Defibrotide in Standard-of-Care Graft-Versus-Host Disease Prophylaxis

By Patrick Daly - Last Updated: December 20, 2022

In a recent, phase II open-label trial, researchers evaluated the impact of adding defibrotide to standard-of-care (SOC) acute graft-versus-host disease (aGVHD) prophylaxis compared with SOC alone. According to the study’s lead author, Michelle Hudspeth, the data suggested defibrotide could potentially improve current SOC for preventing aGVHD after allogeneic hematopoietic stem cell transplant (HSCT). The findings were presented in Haematologica.

The study included 152 patients who were randomized 1:1 to the defibrotide arm (n=79; median age, 57 years [range, 2-69 years]) or the SOC arm (n=73; median age, 56 years [range, 2-72 years]). The 2 arms had comparable characteristics except for myeloablative conditioning use (defibrotide, 76% vs SOC, 61%) and bone marrow-sourced stem cells (defibrotide, 34% vs SOC, 26%). Authors noted that the study was only powered to estimate incidence of aGVHD and was not able to compare treatment differences between the groups.

In the primary analysis, researchers estimated the 100-day post-HSCT cumulative incidence of aGVHD after transplant in the defibrotide group was 38.4% compared with 47.1% in the SOC group (treatment difference, –8.8%; 90% CI, –22.5 to 4.9).

Furthermore, this difference was more prominent in patients who received antithymocyte globulin as part of GVHD prophylaxis (defibrotide 30.4% vs SOC, 47.6%; treatment difference, –17.2%; 90% CI, –41.8 to 7.5). Lastly, the reported day-180 rates of overall survival and serious treatment-emergent side effects (defibrotide, 42% vs SOC, 44%) were similar between the arms.

The authors acknowledged the differences between the arms were not particularly substantial, but they proposed “defibrotide prophylaxis may add a benefit to currently available SOC to prevent aGVHD following [allogeneic HSCT] without adding significant toxicities.”

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