Impact of hematopoietic chimerism at day +14 on engraftment after unrelated donor umbilical cord blood transplantation for hematologic malignancies

1 Department of Hematology, Hospital Universitario La Fe, Valencia 2 Centro de Transfusión de la Comunidad Valenciana, Valencia, Spain Correspondence: Miguel A. Sanz, PhD, MD, Hematology Department, Hospital Universitario La Fe Valencia, Spain 46009 E-mail: sanz_mig{at}gva.es Background: Cord blood transplant is a feasible treatment alternative for adult patients with hematologic malignancies lacking a suitable HLA-matched donor. However, the kinetics of myeloid recovery is slow, and primary graft failure cannot be detected easily early after transplantation. We investigated the impact of hematopoietic chimerism status from unselected marrow cells 14 days after transplantation on predicting engraftment after a cord blood transplant. Design and Methods: Seventy-one adult patients with hematologic malignancies undergoing single-unit unrelated donor cord blood transplantation after a myeloablative conditioning regimen were included in the study. All patients received conditioning regimens based on busulfan, thiotepa and antithymocyte globulin. Chimerism status was assessed analyzing short tandem repeat polymorphisms. Results: The cumulative incidence of myeloid engraftment at 1 month was significantly lower in patients with mixed chimerism than in those with complete donor chimerism (55% vs. 94%; p