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Haploidentical, unrelated donor transplantation yield similar OS outcomes for AML
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Haploidentical transplantation followed by post-transplant cyclophosphamide conferred survival outcomes comparable with matched unrelated donor transplantation in patients with acute myeloid leukemia, according to study results.
Unrelated HLA-matched donors are considered the best alternative for patients with AML in need of hematopoietic stem cell transplantation (HSCT) who lack an HLA-matched sibling donor, according to study background. However, many patients relapse before an appropriate unrelated donor can be identified, and minority patients experience a limited availability of unrelated HLA-matched donors. Haploidentical donors — or half-matched related donors — may thus provide an alternative option.
Stefan O. Ciurea, MD, associate professor in the department of stem cell transplantation at The University of Texas MD Anderson Cancer Center, and colleagues conducted an observational study to compare safety and efficacy outcomes among patients undergoing HLA-matched unrelated and haploidentical HSCT.
The researchers evaluated data from the Center for International Blood and Marrow Transplant Research. The analysis included data from 2,174 adult patients with AML who underwent haploidentical (n = 192) or 8/8 HLA-matched unrelated donor (n = 1,982) HSCT.
Patients undergoing haploidentical HSCT received calcineurin inhibitor (CNI), mycophenolate and post-transplant cyclophosphamide for graft-versus-host disease (GVHD) prophylaxis. One hundred four of these patients underwent myeloablative conditioning, and the other 88 underwent reduced-intensity conditioning.
Patients undergoing HLA-matched unrelated donor HSCT received CNI with mycophenolate or methotrexate for GVHD prophylaxis. Of these patients, 1,245 underwent myeloablative conditioning and 737 received reduced-intensity conditioning.
Patients who underwent haploidentical HSCT experienced lower rates of neutrophil recovery after 30 days whether they receive myeloablative (90% vs. 97%; P = .02) or reduced-intensity conditioning (93% vs. 96%).
However, patients undergoing haploidentical HSCT with myeloablative conditioning achieved lower rates of 3-month acute grade 2 to grade 4 GVHD (16% vs. 33%; P < .0001) and 3-year chronic GVHD (30% vs. 53%; P < .0001). Haploidentical HSCT also was associated with lower rates of 3-month acute GVHD (19% vs. 28%; P = .05) and 3-year chronic GVHD (34% vs. 52%; P = .002) in the reduced-intensity conditioning setting.
In the myeloablative setting, researchers calculated 3-year OS probabilities of 45% (95% CI, 36-54) for patients who underwent haploidentical HSCT and 50% (95% CI, 47-53) for patients who underwent HLA-matched unrelated donor HSCT. The 3-year OS probability rates also were similar in the reduced-intensity setting among patients who underwent haploidentical (46%; 95% CI, 35-56) and HLA-matched unrelated donor HSCT (44%; 95% CI, 40-47).
The researchers acknowledged their inability to ascertain donor choices or the choice of other treatments due to the study’s observational nature may be a limitation to these findings. Further, patients who underwent haploidentical HSCT had poorer performance scores and a longer period from diagnosis to transplantation for recipients of reduced-intensity conditioning regimens.
“A randomized trial is the gold standard for comparing outcomes between donor types,” Ciurea and colleagues concluded. “Based on the results of a multicenter phase 2 trial, there is an ongoing trial that randomizes patients to haploidentical bone marrow or umbilical cord blood grafts (BMT CTN 1101; NCT01597778). It is perhaps timely to plan a trial that randomizes patients to haploidentical or unrelated HLA-matched grafts for hematologic malignancy.” – by Cameron Kelsall
Disclosure: The researchers report no relevant financial disclosures.
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