A platform for rapid patient-derived cutaneous neurofibroma organoid establishment and screening.

Localized cutaneous neurofibromas (cNFs) are benign tumors that arise in the dermis of patients affected by neurofibromatosis type 1 syndrome. cNFs are benign lesions: they do not undergo malignant transformation or metastasize. Nevertheless, they can cover a significant proportion of the body, with some individuals developing hundreds to thousands of lesions. cNFs can cause pain, itching, and disfigurement resulting in substantial socio-emotional repercussions. Currently, surgery and laser desiccation are the sole treatment options but may result in scarring and potential regrowth from incomplete removal. To identify effective systemic therapies, we introduce an approach to establish and screen cNF organoids. We optimized conditions to support the ex vivo growth of genomically diverse cNFs. Patient-derived cNF organoids closely recapitulate cellular and molecular features of parental tumors as measured by immunohistopathology, methylation, RNA sequencing, and flow cytometry. Our cNF organoid platform enables rapid screening of hundreds of compounds in a patient- and tumor-specific manner.

Recurrent spontaneous pneumothorax in an NF1 patient with a novel causative variant: broadening genotype-phenotype correlations.

Neurofibromatosis type 1 (NF1) is an autosomal dominant disease with complete penetrance, most commonly known to affect the skin and eyes. Although lung involvement in the form of cysts and bullae occurs in up to 20% of adults, the seemingly intuitive association of NF1 and spontaneous pneumothorax is not widely recognised among clinicians. Here, we report the second case of recurring spontaneous pneumothorax in the context of NF1 with a confirmed molecular diagnosis. In both cases, the NF1 variants featured a premature stop codon in the C-terminal protein domain. Interestingly, our patient had mild skin symptoms, suggesting that spontaneous pneumothorax may not be correlated with cutaneous disease severity. More genotype-phenotype correlation studies are needed for NF1 in general and for its link to spontaneous pneumothorax in particular.

Contemporary Approach to Neurofibromatosis Type 1-Associated Malignant Peripheral Nerve Sheath Tumors.

Most malignant peripheral nerve sheath tumors (MPNSTs) are clinically aggressive high-grade sarcomas, arising in individuals with neurofibromatosis type 1 (NF1) at a significantly elevated estimated lifetime frequency of 8%-13%. In the setting of NF1, MPNSTs arise from malignant transformation of benign plexiform neurofibroma and borderline atypical neurofibromas. Composed of neoplastic cells from the Schwannian lineage, these cancers recur in approximately 50% of individuals, and most patients die within five years of diagnosis, despite surgical resection, radiation, and chemotherapy. Treatment for metastatic disease is limited to cytotoxic chemotherapy and investigational clinical trials. In this article, we review the pathophysiology of this aggressive cancer and current approaches to surveillance and treatment.

Effect of NFX-179 MEK inhibitor on cutaneous neurofibromas in persons with neurofibromatosis type 1.

This phase 2a trial investigated the efficacy of NFX-179 Topical Gel, a metabolically labile MEK inhibitor, in the treatment of cutaneous neurofibromas (cNFs) in neurofibromatosis type 1. Forty-eight participants were randomized to four treatment arms: NFX-179 Topical Gel 0.05%, 0.15%, and 0.5% or vehicle applied once daily to five target cNFs for 28 days. Treatment with NFX-179 Topical Gel resulted in a dose-dependent reduction in p-ERK levels in cNFs at day 28, with a 47% decrease in the 0.5% NFX-179 group compared to the vehicle (P = 0.0001). No local or systemic toxicities were observed during the treatment period, and systemic concentrations of NFX-179 remained below 1 ng/ml. In addition, 20% of cNFs treated with 0.5% NFX-179 Topical Gel showed a ≥50% reduction in volume compared to 6% in the vehicle group by ruler measurement with calculated volume (P = 0.021). Thus, NFX-179 Topical Gel demonstrated significant inhibition of MEK in cNF with excellent safety and potential therapeutic benefit.

Raman difference spectroscopy and U-Net convolutional neural network for molecular analysis of cutaneous neurofibroma.

