Pediatric malignancies in neurofibromatosis type 1: A population-based cohort study

Editorial: Understanding the Nature of Attention Problems in Neurofibromatosis Type 1: Clinical and Research Implications

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common psychiatric disorders of childhood, and though highly heritable, there is a clear pattern of polygenic inheritance with many genes contributing to its expression. Yet, as described in this issue of the Journal, ADHD is also overrepresented in neurofibromatosis type 1 (NF1), an autosomal dominant disorder resulting from mutations in a single gene and affecting 1 in 3,000 people.1 Although NF1 is named after the characteristic neurofibromas, or benign nerve sheath tumors, and morbidity and mortality are mostly related to the potential development of malignant nerve sheath and other tumors of the nervous system, patients with NF1 also have general cognitive and behavioral difficulties. In the last 25 years, researchers have developed an improved understanding of the difficulties, noting that not all cognitive and behavioral domains are equally affected and there is overlap with other neurodevelopmental disorders. Specifically, prior meta-analyses have shown increased rates of autism spectrum disorder (ASD), with approximately 18% of patients with NF1 meeting diagnostic criteria for ASD.2 Several cohort studies have also previously shown increased rates of ADHD.3 Hou et al.1 have now used an elegant meta-analysis to demonstrate not only that children with NF1 have elevated rates of ADHD, but also that in children with NF1 inattentive symptoms appear to be more prominent than hyperactive/impulsive symptoms.

Pregnancy and the Risk for Cancer in Neurofibromatosis 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is associated with a high risk for cancer. Benign cutaneous neurofibromas of women with NF1 may increase in size and number during pregnancy. However, it is not known whether pregnancy affects the risk for cancer in NF1.

METHODS

We retrieved the pregnancies of women in the Finnish NF1 cohort and in a 10-fold control cohort from the Finnish Medical Birth Register. Cancers occurring during or after pregnancy were obtained from the Finnish Cancer Registry and summarized using standardized incidence ratio (SIR). The cancer incidence of nonNF1 mothers of individuals with NF1 was also estimated.

RESULTS

Totals of 263 pregnancies in 136 women with NF1 and 3176 pregnancies in 1720 controls were observed. In the NF1 group, two cancers were identified during pregnancy and the year following the delivery (SIR 6.44, 95% CI 1.07-19.89). Among controls, the SIR was markedly lower (0.25, 95% CI 0.01-1.08). Within 1-10 years after pregnancy, the SIR of women with NF1 was 7.54 (95% CI 4.15-12.41). The SIR of women with NF1 aged 20-49 years, and without a known history of deliveries was 8.63 (95% CI 6.08-11.81). The nonNF1 mothers displayed a SIR of 0.81 (95% CI 0.66-1.00) after giving birth to a child with NF1.

CONCLUSIONS

The pregnancy-related cancer incidence in women with NF1 is similar to women with NF1 aged 20-49 years overall, although notably higher than in the general population. Giving birth to a child with NF1 does not affect the risk for cancer in women without NF1.

Mortality after cancer diagnosis among children with congenital heart disease in Denmark and Sweden

BACKGROUND

Recent decades have witnessed tangible improvements in childhood cancer survival. However, the prognosis for children with congenital heart disease (CHD), the most prevalent birth defect, remains unclear. Due to improved survival of CHD and childhood cancer, evaluating outcomes within this intersection is important for clinical practice. We aimed to assess mortality post-cancer diagnosis among children with CHD.

METHODS

We conducted a study on the population of Denmark and Sweden, born 1970-2014, with a cancer diagnosis before age 20 in the national cancer registers (end of follow-up 2015; n = 20,665). CHD diagnoses (n = 397) and recorded deaths were retrieved from national health registers. We evaluated the effect of CHD on five-year mortality post-cancer diagnosis fitting Cox proportional hazards regression.

RESULTS

When excluding children with Down syndrome, children with CHD had a higher five-year mortality post-cancer diagnosis compared to children without (HR 1.48, 95% CI 1.18-1.86). This was particularly notable in children with lymphoma (HR 2.17, 95% CI 1.11-4.25) and neuroblastoma (HR 2.39, 95% CI 1.11-5.15). In more recent decades (post-1990), children with CHD had similar five-year mortality as their counterparts without, except for children diagnosed with lymphoma, where mortality remained elevated (HR 3.37, 95% CI 1.65-6.89).

CONCLUSIONS

In this large, register-based cohort study, children with CHD fared worse post-cancer diagnosis-particularly lymphoma and neuroblastoma. While a more positive trend emerged in recent years, lymphoma-related mortality remained disproportionately high among children with CHD, underscoring the need for continued research and interventions to improve outcomes for this vulnerable group.

Identification of the Determinants of Plexiform Neurofibroma Morbidity in Pediatric and Young Adult Neurofibromatosis Type 1 Patients: A Pilot Multivariate Approach

BACKGROUND

Plexiform neurofibromas (PNs) are histologically benign peripheral nerve sheath tumors associated with neurofibromatosis type 1 (NF1) and often lead to significant morbidity due to growth. Management includes watchful waiting, surgery for partial debulking, and, since recently, systemic treatment with MEK inhibitors. However, due to the scarcity of natural history studies, our understanding of the natural progression of PNs to guide clinicians in deciding in whom and when to intervene is scarce. This study aims to describe the characteristics of NF1 patients with PNs and compare those at high risk for PN progression or experiencing significant morbidity from PN (complex PN) with NF1 patients with PNs of lower complexity.

