Triple Post-Transplant Cyclophosphamide (PTCY) Based Gvhd Prophylaxis for HLA Matched or HLA Haploidentical Transplants

We report a retrospective analysis of 198 consecutive allogeneic stem cell transplant (HSCT) recipients, who received post transplant cyclophosphamide (PTCY), cyclosporine and mycophenolate mofetile as g raft-versus-host-disease (GVHD) prophylaxis. The donor was either HLA matched (n=78) (siblings -32- or unrelated -46) , or a haploidentical relative (HAPLO) (n=120). End points of the study were acute and chronic GVHD, transplant related mortality (TRM), relapse, disease free survival (DFS) and graft versus host and relapse free survival (GRFS). The two groups were comparable except for an older age (49 vs 56 years) in the haplo-HLA group. The diagnosis was mainly acute leukemia (57%), myelofibrosis (21%) or lymphoma (12%). Conditioning was myeloablative in 77% and 73% respectively (p=0.57).

Acute GVHD grade II-IV developed in 10% of the HLA matched transplants vs 27% in the HAPLO group (p=0.005). The latter also had more moderate-to-severe cGVHD (4% vs 23%, p<0.001). The cumulative incidence of transplant related mortality (TRM) at 1 year for the HLA matched vs HAPLO patients, was 10% vs 21% (p=0.04) (Fig.1) , with age over 60 years being the major negative predictor in multivariate analysis.

Relapse at 1 year was 24% for HLA matched vs 10% for HAPLO transplants (p=0.051) (Fig.1).

Disease free survival (DFS) at 1 year was 65% and 68% in matched and HAPLO patients, respectively (p=0.85) (Fig.1) and GRFS 55% vs 49% (p=0.18). In multivariate analysis, age over 60 years was the strongest predictor of DFS and GRFS (HR 1.73, p=0.03 and HR 1,65, p= 0.02).

In conclusion: when using the same triple PTCY based GVHD prophylaxis, HLA matched grafts are associated with significantly less acute and chronic GvHD, if compared with HAPLO grafts. There is a trend for reduced TRM at 1 year, especially in chronic myelo-lymphoproliferative disorders, and a trend for increased relapse, resulting in identical disease free survival.

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