In Neurofibromatosis type 1 (NF1), peripheral nerve sheaths tumors are common, with cutaneous neurofibromas resulting in significant aesthetic, painful and functional problems requiring surgical removal. To date, determination of adequate surgical resection margins-complete tumor removal while attempting to preserve viable tissue-remains largely subjective. Thus, residual tumor extension beyond surgical margins or recurrence of the disease may frequently be observed. Here, we introduce Shifted-Excitation Raman Spectroscopy in combination with deep neural networks for the future perspective of objective, real-time diagnosis, and guided surgical ablation. The obtained results are validated through established histological methods. In this study, we evaluated the discrimination between cutaneous neurofibroma (n = 9) and adjacent physiological tissues (n = 25) in 34 surgical pathological specimens ex vivo at a total of 82 distinct measurement loci. Based on a convolutional neural network (U-Net), the mean raw Raman spectra (n = 8,200) were processed and refined, and afterwards the spectral peaks were assigned to their respective molecular origin. Principal component and linear discriminant analysis was used to discriminate cutaneous neurofibromas from physiological tissues with a sensitivity of 100%, specificity of 97.3%, and overall classification accuracy of 97.6%. The results enable the presented optical, non-invasive technique in combination with artificial intelligence as a promising candidate to ameliorate both, diagnosis and treatment of patients affected by cutaneous neurofibroma and NF1.

Histologic correlates of "Choroidal abnormalities" in Neurofibromatosis type 1 (NF1).

Neurofibromatosis type 1 (NF1) is a rare autosomal dominant disorder characterized by proliferation of cells from neural crest origin. The most common manifestations are cutaneous, neurologic, skeletal and ocular. The distinction of NF1 from other syndromes with multiple café-au-lait macules may be difficult in the pediatric age group, and ocular findings, especially Lisch nodules (i.e., melanocytic hamartomas on the irides), are a useful, early diagnostic tool. In recent years, novel ocular manifestations descriptively referred to as "choroidal abnormalities", choroidal "hyperpigmented spots" and "retinal vascular abnormalities" have been recognized in NF1. Choroidal abnormalities (CA) appear as bright patchy nodules that can be best detected with near-infrared ocular coherence tomography imaging (NIR-OCT). Because of their high specificity and sensitivity for NF1, CA have been added as an ocular diagnostic criterion of NF1 as an alternative to Lisch nodules. Although CA are important ocular diagnostic criteria for NF1, the histologic correlates are controversial. We present the postmortem ocular pathology findings of an NF1 patient for whom clinical notes and ocular imaging were available. Findings in this patient included choroidal hyperpigmented spots on funduscopy and retinal vascular abnormalities, both of which have been reported to be closely associated with CA. Histologic examination of the eyes showed multiple clusters of melanocytes of varying sizes in the choroid. Pathologic review of 12 additional postmortem eyes from 6 NF1 patients showed multiple, bilateral choroidal melanocytic aggregates in all eyes. These findings suggest that the CA seen on NIR-OCT and the hyperpigmented spots seen clinically in NF1 patients are manifestations of multifocal choroidal melanocytic clusters, consistent with choroidal melanocytic hamartomas. Lisch nodules, often multiple, were present in all eyes with morphology that differed from the choroidal hamartomas. As such, although CA and Lisch nodules are melanocytic hamartomas, there are clear phenotypical differences in their morphologies.

Autism spectrum disorder profiles in RASopathies: A systematic review.

BACKGROUND: RASopathies are associated with an increased risk of autism spectrum disorder (ASD). For neurofibromatosis type 1 (NF1) there is ample evidence for this increased risk, while for other RASopathies this association has been studied less. No specific ASD profile has been delineated so far for RASopathies or a specific RASopathy individually. METHODS: We conducted a systematic review to investigate whether a specific RASopathy is associated with a specific ASD profile, or if RASopathies altogether have a distinct ASD profile compared to idiopathic ASD (iASD). We searched PubMed, Web of Science, and Open Grey for data about ASD features in RASopathies and potential modifiers. RESULTS: We included 41 articles on ASD features in NF1, Noonan syndrome (NS), Costello syndrome (CS), and cardio-facio-cutaneous syndrome (CFC). Individuals with NF1, NS, CS, and CFC on average have higher ASD symptomatology than healthy controls and unaffected siblings, though less than people with iASD. There is insufficient evidence for a distinct ASD phenotype in RASopathies compared to iASD or when RASopathies are compared with each other. We identified several potentially modifying factors of ASD symptoms in RASopathies. CONCLUSIONS: Our systematic review found no convincing evidence for a specific ASD profile in RASopathies compared to iASD, or in a specific RASopathy compared to other RASopathies. However, we identified important limitations in the research literature which may also account for this result. These limitations are discussed and recommendations for future research are formulated.