METHODS

In this retrospective cohort study using clinical data from hospital records of NF1 patients with PNs seen at the Sophia Children's Hospital in the Netherlands between 2012 and 2023, we assessed determinants of clinical phenotypes and PN characteristics predictive of outcomes, including PN complexity and the timing of intervention for PN. We assessed the outcomes using logistic regression analysis and Cox regression.

RESULTS

Ninety patients with a median age at last evaluation of 15.7 years and a median follow-up duration of 9.8 years were included. Out of 90 individuals with a benign PN, 37 developed plexiform neurofibroma morbidity during follow-up. Older age was (corrected for pathogenic NF1 variant and PN location) significantly associated with plexiform neurofibroma morbidity. Cox regression revealed that craniofacial and trunk PNs were associated with a higher intervention hazard compared to limb PNs.

CONCLUSION

Our pilot multivariate approach identified older age and the location of the PN to be mostly associated with a higher chance of plexiform neurofibroma morbidity and higher intervention hazard. This may contribute to decisions regarding in whom and when to initiate treatment in NF1 patients with PNs.

PET Imaging of Neurofibromatosis Type 1 with a Fluorine-18 Labeled Tryptophan Radiotracer

Neurofibromatosis type 1 (NF1) is a neurocutaneous disorder. Plexiform neurofibromas (PNFs) are benign tumors commonly formed in patients with NF1. PNFs have a high incidence of developing into malignant peripheral nerve sheath tumors (MPNSTs) with a 5-year survival rate of only 30%. Therefore, the accurate diagnosis and differentiation of MPNSTs from benign PNFs are critical to patient management. We studied a fluorine-18 labeled tryptophan positron emission tomography (PET) radiotracer, 1-(2-[18F]fluoroethyl)-L-tryptophan (L-[18F]FETrp), to detect NF1-associated tumors in an animal model. An ex vivo biodistribution study of L-[18F]FETrp showed a similar tracer distribution and kinetics between the wild-type and triple mutant mice with the highest uptake in the pancreas. Bone uptake was stable. Brain uptake was low during the 90-min uptake period. Static PET imaging at 60 min post-injection showed L-[18F]FETrp had a comparable tumor uptake with [1⁸F]fluorodeoxyglucose (FDG). However, L-[18F]FETrp showed a significantly higher tumor-to-brain ratio than FDG (n = 4, p < 0.05). Sixty-minute-long dynamic PET scans using the two radiotracers showed similar kidney, liver, and lung kinetics. A dysregulated tryptophan metabolism in NF1 mice was further confirmed using immunohistostaining. L-[18F]FETrp is warranted to further investigate differentiating malignant NF1 tumors from benign PNFs. The study may reveal the tryptophan-kynurenine pathway as a therapeutic target for treating NF1.

Cancer Predisposition Syndromes in Neuro-oncology

Although most primary central and peripheral nervous system (NS) tumors occur sporadically, there are a subset that may arise in the context of a cancer predisposition syndrome. These syndromes occur due to a pathogenic mutation in a gene that normally functions as a tumor suppressor. With increased understanding of the molecular pathogenesis of these tumors, more people have been identified with a cancer predisposition syndrome. Identification is crucial, as this informs surveillance, diagnosis, and treatment options. Moreover, relatives can also be identified through genetic testing. Although there are many cancer predisposition syndromes that increase the risk of NS tumors, in this review, we focus on three of the most common cancer predisposition syndromes, neurofibromatosis type 1, neurofibromatosis type 2, and tuberous sclerosis complex type 1 and type 2, emphasizing the clinical manifestations, surveillance guidelines, and treatment options.

Germline mutations in pediatric cancer cohort with mixed-ancestry Mexicans

BACKGROUND

Childhood cancer is one of the primary causes of disease-related death in 5- to 14-year-old children and currently no prevention strategies exist to reduce the incidence of this disease. Childhood cancer has a larger hereditary component compared with cancer in adults. Few genetic studies have been conducted on children with cancer. Additionally, Latin American populations are underrepresented in genomic studies compared with other populations. Therefore, the aim of this study is to analyze germline mutations in a group of mixed-ancestry Mexican pediatric patients with solid and hematological cancers.

METHODS

We analyzed genetic variants from 40 Mexican childhood cancer patients and their relatives. DNA from saliva or blood samples was used for whole-exome sequencing. All variants were identified following GATK best practices.

RESULTS

We found that six patients (15%) were carriers of germline mutations in CDKN2A, CHEK2, DICER1, FANCA, MSH6, MUTYH, NF1, and SBDS cancer predisposition genes, and additional new variants predicted to be deleterious by in silico algorithms. A population genetics analysis detected five components consistent with the demographic models assumed for modern mixed-ancestry Mexicans.

CONCLUSIONS

This report identifies potential genetic risk factors and provides a better understanding of the underlying mechanisms of childhood cancer in this population.

Perinatal folate levels do not influence tumor latency or multiplicity in a model of NF1 associated plexiform-like neurofibromas

OBJECTIVE

In epidemiological and experimental research, high folic acid intake has been demonstrated to accelerate tumor development among populations with genetic and/or molecular susceptibility to cancer. Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder predisposing affected individuals to tumorigenesis, including benign plexiform neurofibromas; however, understanding of factors associated with tumor risk in NF1 patients is limited. Therefore, we investigated whether pregestational folic acid intake modified plexiform-like peripheral nerve sheath tumor risk in a transgenic NF1 murine model.

