiation has been associated with an increased risk of solid cancer and leukemia in Japanese atomic bomb survivors, and secondary malignancies, such as sarcoma, are a serious consequence of cancer radiation therapy. The radiation late effects cohort (RLEC) of rhesus macaques (Macaca mulatta) is a unique resource of more than 200 animals for studying the long-term consequences of total-body irradiation in an animal model that closely resembles humans at the genetic and physiologic levels.

METHODS AND MATERIALS

Using clinical records, clinical imaging, histopathology, and immunohistochemistry, this retrospective study characterized the incidence of neoplasia in the RLEC.

RESULTS

Since 2007, 61 neoplasms in 44 of 239 irradiated animals were documented (18.4% of the irradiated population). Only 1 neoplasm was diagnosed among the 51 nonirradiated controls of the RLEC (2.0%). The most common malignancies in the RLEC were sarcomas (38.3% of diagnoses), which are rare neoplasms in nonirradiated macaques. The most common sarcomas included malignant nerve sheath tumors and malignant glomus tumors. Carcinomas were less common (19.7% of diagnoses), and consisted primarily of renal cell and hepatocellular carcinomas. Neoplasia occurred in most major body systems, with the skin and subcutis being the most common site (40%). RNA analysis showed similarities in transcriptional profiles between RLEC and human malignant nerve sheath tumors.

CONCLUSIONS

This study indicates that total-body irradiation is associated with an increased incidence of neoplasia years following irradiation, at more than double the incidence described in aging, nonirradiated animals, and promotes tumor histotypes that are rarely observed in nonirradiated, aging rhesus macaques.

Epidemiological profile and clinical characteristics of 491 Brazilian patients with neurofibromatosis type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a chronic and progressive autosomal dominant genetic and sporadic disease characterized by cutaneous and neurological abnormalities. Plexiform neurofibroma (PN), a significant cause of clinical complications in NF-1, is a benign tumor of the peripheral nerve sheath that involves multiple nerve fascicles. Although there is an important number of patients who are affected by NF1 in Brazil, there is little data on the behavior of the disease in the national literature as well as in other low- and middle-income countries.

METHODS

We performed a retrospective analysis of 491 patients with NF1 followed at two reference centers in Brazil.

RESULTS

Approximately 38% of patients had PNs, resulting in reduced life quality. The median patient age with PNs was 30 years (range: 6 to 83 years). Head and neck, and extremity were the main affected locations with 35.8 and 30.6%, respectively. PNs were classified as asymptomatic in 25.1% of patients, while 52.5% presented symptomatic and inoperable tumors. The most common manifestations related to PNs were disfigurement and orthopedic involvement. Twenty patients developed neoplasms and ten (50%) presented with malignant peripheral nerve sheath tumors (MPNST). The prevalence of MPNST in our study was 2.9%.

CONCLUSIONS

Patients with NF1 experience clinically significant morbidity, especially when it is associated with PN. Though there are many patients affected by NF1 in Brazil and other low- and middle-income countries, there is little data available in the corresponding literature. Our results are comparable to the previous results reported from higher-income countries and international registries.

Signaling pathways and therapeutic approaches in glioblastoma multiforme (Review)

Glioblastoma multiforme (GBM) is the most aggressive type of primary brain tumor and is associated with a poor clinical prognosis. Despite the progress in the understanding of the molecular and genetic changes that promote tumorigenesis, effective treatment options are limited. The present review intended to identify and summarize major signaling pathways and genetic abnormalities involved in the pathogenesis of GBM, as well as therapies that target these pathways. Glioblastoma remains a difficult to treat tumor; however, in the last two decades, significant improvements in the understanding of GBM biology have enabled advances in available therapeutics. Significant genomic events and signaling pathway disruptions (NF‑κB, Wnt, PI3K/AKT/mTOR) involved in the formation of GBM were discussed. Current therapeutic options may only marginally prolong survival and the current standard of therapy cures only a small fraction of patients. As a result, there is an unmet requirement for further study into the processes of glioblastoma pathogenesis and the discovery of novel therapeutic targets in novel signaling pathways implicated in the evolution of glioblastoma.

Extracranial Vertebral Artery-Internal Jugular Vein-Spinal Vein Fistula in Neurofibromatosis Type I: Case Report and Literature Review

Background

A cervical arteriovenous fistula (AVF) in neurofibromatosis type I (NF-1) is uncommon, and it brings challenges and difficulty in treatment.

