Discover of a highly effective covalent inhibitor of CDK6 for triple-negative breast cancer treatment.

CDK4/6 inhibitors are effective in treating HR+/HER2- breast cancer, but they have limitations in treating TNBC and drug-resistant breast cancer. To overcome this challenge, we designed and synthesized a series of novel covalent inhibitors for CDK6 that contain the Palbociclib core pharmacophore. The most promising compound, C32, showed good inhibitory activity against CDK6 (IC50 = 0.013 μM) and good inhibitory effects on MDA-MB-231 (IC50 = 0.061 μM), MDA-MB-468 (IC50 = 0.080 μM) and BT-549 (IC50 = 0.044 μM) cells. Compared with that of Palbociclib, the growth inhibitory activities against these two cell types increased by approximately 200-fold. Compound C32 can effectively inhibit the proliferation and migration of TNBC cells and induce apoptosis and S-phase cell cycle arrest. C32 can also induce excessive mitochondrial oxidative phosphorylation by remodeling cellular metabolic patterns, leading to the generation of ROS and mitochondrial damage. In vivo experiments further demonstrated that C32 has a favorable safety profile and pharmacokinetic properties, while exhibiting significant anti-TNBC effects. As a novel CDK6 covalent inhibitor, C32 is expected to be a candidate compound for the treatment of TNBC.