IMMU-19. NIVOLUMAB-INDUCED CNS DEMYELINATION IN A 15-YEAR-OLD WITH CLASSIC HODGKIN LYMPHOMA

INTRODUCTION: Nivolumab associated neurologic immune-related adverse events (irAEs) have been reported in less than 1% of patients and mainly in the adult population. Here we present a pediatric case of nivolumab related CNS demyelination. Case description: 15-year-old male with nodular sclerosis stage III classic Hodgkin lymphoma was enrolled to receive chemotherapy following SWOG S1826 protocol. Eight weeks after the first dose of nivolumab, he had a single episode of seizure. Prolonged EEG showed no epileptiform discharges. Levetiracetam was initiated. Initial MRI showed a non-enhancing T2 hyperintense focal cortical thickening in the left primary motor cortex. CSF studies were significant for mild lymphocytic pleocytosis. One dose of nivolumab was held with subsequent doses given. Levetiracetam was continued and follow-up EEGs were normal. Repeat MRI done three months later showed multiple new parenchymal hyperintense lesions including in the anterior temporal lobe with central curvilinear enhancement, and faintly enhancing lesions in the left fusiform gyrus, juxtacortical white matter of the right middle temporal gyrus, and left superior cerebellar peduncle, findings consistent with CNS demyelination. At this time, CSF showed 9 WBCs (94% lymphocytes) and oligoclonal bands with negative cytology and flow cytometry making CNS lymphoma highly unlikely. The last two doses of nivolumab were held and he was started on methylprednisolone. The most recent MRI ten weeks after the last dose of nivolumab showed resolution of the abnormal findings. DISCUSSION: There is limited published literature about neurologic complications of immune checkpoint inhibitors (ICPis) in the pediatric population. CNS demyelination and other neurologic irAEs should be suspected in patients presenting with new neurologic symptoms who started any ICPi within the past three months and after other causes including disease progression, metastasis, metabolic or infectious disorders have been ruled out. Treatment varies depending on severity but includes discontinuation of the ICPi and steroids.