ATLANTAPreliminary results suggest that immunotherapy with recombinant interleukin-2 (rIL-2) may prolong survival in younger patients with acute myeloid leukemia in first remission. However, the high rate of refusal or discontinuation of such therapy presents challenges for its acceptance, Jonathan Kolitz, MD, of the Monter Cancer Center, Lake Success, New York, said at ASH 2007 (abstract 157) on behalf of the Cancer and Leukemia Group B.
CALGB conducted a randomized phase III trial (CALGB 19808) of rIL-2 vs observation in 734 younger patients (less than age 60) with AML who were in first remission following consolidation therapy with high-dose cytarabine (HiDAC) or autologous peripheral stem-cell transplantation (ASCT).
The first 302 patients were randomized to receive induction therapy consisting of cytarabine, daunorubicin, and etoposide (ADE) or ADE combined with the P-glycoprotein modulator PSC-833 (Valspodar) (ADEP); all remaining patients received ADE.
Those who achieved a complete response (CR) were treated with post-remission therapy according to cytogenetic risk factors. Patients who had core binding factor AML were administered three courses of HiDAC, while those with non-core binding factor AML underwent ASCT.
Of 716 patients evaluable for re-sponse, 549 (77%) achieved CR. How-ever, less than 40% of these patients (214) proceeded to randomization after HiDAC or ASCT. The remaining 214 patients were equally randomized to rIL-2 for 3 months or observation.
Post-consolidation rIL-2 therapy consisted of alternating low doses (1 106 U/m2) to expand cytotoxic T-cell effector cells with higher-dose bolus treatments (12-15 106 U/m2) to activate this cell population. Median follow-up from post-remission randomization for the surviving patients was 29 months.