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The wide variety of clinical manifestations of the genetic syndrome neurofibromatosis type 1 (NF1) are driven by overactivation of the RAS pathway. Mitogen-activated protein kinase kinase inhibitors (MEKi) block downstream targets of RAS. The recent regulatory approvals of the MEKi selumetinib for inoperable symptomatic plexiform neurofibromas in children with NF1 have made it the first medical therapy approved for this indication in the United States, the European Union, and elsewhere. Several recently published and ongoing clinical trials have demonstrated that MEKi may have potential benefits for a variety of other NF1 manifestations, and there is broad interest in the field regarding the appropriate clinical use of these agents. In this review, we present the current evidence regarding the use of existing MEKi for a variety of NF1-related manifestations, including tumor (neurofibromas, malignant peripheral nerve sheath tumors, low-grade glioma, and juvenile myelomonocytic leukemia) and non-tumor (bone, pain, and neurocognitive) manifestations. We discuss the potential utility of MEKi in related genetic conditions characterized by overactivation of the RAS pathway (RASopathies). In addition, we review practical treatment considerations for the use of MEKi as well as provide consensus recommendations regarding their clinical use from a panel of experts.

RASopathies caused by germline pathogenic variants in genes that encode RAS pathway proteins. These disorders include neurofibromatosis type 1 (NF1), Noonan syndrome (NS), cardiofaciocutaneous syndrome (CFC), and Costello syndrome (CS), and others. RASopathies are characterized by heterogenous manifestations, including congenital heart disease, failure to thrive, and increased risk of cancers. Previous work led by the NCI Pediatric Oncology Branch has altered the natural course of one of the key manifestations of the RASopathy NF1. Through the conduct of a longitudinal cohort study and early phase clinical trials, the MEK inhibitor selumetinib was identified as the first active therapy for the NF1-related peripheral nerve sheath tumors called plexiform neurofibromas (PNs). As a result, selumetinib was granted breakthrough therapy designation by the FDA for the treatment of PN. Other RASopathy manifestations may also benefit from RAS targeted therapies. The overall goal of Advancing RAS/RASopathy Therapies (ART), a new NCI initiative, is to develop effective therapies and prevention strategies for the clinical manifestations of the non-NF1 RASopathies and for tumors characterized by somatic RAS mutations. This report reflects discussions from a February 2019 initiation meeting for this project, which had broad international collaboration from basic and clinical researchers and patient advocates.

Background/Aims: We developed an observer disfigurement severity scale for neurofibroma-related plexiform neurofibromas to assess change in plexiform neurofibroma–related disfigurement and evaluated its feasibility, reliability, and validity. Methods: Twenty-eight raters, divided into four cohorts based on neurofibromatosis type 1 familiarity and clinical experience, were shown photographs of children in a clinical trial (NCT01362803) at baseline and 1 year on selumetinib treatment for plexiform neurofibromas (n = 20) and of untreated participants with plexiform neurofibromas (n = 4). Raters, blinded to treatment and timepoint, completed the 0–10 disfigurement severity score for plexiform neurofibroma on each image (0 = not at all disfigured, 10 = very disfigured). Raters evaluated the ease of completing the scale, and a subset repeated the procedure to assess intra-rater reliability. Results: Mean baseline disfigurement severity score for plexiform neurofibroma ratings were similar for the selumetinib group (6.23) and controls (6.38). Mean paired differences between pre- and on-treatment ratings was −1.01 (less disfigurement) in the selumetinib group and 0.09 in the control (p = 0.005). For the disfigurement severity score for plexiform neurofibroma ratings, there was moderate-to-substantial agreement within rater cohorts (weighted kappa range = 0.46–0.66) and agreement between scores of the same raters at repeat sessions (p > 0.05). In the selumetinib group, change in disfigurement severity score for plexiform neurofibroma ratings was moderately correlated with change in plexiform neurofibroma volume with treatment (r = 0.60). Conclusion: This study demonstrates that our observer-rated disfigurement severity score for plexiform neurofibroma was feasible, reliable, and documented improvement in disfigurement in participants with plexiform neurofibroma shrinkage. Prospective studies in larger samples are needed to validate this scale further. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 is a genetic syndrome characterized by a wide variety of tumor and non-tumor manifestations. Bone-related issues, such as scoliosis, tibial dysplasia, and low bone mineral density, are a significant source of morbidity for this population with limited treatment options. Some of the challenges to developing such treatments include the lack of consensus regarding the optimal methods to assess bone health in neurofibromatosis type 1 and limited data regarding the natural history of these manifestations. In this review, the Functional Committee of the Response Evaluation in Neurofibromatosis and Schwannomatosis International Collaboration: (1) presents the available techniques for measuring overall bone health and metabolism in persons with neurofibromatosis type 1, (2) reviews data for use of each of these measures in the neurofibromatosis type 1 population, and (3) describes the strengths and limitations for each method as they might be used in clinical trials targeting neurofibromatosis type 1 bone manifestations. The Response Evaluation in Neurofibromatosis and Schwannomatosis International Collaboration supports the development of a prospective, longitudinal natural history study focusing on the bone-related manifestations and relevant biomarkers of neurofibromatosis type 1. In addition, we suggest that the neurofibromatosis type 1 research community consider adding the less burdensome measurements of bone health as exploratory endpoints in ongoing or planned clinical trials for other neurofibromatosis type 1 manifestations to expand knowledge in the field. [ABSTRACT FROM AUTHOR]

