Response to combined BRAF/MEK inhibition in adult BRAF V600E mutant spinal pilocytic astrocytoma

Pilocytic astrocytomas are World Health Organisation (WHO) grade I tumors, occurring predominantly supratentorially and in the pediatric population. Although the mainstay of treatment is local therapies such as surgery, targeted systemic therapies may be necessary for recurrent or unresectable disease. The majority of sporadic pilocytic astrocytomas are associated with the BRAF-KIAA fusion gene, which results in constitutive activation of the MAP Kinase pathway. Less frequently, the BRAF V600E point mutation has been described, occurring in less than 10% of supratentorial pilocytic astrocytomas. Tumours with this mutation may respond to targeted therapy against the BRAF/MAP Kinase pathway. We report the first described case of a spinal pilocytic astrocytoma in an adult patient with a BRAF V600E mutation responding to targeted therapy using BRAF and MEK tyrosine kinase inhibitors, and share our experiences with the management of toxicity in this patient population.