Post-transplant cyclophosphamide for GVHD prophylaxis compared to ATG-based prophylaxis in unrelated donor transplantation.

Post-transplant cyclophosphamide (PTCY) effectively prevents graft-versus-host disease after unmanipulated HLA-haploidentical HSCT. The use of PTCY in the unrelated donor HSCT setting is less explored. We conducted a retrospective study of 132 consecutive patients undergoing a matched or 9/10 mismatched unrelated donor HSCT in 4 centers in Spain, 60 with anti-thymocyte globulin (ATG)-based prophylaxis combined with MTX-CsA, and 72 using a PTCY-based regimen. Peripheral blood stem cells were used as graft in most patients (111 patients, 84%); mMUD donors were balanced between groups. Cumulative incidences of grades II-IV and III-IV acute GVHD at 100 days were lower in the PTCy group (46% vs. 67%, p = 0.008; 3% vs. 34%, p = 0.003), without statistically significant differences in the 2-year cumulative incidence of chronic moderate-severe GVHD. At 2 years, no significant differences were observed in overall survival, event-free survival, cumulative incidence of relapse, and non-relapse mortality. GVHD was the most frequent cause of NRM in the ATG group. No differences were observed between groups in the composite endpoint of GVHD-free and relapse-free survival. In this study, PTCy combined with additional immunosuppression after MUD/mMUD HSCT showed a reduction of aGVHD rate with safety results comparable to those obtained with the ATG-based prophylaxis.

Posttransplant cyclophosphamide vs cyclosporin A and methotrexate as GVHD prophylaxis in matched sibling transplantation.

Posttransplant cyclophosphamide (PTCy) effectively prevents graft-versus-host disease (GVHD) after HLA-haploidentical hematopoietic stem cell transplantation (HSCT). The use of PTCy in HLA-identical HSCT is less explored. We conducted a retrospective study of 107 consecutive patients undergoing an HLA-identical sibling (10/10) HSCT in 2 centers in Spain, 50 with GVHD prophylaxis with methotrexate-cyclosporin A (MTX-CsA) and 57 using a PTCy-based regimen with additional immunosuppression. Graft source was unmanipulated mobilized peripheral blood stem cells (PBSC) in most patients (97 patients, 91%). Cumulative incidences of grade II to IV and III to IV acute GVHD at 100 days were lower in the PTCy group (22.6% vs 52.2%, P = .0015; 8.8% vs 24.4%, P = .016), without statistically significant differences in the 2-year cumulative incidence of chronic moderate to severe GVHD (16.7% vs 26%, P = .306). At 2 years, no statistically significant differences were observed in OS (78% vs 56%, P = .088), EFS (62.5% vs 48%, P = .054), relapse (28% vs 27%, P = .47), and NRM (8.8% vs 24%, P = .054). The composite endpoint of GVHD and relapse-free survival (GRFS) was favorable for the PTCy group (24% vs 48%, P = .011), PTCy being the sole independent factor identified in the multivariate analysis for this endpoint. In this study, PTCy combination with additional immunosuppression using mostly PBSCs grafts showed a reduction of acute GVHD rate and an impact on GRFS, with safety results comparable with those obtained with MTX-CsA. Further prospective studies are needed to confirm these observations..