Thrombotic microangiopathy (TMA) is a pathological syndrome characterized by a combination of three key features: microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and organ damage, primarily affecting the kidneys. There are several drugs known to have a definite or probable causal association with TMA, and carfilzomib, a second-generation irreversible proteasome inhibitor (PI), approved for the treatment of multiple myeloma (MM), is one of them. In the medical literature, there have been a growing number of reports describing this serious adverse event occurring in MM patients. The precise mechanisms underlying the development of PI-induced TMA are not yet fully understood. Significant improvements in both renal and hematological aspects have been documented following the administration of eculizumab.

In this report, we present two cases of MM patients who developed TMA while undergoing carfilzomib therapy. These cases were successfully treated at the Haematology Unit, Careggi Hospital in Florence. In our cases as well, the introduction of eculizumab resulted in rapid enhancements in renal function and platelet count, ultimately leading to the discontinuation of hemodialysis after 4 and 2 weeks, respectively.

We assessed 91 patients who received carfilzomib-based therapies at our Haematology Department, during which we identified two cases of DITMA (2.2% incidence). Additionally, we conducted a literature review and discovered a total of 75 documented cases of carfilzomib-induced TMA. Our experience aligns with the cases reported in literature: this adverse event can manifest at any point during treatment, regardless of the specific drug combinations used alongside carfilzomib. The initial and most crucial step in its management involves discontinuing carfilzomib therapy; therefore, recognizing TMA in a timely manner is of utmost importance. Eculizumab could play a role in improving and expediting the resolution of this potentially fatal adverse event, but further studies are needed. In a MM patient receiving carfilzomib, presenting with anemia, thrombocytopenia, and impaired renal function, a carfilzomib-induced TMA should be suspected in order to discontinue the causative agent.