cGAS–STING pathway activation drives the cold-to-hot tumor transition and sensitizes immunotherapy

The cyclic GMP-AMP synthase–stimulator of interferon genes (cGAS–STING) pathway is a central sensor of innate immunity that plays critical roles in recognizing cytosolic DNA and initiating antitumor immune responses. However, this pathway exhibits extensive spatiotemporal duality and context dependency in tumor regulation. In recent years, modulating this pathway to convert immunologically “cold” tumors into immunologically “hot,” inflamed tumors has emerged as a cutting-edge strategy to reverse resistance to immune checkpoint inhibitors (ICIs). This review outlines the molecular mechanisms underlying the activation and regulation of the cGAS–STING pathway, with emphasis on its complex role in orchestrating the tumor immune phenotypic switch. A nuanced analysis of the pathway’s duality distinguishes between acute immunostimulatory activation and chronic, pro-tumorigenic inflammation driven by chromosomal instability (CIN). Furthermore, current evidence regarding direct and indirect T-cell modulation, as well as pathway-mediated remodeling of the tumor microenvironment (TME) across diverse malignancies, is discussed in detail. Crucially, the current bottlenecks in clinical translation are described, including evaluation of the failure of first-generation agonists and the promise of next-generation delivery platforms such as antibody-drug conjugates (ADCs) and nanoparticle systems. Finally, a novel strategic framework is proposed involving mapping of specific STING-targeted modalities to distinct TME phenotypes, such as immune-desert, immune-excluded, and exhausted-inflamed states. A detailed understanding of the cGAS–STING axis has substantial value in providing theoretical guidance and supporting clinical translation in the development of next-generation combination immunotherapies, as well as broadening the patient population benefiting from clinical interventions.