At this year’s ASCO meeting Dennis Slamon presented the primary results of the randomized phase 3 trial of the CDK4/6 inhibitor ribociclib or placebo in combination with fulvestrant in postmenopausal women or men with hormone receptor-positive (HR+) and HER2-negative advanced breast cancer (ABC) [1, 2]. Here, CDK4 is linked to aneurysmal bone cyst.