Transplant-Associated Thrombotic Microangiopathy (TA-TMA): Integrating New Data to Improve Patient Outcomes

Because TA-TMA has overlapping clinical features with other disorders, it is important to rule out (1) thrombotic thrombocytopenic purpura (TTP) by verifying normal levels of ADAMTS13 10%) and normal von Willebrand factor (vWF) multimers; and (2) classic hemolytic uremic syndrome (HUS) caused by Shiga toxin.producing Escherichia coli (STEC), through stool culture and testing for Shiga toxin.7 Lastly, a modified version of the Ham test can differentiate transplant-associated atypical HUS (aHUS) from other TMAs, although this might not be needed in clinical practice. Results showed that treatment with narsoplimab resulted in an objective response rate (ORR) of 61% (95% CI, 40.6%-78.5%; P .0001) in the full analysis set of patients (n = 28) and an ORR of 74% (95% CI, 51.6%-89.8%; P .0001) in the per-protocol group (n = 23). An updated analysis of the study was presented at the 2021 Annual Meeting of the European Society for Blood and Marrow Transplantation (EBMT).19 Response to narsoplimab was found to be consistent across different subgroups regardless of age, sex, and coexisting conditions such as GvHD, significant infection, multiple-organ TMA involvement, mismatched donor, and transfusion within 2 weeks before the first narsoplimab dose. A systematic review and meta-analysis that pooled data from 6 studies (n = 116) revealed that ECU improves survival rate and overall response rate in patients with TA-TMA and exhibits a manageable safety profile.23 The estimated overall response rate, CR rate, and survival rate at the last follow-up (SR) were 71%, 32%, and 52%, respectively.