The current promising direct STAT3 inhibitors which have entered clinical trials include STAT3 antisense-based AZD9150 (Phase I in hepatocellular carcinoma metastatic, Phase II in advanced cancers), OPB-31121 (Phase I in advanced cancers, phase I/II in hepatocellular carcinoma), OPB-51602 (Phase I in advanced cancers, hematologic malignancies), OPB-111077 (Phase I in solid tumors, leukemia), STAT3 decoy (Early phase I in head and neck cancer). Here, STAT3 is linked to leukemia.