Design, Synthesis, and Biological Evaluation of Sulfonamide Derivatives as Potent CDK9 Inhibitors

Targeting CDK9 has become an attractive strategy for antitumor drug development. To obtain CDK9 inhibitors with high activity and safety, we designed and synthesized a series of sulfonamide derivatives as CDK9 inhibitors based on BAY1143572, the first selective CDK9 inhibitor to enter clinical trials. Among them, the representative compound L18 was identified as a potent and selective CDK9 inhibitor (IC₅₀ = 3.8 nM). Biological evaluation showed that L18 significantly inhibited the growth of various tumor cells and induced apoptosis by down-regulating the levels of Myc-1 and c-Myc in MV4-11 cells. Further studies showed that L18 possessed moderate metabolic properties and exhibited an in vivo safety profile superior to that of the positive control. This study provides a potential lead compound for the development of CDK9 inhibitors for cancer therapy.