Case Presentation

A 39-year-old woman was diagnosed with an NF-1-associated spontaneous vertebral artery-internal jugular vein-spinal vein fistula. The fistula was placed by coil embolization. Postoperative examination showed that the fistula closure was satisfied, and the patient's abnormal clinical manifestation disappeared without any complications after 24 months of interventional embolization. As per the literature, interventional embolization is currently the main treatment method, and it has the distinguishing features of less trauma, quick recovery, and a good prognosis.

Conclusion

NF-1 associated with a spontaneous arteriovenous fistula is rare in clinical practice, which carries significant challenges in treatment, but can be effectively treated using endovascular embolism. Endovascular embolism could be the potential choice of treatment in NF-1 associated with AVF.

Tumor growth of neurofibromin-deficient cells is driven by decreased respiration and hampered by NAD+ and SIRT3

Neurofibromin loss drives neoplastic growth and a rewiring of mitochondrial metabolism. Here we report that neurofibromin ablation dampens expression and activity of NADH dehydrogenase, the respiratory chain complex I, in an ERK-dependent fashion, decreasing both respiration and intracellular NAD⁺. Expression of the alternative NADH dehydrogenase NDI1 raises NAD⁺/NADH ratio, enhances the activity of the NAD⁺-dependent deacetylase SIRT3 and interferes with tumorigenicity in neurofibromin-deficient cells. The antineoplastic effect of NDI1 is mimicked by administration of NAD⁺ precursors or by rising expression of the NAD⁺ deacetylase SIRT3 and is synergistic with ablation of the mitochondrial chaperone TRAP1, which augments succinate dehydrogenase activity further contributing to block pro-neoplastic metabolic changes. These findings shed light on bioenergetic adaptations of tumors lacking neurofibromin, linking complex I inhibition to mitochondrial NAD⁺/NADH unbalance and SIRT3 inhibition, as well as to down-regulation of succinate dehydrogenase. This metabolic rewiring could unveil attractive therapeutic targets for neoplasms related to neurofibromin loss.

Genetic Background of Polycythemia Vera

Polycythemia vera belongs to myeloproliferative neoplasms, essentially by affecting the erythroblastic lineage. JAK2 alterations have emerged as major driver mutations triggering PV-phenotype with the V617F mutation detected in nearly 98% of cases. That’s why JAK2 targeting therapeutic strategies have rapidly emerged to counter the aggravation of the disease. Over decades of research, to go further in the understanding of the disease and its evolution, a wide panel of genetic alterations affecting multiple genes has been highlighted. These are mainly involved in alternative splicing, epigenetic, miRNA regulation, intracellular signaling, and transcription factors expression. If JAK2 mutation, irrespective of the nature of the alteration, is known to be a crucial event for the disease to initiate, additional mutations seem to be markers of progression and poor prognosis. These discoveries have helped to characterize the complex genomic landscape of PV, resulting in potentially new adapted therapeutic strategies for patients concerning all the genetic interferences.

Utility of next-generation sequencing in genetic testing and counseling of disorders involving the musculoskeletal system—trends observed from a single genetic unit

Background

Disorders involving the musculoskeletal system are often identified with short stature and a range of orthopedic problems. The clinical and genetic heterogeneity of these diseases along with several characteristic overlaps makes definitive diagnosis difficult for clinicians. Hence, using molecular testing in addition to conventional tests becomes essential for appropriate diagnosis and management.

Methods

Comprehensive clinical examination, detailed pretest and posttest counseling, molecular diagnosis with next-generation sequencing (NGS), genotype–phenotype correlation and Sanger sequencing for targeted variant analysis.

Results

This manuscript reports a molecular spectrum of variants in 34 orthopedic cases referred to a single genetic unit attached to a tertiary care hospital. The diagnostic yield of NGS-based tests coupled with genetic counseling and segregation analysis was 79% which included 7 novel variants. In about 53% (i.e. 18/34 cases), molecular testing outcome was actionable since 8 of the 18 underwent prenatal diagnosis, as they were either in their early gestation or had planned a pregnancy subsequent to molecular testing, while ten cases were premaritally/prenatally counseled for the families to take informed decisions as they were in the reproductive age.

Conclusions

The report highlights the importance of NGS-based tests even in a low resource setting as it helps patients, families and healthcare providers in reducing the economic, social and emotional burden of these disorders.

