Long-Term Results of Busulfan Plus High-Dose Idarubicin as a Conditioning Regimen to Autologous Stem Cell Transplantation Following Cytarabine Consolidation in Young Patients with Favorable or Intermediate-Risk Acute Myeloid Leukemia.

OBJECTIVE

To evaluate the long-term efficacy and safety of high-dose idarubicin plus busulfan (I-Bu) conditioning followed by autologous stem cell transplantation (ASCT) compared to intermediate- to high-dose cytarabine (Ara-C) consolidation in young acute myeloid leukemia (AML) patients with favorable- or intermediate-risk in first complete remission (CR1).

METHODS

We retrospectively analyzed clinical data from 59 young AML patients (aged ≤ 65 years) with favorable- or intermediate-risk disease who received the I-Bu conditioning regimen followed by ASCT between December 2004 and December 2021 (ASCT group). Clinical outcomes were compared with 57 favorable- and intermediate-risk AML patients treated with intermediate- to high-dose Ara-C consolidation chemotherapy alone (chemotherapy group). Overall survival (OS) and disease-free survival (DFS) were evaluated, and univariate and multivariate analyses were performed to identify prognostic factors associated with OS.

RESULTS

A total of 116 patients were included with a median follow-up of 79.5 months. Median OS was not reached in either group. The ASCT group achieved a significantly higher 2-year OS rate (84.5% vs 59.7%, P=0.0018) and sustained a significant OS benefit in the 10-year OS rate (P=0.0017). DFS rate also showed superiority in the ASCT group at 2-year (77.7% vs 53.5%, P=0.0037) and maintained this benefit in the 10-year DFS rate (P=0.0038). Multivariate Cox regression identified treatment modality as an independent prognostic factor for OS (HR = 3.12, 95% CI: 1.48-6.59, P=0.0028). In subgroup analysis, ASCT significantly improved OS (P<0.001) and DFS (P=0.0014) in favorable-risk patients, whereas no differences were observed in intermediate-risk patients (OS, P=0.13; DFS, P=0.21).

CONCLUSION

The I-Bu conditioning regimen followed by ASCT provides durable survival benefits and a favorable safety profile for young, favorable-risk AML patients in CR1, representing a potential post-remission therapeutic option. Its role in intermediate-risk AML requires further validation.