BLOG: Optimizing donor selection in aplastic anemia — evolving trends in transplantation
- Outcomes after haploidentical transplant for severe aplastic anemia have improved significantly with use of post-transplant cyclophosphamide.
- Umbilical cord blood transplant outcomes also have improved.
Aplastic anemia is a bone marrow failure process that presents with pancytopenia and bone marrow hypoplasia/aplasia.
It results from an immune-mediated injury to multipotent hematopoietic stem cells.
Traditionally, young patients — those aged 40 years or younger — with severe aplastic anemia are considered for upfront allogeneic transplant in the presence of a matched sibling donor.
Unrelated donor transplants and alternative donor transplants (ie, mismatched unrelated, haploidentical or umbilical cord blood) are considered at various stages of aplastic anemia.
The outcome of haploidentical transplants in severe aplastic anemia has improved significantly in the era of post-transplant cyclophosphamide to prevent graft-versus-host disease.
In parallel, umbilical cord blood transplant outcomes in severe aplastic anemia are improving based on recent retrospective studies. These improvements are related to better umbilical cord blood unit selection practices, as well as use of reduced intensity conditioning regimens that include total body irradiation and do not include anti-thymocyte globulin.
A recent retrospective study conducted in Japan showed similar OS and failure-free survival with umbilical cord blood transplants as haploidentical transplants. However, haploidentical transplants were associated with better engraftment.
I think the pendulum has swung in the direction of haploidentical transplants, but umbilical cord blood transplants provide a very reasonable option for patients who do not have haploidentical transplant options. Also, in cases of suboptimal haploidentical options — related to advanced donor age, significant donor-specific HLA antibodies or evidence of donor clonal hematopoiesis — umbilical cord blood transplants might be more optimal.
Engraftment following umbilical cord blood transplant is expected to improve as ex vivo expansion approaches, as well as approaches designed to improve umbilical cord blood homing, are applied and further developed.
I think “donor choice” for patients with aplastic anemia might become an area of focus for personalized medicine/precision medicine in the future, when these patients have more than one donor option with excellent transplant outcomes.
For more information:
Omar Aljitawi, MBBS, can be reached at omar_aljitawi@urmc.rochester.edu.
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