LAUSR

Abstract Immune checkpoint inhibitors (ICIs) are being used increasingly in the treatment of several cancers and have been associated with neurological complications including immune checkpoint inhibitor-induced encephalitis (ICI-iE). We present two cases of ICI-iE with the novel agent dostarlimab, which to our knowledge are the first reported with this agent. These cases add to the growing body of literature on ICI-iE, demonstrating two cases of meningoencephalitis associated with the novel agent dostarlimab treated successfully with prednisone. As imaging studies may be unrevealing, clinicians must maintain a high index of suspicion for ICI-iE in any patient who develops altered mental status on ICI therapy, with low threshold to obtain lumbar puncture for evidence of inflammatory CSF and to exclude other causes. It is important to note that many neurological presentations of ICIs can also be secondary to tumor metastasis and other paraneoplastic syndromes, making the diagnosis challenging. Prognosis can be good with early recognition and treatment with corticosteroids. Whether patients can be rechallenged with ICI is to be determined in larger studies given the rarity of this complication.