Anti-PD-L1 therapy-associated hypophysitis and limbic encephalitis

Excerpt

A 71-year-old woman with history of neuro-endocrine tumor was admitted to our intensive care unit (ICU) with fluctuating level of consciousness preceded by the subacute onset of a working memory deficit. She had been treated 5 months before with two cycles of 1500 mg Durvalumab—an anti-PD-L1 (Program Death-Ligand 1) antibody. Figure 1 (panel A) shows initial magnetic resonance imaging (MRI). Remarkably, arterial spin labeling (ASL) exhibited a hyperperfusion suggestive of hypermetabolism, which has been described in encephalitis. Cerebrospinal fluid (CSF) analysis showed a lymphocytic pleocytosis (8 cells/µL) with high protein rate (183 mg/dL) and positive oligoclonal bands. Antineuronal antibodies including onconeuronal antibodies were absent in serum and CSF. No evidence of cancer relapse was found. Exploration of the hypothalamic–pituitary–adrenal axis showed central hypothyroidism, hypogonadism, and diabetes insipidus. She was diagnosed with autoimmune hypophysitis and limbic encephalitis associated with immune checkpoint inhibitor (ICI) treatment. Rapid improvement was observed after high dose intravenous steroids and therapeutic plasma exchange. One-month control MRI found improvement of limbic lesions with regression of pituitary swelling (Fig. 1, panel B).

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