ICT10336 is a hypoxia-reactive prodrug of the ATR inhibitor AZD6738. It specifically activates under hypoxic conditions in vitro, selectively releasing AZD6738. This action inhibits ATR activation at the T1989 and S428 phosphorylation sites, consequently disrupting HIF1a-mediated adaptation of hypoxic cancer cells and inducing cell death in both 2D and 3D cancer models. ICT10336 is also a metabolic substrate of CYPOR activity.