Synthetic optimization and subsequent biological evaluationled to the identification of a small molecule, SMI-10B13, that has a binding affinity value (KD) as low as 7 μM and demonstrated IC50 values of136 and 164 nM in suppressing OSM-mediated STAT3 phosphorylation inT47D and MCF-7 human breast cancer cell lines, respectively. The gene discussed is STAT3; the disease is breast carcinoma.