A case series of PD-1 inhibitor-associated paraneoplastic neurologic syndromes.

Immune checkpoint inhibitors (ICIs) are highly efficacious for treating many solid tumor types. Because of their immune-activating mechanism of action, ICIs can trigger various immune-mediated toxicities. We present three cases: i) a woman with anti-Ri brainstem encephalitis; ii) a man with anti-Hu sensory neuronopathy; and iii) a woman with suspected combined anti-Hu and anti-NMDA paraneoplastic syndromes associated with the initiation of the ICIs pembrolizumab and nivolumab. These cases suggest that ICIs can induce both humoral and cell-mediated paraneoplastic neurologic syndromes. Identifying biomarkers that predict risk of developing ICI-associated paraneoplastic syndromes and the development of efficacious treatment strategies for neurologic ICI-toxicities are critical unmet needs.