Twenty patients were identified (16 AE, 4 myelitis). Median age at symptom onset was 67 years (range 48-86). 11 (55%) were male. Median follow up time from cancer diagnosis to last visit was 41 months (range 3-130). Cancers included renal cell carcinoma in 5 (25%), melanoma in 3 (15%), SCLC in 3 (15%), breast adenocarcinoma in 2 (10%), others in 7 (35%). ICI included ipilimumab/nivolumab in 8 (40%), nivolumab in 4 (20%), pembrolizumab in 4 (20%), atezolizumab in 4 (20%). AE and myelitis irAEs developed at a median of 14 days (range 2-180) from last ICI treatment. Serum neural antibodies included Ma2 (1:3200), CRMP5 (1:3840), MOG (1:100). Other concurrent neurologic irAE included meningitis, cranial neuropathy, polyradiculopathy, myositis in 4 (20%). ICI was discontinued in all but two (90%). All patients received corticosteroids. Four received additional plasmapheresis or IVIG.
Treatment response included partial (62.5%) or no improvement (37.5%) in AE. For myelitis, all patients had partial improvement. Fourteen (70%) died at a median time of 11.5 months (range 0-35) since the onset of irAE. Median mRS at last visit was 2 for the 6 patients that were alive at follow up. Two myelitis patients (50%) were wheelchair-dependent at last visit.