Aims: Ferroptosis, an iron-dependent form of regulated cell death, has emerged as a major contributor to neuronal injury following ischemic stroke. Because our previous cancer-cell screens identified ataxia-telangiectasia mutated (ATM), a DNA damage response kinase, as a ferroptosis regulator, we investigated whether ATM inhibition protects neural tissue after ischemic stroke and examined determinants of therapeutic response.

Methods: ATM inhibitors, including the brain-penetrant clinical compound AZD1390, were evaluated in cultured cancer and neuronal cells, oxygen-glucose-deprived organotypic rat and mouse brain slices, and permanent middle cerebral artery occlusion models using multiple inbred and Rabep2-genotype mouse strains. Cell viability, cytotoxicity, lipid peroxidation, ferroptosis-associated markers, infarct volume, and collateral vessel density were assessed. Topical AZD1390 was also tested in mice with impaired collateral networks.

Results: ATM inhibition reduced ferroptosis-associated lipid oxidative injury and protected neurons in multiple preclinical models of stroke. AZD1390 significantly decreased lipid peroxidation, protected neurons from cell death, and limited infarct volume in B6/J and B6/NJ mice, but not in BALB mice. Strikingly, treatment efficacy varied among mouse strains and correlated with differences in the collateral vascular network. The protective effect of systemic AZD1390 was similarly lost in Rabep2-knockout mice with deficient collateral networks. The efficacy of oral AZD1390 was associated with collateral vascular density. Early topical administration also reduced infarct volume in mice with limited collateral networks; however, differences in treatment timing and route prevent direct attribution of this effect to improved local drug delivery.

Conclusion: This work implicates ferroptosis-associated lipid oxidative injury in ischemic neuronal death, identifies ATM inhibition as a candidate translational strategy warranting further mechanistic validation, and highlights collateral vascular anatomy as a potential factor associated with therapeutic response. Collectively, these findings broaden the pathophysiological and translational framework for ferroptosis-targeting strategies in stroke.