Cell-permeable. A potent inhibitor of the human epidermal growth factor receptor 2 (HER2) tyrosine kinase (IC₅₀ = 6 nM). Displays > 4000-fold selectivity over EGFR, FGFR, PDGFR, JAK1 and Src. TAK 165 inhibits bladder, kidney and androgen-independent prostate cancer in vitro and in vivo.