Cyclin-dependent kinases 12 and 13 (CDK12/13) safeguard genomic integrity by preferentially regulating gene expression in the DNA damage response (DDR). The CDK12/13-mediated upregulation of DDR genes and pathways significantly contributes to both tumorigenesis and the development of resistance to antitumor therapies. Thus, the functional inhibition of CDK12/13 offers an attractive strategy to combat carcinogenesis, particularly for refractory and treatment-resistant cancers. Here, we report the discovery of compound