Severe Pancytopenia Induced by Pembrolizumab in Metastatic Adenocarcinoma: A Case Report

Immune checkpoint inhibitors (ICIS) are an integral anti-tumor therapy for many malignancies. Most patients show very good tolerability to ICIs; however, serious immune-related adverse events (IRAE's) with ICIS have been poorly documented and prevent some patients from continuing ICIs or even become the direct cause of patient death. Here, we present the case of a 74 year-old male patient with metastatic lung adenocarcinoma who received three doses of Pembrolizumab and developed pancytopenia after each dose. Although the rst 2 episode of pancytopenia resolved with a treatment regimen of granulocyte colony-stimulating factor (G-CSF), packed red blood cell and platelet transfusion, the third episode showed extreme resistance to these treatments.