CDK4 and neutropenia: The incidence of grade 3 neutropenia with palbociclib, ribociclib, abemaciclib, and dalpiciclib were 64.6% to 68.4%, 53.4% to 65.0%,18.6% to 28.2%, 84.2% to 85.8%, respectively, all ≥ 10%.[20] Therefore, the moderate and severe adverse reactions of the 4 CDK4/6 inhibitors all scored 1 point.