A review of trilaciclib, a first-in-class cyclin-dependent kinase 4/6 inhibitor, for the management of metastatic small-cell lung cancer

Cyclin-dependent kinases (CDKs) play a major role in regulating transitions within the cell cycle. Given the roles of CDK4/6 in promoting oncogenesis, selective inhibition of CDK4/6 has emerged as a novel approach for the treatment of breast cancer and various other tumors. While first and second generation CDK4/6 inhibitors were instrumental in targeting cell cycle pathways, they had numerous drawbacks such as limited selectivity and off-target effects. For that reason, a third generation of inhibitors was introduced and provided improved selectivity towards CDK4/6 leading to fewer side effects. To date, four compounds have been approved by the FDA as selective inhibitors of CDK4/6: palbociclib, ribociclib, abemaciclib, and trilaciclib. In this mini review, we summarize the biological, clinical, and chemical aspects of trilaciclib, a first-in-class CDK4/6 inhibitor notable for its dual role in cell cycle regulation and myelopreservation. Trilaciclib was granted FDA approval on February 2021, to improve the outcome of patients with metastatic-stage small cell lung cancer (SCLC) by protecting bone marrow suppression during chemotherapy.