The Dual Role of DNA Cross-linking Agents: From Genotoxicity to cGAS-STING-Mediated Immune Activation.

DNA cross-linking agents remain a cornerstone of cancer chemotherapy. While their efficacy was traditionally attributed to direct genotoxicity, blocking DNA replication and transcription to induce cell death, recent evidence suggests that their therapeutic activity also involves innate immune activation. Aberrant repair of DNA lesions generates cytosolic DNA fragments, which are sensed by cyclic GMP-AMP synthase (cGAS). This activates the cGAS-STING (stimulator of interferon genes) pathway, driving the production of type I interferons and proinflammatory cytokines, thereby eliciting antitumor immunity. This review traces the molecular trajectory from DNA lesions formation to immune stimulation. We summarize the chemistry of classical and emerging DNA cross-linking agents, the replication stress they impose, and DNA damage response (DDR) generating cytosolic DNA as a trigger for innate immune activation. We then highlight key mechanistic insights into cGAS-STING signaling. Finally, we discuss therapeutic opportunities in their combinations with STING agonists for more effective immune activation. Collectively, this framework reframes DNA cross-linking agents from simple cytotoxins into in situ vaccines that harness DNA damage-driven immunity.