A potent ATR (ATM and Rad3-related) inhibitor (IC₅₀ = 25 nM). It also inhibits the activity of PI3Kα, mTOR and DNA-PKC with IC₅₀'s of 170, 0.6 and 36 nM, respectively. ETP-46464 inhibits the restart of stalled replication forks and abrogates S phase arrest after exposure to hydroxyurea.