Abstract 2578: Synergistic activity of lenalidomide and interleukin-21 in chronic lymphocytic leukemia

Interleukin-21 (IL-21) is an immunomodulatory cytokine with cytotoxic activity against chronic lymphocytic leukemia (CLL) B cells. Its cytotoxic activity has been shown in part to directly correlate with level of surface expression of the IL-21 receptor (IL-21R) on CLL cells. Although CpG and CD40 ligand have been show to induce upregulation of IL-21R, their limited availability for clinical use prompted us to investigate alternative immunomodulatory agents such as lenalidomide. We observed that treatment of CLL B cells with 0.5 μM lenalidomide upregulated IL-21R expression in 7/10 patients (samples with