Design, synthesis, and biological evaluation of 2,6,7-substituted pyrrolo[2,3-d]pyrimidines as cyclin dependent kinase inhibitor in pancreatic cancer cells.

Pancreatic cancer is a highly malignant tumor, and more effective treatment is urgently needed to lengthen the life of patients. In this paper a class of new 2,6,7-substituted pyrrolo[2,3-d]pyrimidine derivatives of CDK 4/6 inhibitor ribociclib (1) was designed and synthesized to investigate their effect on the proliferation of pancreatic cancer cells. The structure-activity relationship (SAR) of synthetic compounds was analyzed based on both their in vitro anti-proliferative activity and the CDK4 inhibitory activity. A series of 6-anilinocarbonyl-substituted pyrrolo[2,3-d]pyrimidine derivatives (25, 41-48) showed the significantly increased potency against two proliferating cancer cell lines (MIA PaCa-2 and BxPC-3) in MTT assay though their CDK4 inhibitory activity were lower in a varying range compared to 1. The most potent compound 41 was identified as a highly selective and potent CDK 4/6 inhibitor in the human kinases profiling assay, it also exhibited the favorable in vitro pharmacokinetic properties for further in vivo evaluation. Meanwhile, 41 exhibited the potential as a combination partner with mTOR inhibitor to treat pancreatic cancer. Alternatively, introducing of sulfonamide fragment into C2-substituent of pyrrolo[2,3-d]pyrimidine provided the clue for future optimization to afford new CDK9 inhibitors.