Interleukin-2 after autologous stem-cell transplantation for adult patients with acute myeloid leukemia in first complete remission

Purpose: To determine the disease-free survival (DFS) and toxicity of administering interleukin-2 (IL-2) immunotherapy early after autologous stem-cell transplantation (ASCT) to simulate a graft versus leukemia effect observed in allogeneic transplantation. Patients and Methods: Fifty-six patients with acute myeloid leukemia in first remission received a single consolidation of high-dose cytarabine-idarubicin at a median of 1.1 month postremission with the intent to proceed to ASCT and IL-2 9 × 10⁶ U/m ²/24 h for 4 days, followed by 10 days of IL-2 1.6 × 10 ⁶ U/m²/24 h on hematologic recovery. Results: Eighty-four percent of patients received the intended ASCT, and 68% of patients received IL-2 treatment. With a median follow-up of 39.4 months (range, 1.2 to 76.3 months), the 2-year cumulative probability of DFS for all 56 patients is 68% (95% confidence interval [CI], 55% to 80%) and 74% (95% CI, 57% to 85%) for the 39 patients undergoing IL-2 treatment after ASCT. The 2-year cumulative probability of DFS for favorable, intermediate, and unfavorable cytogenetics is 88% (95% CI, 59% to 97%), 48% (95% CI, 26% to 67%), and 70% (95% CI, 23% to 93%), respectively. Toxicities from IL-2 were mainly thrombocytopenia, leukopenia, fever, and fluid retention. Two septic deaths occurred during neutropenia, which includes one during consolidation and one during transplant, for an overall 4% mortality rate. Conclusion: These results suggest that a moderate dose of IL-2 after high-dose cytarabine-idarubicin-mobilized ASCT is associated with a low regimen-related toxicity and may improve DFS. A phase III study of IL-2 is now warranted.