STAT3-IN-12 is a potent STAT3 signal inhibitor that can inhibit IL-6 induced JAK/STAT3 signalling pathway activation. STAT3-IN-12 inhibits cancer cell growth, migration, and induce cell apoptosis as well as cycle arrest. STAT3-IN-12 can be used in cancer-related research, such as hepatocellular carcinoma (HCC) and oesophageal carcinoma.