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


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<0.0001). For patients achieving myeloid recovery, the median time of engraftment was 16 days when donor chimerism at day + 14 was higher than 90%, compared with 24 days when donor chimerism was below this level (p<0.001). A donor chimerism level of 65% was found to be the best cut-off point for predicting primary graft failure, with a sensitivity of 97% and a specificity of 80%. The incidence of primary graft failure was 67% for patients with less than 65% donor chimerism at day +14 as compared to only 2% for those with more than 65% donor chimerism (p<0.001). Patients with mixed chimerism also had a lower cumulative incidence of platelet engraftment than those with complete chimerism (62% vs. 89%; p=0.01).


CONCLUSIONS
Donor-recipient chimerism status at day +14 predicts engraftment after a single-unit cord blood transplant in adults.
Moscardó
Federico
F
1Department of Hematology, Hospital Universitario La Fe, Valencia, Spain.
Sanz
Jaime
J
Senent
Leonor
L
Cantero
Susana
S
de la Rubia
Javier
J
Montesinos
Pau
P
Planelles
Dolores
D
Lorenzo
Ignacio
I
Cervera
Jose
J
Palau
Javier
J
Sanz
Miguel A
MA
Sanz
Guillermo F
GF
D000293:Adolescent; D000328:Adult; D001792:Blood Platelets / Q000378:metabolism; D001854:Bone Marrow Cells / Q000378:metabolism; D036101:Cord Blood Stem Cell Transplantation / Q000379:methods*; D005260:Female; D006086:Graft vs Host Disease / Q000378:metabolism / Q000401:mortality / Q000517:prevention & control; D019337:Hematologic Neoplasms / Q000601:surgery*; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D022423:Myeloid Cells / Q000378:metabolism; D015996:Survival Rate; D013997:Time Factors; D018183:Transplantation Chimera; D019172:Transplantation Conditioning / Q000379:methods; D016896:Treatment Outcome; D055815:Young Adult