This study of 2,174 adults with acute myeloid leukemia (AML) compared using haploidentical (n=192) and 8/8 HLA-matched unrelated donor (n=1,982) grafts. Haploidentical recipients received a calcineurin inhibitor, mycophenolate, and post-transplant cyclophosphamide to prevent graft-versus-host disease (GVHD); matched unrelated donor transplant recipients received a calcineurin inhibitor with mycophenolate or methotrexate. Haploidentical transplant recipients experienced significantly lower 3-month acute grade II-IV (16% vs. 33%) and 3-year chronic GVHD (30% vs. 53%), respectively, compared to matched unrelated donor transplants (p<0.0001) who received myeloablative conditioning. Findings were similar for reduced-intensity conditioning. The researchers analyzed survival for myeloablative and reduced-intensity transplants separately, and in the myeloablative cohort, 3-year overall survival was higher in unrelated donor (50%) compared with haploidentical (45%) but the difference didn’t reach statistical significance (p=0.38). For reduced-intensity conditioning, the rates were 46% and 44% (p=0.71). The authors noted limitations of their analysis, including the use of different donor sources (bone marrow for haploidentical transplants vs. peripheral blood for unrelated donor transplants). In addition, they noted that to confirm the survival differences of about 5% between the donor groups, a study would require approximately 1,500 patients in each of the four donor groups.
Haploidentical vs. Matched Unrelated HCT for AML