Current Aspects on the Pathophysiology of Bone Metabolic Defects during Progression of Scoliosis in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1), which is the most common phacomatoses, is an autosomal dominant disorder characterized by clinical presentations in various tissues and organs, such as the skin, eyes and nervous and skeletal systems. The musculoskeletal implications of NF1 include a variety of deformities, including scoliosis, kyphoscoliosis, spondylolistheses, congenital bony bowing, pseudarthrosis and bone dysplasia. Scoliosis is the most common skeletal problem, affecting 10-30% of NF1 patients. Although the pathophysiology of spinal deformities has not been elucidated yet, defects in bone metabolism have been implicated in the progression of scoliotic curves. Measurements of Bone Mineral Density (BMD) in the lumbar spine by using dual energy absorptiometry (DXA) and quantitative computer tomography (QCT) have demonstrated a marked reduction in Z-score and osteoporosis. Additionally, serum bone metabolic markers, such as vitamin D, calcium, phosphorus, osteocalcin and alkaline phosphatase, have been found to be abnormal. Intraoperative and histological vertebral analysis confirmed that alterations of the trabecular microarchitecture are associated with inadequate bone turnover, indicating generalized bone metabolic defects. At the molecular level, loss of function of neurofibromin dysregulates Ras and Transforming Growth factor-β1 (TGF-β1) signaling and leads to altered osteoclastic proliferation, osteoblastic activity and collagen production. Correlation between clinical characteristics and molecular pathways may provide targets for novel therapeutic approaches in NF1.

Efficacy and Safety of Selumetinib in Pediatric Patients With Neurofibromatosis Type 1: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVES

Although the recent approval of selumetinib is expected to transform the management of children with Neurofibromatosis type 1 (NF1), particularly those with symptomatic and inoperable PN, no systematic review has summarized their efficacy and safety based on the latest studies. This study was conducted to systematically evaluate the efficacy and safety of selumetinib in children with NF1 METHODS: Original articles reporting the efficacy and safety of selumetinib in patients with NF1 were identified in PubMed and EMBASE up to January 28, 2021. The pooled objective response rates (ORRs) and disease control rates (DCRs) were calculated using the DerSimonian-Laird method based on random-effects modeling. The pooled proportion of adverse events (AEs) was also calculated. The quality of the evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation system.

RESULTS

Five studies involving 126 patients were included in our analysis. The studies had a very low to moderate quality of the evidence. The pooled ORR was 73.8% (95% CI: 57.3-85.5%), and the DCR was 92.5% (95% CI: 66.5-98.7%). The two most common AEs were diarrhea, which had a pooled rate of 63.8% (95% CI, 52.9-73.4%) and an increase in creatine kinase levels, which had a pooled rate of 63.3% (95% CI, 35.6-84.3%).

DISCUSSION

Our results indicate that selumetinib is an effective and safe treatment for pediatric patients with symptomatic, inoperable plexiform neurofibromas. Further larger-scale randomized controlled studies are needed to confirm the long-term outcome of patients treated with this drug.

Expression of neurofibromin 1 in colorectal cancer and cetuximab resistance

Neurofibromin 1 (NF1) is a tumor suppressor that has been previously reported to regulate RAS‑MAPK signaling. The present study investigated the possible relationship between NF1 expression and anti‑EGFR antibody (cetuximab) sensitivity in colorectal cancer cell lines. In addition, primary or metastatic colorectal cancer samples from patients treated with cetuximab were assessed for the association of cetuximab sensitivity. The quantities of the NF1 transcript, NF1‑related pathway enrichment and NF1 mutation profile were measured and investigated using RNA sequencing and targeted DNA sequencing. Based on growth inhibition and colony formation assay results, cell lines were designated to be cetuximab‑sensitive (NCI‑H508 and Caco2) or cetuximab‑resistant (KM12C and SM480). Western blotting revealed NF1 was highly expressed in cetuximab‑sensitive cell lines whilst there was little expression in their cetuximab‑resistant counterparts. Knocking down NF1 expression using small interfering RNA in the cetuximab‑sensitive cell lines enhanced the phosphorylation of MEK and ERK according to western blotting. NF1 knockdown also reduced apoptosis, as observed by the decreased number of apoptotic bodies by DAPI nuclear staining and reduced cleavage of caspase and poly‑(ADP ribose) polymerase. NF1 overexpression by transfection with GTPase‑activating protein‑related domain subunit rendered the cetuximab‑resistant cell lines, KM12C and SW480, more susceptible to cetuximab‑induced apoptosis. RNA sequencing of 111 RAS and BRAF^V600 wild‑type tumor samples collected from cetuximab‑treated patients with metastatic colorectal cancer revealed that the pre‑treatment NF1 expression levels were not associated with the cetuximab response. However, tumor samples obtained after cetuximab treatment displayed slightly lower NF1 transcript levels compared with those in the pre‑treatment samples, suggesting that exposure to the anti‑EGFR antibody may be associated with reduced NF1 expression levels. Next‑generation sequencing revealed that the frequency of inactivating mutations in NF1 were rare (1.8%) in patients with colorectal cancer and were not associated with the protein expression levels of NF1 except for in a small number of cases (0.5%), where the biallelic inactivation of NF1 was observed. To conclude, the present study showed that modification of NF1 expression can affect sensitivity to cetuximab in colorectal cancer cell lines, though a limitation exists in terms of its potential application as a biomarker for RAS and BRAF^V600 wild‑type tumors.

