Cerebral Infarction as a Rare Adverse Event of Immune Checkpoint Inhibitors in Patients With Head and Neck Squamous Cell Carcinoma: A Case Series

Immune checkpoint inhibitors (ICIs) are a novel treatment option for treating head and neck squamous cell carcinoma (HNSCC). Among the immune-related adverse effects, cerebral infarction (CI) is a rare but fatal complication, and it has been reported in various cancers, except HNSCC. Herein, we describe three cases of patients diagnosed with HNSCC who experienced CI following ICI treatment. In addition, we conducted a comprehensive literature review on ICI-related thrombosis. Three patients with recurrent HNSCC were treated with nivolumab. Two patients had a history of CI, or heart disease, and were concurrently prescribed antithrombotic medications during nivolumab treatment. The number of nivolumab administrations varied from 1-25 before the onset of CI. All patients experienced worsening of neurological symptoms due to CI, irrespective of antithrombotic treatment, and they ultimately succumbed to the disease within 16-222 days following their initial ICI administration. ICIs may cause thromboembolisms, leading to CI. Based on our review of the literature, a history of thromboembolism or heart disease could be a risk factor for ICI-related thrombosis.