Cyclin-dependent kinase 4/6 inhibitors for cancer therapy: a patent review (2015 - 2019).

INTRODUCTION: Cyclin-dependent kinases 4 and 6 (CDK4/6) along with their upstream/downstream components are pivotal regulators for the cell cycle progression. The dysfunction of CDK4/6 is the common feature and promoting factor in various cancer types. In-depth research on CDK4/6 inhibitors has afforded therapeutic agents, while new challenges and ideas are emerging concomitantly. AREAS COVERED: This review focuses on patent publications related to CDK4/6 inhibitors which could be utilized for anti-cancer purposes during the period 2015-2019. EXPERT OPINION: The increasingly comprehensive and thorough understanding of CDK4/6 inhibitors facilitates them to break through the current limitations. Hence the utilization of CDK4/6 inhibitors for cancer therapy in the near future is likely to be performed in diverse forms and for distinct purposes. Selectivity over kinases is still crucial to new agent development but shall be prudently dealt with. The gradually revealing of resistance and adverse events proposed another issue that calls for new tackling strategies.