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.

NF1-Driven Rhabdomyosarcoma Phenotypes: A Comparative Clinical and Molecular Study of NF1-Mutant Rhabdomyosarcoma and NF1-Associated Malignant Triton Tumor.

PURPOSE: Alterations of the NF1 tumor suppressor gene is the second most frequent genetic event in embryonal rhabdomyosarcoma (ERMS), but its associations with clinicopathologic features, outcome, or coexisting molecular events are not well defined. Additionally, NF1 alterations, mostly in the setting of neurofibromatosis type I (NF1), drive the pathogenesis of most malignant peripheral nerve sheath tumor with divergent RMS differentiation (also known as malignant triton tumor [MTT]). Distinguishing between these entities can be challenging because of their pathologic overlap. This study aims to comprehensively analyze the clinicopathologic and molecular spectrum of NF1-mutant RMS compared with NF1-associated MTT for a better understanding of their pathogenesis. METHODS: We investigated the clinicopathologic and molecular landscape of a cohort of 22 NF1-mutant RMS and a control group of 13 NF1-associated MTT. Cases were tested on a matched tumor-normal hybridization capture-based targeted DNA next-generation sequencing. RESULTS: Among the RMS group, all except one were ERMS, with a median age of 17 years while for MTT the mean age was 39 years. Three MTTs were misdiagnosed as ERMS, having clinical impact in one. The most frequent coexisting alteration in ERMS was TP53 abnormality (36%), being mutually exclusive from NRAS mutations (14%). MTT showed coexisting CDKN2A/B and PRC2 complex alterations in 38% cases and loss of H3K27me3 expression. Patients with NF1-mutant RMS exhibited a 70% 5-year survival rate, in contrast to MTT with a 33% 5-year survival. All metastatic NF1-mutant ERMS were associated with TP53 alterations. CONCLUSION: Patients with NF1-mutant ERMS lacking TP53 alterations may benefit from dose-reduction chemotherapy. On the basis of the diagnostic challenges and significant treatment and prognostic differences, molecular profiling of challenging tumors with rhabdomyoblastic differentiation is recommended.

Whole-exome sequencing revealed a likely pathogenic variant in NF1 causing neurofibromatosis type I and Arrhythmogenic Cardiomyopathy.

BACKGROUND: Neurofibromatosis type I (NF1) is a genetic disorder characterized by the tumor's development in nerve tissue. Complications of NF1 can include pigmented lesions, skin neurofibromas, and heart problems such as cardiomyopathy. In this study, we performed whole-exome sequencing (WES) on an Iranian patient with NF1 to identify the genetic cause of the disease. METHODS: Following clinical assessment, WES was used to identify genetic variants in a family with a son suffering from NF1. No symptomatic manifestations were observed in other family members. In the studied family, in silico and segregation analysis were applied to survey candidate variants. RESULTS: Clinical manifestations were consistent with arrhythmogenic cardiomyopathy (ACM). WES detected a likely pathogenic heterozygous missense variant, c.3277G > A:p.Val1093Met, in the NF1 gene, confirmed by PCR and Sanger sequencing. The patient's parents and brother had a normal sequence at this locus. CONCLUSIONS: Although there is no cure for NF1, genetic tests, such as WES, can detect at-risk asymptomatic family members. Furthermore, cardiac evaluation could also help these patients before heart disease development.

STING activation reprograms the microenvironment to sensitize NF1-related malignant peripheral nerve sheath tumors for immunotherapy.