Neurofibromin 1 in mushroom body neurons mediates circadian wake drive through activating cAMP-PKA signaling

Various behavioral and cognitive states exhibit circadian variations in animals across phyla including Drosophila melanogaster, in which only ~0.1% of the brain's neurons contain circadian clocks. Clock neurons transmit the timing information to a plethora of non-clock neurons via poorly understood mechanisms. Here, we address the molecular underpinning of this phenomenon by profiling circadian gene expression in non-clock neurons that constitute the mushroom body, the center of associative learning and sleep regulation. We show that circadian clocks drive rhythmic expression of hundreds of genes in mushroom body neurons, including the Neurofibromin 1 (Nf1) tumor suppressor gene and Pka-C1. Circadian clocks also drive calcium rhythms in mushroom body neurons via NF1-cAMP/PKA-C1 signaling, eliciting higher mushroom body activity during the day than at night, thereby promoting daytime wakefulness. These findings reveal the pervasive, non-cell-autonomous circadian regulation of gene expression in the brain and its role in sleep.

Classification and Treatment of Pediatric Gliomas in the Molecular Era

The overall survival of pediatric gliomas varies over a wide spectrum depending on the tumor grade. Low-grade gliomas have an excellent long-term survival, with a possible burden of surgery, irradiation, and chemotherapy; in contrast, high-grade gliomas generally have a short-term, devastating lethal outcome. Recent advances in understanding their molecular background will transform the classification and therapeutic approaches of pediatric gliomas. Molecularly targeted treatments may acquire a leading role in the primary treatment of low-grade gliomas and may provide alternative therapeutic strategies for high-grade glioma cases in the attempt to avoid the highly unsuccessful conventional therapeutic approaches. This review aims to overview this progress.

Associative Learning Requires Neurofibromin to Modulate GABAergic Inputs to Drosophila Mushroom Bodies

Cognitive dysfunction is among the hallmark symptoms of Neurofibromatosis 1, and accordingly, loss of the Drosophila melanogaster ortholog of Neurofibromin 1 (dNf1) precipitates associative learning deficits. However, the affected circuitry in the adult CNS remained unclear and the compromised mechanisms debatable. Although the main evolutionarily conserved function attributed to Nf1 is to inactivate Ras, decreased cAMP signaling on its loss has been thought to underlie impaired learning. Using mixed sex populations, we determine that dNf1 loss results in excess GABAergic signaling to the central for associative learning mushroom body (MB) neurons, apparently suppressing learning. dNf1 is necessary and sufficient for learning within these non-MB neurons, as a dAlk and Ras1-dependent, but PKA-independent modulator of GABAergic neurotransmission. Surprisingly, we also uncovered and discuss a postsynaptic Ras1-dependent, but dNf1-independnet signaling within the MBs that apparently responds to presynaptic GABA levels and contributes to the learning deficit of the mutants.

