Differential Diagnosis in the Management of CPI Immunotoxicity: Case Series of Etiologies not to Miss

Objective To present on treatable conditions arising with exposure to checkpoint inhibiting immunotherapy for malignancy. Each case was diagnostically obscured by presumed immunotoxicity. Background Neurological immune-related adverse events (n-irAEs) are rising in incidence adoption of inhibitors (CPIs) many cancers. 1-3% patients treated CPIs experience severe n-irAEs potential persistent functional disability or mortality. Diagnosis can be challenging immunologically vulnerable frequently multifactorial problems from their cancer and infectious, metabolic, iatrogenic complications. Design/Methods Three informative cases a single institution were analyzed. Results 1. An 80-year old woman metastatic melanoma recent treatment ipilimumab+pembrolizumab developed acute leg weakness. Given her EMG CSF findings, she began suspected CPI-induced atypical GBS myositis. Concomitantly found have B12 folate deficiencies, then gradually improved baseline vitamin repletion, steroids, plasma exchange. 2. A 27-year ipilimumab+nivolumab autoimmune hepatitis intractable vomiting. weeks after dabrafenib trametinib, confusion, diplopia, ataxia along weakness areflexia. She possible GBS, but concurrently thiamine deficiency sequela Wernicke's encephalopathy MRI Brain. Her confusion supplementation had 3. 57-year lung adenocarcinoma who progressed durvalumab pembrolizumab. Two later, fevers, rash, lethargy. supportively continued worsen until neurological workup revealed limbic hyperintensities Brain pleocytosis +HSV1. minor clinical improvement acyclovir remained cognitively debilitated. Conclusions complex circumstances when working up n-irAEs, systematic approach broad differential must utilized this important intersection neurology immunology.