Neurofibromatosis type 1 (NF1) is caused by mutations in the NF1 gene that encodes neurofibromin, a RAS GTPase-activating protein. Inactivating NF1 mutations cause hyperactivation of RAS-mediated signaling, resulting in the development of multiple neoplasms, including malignant peripheral nerve sheath tumors (MPNSTs). MPNSTs are an aggressive tumor and the main cause of mortality in patients with NF1. MPNSTs are difficult to resect and refractory to chemo- and radiotherapy, and no molecular therapies currently exist. Immune checkpoint blockade (ICB) is an approach to treat inoperable, undruggable cancers like MPNST, but successful outcomes require an immune cell-rich tumor microenvironment. While MPNSTs are noninflamed "cold" tumors, here, we converted MPNSTs into T cell-inflamed "hot" tumors by activating stimulator of IFN genes (STING) signaling. Mouse genetic and human xenograft MPNST models treated with a STING agonist plus ICB exhibited growth delay via increased apoptotic cell death. This strategy offers a potential treatment regimen for MPNSTs.

Incidence of tethered cord syndrome in neurofibromatosis types 1 and 2 pediatric patients: a population-level analysis.

PURPOSE: Tethered spinal cord syndrome (TCS) is characterized by cutaneous attachments on the filum terminale that stretch the spinal cord, leading to musculoskeletal and urogenital sequelae. While the neurocutaneous associations with TCS remain undefined, a recent study reports a high incidence of TCS among a pediatric neurofibromatosis (NF) cohort. This present study utilizes a population-level database to estimate TCS incidence among pediatric patients with neurofibromatosis types 1 and 2 (NF1, NF2). METHODS: The TriNetX Research Network was queried to identify patients diagnosed with NF and/or TCS before the age of 21. Symptomatic TCS requiring surgical intervention was identified using corresponding procedural codes within 12 months following TCS diagnosis. Odds ratios (OR) were calculated to measure the associations of NF1/NF2 with TCS. RESULTS: 19,426 pediatric NF patients were evaluated (NF1: 18,383, NF2: 1042). The average ages of TCS diagnosis among NF1, NF2, and non-NF patients were 12, 16, and 9 years, respectively. The incidence of TCS was 1.2% in NF1 patients and 7.3% in NF2 patients, compared to 0.074% in the general population. The associations of NF incidence with TCS were significantly increased in both NF1 (OR 16.42; 14.38-18.76) and NF2 (OR 105.58; 83.56-133.40) patients compared to the general population. Symptomatic TCS requiring surgical intervention was not significantly associated with NF1/NF2 patients compared to the general TCS population. CONCLUSION: This analysis demonstrates a high incidence of TCS but delayed intervention in pediatric NF patients. Considering TCS counseling, spinal MRI, and earlier intervention may be warranted for NF patients experiencing musculoskeletal symptomatology.

Cutaneous toxicities of mitogen-activated protein kinase inhibitors in children and young adults with neurofibromatosis-1.

PURPOSE: Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder which commonly causes neoplasms leading to disfigurement or dysfunction. Mitogen-activated protein kinase inhibitors (MEKi) are generally well-tolerated treatments which target neural tumor progression in patients with NF1. However, cutaneous adverse events (CAEs) are common and may hinder patients' abilities to remain on treatment, particularly in children. We aim to characterize CAEs secondary to MEKi treatment in pediatric and young adult patients with NF1. METHODS: We reviewed institutional medical records of patients under 30 years with a diagnosis of "NF1," "NF2," or "other neurofibromatoses" on MEKi therapy between January 1, 2019 and June 1, 2022. We recorded the time-to-onset, type, and distribution of CAEs, non-cutaneous adverse events (AEs), AE management, and tumor response. RESULTS: Our cohort consisted of 40 patients with NF1 (median age, 14 years). Tumor types included low-grade gliomas (51%) and plexiform neurofibromas (38%). MEKi used included selumetinib (69%), trametinib (25%), and mirdametinib (6%). A total of 74 CAEs occurred, with 28 cases of acneiform rash (38%). Other common CAEs were paronychia, seborrheic dermatitis, eczema, xerosis, and oral mucositis. The most common treatments included oral antibiotics and topical corticosteroids. Most patients had clinical (stable or improved) tumor response (71%) while 29% had tumor progression while on a MEKi. There was no significant association between CAE presence and tumor response (p = 0.39). CONCLUSIONS: Improvement in characterization of MEKi toxicities and their management is important to develop treatment guidelines for pediatric and young adult patients with NF1 on MEKi therapy.