RESULTS

We observed no significant differences in overall survival according to folate group. Relative to controls (180 days), median survival did not statistically differ in deficient (174 days, P = 0.56) or supplemented (177 days, P = 0.13) folate groups. Dietary folate intake was positively associated with RBC folate levels at weaning, (P = 0.023, 0.0096, and 0.0006 for deficient vs. control, control vs. supplemented, and deficient vs. supplemented groups, respectively). Dorsal root ganglia (DRG), brachial plexi, and sciatic nerves were assessed according to folate group. Mice in the folate deficient group had significantly more enlarged DRG relative to controls (P = 0.044), but no other groups statistically differed. No significant differences for brachial plexi or sciatic nerve enlargement were observed according to folate status.

Shedding New Light: Novel Therapies for Common Disorders in Children with Neurofibromatosis Type I

Neurofibromatosis type I (NF1) is a common dominantly inherited disorder, and one of the most common of the RASopathies. Most individuals with NF1 develop plexiform neurofibromas and cutaneous neurofibromas, nerve tumors caused by NF1 loss of function in Schwann cells. Cell culture models and mouse models of NF1 are being used to test drug efficacy in preclinical trials, which led to Food and Drug Administration approval for use of MEK inhibitors to shrink most inoperable plexiform neurofibromas. This article details methods used for testing in preclinical models, and outlines newer models that may identify additional, curative, strategies.

Genetic susceptibility in children, adolescents, and young adults diagnosed with soft-tissue sarcomas

Soft tissue sarcomas (STS) may arise as a consequence of germline variants in cancer predisposition genes (CPGs). We believe that elucidating germline sarcoma predisposition is critical for understanding disease biology and therapeutic requirements. Participation in surveillance programs may allow for early tumor detection, early initiation of therapy and, ultimately, better outcomes. Among children, adolescents, and adults diagnosed with soft-tissue sarcomas and examined as part of published germline sequencing studies, pathogenic/likely pathogenic (P/LP) variants in CPGs were reported in 7-33% of patients. P/LP germline variants were detected most frequently in TP53, NF1 and BRCA1/2. In this review, we describe reported associations between soft tissue sarcomas and germline variants in CPGs, with mentioning of locally aggressive and benign soft tissue tumors that have important associations with cancer predisposition syndromes. We also discuss recommendations for diagnostic germline genetic testing. Testing for sarcoma-predisposing germline variants should be considered as part of the routine clinical workup and care of any child, adolescent, or adult diagnosed with STS and take into account consequences for the whole family.

Loss of Nf1 and Ink4a/Arf Are Associated with Sex-Dependent Growth Differences in a Mouse Model of Embryonal Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is an aggressive form of cancer that accounts for half of all pediatric soft tissue sarcomas. Little progress has been made in improving survival outcomes over the past three decades. Mouse models of rhabdomyosarcoma are a critical component of translational research aimed at understanding tumor biology and developing new, improved therapies. Though several models exist, many common mutations found in human rhabdomyosarcoma tumors remain unmodeled and understudied. This study describes a new model of embryonal rhabdomyosarcoma driven by the loss of Nf1 and Ink4a/Arf, two mutations commonly found in patient tumors. We find that this new model is histologically similar to other previously-published rhabdomyosarcoma models, although it substantially differs in the time required for tumor onset and in tumor growth kinetics. We also observe unique sex-dependent phenotypes in both primary and newly-developed orthotopic syngeneic allograft tumors that are not present in previous models. Using in vitro and in vivo studies, we examined the response to vincristine, a component of the standard-of-care chemotherapy for RMS. The findings from this study provide valuable insight into a new mouse model of rhabdomyosarcoma that addresses an ongoing need for patient-relevant animal models to further translational research.

ERN GENTURIS tumour surveillance guidelines for individuals with neurofibromatosis type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a multisystem genetic disorder, predisposing development of benign and malignant tumours. Given the oncogenic potential, long-term surveillance is important in patients with NF1. Proposals for NF1 care and its specific manifestations have been developed, but lack integration within routine care. This guideline aims to assimilate available information on NF1 associated tumours (based on evidence and/or expert opinion) to assist healthcare professionals in undertaking tumour surveillance of NF1 individuals.

METHODS

By comprehensive literature review, performed March 18th 2020, guidelines were developed by a NF1 expert group and patient representatives, conversant with clinical care of the wide NF1 disease spectrum. We used a modified Delphi procedure to overcome issues of variability in recommendations for specific (national) health care settings, and to deal with recommendations based on indirect (scarce) evidence.

FINDINGS

We defined proposals for personalised and targeted tumour management in NF1, ensuring appropriate care for those in need, whilst reducing unnecessary intervention. We also incorporated the tumour-related psychosocial and quality of life impact of NF1.

INTERPRETATION

The guideline reflects the current care for NF1 in Europe. They are not meant to be prescriptive and may be adjusted to local available resources at the treating centre, both within and outside EU countries.

FUNDING

This guideline has been supported by the European Reference Network on Genetic Tumour Risk Syndromes (ERN GENTURIS). ERN GENTURIS is funded by the European Union. DGE is supported by the Manchester NIHRBiomedical Research Centre (IS-BRC-1215-20007).

