Autologous Stem Cell Transplantation (ASCT) in 121 Acute Myeloid Leukemias (AML): A Single Center Experience From 1988 to 2010

Despite the fact that allogeneic SCT currently offers patients with high risk AML the best chance of cure, we've aimed to investigate the outcome of AML patients who have undergone ASCT in our center, considered as one of spanish reference hospital in SCT, and the parameters that have been able to influence in relapse rate (RR), overall survival (OS) and relapse free survival (RFS).

Retrospective study in 121 AML patients who have undergone ASCT between 1988 and 2010. The analysis has been performed in 95 patients (50 male and 45 female) by excluding 26 acute promyelocitic leukemias (APL): 62 patients until 1999 and 33 since 2000. Median age was 45 [18–74] and median lecocyte count, 17250/μL [1000–318000]. 90% were “de novo” AML and 92% were in first complete remission (1°CR). Cytogenetic risk was as follows: 64% intermediate, 29% high and 7% low. Conditioning regimens were oral BuCy (62%), CyTBI (24%) and intravenous BuCy (12%). Stem cell source was bone marrow (BM) in 46 patients (48%), but the use of peripheral blood (PB) was generalized since 1997. Colony-stimulating factors were used in 52% of total patients. Median time from last treatment was 94 days [30–285].

The median follow-up of this study was 125 months [0–216]. OS at 1, 3 and 5 years were 59%, 46% and 44%. RFS at 1, 3 and 5 years were 60%, 49% and 48%. There was no relapse after 5 years from ASCT. Early mortality (before day +100) was 12% (9 in 11 patients between 1988 and 1999) and late mortality was 47% (34 in 45 patients because of relapse, with no significant difference between 1988–1999 and 2000–2010). Secondary malignancies incidence was 13% (5 in 6 patients suffered from haematologic neoplasms: 4 MDS at 43, 89, 90 and 97 months and 1 Follicular Lymphoma at 50 months), median age of these patients was slightly higher (53, 5 years old) and none of them had received TBI. Multivariable analysis showed that RFS at 5 years was influenced by: disease status at ASCT (55% if 1°CR vs 0% if ≥2°CR/PR/refractory disease, p<0, 0001), leucocyte count at diagnosis (p<0, 0001, without a significant cut-off), ethiologic classification (53% if “de novo” AML vs 19% if secondary AML, p=0, 002), age of recipient (60% if younger than 40 years old vs 45% if older, p=0, 031) and year of ASCT (62% if 2000–2010 vs 44% if 1988–1999, p=0, 043). Other parameters as stem cell source, conditioning regimen or cytogenetic risk had no significance in univariable analysis. Relapse was influenced by the presence of minimal residual disease (MRD) at time of ASCT (p=0, 03, with available data in 47 patients, only since 1997) and by a CD34 cells count higher than 3 × 10⁶/kg (p=0, 04, with available data in 49 patients, only in case of PB as stem cell source).

ASCT is an effective procedure of cure in AML patients (global RFS of 48% at 5 years), even in high cytogenetic risk (38% with no significant difference), offering its best outcomes in young patients diagnosed of “de novo” AML without hyperleucocytosis, who have undergone the transplantation in 1°CR since 2000.

No relevant conflicts of interest to declare.