A potent and selective inhibitor of NEDD8 (Neural precursor cell expressed, developmentally down-regulated 8)-activating enzyme (NAE) (IC₅₀ = 4.7 nM) with potential anticancer activity. NAE activates NEDD8, an ubiquitin-like (UBL) protein that modifies cellular targets in a pathway that is parallel to but distinct from the ubiquitin-proteasome pathway (UPP). Supresses the growth of tumor xenografts in mice.