Nervous system (NS) Tumors in Cancer Predisposition Syndromes

Genetic syndromes which develop one or more nervous system (NS) tumors as one of the manifestations can be grouped under the umbrella term of NS tumor predisposition syndromes. Understanding the underlying pathological pathways at the molecular level has led us to many radical discoveries, in understanding the mechanisms of tumorigenesis, tumor progression, interactions with the tumor microenvironment, and development of targeted therapies. Currently, at least 7-10% of all pediatric cancers are now recognized to occur in the setting of genetic predisposition to cancer or cancer predisposition syndromes. Specifically, the cancer predisposition rate in pediatric patients with NS tumors has been reported to be as high as 15%, though it can approach 50% in certain tumor types (i.e., choroid plexus carcinoma associated with Li Fraumeni Syndrome). Cancer predisposition syndromes are caused by pathogenic variation in genes that primarily function as tumor suppressors and proto-oncogenes. These variants are found in the germline or constitutional DNA. Mosaicism, however, can affect only certain tissues, resulting in varied manifestations. Increased understanding of the genetic underpinnings of cancer predisposition syndromes and the ability of clinical laboratories to offer molecular genetic testing allows for improvement in the identification of these patients. The identification of a cancer predisposition syndrome in a CNS tumor patient allows for changes to medical management to be made, including the initiation of cancer surveillance protocols. Finally, the identification of at-risk biologic relatives becomes feasible through cascade (genetic) testing. These fundamental discoveries have also broadened the horizon of novel therapeutic possibilities and have helped to be better predictors of prognosis and survival. The treatment paradigm of specific NS tumors may also vary based on the patient's cancer predisposition syndrome and may be used to guide therapy (i.e., immune checkpoint inhibitors in constitutional mismatch repair deficiency [CMMRD] predisposition syndrome) [8]. Early diagnosis of these cancer predisposition syndromes is therefore critical, in both unaffected and affected patients. Genetic counselors are uniquely trained master's level healthcare providers with a focus on the identification of hereditary disorders, including hereditary cancer, or cancer predisposition syndromes. Genetic counseling, defined as "the process of helping people understand and adapt to the medical, psychological and familial implications of genetic contributions to disease" plays a vital role in the adaptation to a genetic diagnosis and the overall management of these diseases. Cancer predisposition syndromes that increase risks for NS tumor development in childhood include classic neurocutaneous disorders like neurofibromatosis type 1 and type 2 (NF1, NF2) and tuberous sclerosis complex (TSC) type 1 and 2 (TSC1, TSC2). Li Fraumeni Syndrome, Constitutional Mismatch Repair Deficiency, Gorlin syndrome (Nevoid Basal Cell Carcinoma), Rhabdoid Tumor Predisposition syndrome, and Von Hippel-Lindau disease. Ataxia Telangiectasia will also be discussed given the profound neurological manifestations of this syndrome. In addition, there are other cancer predisposition syndromes like Cowden/PTEN Hamartoma Tumor Syndrome, DICER1 syndrome, among many others which also increase the risk of NS neoplasia and are briefly described. Herein, we discuss the NS tumor spectrum seen in the abovementioned cancer predisposition syndromes as with their respective germline genetic abnormalities and recommended surveillance guidelines when applicable. We conclude with a discussion of the importance and rationale for genetic counseling in these patients and their families.

Systematic Review of Pediatric Brain Tumors in Neurofibromatosis Type 1: Status of Gene Therapy

As oncology practice is rapidly shifting away from toxic chemotherapy, gene therapy provides a highly specific therapeutic approach for brain tumors. In this systematic review, we investigate gene therapy's status in pediatric brain tumors and future recommendations. The search was conducted systematically using PubMed, Cochrane, Google Scholar, and ClinicalTrials.gov databases. The field search used in the process was selected based on the keywords and Medical Subject Headings (MeSH), depending on the database used. We included cases of neurofibromatosis type 1 (NF1) brain tumors in all age groups with the additional inclusion of English language, free full text, articles published within the last 20 years, randomized controlled trials (RCTs), observational studies, systematic reviews, and meta-analyses. We excluded case reports, case studies, and editorials. The search identified a total of 1,213 articles from the databases. We included 19 studies with 16 narrative reviews, one systematic review, and two randomized clinical trials with 43 patients. After reviewing all data in the articles, we found that gene therapy can improve standard treatment efficacy when used as adjuvant therapy. It can be used to overcome barriers such as chemotherapy resistance by downregulating resistance genes. It is associated with mild toxicity when compared with other available treatment options, but given the overall poor prognosis in pediatric brain tumors, further studies are warranted.

[Progress in diagnosis and treatment of neurofibromatosis in children]

Neurofibromatosis type 1（NF1） is an autosomal dominant genetic disease in which a mutation in the NF1 gene on chromosome 17q11.2 results in inactivation or down-regulation of neurofibromin. This results in a series of neurocutaneous lesions characterized by neurofibromatosis. Patients with plexiform neurofibromas（PN）, as one of the main manifestations of NF1, often experience pain, dysfunction, skeletal deformities, changes in appearance and other symptoms. In severe cases, compression of the airways and vital organs occurs, and the PN is at risk of malignancy progression. At present, its treatment is still challenging. Surgery is the primary treatment for PN, but complete resection is often difficult. In recent years, chemotherapy for PN has become a hot topic. This article reviews the research progress in the pathogenesis, diagnosis and treatment of PN in recent years.

Current concepts of neurofibromatosis type 1: pathophysiology and treatment

Neurofibromatosis type 1 is the most common tumor predisposition syndrome inherited in an autosomal dominant (100% penetrance) fashion with a wide variety of expressivity. From the perspective of plastic surgery, the most significant clinical symptoms, including disfiguration, peripheral neurologic symptoms, and skeletal abnormalities, are caused by various tumors originating from the affected nerves. Surgical removal is the standard of care for these tumors. However, the outcome is frequently unsatisfactory, facilitating the search for additional therapeutic adjuvants. Current trials of molecularly targeted therapies are promising. Abbreviations: CALMs, café-au-lait macules; CNs, cutaneous neurofibromas; FDG, 18F-fluoro-deoxy-glucose; MAPK, mitogen-activated protein kinase; MPNSTs, malignant peripheral nerve sheath tumors; MRI, magnetic resonance imaging; NF1, neurofibromatosis type 1; NIH, National Institutes of Health; PET, positron emission tomography; PN, plexiform neurofibromas; TME, tumor microenvironment.

