Purpose: Although remission can be achieved in 80% of children with acute myelogenous leukemia (AML), many patients experience relapse. Because interleukin-2 (IL-2) can induce remission in patients with overt evidence of AML, we hypothesized that IL-2 given to patients in first remission after intensive consolidation chemotherapy might prevent relapse. This study sought to determine whether such an approach was feasible.
Patients and methods: Twenty-one patients in complete remission received IL-2 after completion of treatment on Children's Cancer Group (CCG) protocol 2941. Recombinant IL-2 9 x 10(6) IU/m2 daily by continuous intravenous infusion (c.i.v.) was given for 4 days. After 4 days rest, IL-2 1.6 x 10(6) IU/m2 daily c.i.v. was resumed for 10 days. We monitored patients for toxicity and measured absolute lymphocyte count, the absolute count of cells that express CD56 and CD3 antigen, and soluble IL-2 receptor alpha-chain (sIL-2R alpha) levels before the start of IL-2 and after completion of each of the two courses of IL-2.
Results: Observed toxicities included fever (57%), vascular leak (48%), hypotension (38%), tachycardia (14%), rash (29%), septicemia (5%), thrombocytopenia (29%), elevated transaminase (14%), electrolyte disturbance (29%), and hyperglycemia (10%). No patient required cardiac pressors or transfer to an intensive care unit. All patients studied developed an increase in lymphocyte count, CD56 count, CD3 count, and sIL-2R alpha levels after treatment with IL-2.
Conclusion: This schedule of IL-2 was reasonably well tolerated by children with AML in first remission. After treatment, increased levels of sIL-2R alpha were observed. CCG is conducting a randomized prospective trial to assess the efficacy of IL-2 to prevent the relapse of AML (CCG-2961).