Keer, Jan Van

Abstract Background: Thrombotic microangiopathy (TMA) is a hematologic syndrome associated with endothelial injury, microvascular thrombosis, and hemolytic anemia resulting in end organ damage. TMA is rarely associated with multiple myeloma (MM) and is usually reported in the setting of allogeneic hematopoietic stem cell transplants (AHSCT), with associated graft versus host disease and calcineurin inhibitor use. We present 11 cases of TMA in MM patients not associated with AHSCT. Methods: Cases were collected from multiple centers in patients with confirmed diagnosis of MM. TMA was diagnosed by the presence of thrombocytopenia and evidence of microangiopathic hemolytic anemia. Results: Eleven patients with MM were identified to have developed TMA during the course of their disease. Two patients presented with TMA at the time of MM diagnosis. A third had been off treatment for over a year prior to presenting with a TMA which correlated with a significant increase in her free light chains. The other cases occurred during active treatment. All remaining patients received proteasome inhibitors, with three patients on bortezomib-based regimens and five patients on carfilzomib. One patient on a bortezomib-based regimen had been stable prior to developing a TMA in the setting of sepsis. In the remaining patients, the TMA developed rapidly after initiating the proteasome inhibitor. In all cases, the TMA improved after drug withdrawal. One patient was later rechallenged with bortezomib and again developed TMA. Discussion: A review of the literature reveals only nine cases of TMA with MM. Of these, 4 patients had TMA as the initial presentation of MM, and 5 patients were on treatment, most often bortezomib-based regimens. Our series patients match those in the literature closely and demonstrate that TMAs can occur in MM outside of the context of AHSCT. In roughly one third of patients, TMAs were the initial presentation of MM and improved with treatment of the MM. In others, the use of proteasome inhibitors appears to be associated with development of TMA. In these cases, the temporal correlation, resolution of TMA after medication withdrawal, and the instance of recurrence of TMA with rechallenge of bortezomib, support a causal relationship between the medication and the TMA. Thus, a high clinical suspicion for TMA must exist for patients on proteasome inhibitors who develop worsening anemia and thrombocytopenia. Medication should be withdrawn if TMA is diagnosed. Disclosures Vij: Onyx: Consultancy, Honoraria, Research Funding, Speakers Bureau; Millennium: Honoraria, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; BMS: Consultancy; Takeda: Consultancy, Research Funding; Novartis: Consultancy; Sanofi: Consultancy; Janssen: Consultancy; Merck: Consultancy.

A variety of medications have been implicated in the causation of thrombotic microangiopathy (TMA). Recently, a few case reports have emerged of TMA attributed to the proteasome inhibitors (PI) bortezomib and carfilzomib in patients with multiple myeloma. The aim of this case series was to better characterize the role of PI in the etiology of drug‐induced TMA. We describe eleven patients from six medical centers from around the world who developed TMA while being treated with PI. The median time between medication initiation and diagnosis of TMA was 21 days (range 5 days to 17 months). Median laboratory values at diagnosis included hemoglobin—7.5 g dL−1, platelet count—20 × 109/L, LDH—698 U L−1, creatinine—3.12 mg dL−1. No patient had any other cause of TMA, including ADAMTS13 inhibition, other malignancy or use of any other medication previously associated with TMA. Nine patients had resolution of TMA without evidence of hemolysis after withdrawal of PI. Two patients had stabilization of laboratory values but persistent evidence of hemolysis despite medication withdrawal. One patient had recurrence of TMA with rechallenge of PI. There is a strong level of evidence that PI can cause DITMA. In evaluating patients with suspected TMA, PI use should be recognized as a potential etiology, and these medications should be discontinued promptly if thought to be the cause of TMA. Am. J. Hematol. 91:E348–E352, 2016. © 2016 Wiley Periodicals, Inc.