Targeted Therapies for the Neurofibromatoses

Over the past several years, management of the tumors associated with the neurofibromatoses has been recognized to often require approaches that are distinct from their spontaneous counterparts. Focus has shifted to therapy aimed at minimizing symptoms given the risks of persistent, multiple tumors and new tumor growth. In this review, we will highlight the translation of preclinical data to therapeutic trials for patients with neurofibromatosis, particularly neurofibromatosis type 1 and neurofibromatosis type 2. Successful inhibition of MEK for patients with neurofibromatosis type 1 and progressive optic pathway gliomas or plexiform neurofibromas has been a significant advancement in patient care. Similar success for the malignant NF1 tumors, such as high-grade gliomas and malignant peripheral nerve sheath tumors, has not yet been achieved; nor has significant progress been made for patients with either neurofibromatosis type 2 or schwannomatosis, although efforts are ongoing.

Recurrent NF1 gene variants and their genotype/phenotype correlations in patients with Neurofibromatosis type I

Neurofibromatosis type I, a genetic condition due to pathogenic variants in the NF1 gene, is burdened by a high rate of complications, including neoplasms, which increase morbidity and mortality for the disease. We retrospectively re-evaluated the NF1 gene variants found in the period 2000-2019 and we studied for genotype/phenotype correlations of disease complications and neoplasms 34 variants, which were shared by at least two unrelated families (range 2-11) for a total 141 of probands and 21 relatives affected by Neurofibromatosis type I. Recurrent variants could be ascribed to the most common mutational mechanisms (C to T transition, microsatellite slippage, non-homologous recombination). In genotype/phenotype correlations, the variants p.Arg440*, p.Tyr489Cys, and p.Arg1947*, together with the gross gene deletions, displayed the highest rates of complications. When considering neoplasms, carriers of variants falling in the extradomain region at the 5' end of NF1 had a lower age-related cancer frequency than the rest of the gene sequence, showing a borderline significance (p = 0.045), which was not conserved after correction with covariates. We conclude that (1) hotspots in NF1 occur via different mutational mechanisms, (2) several variants are associated with high rates of complications and cancers, and (3) there is an initial evidence toward a lower cancer risk for carriers of variants in the 5' end of the NF1 gene although not significant at the multivariate analysis.

Neurofibromatosis Type 1 in Children: A Single-Center Experience

OBJECTIVE

Neurofibromatosis (NF) is the most common autosomal dominantly inherited neurocutaneous syndrome. The characteristic features of NF type 1 (NF-1) are café au lait spots, axillary and inguinal freckling, peripheral neurofibromas, optic pathway glioma, and Lisch nodules. The present study aimed to analyze the clinical features of children with NF-1.

MATERIALS AND METHODS

In this study, the children with NF-1 diagnosed and followed-up in our center between 2000 and 2020 were retrospectively evaluated. Demographic and clinical features of patients were defined.

RESULTS

The study group consisted of 52 patients. Of those, 25 were boys and 27 were girls. The children's median age at diagnosis was 5.9 years (1-15.8). Café au lait (CAL) spots and axillary/inguinal freckling were observed in 50 and 24 patients, respectively. Neurofibroma was present in 22 cases. Ten of the cohort had optic gliomas, and 39 of them had cranial hamartomas. Orthopedic complications such as scoliosis, tibial pseudoarthrosis, and osteoporosis were observed in 13 patients. Eleven children had neurocognitive disorders.

CONCLUSIONS

Early diagnosis is important in neurofibromatosis to prevent the complications of the disease. Also, neurological development and secondary malignancy follow-up should be done carefully in this group of patients.

Lymphoproliferative malignancies in patients with neurofibromatosis 1

Neurofibromatosis 1 (NF1) is an inherited, autosomal-dominant, tumor predisposition syndrome with a birth incidence as high as 1:2000. A patient with NF1 is four to five times more likely to develop a malignancy as compared to the general population. The number of epidemiologic studies on lymphoproliferative malignancies in patients with NF1 is limited. The aim of this study was to determine the incidence rate of lymphoproliferative malignancies (lymphoma and leukemia) in NF1 patients followed in our referral center for neurofibromatoses. We used the Informatics for Integrated Biology and the Bedside (i2b2) platform to extract information from the hospital’s electronic health records. We performed a keyword search on clinical notes generated between Jan/01/2014 and May/11/2020 for patients aged 18 years or older. A total of 1507 patients with confirmed NF1 patients aged 18 years and above were identified (mean age 39.2 years; 57% women). The total number of person-years in follow-up was 57,736 (men, 24,327 years; women, 33,409 years). Mean length of follow-up was 38.3 years (median, 36 years). A total of 13 patients had a medical history of either lymphoma or leukemia, yielding an overall incidence rate of 22.5 per 100,000 (0.000225, 95% confidence interval (CI) 0.000223–0.000227). This incidence is similar to that of the general population in France (standardized incidence ratio 1.07, 95% CI 0.60–1.79). Four patients had a medical history leukemia and 9 patients had a medical history of lymphoma of which 7 had non-Hodgkin lymphoma, and 2 had Hodgkin lymphoma. Our results show that adults with NF1 do not have an increased tendency to develop lymphoproliferative malignancies, in contrast to the general increased risk of malignancy. While our results are consistent with the recent population-based study in Finland, they are in contrast with the larger population-based study in England whereby NF1 individuals were found to be 3 times more likely to develop both non-Hodgkin lymphoma and lymphocytic leukemia. Large-scale epidemiological studies based on nationwide data sets are thus needed to confirm our findings.

