LGG-48. PROLIFIC GROWTH OF BRAF V600E MUTANT PILOCYTIC ASTROCYTOMA WHILE ON KETOGENIC DIET: CASE REPORT

Epilepsy is a common diagnosis among pediatric patients with supratentorial tumors, particularly infiltrating gliomas. The ketogenic diet can be a successful antiepileptic therapy for patients with medically intractable epilepsy. Acetoacetate, a main ketone released during ketosis, has been shown to increase BRAF(V600E) binding to MEK1 and MEK1 phosphorylation in BRAF(V600E) mutant melanoma cells, thereby promoting proliferation and tumor growth (Kang et al, 2015, Xia et al, 2017). BRAF(V600E) mutation is common in pediatric low-grade gliomas. Therefore, use of a ketogenic diet to manage coincident epilepsy could, in theory, promote tumor growth. However, this has not been previously reported in a human patient. We present a 3 year-old male with a non-NF1 optic pathway BRAF(V600E) mutant pilocytic astrocytoma and medically intractable epilepsy. He was treated with carboplatin and bevacizumab for 1 year, with good tumor response and vision recovery. He showed stable, non-progressive disease for several months. He was placed on a ketogenic diet 9 months into treatment and became seizure free. Tumor recurrence occurred at 8 months off therapy, at which time a biopsy demonstrated BRAF(V600E) mutation. The tumor progressed rapidly despite treatment with Trametinib and Dabrafenib, leading to salvage therapy with carboplatin, vinblastine, bevacizumab, and XRT, without tumor control. We discuss the potential effect of the ketogenic diet on this patient’s outcome.