Implications of mosaicism in variant interpretation: A case of a de novo homozygous NF1 variant

Neurofibromatosis type 1 is a common multisystem autosomal dominant syndrome caused by pathogenic heterozygous variants in the neurofibromin gene (NF1). It is associated with a substantially increased cancer risk. Mosaicism for NF1 has been clinically well-established for "second hit" variants in skin lesions and tumor tissues. Here, we report on a 3-month-old boy with multiple café au lait macules (CAMs) and juvenile myelomonocytic leukemia (JMML) who was found to carry a previously established pathogenic NF1 variant (c.586+5G>A), as revealed by whole-exome sequencing. Surprisingly, however, this variant was detected in the homozygous state in the patient and was absent in the parents and siblings. Deep sequencing of this variant using blood, buccal swabs and skin samples was performed. As expected for an NF1 gene mutation promoting JMML, the variant was detected in 90.6% of the blood DNA reads, in sharp contrast to the mere 5% and 0.74% of reads in the saliva- and skin fibroblast-derived DNA, respectively. Our analysis, therefore, confirmed postzygotic origin of the variant followed by a mitotic event resulting in its homozygosity, although we could not differentiate between the possibilities of a gene conversion and mitotic crossover. Apparently de novo homozygous variants should trigger a careful investigation into mosaicism to achieve accurate interpretation.

Hyperpigmented spots at fundus examination: a new ocular sign in Neurofibromatosis Type I

BACKGROUND

Neurofibromatosis Type I (NF1), also termed von Recklinghausen disease, is a rare genetic disorder that is transmitted by autosomal dominant inheritance, with complete penetrance and variable expressivity. It is caused by mutation in the NF1 gene on chromosome 17 encoding for neurofibromin, a protein with oncosuppressive activity, and it is 50% sporadic or inherited. The disease is characterized by a broad spectrum of clinical manifestations, mainly involving the nervous system, the eye and skin, and a predisposition to develop multiple benign and malignant neoplasms. Ocular diagnostic hallmarks of NF1 include optic gliomas, iris Lisch nodules, orbital and eyelid neurofibromas, eyelid café-au-lait spots. Choroidal nodules and microvascular abnormalities have recently been identified as additional NF1-related ocular manifestations. The present study was designed to describe the features and clinical significance of a new sign related to the visual apparatus in NF-1, represented by hyperpigmented spots (HSs) of the fundus oculi.

RESULTS

HSs were detected in 60 (24.1%) out of 249 patients with NF1, with a positive predictive value of 100% and a negative predictive value of 44.2%. None of the healthy subjects (150 subjects) showed the presence of HSs. HSs were visible under indirect ophthalmoscopy, ultra-wide field (UWF) pseudocolor imaging and red-only laser image, near-infrared reflectance (NIR)-OCT, but they were not appreciable on UWF green reflectance. The location and features of pigmentary lesions matched with the already studied NF1-related choroidal nodules. No significant difference was found between the group of patients (n = 60) with ocular HSs and the group of patients (n = 189) without ocular pigmented spots in terms of age, gender or severity grading of the disease. A statistically significant association was demonstrated between the presence of HSs and neurofibromas (p = 0.047), and between the presence of HSs and NF1-related retinal microvascular abnormalities (p = 0.017).

CONCLUSIONS

We described a new ocular sign represented by HSs of the fundus in NF1. The presence of HSs was not a negative prognostic factor of the disease. Following multimodal imaging, we demonstrated that HSs and choroidal nodules were consistent with the same type of lesion, and simple indirect ophthalmoscopy allowed for screening of HSs in NF1.

Cancer Stem Cells: Significance in Origin, Pathogenesis and Treatment of Glioblastoma

Cancer stem cells (CSCs), known also as tumor-initiating cells, are quiescent, pluripotent, self-renewing neoplastic cells that were first identified in hematologic tumors and soon after in solid malignancies. CSCs have attracted remarkable research interest due to their role in tumor resistance to chemotherapy and radiation treatment as well as recurrence. Extensive research has been devoted to the role of CSCs in glioblastoma multiforme (GBM), the most common primary brain tumor in adults, which is characterized by a dismal prognosis because of its aggressive course and poor response to treatment. The aim of the current paper is to provide an overview of current knowledge on the role of cancer stem cells in the pathogenesis and treatment resistance of glioblastoma. The six regulatory mechanisms of glioma stem cells (GSCs)—tumor microenvironment, niche concept, metabolism, immunity, genetics, and epigenetics—are reviewed. The molecular markers used to identify GSCs are described. The role of GSCs in the treatment resistance of glioblastoma is reviewed, along with future treatment options targeting GSCs. Stem cells of glioblastoma thus represent both a driving mechanism of major treatment difficulties and a possible target for more effective future approaches.