Clinical spectrum of neurofibromatosis type 1 among children in a tertiary care center

Objectives:

To identify the clinical and neuroradiological features of neurofibromatosis type 1 and the risk of malignancy in a pediatric age group.

Methods:

This observational retrospective cohort study was conducted at King Saud University Medical City, Riyadh, Kingdom of Saudi Arabia, for the patients with neurofibromatosis type 1 who were seen and had follow up from January 2000 to January 2019.

Results:

A total of 50 children were included. Approximately 90% of patients presented with café-au-lait macules, and 34% had skin-fold freckling. Moreover, 42% of the participants had a first-degree relative with neurofibromatosis type 1, and about a quarter presented with associated epilepsy. About 90% of the neuroradiological features were consistent with those of neurofibromatosis type 1. About 52% of the patients had one or multiple types of tumors, and 34% presented with optic pathway glioma.

Conclusion:

This study described clinical spectrum of neurofibromatosis type 1 among children. It showed also a higher percentage of tumors than previous studies.

Genotype-Phenotype Correlations in Neurofibromatosis Type 1: A Single-Center Cohort Study

Simple Summary

Neurofibromatosis type 1 (NF1) is a complex disorder characterized by a multisystem involvement and cancer predisposition. It is caused by genetic variants in NF1, a large tumor suppressor gene encoding a cytoplasmatic protein (neurofibromin) with a regulatory role in essential cellular processes. Genotype–phenotype correlations in NF1 patients are so far elusive. We retrospectively reviewed clinical, radiological, and genetic data of 583 individuals with at least 1 National Institutes of Health (NIH) criterion for NF1 diagnosis, including 365 subjects fulfilling criteria for the diagnosis. Novel genotype–phenotype correlations were identified through uni- and multivariate statistical analysis. Missense variants negatively correlated with neurofibromas. Skeletal abnormalities were associated with frameshift variants and whole gene deletions. The c.3721C>T; p.(R1241*) variant positively correlated with structural brain alterations, whereas the c.6855C>A; p.(Y2285*) variant was associated with a higher prevalence of Lisch nodules and endocrinological disorders. These novel NF1 genotype–phenotype correlations may have a relevant role in the implementation of patients’ care.

Abstract

Neurofibromatosis type 1 (NF1) is a proteiform genetic condition caused by pathogenic variants in NF1 and characterized by a heterogeneous phenotypic presentation. Relevant genotype–phenotype correlations have recently emerged, but only few pertinent studies are available. We retrospectively reviewed clinical, instrumental, and genetic data from a cohort of 583 individuals meeting at least 1 diagnostic National Institutes of Health (NIH) criterion for NF1. Of these, 365 subjects fulfilled ≥2 NIH criteria, including 235 pediatric patients. Genetic testing was performed through cDNA-based sequencing, Next Generation Sequencing (NGS), and Multiplex Ligation-dependent Probe Amplification (MLPA). Uni- and multivariate statistical analysis was used to investigate genotype–phenotype correlations. Among patients fulfilling ≥ 2 NIH criteria, causative single nucleotide variants (SNVs) and copy number variations (CNVs) were detected in 267/365 (73.2%) and 20/365 (5.5%) cases. Missense variants negatively correlated with neurofibromas (p = 0.005). Skeletal abnormalities were associated with whole gene deletions (p = 0.05) and frameshift variants (p = 0.006). The c.3721C>T; p.(R1241*) variant positively correlated with structural brain alterations (p = 0.031), whereas Lisch nodules (p = 0.05) and endocrinological disorders (p = 0.043) were associated with the c.6855C>A; p.(Y2285*) variant. We identified novel NF1 genotype–phenotype correlations and provided an overview of known associations, supporting their potential relevance in the implementation of patient management.

Circulating free DNA in the plasma of individuals with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant syndrome whose characteristic manifestations include benign neurofibromas, yet NF1 is also associated with a high risk of cancer. Measurements of circulating free plasma DNA (cfDNA) are gaining wider applicability in cancer diagnostics, targeting of therapy, and monitoring of therapeutic response. Individuals with NF1 are likely to be followed up using this method, but the effects of NF1 and neurofibromas on cfDNA levels are not known. We studied peripheral blood samples from 19 adults with NF1 and 12 healthy controls. The cfDNA was isolated from plasma with QIAamp Circulating Nucleic Acid Kit and quantified using the Qubit 2.0 Fluorometer. The cfDNA concentration of each sample was normalized relative to the plasma protein concentration. The normalized median concentration of cfDNA in plasma was 19.3 ng/ml (range 6.6-78.6) among individuals with NF1 and 15.9 ng/ml (range 4.8-47.0) among controls (p = .369). Individuals with NF1 who also had plexiform neurofibroma (pNF) showed non-significantly elevated cfDNA concentration compared to individuals with NF1 and without known pNF (median 25.4 vs. 18.8 ng/ml, p = .122). The effect of NF1 on cfDNA seems to be relatively small and NF1 is therefore unlikely to hamper the use of cfDNA-based assays.

