Although ALT is an adaptive mechanism through which cancer cells achieve proliferative immortality, the elevated levels of replication stress observed in ALT tumors constitute a potential therapeutic vulnerability.<h4>Methods</h4>Leveraging CRISPR/Cas9 screening data from the Cancer Dependency Mapping Project, coupled with patient-derived cell lines and xenografts, we identified SMARCAL1 as a novel synthetic lethal vulnerability in ATRX-deficient glioma models that engage ALT. This evidence concerns the gene ATRX and cancer.