PTHP-01. Targeted therapy for brainstem pilocytic astrocytoma in a pediatric patient

Abstract BACKGROUND Pilocytic astrocytomas are most common low-grade brain tumors in children that are slow-growing and responsive to treatment. However, they can have significant morbidity and mortality based on the location of the tumor. We present a case of resistant pediatric brainstem pilocytic astrocytoma that caused significant morbidity. Case presentation: 3-year-old boy presented with recurrent cyanotic seizures since 1 year of age. MRI brain obtained after he had 11 seizures in a week showed a 5 cm x 1 cm cervico-medullary tumor with severe spinal canal stenosis and cord edema. Biopsy confirmed a low-grade glioma with a BRAFV600E mutation. He was initially started on dabrafenib monotherapy but had tumor progression after 14 months. He continued to have worsening episodes of apnea that eventually led to cardiopulmonary arrest and tracheostomy at 15 months from diagnosis, leading to ventilator and G-tube dependence. He was then started on vincristine and carboplatin chemotherapy for 5 months but continued to have tumor progression during this time. Chemotherapy was discontinued, and combination therapy with dabrafenib and trametinib targeted therapy was started at 22 months from diagnosis. Result: Imaging four months after starting combination dabrafenib and trametinib showed near complete resolution of the prior signal intensity and cord edema. He is in sustained remission for 21 months now on combination therapy. His apneic episodes have ceased, and he was gradually weaned off his ventilator. CONCLUSION While pilocytic astrocytomas are low-grade tumors, there can still be a significant morbidity and neurological impact on quality of life. Targeted therapies have shown significant improvement in patient outcomes for low-grade gliomas, which are resistant to traditional chemotherapy.