TTK (TTK protein kinase) is a serine/threonine kinase primarily known for its role in mitotic spindle assembly checkpoint signaling and kinetochore-spindle microtubule attachment repair 123. TTK phosphorylates multiple checkpoint regulators including MAD1L1, CDCA8/Borealin, SKA3, and KNL1 to coordinate proper chromosome 6 12. Beyond mitotic functions, recent evidence reveals TTK's dysregulation in multiple cancers. In bladder cancer, TTK promotes proliferation and inhibits apoptosis by enhancing mitophagy through ULK1 phosphorylation, preventing mitochondrial apoptosis 4. In esophageal squamous cell carcinoma, the ANXA2/TTK complex activates Akt/mTOR signaling to drive epithelial-mesenchymal transition and metastasis 5. TTK is also transcriptionally upregulated through histone lactylation in pancreatic cancer, establishing a positive feedback loop with glycolysis that promotes oncogenesis 6. In T-cell lymphoma, TTK phosphorylates p38α to suppress AMPK/mTOR-mediated autophagy, and TTK inhibition restores anti-tumor immunity 7. TTK inhibitors like OSU13 induce DNA damage, trigger STING-mediated innate immunity, and synergize with anti-PD-1 immunotherapy 8. These findings establish TTK as both a critical cell cycle regulator and an emerging multi-cancer therapeutic target.