Rare cancers and other rare nonmalignant tumors comprise 25% of all cancer diagnoses and account for 25% of all cancer deaths. They are difficult to study due to many factors, including infrequent occurrence, lack of a universal infrastructure for data and/or tissue collection, and a paucity of disease models to test potential treatments. For each individual rare cancer, the limited number of diagnosed cases makes it difficult to recruit sufficient patients for clinical studies, and rare cancer research studies are often siloed. As a result, progress has been slow for many of these cancers. While rare cancer research efforts have increased over time, the breadth of the research landscape is not known. A recent literature search revealed a sharp increase in rare tumor, and rare cancer publications began in the early 2000s. To identify rare cancer research efforts being conducted in the US and globally, we conducted an online search of rare tumor/rare cancer research programs and identified 76 programs. To gain a deeper understanding of these programs, we composed and conducted a survey to ask programs for details about their research efforts. Of the 42 programs contacted to complete the survey, 23 programs responded. Survey results show most programs are collecting clinical data, molecular data, and biospecimens, and many are conducting molecular analyses. This landscape analysis demonstrates that multiple rare cancer research efforts are ongoing, and the rare cancer community may benefit from collaboration among stakeholders to accelerate research and improve patient outcomes. [ABSTRACT FROM AUTHOR]

Objectives: To characterize otologic and audiologic manifestations in our NF1 cohort and explore the relationship between otologic and audiologic findings in a subset of patients with ear‐related plexiform neurofibromas (PNs). Methods: Audiologic and otologic clinical evaluations were conducted on 102 patients with NF1 in a natural history study (5–45 years; M = 14.4 years; Mdn = 14). Testing included pure tone and speech audiometry, middle ear function, neurodiagnostic auditory brainstem response (ABR), auditory processing, and MRIs of the head and neck region. Patients referred to this study had an overall higher incidence and burden of PNs than the overall NF1 population. Results: The majority of subjects in this cohort had normal hearing sensitivity (81%) and normal middle ear function (78%). Nineteen participants had hearing loss that ranged in degree from mild to profound, with the majority in the mild range. Hearing loss was twice as likely to be conductive than sensorineural. In patients with ear‐related PNs (n = 12), hearing loss was predominantly conductive (60%). Seventy‐five percent of ears with PNs had atypical tympanometric tracings that could not be characterized by the classic categories. In all 20 patients with a PN in the temporal bone, the ear canal was affected, and the PNs often extended to the surrounding soft tissue regions. Conclusions: People with NF1‐related PNs in the temporal bone and adjacent skull base should have audiometric and otologic monitoring. Addressing hearing concerns should be part of routine clinical evaluations in patients with NF1. Magnetic resonance imaging (MRI) should be performed in patients with NF1 who have hearing loss. Level of Evidence: 3 Laryngoscope, 133:2770–2778, 2023 Audiologic and otologic clinical evaluations were conducted on 102 patients with NF1 including a subset of patients with ear‐related plexiform neurofibromas in a natural history study. Nineteen percent had hearing loss that ranged in degree from mild to profound with the majority in the mild range. People with NF1 are at risk for hearing loss, and in children, the hearing loss could be educationally significant. [ABSTRACT FROM AUTHOR]

This summary describes a publication about a study called SPRINT. The SPRINT study included 50 children with neurofibromatosis type 1 (NF1) and plexiform neurofibroma (PN) that could not be removed with surgery. PNs are tumors that grow along nerves and can cause various problems for children, such as pain, changes to appearance, and muscle weakness. In SPRINT, the study team wanted to learn whether a medication called selumetinib was able to shrink the PN caused by NF1 (also known as NF1-related PN), and if shrinking PNs helped relieve children of the problems caused by it. To assess how selumetinib might help, children had scans to measure the size of their PN, completed questionnaires, and had a variety of other tests done by their doctor. Their caregivers also completed questionnaires about their child. The children took selumetinib capsules twice a day on an empty stomach. The results showed that selumetinib was able to shrink the PN for most children (68%). The results also showed that the problems caused by the children's PNs mostly improved while on selumetinib treatment. SPRINT also showed that the side effects of selumetinib were mainly mild and could be managed by doctors. Before SPRINT, there were not many treatment options for children with NF1 and PN as there were no medications that had been shown to shrink PN, and surgery was not always possible. SPRINT showed that this medication shrinks most PNs and could help children with NF1 and PN. In April 2020, selumetinib was approved by the US Food and Drug Administration (FDA) because of the results of SPRINT. Selumetinib was the first and, as of February 2024, is the only medicine that can be prescribed by doctors to help children with NF1-related PN. Clinical Trial Registration: NCT01362803 (SPRINT) (ClinicalTrials.gov) [ABSTRACT FROM AUTHOR]