Pembrolizumab-induced acute thrombosis: A case report

RATIONALE: Acute thrombosis has not been reported in the literature so far in lung cancer patients as an immune-related adverse event (irAE) associated with PD-1 pathway inhibitors. PATIENTS CONCERNS: Here, we for the first time present two NSCLC (non-small cell lung cancer) patients suffering from acute thrombosis as a pembrolizumab-induced irAE. Immediate treatment with continuous heparin infusion improved their symptoms and enabled them to continue pembrolizumab administration. METHODS: Ethical approval was given by the ethics committee of Osaka International Cancer Institute and the informed consents were given by the patients. DIAGNOSIS: Serum D-dimer level testing, venous ultrasonography, enhanced computed tomography (CT). INTERVENTIONS: Continuous heparin infusion, direct oral anticoagulants (DOAC). OUTCOMES: Immediate continuous heparin infusion improved their symptoms and continuing pembrolizumab with direct oral anticoagulant successfully induced tumor shrinkage. LESSONS: Reinvigoration of exhausted T cells by pembrolizumab induced systemic inflammation possibly resulting in development of thrombosis. Although acute thrombosis is a rare irAE, it may lead to cessation of treatment and can be lethal.