We next sought to substantiate the mechanism shown in vitro that lenalidomide reverses T-cell dysfunction by preventing IL-10 production by CLL cells and IL-10-induced phosphorylation of Y705-STAT3 in T cells, using peripheral blood samples collected and cryopreserved from patients treated with lenalidomide monotherapy. The gene discussed is STAT3; the disease is B-cell chronic lymphocytic leukemia.