Low dose interleukin-2 following intensification therapy with high dose cytarabine for acute myelogenous leukemia in first complete remission

The most important problem in the therapy of patients with acute myeloid leukemia (AML) is relapse after intensive therapy. We sought to determine if interleukin-2 (low-dose with intermittent boluses) administration could be feasibly administered after standard therapy to potentiate anti-tumor immunity in a fashion analogous to the post-allogeneic stem cell transplant graft-vs-leukemic effect. Adults with de novo AML received daunorubicin and cytosine arabinoside induction therapy. Patients achieving complete remission received high dose ara-C (HIDAC) for three courses followed by low dose rIL-2 (Amgen), administered by continuous infusion (450,000 U/m(2)/day) for 10 weeks with intermittent boluses (500,000/U/m(2) over 2 hr) given in weekly intervals starting on Week 4. Of the 32 enrolled patients, 27 achieved CR; 8/11 who received rIL-2 completed therapy. 6/11 are long term survivors (median follow-up, 139 months). rIL-2 was well tolerated and associated with a 5-fold increase in circulating NK-lymphocytes and a 3-fold increase in circulating T-cells. Mononuclear cells from patients receiving rIL-2 exhibited enhanced cytolytic activity in vitro against cryopreserved autologous leukemia cells. This study supports further investigation of immunotherapy in the post-intensive chemotherapy setting in the management of patients with AML.