Clinical severity in Japanese patients with neurofibromatosis 1 based on DNB classification

Patient characteristics, treatment patterns, healthcare resource utilization, and costs among patients diagnosed with neurofibromatosis type 1 with and without plexiform neurofibromas in Japan

OBJECTIVES

The objectives of this study were to retrospectively investigate the patient characteristics, treatment patterns, healthcare resource utilization (HCRU), and healthcare costs related to management of neurofibromatosis type 1 (NF1) in Japan.

METHODS

Cohorts of NF1 patients with or without plexiform neurofibromas (PN) were identified from the Medical Data Vision database in 2008-2019. Baseline characteristics, NF1 medications, HCRU, and associated costs were assessed using descriptive statistics. All-cause HCRU and costs following the first confirmed NF1 diagnosis date were analyzed per patient per year (PPPY) in Japanese Yen (JPY) and United States Dollar (USD).

RESULTS

A total of 4394 NF1 patients without PN and 370 NF1 patients with PN were identified. The mean age was 35.0 and 36.9 years, respectively. The proportion of patients with PN treated with medications was higher than that in patients without PN (except for antirheumatic/immunologic agents). Analgesics/non-steroidal anti-inflammatory drugs were the most frequently prescribed NF1 medications (44.3% and 56.0% in patients without and with PN, respectively), followed by inpatient prescriptions of opioids/opioid-like agents (17.8% and 27.6%, respectively). Inpatient admissions accounted for the highest costs in both cohorts with the average cost PPPY being JPY 2,133,277 (USD 19,861) for patients without PN and JPY 1,052,868 (USD 9802) for patients with PN.

CONCLUSIONS

NF1 is treated primarily with supportive care with analgesics/non-steroidal anti-inflammatory drugs being the most frequently prescribed NF1 medications in Japan. Findings underscored the unmet need and substantial economic burden among patients with NF1 and highlighted the need for new treatment options for patients with this disease.

Genotype-phenotype correlations of neurofibromatosis type 1: a cross-sectional study from a large Chinese cohort

BACKGROUND

Neurofibromatosis type 1 (NF1) is a highly heterogeneous autosomal genetic disorder characterized by a broad spectrum of clinical and molecular manifestations. The correlations between genotype and phenotype in NF1 remain elusive. This study aimed to elucidate genotype-phenotype associations in a large Chinese cohort of NF1 patients.

METHODS

We included NF1 patients from our center who underwent genetic testing for NF1 variants and systemic examination. Genotype-phenotype correlation analyses were performed, focusing on variation types and involved neurofibromin domains.

RESULTS

A total of 195 patients were enrolled, comprising 105 males and 90 females, with a median age of 18 years. Truncating variants, single amino acid variations, and splicing variants accounted for 139/195 (71.3%), 23/195 (11.8%), and 33/195 (16.9%), respectively. Patients with splicing variants exhibited a significantly higher prevalence of spinal plexiform neurofibromas (spinal PNF) than those with truncating variants (76.4% vs. 51.8%; p = 0.022). Variations affecting the PKC domain were associated with higher rates of cutaneous neurofibromas (CNF) (100% vs. 64.9%, p < 0.001), Lisch nodules (100% vs. 61.2%, p < 0.001), plexiform neurofibromas (PNF) (100% vs. 95.7%, p = 0.009), and psychiatric disorders (11.8% vs. 1.6%, p = 0.042). Patients with mutations in the CSRD had an elevated risk of secondary primary malignancies (11.6% vs. 2.8%, p = 0.015). GRD involvement might enhance the risk of Lisch nodules (76.9% vs. 53.7%, p = 0.044). Variations in the Sec14-PH domain were correlated with a higher rate of CNF (76.8% vs. 58.6%, p = 0.014). Additionally, we found that the p.R1748* variants carry a high risk of malignancy.

CONCLUSION

Our study suggested some novel genotype-phenotype correlations within a Chinese cohort, providing innovative insights into this complex field that may contribute to genetic counseling, risk stratification, and clinical management for the NF1 population.

