Comparison of intensive chemotherapy, allogeneic or autologous stem cell transplantation as post-remission treatment for adult patients with high-risk acute lymphoblastic leukemia. Results of the PETHEMA ALL-93 trial.

BACKGROUND AND OBJECTIVES: The optimal post-remission therapy for adults with high-risk acute lymphoblastic leukemia (ALL) is not well established. This multicenter randomized trial by the Spanish PETHEMA Group was addressed to compare three options of post-remission therapy in adults with high-risk ALL: chemotherapy, allogeneic stem cell transplantation (SCT) and autologous SCT.

DESIGN AND METHODS: A total of 222 valid high-risk ALL patients entered the trial. All received a standard five-drug/five-week induction course. Patients in complete remission with an HLA-identical family donor were assigned to allogeneic SCT (n=84) and the remaining were randomized to autologous SCT (n=50) or to delayed intensification followed by maintenance chemotherapy up to 2 years in complete remission (n=48).

RESULTS: Overall, 183 patients achieved complete remission (82%). With a median follow-up of 70 months, the median disease-free survival and overall survival were 17 and 23 months, respectively. The 5-year disease-free survival and overall survival were 35% (95% CI, 30%-41%) and 34% (95% CI, 28%-39%), respectively. Patients allocated to the chemotherapy, allogeneic and autologous SCT were comparable in the main pre-treatment ALL characteristics and the rate of response to therapy. Intention-to-treat analysis showed no differences between patients according to whether they had or did not have a donor in disease-free survival (39%, 95% CI 30-48% vs. 33%, 95% CI 23-41%) and overall survival (44%, 95% CI 35-52% vs. 35%, 95% CI 25-44%), as well as for autologous SCT vs. chemotherapy comparisons (disease-free survival: 40%, 95% CI 28-52% vs. 51%, 95% CI 37-67%; overall survival: 43%, 95% CI 29-58% vs. 52%, 95% CI 39-65%). No differences were observed when the analysis was made on the basis of the treatment actually performed.

INTERPRETATION AND CONCLUSIONS: This study failed to prove that, when a family donor is available, allogeneic SCT produces a better outcome than autologous SCT or chemotherapy in adults with high-risk ALL.