LIF and cancer: Unfortunately, two promising phase III clinical trials with inhibitors of JAK/STAT3 (i.e. the JAK1/JAK2 inhibitor ruxolitinib and the STAT3 inhibitor napabucasin), the leading effector pathway of LIF stimulation in cancer cells, were stopped due to futility (Boston Biomedical 2019; Hurwitz et al. 2018).