A rare disease and education: Neurofibromatosis type 1 decreases educational attainment

Rare heritable syndromes may affect educational attainment. Here, we study education in neurofibromatosis 1 (NF1) that is associated with multifaceted medical, social and cognitive consequences. Educational attainment in the Finnish population‐based cohort of 1408 individuals with verified NF1 was compared with matched controls using Cox proportional hazards model with delayed entry and competing risk for death. Moreover, models accounting for the effects of cancer at age 15–30 years, parental NF1 and developmental disorders were constructed. Overall, the attainment of secondary education was reduced in individuals with NF1 compared to controls (hazard ratio 0.83, 95%CI 0.74–0.92). History of cancer and developmental disorders were major predictors of lack of secondary education. Individuals with NF1 obtained vocational secondary education more often than general upper secondary education. Consequently, NF1 decreased the attainment of Bachelor's and Master's degrees by 46%–49% and 64%–74%, respectively. Surprisingly, the non‐NF1 siblings of individuals with NF1 also had lower educational attainment than controls, irrespective of parental NF1. In conclusion, NF1 is associated with reduced educational attainment and tendency for affected individuals to obtain vocational instead of academic education. Individuals living with NF1, especially those with cancer, developmental disorders or familial NF1, need effective student counseling and learning assistance.

Clinical diagnosis of neurofibromatosis type I in multiple family members due to cosegregation of a unique balanced translocation with disruption of the NF1 locus: Testing considerations for accurate diagnosis

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder that causes a predisposition to develop tumors along the peripheral nervous system. The NF1 gene, located at 17q11.2, has the highest mutation rate among known human genes and about half of NF1 patients have de novo pathogenic variants. We present a case of clinical NF1 diagnoses in multiple family members with phenotypes ranging from mild to severe. Chromosome analysis of the 3-year-old female proband with NF1 resulted in an abnormal karyotype that was inherited from her mother: 46,XX,t(4;17)(q21.3;q11.2) mat. However, no NF1 genetic variants were identified by either NGS analysis of NF1 DNA coding regions, deletion-duplication studies, or by cytogenomic microarray copy number analysis. Follow-up chromosome studies of the proband's two male siblings demonstrated cosegregation of the same balanced translocation and a clinical diagnosis of NF1. Based on the cosegregation of the translocation with the NF1 clinical presentation in this family, we hypothesized that the NF1 gene may have been disrupted by this unique rearrangement. Subsequent fluorescence in situ hybridization (FISH) analysis of the metaphase cells of an affected sibling revealed a disruption of the NF1 gene confirming the underlying basis of the clinical NF1 presentation in this family. The utilization of traditional cytogenetic as well as evolving molecular methods was not only pivotal in the diagnosis of NF1 and management for this family, but is also pertinent to other patients with a family history of NF1.

Preventative Effect of Mebendazole against Malignancies in Neurofibromatosis 1

Patients with RASopathy Neurofibromatosis 1 (NF1) are at a markedly increased risk of the development of benign and malignant tumors. Malignant tumors are often recalcitrant to treatments and associated with poor survival; however, no chemopreventative strategies currently exist. We thus evaluated the effect of mebendazole, alone or in combination with cyclooxygenase-2 (COX-2) inhibitors, on the prevention of NF1-related malignancies in a cisNf1+/−;Tp53+/− (NPcis) mouse model of NF1. Our in vitro findings showed that mebendazole (MBZ) inhibits the growth of NF1-related malignant peripheral nerve sheath tumors (MPNSTs) through a reduction in activated guanosine triphosphate (GTP)-bound Ras. The daily MBZ treatment of NPcis mice dosed at 195 mg/kg daily, initiated 60 days after birth, substantially delayed the formation of solid malignancies and increased median survival (p < 0.0001). Compared to placebo-treated mice, phosphorylated extracellular signal-regulated kinase (pERK) levels were decreased in the malignancies of MBZ-treated mice. The combination of MBZ with COX-2 inhibitor celecoxib (CXB) further enhanced the chemopreventative effect in female mice beyond each drug alone. These findings demonstrate the feasibility of a prevention strategy for malignancy development in high-risk NF1 individuals.

Advanced pharmacological therapies for neurofibromatosis type 1-related tumors

Neurofibromatosis Type 1 (NF1) is an autosomal dominant tumor-predisposition disorder that is caused by a heterozygous loss of function variant in the NF1 gene, which encodes a protein called neurofibromin. The absence of neurofibromin causes increased activity in the Rat sarcoma protein (RAS) signalling pathway, which results in an increased growth and cell proliferation. As a result, both oncological and non-oncological comorbidities contribute to a high morbidity and mortality in these patients. Optic pathways gliomas, plexiform neurofibromas and malignant peripheral nerve sheath tumor (MPNST) are the most frequent NF1-associated tumors. The treatment of these complications is often challenging, since surgery may not be feasible due to the location, size, and infiltrative nature of these tumors, and standard chemotherapy or radiotherapy are burdened by significant toxicity and risk for secondary malignancies. For these reasons, following the novel discoveries of the pathophysiological mechanisms that lead to cell proliferation and tumorigenesis in NF1 patients, emerging drugs targeting specific signalling pathways (i.e. the MEK/ERK cascade), have been developed with promising results.

