LAUSR

Introduction Nivolumab, a programmed death-1(PD-1) inhibitor antibody, have demonstrated anti-tumor activity for multiple malignancies. Such immune checkpoint inhibitors induce novel and distinctive adverse effects, which are collectively named immune-related adverse events. Immune-related adverse events can theoretically occur at any part of the body, including the haemopoietic system. Most immune-related adverse events developed within 10 weeks of receiving immunotherapy. Thus far, there is no report of immune thrombocytopenia as an immune-related adverse event developed after discontinuation of immunotherapy. Case report We describe a 62-year-old male with metastatic non-small cell lung cancer developed immune thrombocytopenia nearly two months after discontinuation of nivolumab. When thrombocytopenia was detected, the patient was undergoing radiotherapy of supraclavicular lymph nodes. After complex diagnosis-by-exclusion process, nivolumab-induced immune thrombocytopenia was diagnosed. Management and outcome Intravenous immunoglobulins 20 g daily for 5 days, intravenous methylprednisolone 40 mg daily for 14 days followed by oral prednisone, intermittent platelet transfusion and oral thrombopoietin receptor (eltrombopag 25 mg daily) were administered. After 30 days, his platelet count had achieved a level of adequate hemostasis and continued to improvement during the tapering period. Discussion Most immune-related developed 6 months of immunotherapy. Clinicians need to be aware of a clinical diagnostic complex, developing months to years after discontinuation of immunotherapy, which recently is termed delayed immune-related events. This case is the first report of immune checkpoint inhibitors-induced thrombocytopenia that developed nearly 2 months after discontinuation of treatment with nivolumab for metastatic NSCLC. In future clinical practice, patients who have received immune checkpoint inhibitors develop new or unexplained symptom, irrespective of interval post-immunotherapy, immune-related adverse events should be considered.