Impact of trametinib on the neuropsychological profile of NF1 patients.

PURPOSE: The use of trametinib in the treatment of pediatric low-grade gliomas (PLGG) and plexiform neurofibroma (PN) is being investigated in an ongoing multicenter phase II trial (NCT03363217). Preliminary data shows potential benefits with significant response in the majority of PLGG and PN and an overall good tolerance. Moreover, possible benefits of MEK inhibitor therapy on cognitive functioning in neurofibromatosis type 1 (NF1) were recently shown which supports the need for further evaluation. METHODS: Thirty-six patients with NF1 (age range 3-19 years) enrolled in the phase II study of trametinib underwent a neurocognitive assessment at inclusion and at completion of the 72-week treatment. Age-appropriate Wechsler Intelligence Scales and the Trail Making Test (for children over 8 years old) were administered at each assessment. Paired t-tests and Reliable Change Index (RCI) analyses were performed to investigate change in neurocognitive outcomes. Regression analyses were used to investigate the contribution of age and baseline score in the prediction of change. RESULTS: Stable performance on neurocognitive tests was revealed at a group-level using paired t-tests. Clinically significant improvements were however found on specific indexes of the Wechsler intelligence scales and Trail Making Test, using RCI analyses. No significant impact of age on cognitive change was evidenced. However, lower initial cognitive performance was associated with increased odds of presenting clinically significant improvements on neurocognitive outcomes. CONCLUSION: These preliminary results show a potential positive effect of trametinib on cognition in patients with NF1. We observed significant improvements in processing speed, visuo-motor and verbal abilities. This study demonstrates the importance of including neuropsychological evaluations into clinical trial when using MEK inhibitors for patients with NF1.

Efficacy and safety of selumetinib in patients with neurofibromatosis type 1 and inoperable plexiform neurofibromas: a systematic review and meta-analysis.

BACKGROUND: The approval of selumetinib in patients with neurofibromatosis type 1(NF1) and inoperable plexiform neurofibromas (PN) has reshaped the landscape of clinical management of the disease, and further comprehensive evaluation of the drug's efficacy and safety is needed. METHODS: Original articles reporting on the efficacy and safety of elumetinib in patients with NF1 were comprehensively searched in the Pubmed database, Embase database, Cochrane Library, and Web of Science database and screened for inclusion of studies that met the criteria. We pooled the objective response rate (ORR), disease control rate (DCR), disease progression rate (DPR), and the rate of improvement in PN-related complications using meta-analysis. The incidence of drug-related adverse events was also statistically analyzed. RESULTS: This study included 10 clinical trials involving 268 patients. The pooled ORR was 68.0% (95% CI 58.0-77.3%), the DCR was 96.8% (95% CI 90.8-99.7%) and the DPR was only 1.4% (95% CI 0-4.3%). The pooled improvement rate was 75.3% (95% CI 56.2-90.9%) for pain and 77.8% (95% CI 63.1-92.5%) for motor disorders. Most adverse events were mild, with the most common being gastrointestinal reactions (diarrhea: 62.5%; vomiting: 54.5%). CONCLUSION: Our study demonstrates that selumetinib is effective in patients with NF1 and PN, significantly improving the serious complications associated with PN as well as having tolerable toxicities. Our findings help to increase clinicians' confidence in applying selumetinib and promote the clinical adoption and benefit of the new drug.

A Systematic Review on Visual-Processing Deficits in Neurofibromatosis Type 1: What Possible Impact on Learning to Read?

This systematic review aimed to examine the possible implication of visual-perceptual, visuo-attentional and oculomotor processing in the reading deficits frequently experienced by children with Neurofibromatosis type 1 (NF1), as previously shown in dyslexia. Using PRISMA methodological guidelines, we examined 49 studies; most of these reported visual-processing deficits in this population, raising the importance of directly studying the visuo-perceptual and visuo-attentional processes and eye-movement control involved in the learning-to-read process in NF1. The discussion provides a reflection for a better understanding of how visual-processing skills interact with reading deficits in NF1, as well as new avenues for their screening and care.