Central nervous system manifestations. Neurological manifestations have been observed in 55% of patients with NF1.18 These include headache, hydrocephalus, epilepsy, lacunar stroke, white matter disease, intraspinal neurofibroma, facial palsy, radiculopathy, and polyneuropathy. Tumors include optic pathway tumors, meningioma, and cerebral glioma. Glioma is the predominant tumor type in NF1 and occurs in all parts of the nervous system, with a predilection for the optic pathways, brainstem, and cerebellum.18
Malignant peripheral nerve sheath tumors. There is an 8% to 13% lifetime risk for malignant peripheral nerve sheath tumors (MPNST), predominantly in individuals between the ages of 20 and 35.19,20 Any change in neurofibroma from soft to hard, or a rapid increase in the size, is suspicious for MPNST. Other symptoms include persistent pain lasting for longer than a month, pain that disturbs sleep, and new neurological deficits. These cancers can be hard to detect, leading to poor prognosis secondary to metastasis.19,20 The greatest risk factors for MPNST are pain associated with a mass and the presence of cutaneous and subcutaneous neurofibromas.21
Treatment is symptom based, but there is a new option
Treatment is individualized to the patient’s symptoms. Neurofibromas that are disfiguring, disruptive, or malignant may be surgically removed.
In April 2020, the US Food and Drug Administration (FDA) approved selumetinib (Koselugo) for the treatment of pediatric patients (ages ≥ 2 years) with NF1 who have symptomatic, inoperable plexiform neurofibromas (PNs).22 In a clinical trial, patients received selumetinib 25 mg/m2 orally twice a day until they demonstrated disease progression or experienced “unacceptable” adverse events.22,23 The overall response rate was 66%, defined as “the percentage of patients with a complete response and those who experienced more than a 20% reduction in PN volume on MRI that was confirmed on a subsequent MRI within 3 to 6 months.”22
Of note, all patients had a partial, not complete, response. Common adverse effects included vomiting, rash, abdominal pain, diarrhea, and nausea.23 Selumetinib may also cause more serious adverse effects, including cardiomyopathy and ocular toxicity. Prior to treatment initiation and at regular intervals during treatment, patients should undergo cardiac and ophthalmic evaluation.22,23 Selumetinib was granted priority review and orphan drug status by the FDA.22
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