A potent and selective ALK (anaplastic lymphoma kinase) inhibitor that blocked the growth of ALCL (anaplastic large cell lymphoma)-derived and ALK-dependent cell lines with IC₅₀ = 2-10 nM. NVP-TAE684 treatment resulted in a rapid and sustained inhibition of phosphorylation of NPM-ALK (Nucleophosmin-anaplastic lymphoma kinase) and its downstream effectors and subsequent induction of apoptosis and cell cycle arrest.