Distinct Transcriptional Profiles in the Different Phenotypes of Neurofibroma from the Same Subject with Neurofibromatosis 1

Neurofibromatosis 1 is a prevalent hereditary neurocutaneous disorder. Among the clinical phenotypes of neurofibromatosis 1, cutaneous neurofibroma (cNF) and plexiform neurofibroma (pNF) have distinct clinical manifestations, and pNF should be closely monitored owing to its malignant potential. However, the detailed distinct features of neurofibromatosis 1 phenotypes remain unknown. To determine whether the transcriptional features and microenvironment of cNF and pNF differ, single-cell RNA sequencing was performed on isolated cNF and pNF cells from the same patient. Six cNF and five pNF specimens from different subjects were also immunohistochemically analyzed. Our findings revealed that cNF and pNF had distinct transcriptional profiles even within the same subject. pNF is enriched in Schwann cells with characteristics similar to those of their malignant counterpart, fibroblasts, with a cancer-associated fibroblast-like phenotype, angiogenic endothelial cells, and M2-like macrophages, whereas cNF is enriched in CD8 T cells with tissue residency markers. The results of immunohistochemical analyses performed on different subjects agreed with those of single-cell RNA sequencing. This study found that cNF and pNF, the different neurofibromatosis phenotypes in neurofibromatosis 1, from the same subject are transcriptionally distinct in terms of the cell types involved, including T cells.

Neurofibromatosis 1 (von Recklinghausen Disease)

Neurofibromatosis 1 (NF1), also known as von Recklinghausen disease, is one of the most common neurocutaneous genetic disorders. Loss of function of the NF1 gene results in overactivation of the RAS/MAPK pathway, leading to neurocutaneous manifestations and osseous abnormalities. Because of medical progress, molecular testing for NF1 after genetic counseling is now available in Japan. In addition, revised diagnostic criteria for NF1 were proposed by NF1 experts of an international panel in 2021. Because the overall degree of severity and manifestations in each patient are not predictable, age-specific annual monitoring and patient education by a multidisciplinary team are important for the management of NF1. Although treatment of plexiform neurofibroma has been challenging, selumetinib (an oral selective MEK1/2 inhibitor), which targets a pathway downstream of RAS, was approved in 2022 for use in children with inoperable, symptomatic plexiform neurofibromas in Japan. This article summarizes recent progress in diagnosis, clinical characteristics, and treatment of various manifestations of NF1 and proposes the future direction required to resolve unmet needs in patients with NF1 in Japan.

Quality of life in patients with neurofibromatosis type 1: a nationwide database study in Japan from 2015 to 2019

BACKGROUND

This study examined the association between dermatological, neurological, and bone manifestations of neurofibromatosis type 1 (NF1) and quality of life (QoL) in patients with NF1 using a nationwide database of all patients who newly claimed for medical expense subsidies in Japan from 2015 to 2019.

METHODS

The Japanese Ministry of Health, Labour and Welfare provided the "National Database of Designated Intractable Diseases of Japan" containing clinical and personal records ("Medical Certificates of Designated Intractable Diseases") of all patients with NF1 following approval of the study protocol. To examine the association between the severity of symptoms and QoL, multinominal logistic regression analyses were performed, adjusted for potential confounders.

RESULTS

The final study population consisted of 1,487 patients (775 females and 712 males; mean (standard deviation) age, 45.4 (17.9) years). More than 50% and nearly 45% of participants were recorded as having moderate or severe "pain/discomfort" and "anxiety/depression," respectively. The severity of neurological symptoms was significantly associated with all components of QoL, whereas the severity of dermatological symptoms was significantly associated with only moderate or severe subjective and mental health-related components of QoL, and the severity of bone lesions was associated with only moderate or severe physical health-related components of QoL. Subjective and mental health-related components of QoL tended to be deteriorated more than physical health-related components of QoL in younger and female patients.

