Immune checkpoint inhibitors (ICI) improve the prognosis of patients with advanced non-small cell lung cancer. However, clinicians should be aware of potentially life-threatening immune-related adverse events (irAEs). We report a case of a 67-year-old man with lung adenocarcinoma who developed an acute ischemic stroke after the second administration of pembrolizumab. The patient benefited from thrombolysis and mechanical thrombectomy with improved neurological outcome. An anti-phospholipid syndrome (APS) was diagnosed. Simultaneously, he developed a grade IV autoimmune hepatitis. Bothmanifestations were considered irAEs and the ICI treatment was discontinued. Steroids were initiated resulting in irAEs resolution. Remarkably, the patient achieved a complete oncological response and persistent remission after one year follow-up despite early discontinuation of pembrolizumab. Of note, APS is rarely reported as irAE. To our knowledge, this is the first case reported in the context of lung cancer. A systematic review of the literature is provided.