Thrombotic thrombocytopenic purpura associated to dual checkpoint inhibitor therapy for metastatic melanoma

Dual checkpoint inhibitor therapy has known immune-related adverse events. However, checkpoint inhibitor-associated thrombotic thrombocytopenic purpura is very rarely reported. We present a case of a 70-year old man with advanced melanoma, presenting with severe thrombocytopenia, hemolytic anemia with schistocytes and suppressed ADAMTS-13 activity by ADAMTS-13 inhibitors. We discuss differential diagnoses and speculated mechanisms of this obviously therapy-related adverse event, which should be considered by clinicians prescribing these drugs.