CONCLUSIONS

Severities of neurological and dermatological symptoms were significantly associated with subjective and mental health-related components of QoL, while the severity of bone symptoms was associated with only moderate and severe deterioration of physical health-related components of QoL.

Health-related quality of life in patients with neurofibromatosis 1 in Japan: A questionnaire survey using EQ-5D-5L

Neurofibromatosis 1 (NF1) is a genetic disorder characterized by various symptoms including dermatological, neurological, and osseous manifestations. These complications often cause cosmetic or functional disturbances, resulting in a significant impact on quality of life (QOL). However, there are limited data on QOL of individuals with NF1 in Japan. Therefore, we studied health-related QOL in patients with NF1 compared with that in general populations and the association with severity grade using EQ-5D. A cross-sectional study was conducted for 73 adult NF1 patients (26 males and 47 females; mean age, 44.16 years). The EQ-5D-5L values and visual analog scale (VAS) in patients with NF1 were 0.738 ± 0.137 and 69.93 ± 19.14, respectively. Both scores were significantly lower in patients with NF1 than in healthy volunteers (p < 0.0001). The score for anxiety/depression was the highest among the five items of EQ-5D. Although we investigated differences in the index value and VAS between stage 2 or less and stage 3 or higher, there was no difference in the scores between groups related to certification criteria for the public medical expenses subsidy system. EQ-5D-5L is a valuable assessment tool for health-related QOL in patients with NF1, but it might not be sufficient for severity certification of NF1 in Japan. We would need the revision of the current certification based on the patients' demand in the future. Our findings might be useful for assessment of therapeutic effects and appropriate resource allocation in the care of patients with NF1.

Distribution of diffuse plexiform neurofibroma on the body surface in patients with neurofibromatosis 1

Neurofibromatosis 1 (NF1) is a genetic disease characterized by cutaneous, neurological and osseous abnormalities. Approximately 20% of patients develop plexiform neurofibroma (PN), resulting in impaired quality of life. To evaluate distribution of diffuse PN on the body surface, a retrospective study was conducted for 354 patients with NF1 from 2007 to 2018 in Japan. We investigated a total of 40 patients with clinically apparent superficial diffuse PN. In the cases evaluated, 57.4% of the diffuse PN were located on the trunk, 19.2% the head and neck, 12.8% the lower limbs and 10.6% the upper limbs. Remarkably, 75.0% of the diffuse PN were located on the dorsal side. The frequency was significantly higher on the trunk than on the head and neck (P = 0.026). Our findings provide useful information for giving attention to the high possibility of diffuse PN on the dorsal side before progression in childhood and for future treatment in NF1.

Evaluation of neurofibromatosis type 1 progression using a nationwide registry of patients who submitted claims for medical expense subsidies in Japan between 2008 and 2012

BACKGROUND

No study to date has followed disease progression in patients with neurofibromatosis type 1 (NF1), including the incidence of various manifestations, using a national registry. Here we examined the state of NF1 progression using a nationwide registry of patients who submitted claims to receive medical expense subsidies for NF1 in Japan over a five-year period. A total of 342 eligible patients (194 females and 148 males) with NF1 who newly submitted claims for medical expense subsidies in Japan in 2008 were followed until 2012.

RESULTS

More than half of the patients were classified as Stage 5 in 2008. Of the eligible patients, 205 (60%) submitted claims to renew the subsidies between 2009 and 2012. During the study period, NF1 stage progressed in 30 patients, yielding an overall stage progression rate of 19% and progression incidence rate per 100 person-years of 12.2. Both stage progression rate and progression incidence rate were the highest in the 0-19 year age group at the time of registration and, as compared to other age groups, progression of neurological and bone manifestations was more prevalent in this age group.

CONCLUSIONS

The progression of neurological and bone manifestations was more prevalent in the 0-19 year age group compared to other age groups. The registry we used in the present study is useful for understanding the characteristics of patients with uncommon conditions, such as NF1. Our findings also highlight the feasibility of conducting quality research using registries of patients with rare diseases, such as NF1, that were not designed specifically for scientific research.