STAT3 is constitutively activated by phosphorylation in CLL [29, 30], drives the expression of genes involved in CLL progression and cell survival, as well as CLL poor prognosis markers such as LPL, ROR1 and WNT5a [31–36], and UGT2B17, as we report here. Here, STAT3 is linked to B-cell chronic lymphocytic leukemia.