Antitumor Effect of Selumetinib for Brainstem Glioma in an Adult With NF1: A Case Report

NF1 is a known tumor predisposition syndrome associated with various tumors of the nervous system, including low-grade glioma in the pediatric population. NF1-associated brainstem tumors are less clinically progressive and rarely result in early death. However, a small subset of brainstem gliomas may act more aggressively in adults, especially when contrast enhancement appears. However, standard therapy for NF1-associated brainstem glioma remains controversial, and there is limited information available on the pathological and genetic findings.

A 38-year-old man presented with diplopia and was diagnosed with a midbrain tumor on MRI. The tumor increased in size during a 2-month follow-up period, and the patient underwent an open biopsy by the occipital transtentorial approach. Histopathological diagnosis revealed a low-grade glioma, isocitrate dehydrogenase wild type, and H3 wild type. An NF1 mutation was detected using a cancer gene panel test. The MAPK kinase inhibitor, selumetinib, was prescribed as first-line treatment. The patient achieved a good clinical response, with impressive radiological regression of the disease and no major adverse events. After 6 months of selumetinib use, the patient discontinued the medication. However, the disease recurred 6 months later, prompting the initiation of carboplatin therapy.

Primary treatment with MAPK kinase inhibitors can lead to tumor regression in brainstem glioma in an adult patient with NF1. We recommend that patients with brainstem glioma undergo biopsy and mutation testing, especially those with an unusually aggressive clinical course.