Drug-induced Thrombotic Microangiopathy with Concurrent Proteasome Inhibitor Use in the Treatment of Multiple Myeloma: A Case Series and Review of the Literature

Thrombotic microangiopathy (TMA) is a life-threatening clinical syndrome characterized by hemolytic anemia, thrombocytopenia, and microvascular thrombosis, resulting in ischemia and organ damage. Multiple myeloma (MM) is a neoplasm arising from clonal plasma cells within the bone marrow. The treatment frequently includes multi-agent immunochemotherapy, often with the use of proteasome inhibitors (PIs) such as bortezomib, carfilzomib, or ixazomib. There are increasing reports of TMA in association with PI exposure. This review summarizes the epidemiology, pathogenesis, and diagnosis of PI-related drug-induced TMA. We will outline the definition and diagnosis of TMA and explore an important cause of hemolysis in patients with MM: drug-induced TMA after PI exposure, an increasingly recognized therapeutic complication. This will be emphasized through the description of 3 novel cases of TMA. These illustrative cases occurred after treatment with high-dose weekly carfilzomib, cyclophosphamide, and dexamethasone as part of the MCRN003/MYX1 phase II clinical trial (NCT02597062) in relapsed MM.