A potent multitargeted inhibitor of histone deacetylase (HDAC) and the receptor kinases epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2), with IC₅₀ values of 4.4, 2.4, and 15.7 nM, respectively. Displays potent antiproliferative and proapoptotic activities against cultured and implanted tumor cells that are sensitive or resistant to several approved single-targeted drugs.