Predictors of Transplant-Associated Thrombotic Microangiopathy in Patients With Overlap or Chronic Graft-vs-Host-Disease.

Background: Recent data suggest that novel biologic agents are associated with increased risk of thrombotic microangiopathy (TMA). Ruxolitinib, an approved treatment for graft-vs-host-disease (GVHD), has been associated with thrombocytopenia of unclear etiology.

Methods: We investigated factors and outcomes associated with transplant-associated thrombotic microangiopathy (TA-TMA) in patients with GVHD. We retrospectively enrolled consecutive allogeneic hematopoietic cell transplantation recipients with overlap or chronic GVHD at our Joint Accreditation Committee ISCT-Europe & EBMT-accredited unit (January 2016-June 2019). Ruxolitinib has been administered off-label since 2016.

Results: Among 160 patients with GVHD, 18 were diagnosed with TA-TMA. TA-TMA developed at a median of 150 posttransplant days (range, 98-3013). Among pre- and posttransplant factors, TA-TMA was associated only with ruxolitinib administration and severe GVHD. Interestingly, these 2 variables did not correlate with each other. In the multivariate analysis, both were independent predictors of TA-TMA. Time-dependent analysis confirmed ruxolitinib's association with TA-TMA. With a follow-up of 38.4 months (4.6-83.9) in surviving patients, 5-year overall survival was 52.9%, independently predicted by TA-TMA, severe acute GVHD, and CD34+ cells infused. Ruxolitinib was not associated with survival outcomes.

Conclusions: Our data suggest that ruxolitinib and GVHD severity are associated with TA-TMA. Given the expanding use of ruxolitinib in GVHD and ongoing trials on chronic GVHD, further studies are warranted to confirm these findings.