THZ2 is primarily used as a selective inhibitor of CDK7 (cyclin-dependent kinase 7), making it a valuable tool in cancer research. It has shown potent activity against various cancer cell lines, particularly in transcriptionally addicted cancers such as small cell lung cancer and certain leukemias. By inhibiting CDK7, THZ2 disrupts the phosphorylation of the RNA polymerase II C-terminal domain, leading to rapid downregulation of key oncogenes like MYC and MCL1. This results in cell cycle arrest and apoptosis in tumor cells. Due to its ability to target super-enhancer-associated genes, THZ2 is widely used in studies exploring transcriptional regulation in cancer and is considered a prototype for developing new targeted anticancer therapies.