Ncmp-17. plasma exchange for immune checkpoint inhibitor induced acute demyelinating polyneuropathy refractory to ivig

Abstract The use of immune checkpoint inhibitors in the treatment of cancer has gained prominence due to their effectiveness. Unfortunately, neurological immune-related adverse events represent a growing problem in neuro-oncology practice. Many of these cases are rare and their diagnoses and management can be challenging. We present a case of a 69-year-old male with urothelial carcinoma status post left nephrectomy who developed bilateral lower extremity weakness that began following his first dose of Atezolizumab. After three doses, his lower extremity weakness worsened to the point where he could not walk. A NCV study was performed and was consistent with acute demyelinating polyneuropathy. A cervical MRI (Magnetic Resonance Imaging) showed an enhancing lesion at C6-C8. He was treated with three days of intravenous methylprednisolone every six hours for three days followed by three days of 0.4gm/kg IVIG. He regained his ability to walk after IVIG treatment. The enhancing lesion noted on MRI remained. Three weeks after the first IVIG treatment, he declined significantly, redeveloping symptoms where he could not ambulate and required assistance to use the toilet. He had no lower extremity reflexes and had loss of proprioception of his hands. He was scheduled for another IVIG infusion at .4gm/kg followed by a dose of IVIG .6gm/kg the next day, and then four more days of IVIG .25gm/kg. His lower extremity weakness and difficulty walking remained so he was arranged for plasmapheresis x five cycles. His weakness improved, reflexes returned, and he no longer had proprioceptive loss of his hands. A cervical MRI obtained one month after plasma exchange showed resolution of the C6-C8 enhancing lesion. He is now ambulating with a cane. This case highlights the effectiveness of plasma exchange in a case that was refractory to IVIG