As a result, small molecule inhibitors have been developed that target thismitogenic pathway, and three of them, known as cyclin-dependent kinases 4 and 6(CDK4/6) inhibitors (palbociclib, ribociclib, and abemaciclib), are currentlyavailable for the treatment of aBC in combination with aromatase inhibitors orfulvestrant [6]. This evidence concerns the gene CDK4 and aneurysmal bone cyst.