Publication Date:
2014-12-06
Description:
Introduction: Mixed chimerism (MC) and minimal residual disease (MRD) strongly predict risk for relapse in children with acute lymphoblastic leukemia (ALL) following allogeneic stem cell transplantation (allo-SCT). Preemptive immunotherapy (IT), e.g. withdrawal of immunosuppression (WD-IS) or donor lymphocyte infusion (DLI) guided by chimerism and MRD monitoring can prevent impending relapse in allo-SCT recipients. In this study we retrospectively analyzed chimerism and MRD monitoring and the effect of preemptive IT in all pts undergoing allo-SCT for ALL in our institution. Patients: Between January 2005 and July 2014, a total of 89 children and adolescents (median age 11.5; range 2.2-26.0 years) with ALL (pB-ALL, n=63; T-ALL, n=20; biphenotypic/bilinear ALL, n=6) were transplanted in our center after remission induction treatment. 47 pts were in first, 26 pts were in second, 15 pts were in third, and 1 pt was in fourth complete remission (CR) at time of transplant. 18 pts received grafts from matched sibling donors (MSD), 61 pts from matched unrelated donors (MUD), and 10 pts were grafted from a haploidentical parent. Pts who received their graft from a matched donor (n=79) all underwent a fully myeloablative conditioning regimen consisting of TBI (12 Gy) and etoposide. Pts who were grafted from a haploidentical donor were prepared with fludarabine, thiotepa and melphalane. Methods: Serial and semi quantitative analyses of post-transplant hematopoietic chimerism in peripheral blood were performed weekly until day 200 and monthly thereafter. Bone marrow analyses were done at days +30, +60, +90, +180 and +365 post-transplant. Thereby, MRD was assessed in 56 pts, whereas no diagnostic material was available in 33 pts. Standardized quantification of MRD was performed according to the guidelines of the Euro-MRD-Group. All patients should receive preemptive IT if they develop MC after day +28. Results: 64/89 pts (72%) showed complete chimerism (CC) in all follow-up analyses, and 25/89 pts (28%) developed MC although all pts received a fully myeloablative conditioning regimen. From 56 pts in whom MRD could be assessed, 40 pts remained MRD negative and 16 developed MRD positivity after transplantation. IT (WD-IS, n=12; DLI, n=14) was initiated based on chimerism analysis in 22/25 pts with MC, and was guided by MRD detection in 4 pts. For the total cohort of pts, probability of event free (pEFS) and overall survival (pOS) were 0.67 and 0.77, respectively. Furthermore, cumulative incidence of treatment related mortality (CI-TRM) and relapse (CI-relapse) were 0.11 and 0.24 for all pts. Chimerism: pEFS was 0.74 in CC-pts and 0.51 in MC-pts (p0.68) in both groups, CI-relapse was 0.17 in CC- and 0.41 in MC-pts (p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
Permalink