Anti T-cell lymphocyte globulin (ATLG) and post-transplant cyclophosphamide (PTCy) are now widely used strategies to prevent graft-versus-host disease after allogeneic stem cell transplantation. Data comparing immune reconstitution (IR) between ATLG and PTCy is scarce. This retrospective study conducted at the University Medical-Center Hamburg- Eppendorf (UKE) compares after myeloablative PBSC allogeneic stem cell transplant between PTCy (n=123) and ATLG (n=476). Detailed phenotypes of T, B natural killer (NK), natural killer T (NKT) cells were analyzed by multicolor flow at day 30, 100 and 180 posttransplant. Incidence of infections, viral reactivations graft-versus-host disease and relapse were collected.
Neutrophil engraftment was significantly delayed in the PTCy group (median day 12 vs. 10, p < 0.001) with a high incidence of infection before day+100 in the PTCy arm but a higher EBV reactivation in the ATLG arm and comparable CMV reactivation. Overall incidence of acute GVHD was similar but moderate/severe chronic GVHD was more seen after PTCy (44% vs. 38%, p = 0.005). ATLG resulted in a faster reconstitution of CD8+ T-cells, NK cells, NKT cells, and γδT cells while CD4 T-cells and B-cells reconstituted faster after PTCy. Similar reconstitution was observed for T-regulatory cells and B-cells. NRM, relapse incidence, DFS, and overall survival did not differ significantly between both arms.
Even though difference in IR have been translated into decreased incidence of infections and moderate/severe cGVHD in the ATLG group they had no impact on any of the other longterm outcomes. However, it remains undetermined which regimen is better as graft-versushost disease prophylaxis.
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