Response to trametinib treatment in a pediatric case of refractory optic pathway glioma with KIAA1549-BRAF fusion gene

Abstract

Trametinib, a MEK inhibitor, is expected to have efficacy for low-grade glioma with BRAF fusion. However, there are limited data on its safety and efficacy, especially in Japanese children. Here, we report a case of KIAA1549-BRAF fusion pediatric refractory optic pathway glioma (OPG) treated with trametinib. An 8-year-old girl was diagnosed with OPG at 7 months of age. She received five types of chemotherapy and underwent four surgeries. However, the tumor size continued increasing, resulting in hydrocephalus and progressive consciousness disturbance. Ventriculoperitoneal shunting was not performed because of the extremely high cerebrospinal fluid (CSF) protein concentration. Since KIAA1549-BRAF fusion was detected by cancer multi-gene panel testing, she received trametinib monotherapy for 2 months, during which the tumor size remained stable and CSF protein concentration decreased. No grade 3 or higher adverse events per the Common Terminology Criteria for Adverse Events occurred. Trametinib was safe and effective in our case, and further evaluation in a large cohort should be conducted for confirmation.