Unexpected discovery of a diffuse astrocytoma of the conus medullaris in an elderly NF1 patient

Neurofibromatosis type 1 (NF1) is one of the most common genetic neurocutaneous disorders, and it is well known to be associated with peripheral or central nervous system malignancies. The most common malignant tumors are malignant peripheral nerve sheath tumors (MPNSTs); MPNSTs are the most common cause of death in patients with NF1. Central nervous system malignancies rarely occur. So far, the occurrence of spinal cord malignancies is exceedingly rare. Herein, we report a rare case of a 69-year-old male with NF1 following tumor resection twice for cutaneous MPNSTs developing intramedullary diffuse astrocytoma in the conus medullaris, which initially presented with traumatic spinal cord injury associated with a compression fracture from fall. Contrast-enhanced magnetic resonance imaging and biopsy of the spinal cord were required to establish the final diagnosis.

Nonoptic pathway tumors in children with neurofibromatosis type 1

OBJECTIVE

To define the radiologic features and natural history of nonoptic pathway tumors (non-OPTs) in children with neurofibromatosis type 1 (NF1).

METHODS

We performed a retrospective cross-sectional analysis of 64 children with NF1 harboring 100 probable non-OPTs. Age at diagnosis, sex, tumor location, number of tumors, symptomology, concurrent OPT, radiographic progression (defined as qualitative and quantitative increases in size), and treatment were assessed. Tumor volumes were measured from initial presentation until treatment or end of disease progression.

RESULTS

Sixty-three percent of probable non-OPTs progressed over time, where radiographic progression was concomitantly associated with clinical progression. Fifty-two percent of patients had incidentally identified probable non-OPTs. Twenty-five percent of patients were symptomatic at initial diagnosis, all of whom harbored tumors that grew on subsequent scans and required tumor-directed therapy. There were no clinical differences between probable non-OPTs localized to the brainstem vs other locations with respect to age, sex, concurrent optic pathway glioma, symptomology, and treatment. The average time from diagnosis to stabilization or decrease in tumor size was 2.34 years (SD, 2.15 years). Nineteen biopsied lesions were all histopathologically confirmed as tumor. Six children (9%) had deep extensive tumors, who presented earlier (mean age at diagnosis, 3.88 years), required multiple treatments, and had a shorter mean progression-free survival (48 months).

CONCLUSIONS

Over half of children with NF1 in this study developed probable non-OPTs, the majority of which were clinically and radiographically progressive. While brainstem and nonbrainstem gliomas share similar clinical features and natural history, deep extensive tumors comprise a distinct aggressive group of tumors that warrant close attention.

Incidence of second malignancies in individuals diagnosed with malignant peripheral nerve sheath tumors

BACKGROUND

The incidence of malignant peripheral nerve sheath tumors (MPNSTs) is low in the general population, although individuals with Neurofibromatosis Type I (NF1) are particularly susceptible. These tumors generally have a high probability of metastasis. The rate and types of second malignancies (SMNs) after a primary diagnosis of MPNST are not well characterized. We aimed to quantify the rate of SMNs among individuals with a first primary MPNST using population-based data.

METHODS

We estimated age-standardized incidence rates (SIRs) for SMNs among 1,579 primary MPNST cases between ages 0-85+ using SEER 18 (2000-2015). We estimated incidence rate ratios (IRRs) and 95% confidence intervals (95% CI) for SMNs in MPNST cases compared with general population rates. We conducted sex-stratified and age-restricted analyses (< 30 years at diagnosis).

RESULTS

Seven percent (108/1579) of MPNST cases developed a SMN (SIR of 4635 cases/million). Compared to the general population, MPNST cases were more likely to develop SMNs (IRR: 29.3; 95% CI 23.8-34.8) and had a much higher rate of second MPNSTs (IRR: 15,992.9; 95% CI 9594.5-22,391.3). Aside from a second MPNST, second cancers were frequently diagnosed in the breast, lung, skin, and soft tissue in females and were myeloid and skin malignancies in males. When restricted to < 30 years of age, second MPNSTs were the most common cancers diagnosed.

CONCLUSIONS

The rate of SMNs among MPNST cases is tremendously higher than that observed among individuals with other cancers, particularly for second MPNSTs. These findings suggest rates of SMNs may also be higher in NF1 individuals.

Secondary Sarcomas: Biology, Presentation, and Clinical Care

Secondary sarcomas are a subset of sarcomas that occur in patients with prior cancer diagnoses and are associated with environmental or genetic factors. Although secondary sarcomas are rare in general, there are predisposing factors that can substantially increase this risk in certain populations. Herein, we review the environmental factors with the strongest association of sarcoma risk, including chemical exposure, certain viruses, cytotoxic and immunosuppressive agents, chronic edema, and radiation exposure. Additionally, the most common genetic disorders that carry a predisposition for sarcoma development will be discussed, including hereditary retinoblastoma (RB), Li-Fraumeni syndrome (LFS), neurofibromatosis type 1 (NF1), and DICER1 syndrome. Although treatment does not generally differ for sporadic versus secondary sarcomas, awareness of the risk factors can alter therapeutic strategies to minimize risk, aid prompt diagnosis by increasing clinical suspicion, and allow for appropriate surveillance and genetic counseling for those patients with cancer predisposition syndromes.

Glioblastoma in adults with neurofibromatosis type I: A report of two cases

Neurofibromatosis type I (NF1) is a familial tumor syndrome with an autosomal-dominant inheritance. NF1-associated tumors often include neurofibromas, malignant peripheral nerve sheath tumors and pilocytic astrocytomas of the optic nerve. The presentation of NF1 patients with glioblastoma is a rare occurrence, with only a handful of cases reported in the literature. We report two cases of glioblastomas occurring in adults with NF1 and briefly review the relevant literature.