Autologous Hematopoietic Stem Cell Transplantation for High-risk Acute Lymphoblastic Leukemia: non-Randomized Study with a maximum Follow-up of more than 22 Years

OBJECTIVE: To evaluate the efficacy and toxicity of autologous hematopoietic stem cell transplantation (AHSCT) for high-risk acute lymphoblastic leukemia (ALL). MATERIAL AND METHODS: Overall, 128 high-risk ALL patients at a median age of 26 years (range 18–56 years) at diagnosis received AHSCT between 1991–2008. Induction treatment was anthracycline-based in all patients. Conditioning regimen consisted of CAV (cyclophosphamide, cytarabine, etoposide) in 125 patients whereas 3 subjects received cyclophosphamide and TBI (total body irradiation). Bone marrow was stored for 72 hours in 4°C and re-infused 24 hours after conditioning completion. Bone marrow was a source of stem cells in 119 patients, peripheral blood in 2 and 7 subjects received both bone marrow and peripheral blood. RESULTS: With a median follow-up after AHSCT of 1.6 years (range 0.1–22.3 years), the probability of leukemia-free survival (LFS) for the whole group at 10 years was 27% and 23% at 20 years. Transplant-related mortality at 100 days after AHSCT was 3.2%. There was a strong tendency for better LFS for MRD-negative patients if compared with patients who had positive or unknown MRD status at AHSCT (32% vs 23% and 25%, respectively; p=0.06). There was no difference in LFS between B- and T-lineage ALL as well as between patients transplanted in first complete remission (CR1) and CR2. LFS at 10 years for patients with Philadelphia-positive (Ph+) ALL at transplant was 20% and this was comparable with subjects with negative and missing Ph status (26% and 28%; p=0.97). CONCLUSIONS: The results of AHSCT for high-risk ALL remains unsatisfactory with low probability of long-term LFS.