Comparable outcomes of haploidentical transplant with TBF conditioning versus matched unrelated donor with fludarabine/busulfan conditioning for acute myeloid leukemia

We compared transplant outcomes of 708 acute myeloid leukemia (AML) patients receiving haploidentical allogeneic hematopoietic-cell transplantation using thiotepa/busulfan/fludarabine (TBF) conditioning with posttransplant cyclophosphamide (ptCy), to 2083 patients receiving matched unrelated donor (MUD) transplantation using fludarabine/busulfan (FB) conditioning and in vivo T-cell depletion. For intermediate cytogenetic risk AML transplanted in first complete remission (CR1), multivariate analysis revealed that haplo-TBF significantly increased nonrelapse mortality (NRM) (HR 2.1;p = 0.0006) but did not affect relapse incidence (RI), leukemia-free survival (LFS), overall survival (OS), or graft-versus-host disease-free, relapse-free survival (GRFS). For high cytogenetic risk AML transplanted in CR1, haplo-TBF significantly increased NRM (HR = 2.7;p = 0.02), decreased RI (HR = 0.45;p = 0.03) but had no influence on LFS, OS, or GRFS. For AML transplanted in CR2, haplo-TBF significantly increased NRM (HR = 2.36;p = 0.008), decreased RI (HR = 0.38;p = 0.005), but had no influence on LFS, OS, or GRFS. Finally, for AML patients transplanted with active disease, haplo-TBF had no influence on transplant outcomes. In conclusion, compared to MUD-FB, haplo-TBF increased NRM, reduced RI in high-risk AML in CR, resulting in similar LFS, OS, and GRFS. These results comparing two different approaches support the use of a haploidentical family donor for high-risk AML patients lacking a matched sibling donor.

Automated summary

The study compared the outcomes of haploidentical allogeneic hematopoietic-cell transplantation and matched unrelated donor transplantation for AML patients in different risk groups and remission statuses. The results showed that haploidentical transplantation increased nonrelapse mortality and decreased relapse incidence in high-risk AML in CR, leading to similar leukemia-free survival, overall survival, and graft-versus-host disease-free, relapse-free survival compared to matched unrelated donor transplantation. This suggests the potential benefits of using haploidentical family donors for high-risk AML patients without matched sibling donors.