Light-controlled CRISPR-dCas9 epigenome editing: advanced drug-delivery strategies and oncology applications

Cancer is increasingly recognized as a disease of the dysregulated epigenome; however, current epi-drugs are blunt, systemically toxic instruments. Catalytically dead CRISPR nucleases (dCas9) linked to chromatin effectors have now made it possible not only to write and erase epigenetic marks at specified loci without double-strand breaks but also to add an element of optogenetics, or reversible and light-encoded control over the timing and localization of the editors. In this review, the technological underpinnings of light-controlled CRISPR-dCas9 epigenome editing, which include architectures of dCas9 scaffold and guide, blue-to-near-infrared photoswitches, and high-gain epigenetic effector designs, are synthesized, and viral, non-viral, and stimuli-responsive delivery platforms, which have to be co-optimized with clinical light interfaces, are discussed. We then outline four functional routes by which opto-epigenome editors may be used therapeutically in cancer: tumor suppressor reactivation; oncogene and super-enhancer repression with metabolic rewiring; control of cancer stem cell differentiation; and immunomodulation of the tumor microenvironment. Lastly, a translational roadmap is defined in terms of preclinical model tiers, biomarker strategies, regulatory and manufacturing factors, and future directions, including NIR and bioluminescent actuation, implantable μLED devices, and AI-guided closed-loop illumination. Together, these aspects constitute design principles for advancing light-addressable epigenome editors toward first-in-human studies and for integrating them into combination regimens as a new class of precision cancer therapeutics.