Donor Stem Cell Source Does Not Impact Outcome of High Risk (HR) Acute Myeloblastic Leukaemia (AML) Patients After Reduced Intensity Conditioning Allogeneic Hematopoietic Stem Cell Transplantation (RIC-ALLO).

Abstract 4339

Allogeneic Stem Cell Transplantation (ASCT) offers a potential curative treatment approach of HR AML patients (pts). Over years, the use of umbilical cord blood (UCB) has become an attractive alternative stem cell source for those pts lacking a suitable HLA matched related or unrelated donor.

The aim of this analysis was to assess the outcome of 50 pts who received a RIC-ALLO in our centre between 2005 and 2008 with a special focus on three different donor sources: identical sibling, unrelated donor or UCB.

All pts had HR AML in complete remission (CR) at time of transplant. HR features were defined as at least one of the following criteria: CR1 with unfavourable cytogenetics, secondary AML, more than one induction chemotherapy for obtaining CR or CR2 and above. Reasons for RIC regimen were older age, unfit physical condition, comorbidities or prior autologous transplant. All pts received a Fludarabine-based RIC regimen with GVHD prophylaxis consisting in CSA alone or CSA and MMF.

The median age of all pts was 51 (range, 19-70) years. 28 pts had identical sibling donors, 7 pts had a matched 10/10 (5 pt) or mismatched 9/10 (2 pt) unrelated donors and 15 pt received a single or double UCBT. Pts characteristics were comparable between the three groups but for pt age [identical sibling group: 52 (range, 35-70) years; unrelated donor group: 61 (range, 50-66) years; UCB group: 44 (range, 19-61) years].

After a median follow-up of 886 (range, 336-1528) days, 20 pts have died (disease=6, treatment related=14) and 8 pts have experienced relapse. Four year OS and EFS for all pts were 57% and 54%, respectively with no significant difference between the 3 groups (2 year OS: 61%, 54% and 66%; 2 year EFS: 59%, 54% and 45% respectively). One year TRM was 20% for the entire group and did not significantly differ between the 3 groups.

Despite the obvious limitations of this small series, results seem to indicate that in this population, donor type does not highly influence outcome. This is quite encouraging as most of the pts lack a compatible sibling donor. This may invite to consider privileging a rapid identification of an alternative donor rather than a given donor type when a match sibling is not available. Thus concomitant search for both graft type should be undertaken in order to perform allo SCT in a larger number of pts otherwise not treated because of early progression as illustrated in the underrepresentation of alternative transplant as compared with familial transplant in this retrospective study (28 familial vs 22 alternative).