Chimeric antigen receptor modified T cells (CAR-t) have emerged as a promising and powerful immunotherapy in refractory lymphoid malignancies. However, CAR-t cell therapy is associated with a high frequency of neurotoxicity, such as language dysfunction and encephalopathy. The exact mechanisms of such neurotoxic syndromes have remained elusive.

EEG has emerged as an important tool of patient monitoring and may provide unique insights into the pathophysiology of CAR-t therapy associated neurotoxicities.

We reviewed the clinical presentation and EEG findings of 20 unique adult patients with language deficits as the initital symptom of neurotoxicity after CAR-t cell therapy. Patients were treated at the Massachusetts General Hospital, Boston, USA and Kings College Hospital, London, UK. The cohort included patients treated with CD19 directed CAR-t cells for non-Hodgkins lymphoma (n=17), acute lymphoblastic leukaemia (n=1), follicular lymphoma (n=1) and chronic lymphocytic leukaemia (n=1). The aim of this study is to describe the types of language deficits seen in this patient cohort and to characterise the pattern and electrographic signature in these patients at the time of language impairment.