Table 1.

Comparison of CDK4/6 inhibitors.

Drug	Palbociclib (Pfizer) (PD0332991, lbrance)	Ribociclib (Novartis) (LEE011)	Abemaciclib (Eli Lilly) (LY2835219)
IC50 (in vitro kinase assay, recombinant proteins)	CDK4: 9-11 nM CDK6: 15 nM	CDK4: 10 nM CDK6: 39 nM	CDK4: 2 nM CDK6: 5 nM CDK9: 57 nM
Cell cycle arrest	G1	G1	G1, G2
Off-targets	TTK, TRK, ULK2-3, PIK3R4, PIP5K2C, PIK3CD, PIP4K2A/C CAMK2δ, FLT3, PIP4K2B, HIPK1-3, MPSK1, CDK16/17, CLK1-2, CSNK2α	TTK, GAK, QIK, CAMK2δ, CAMK2α-γ	CDK1/2/5/7-9/12-17/19, CAMK2δ, CAMK2α-γ, FLT3, PIP4K2B, HIPK1-3, MPSK1, CLK1-2, CSNK2α1-2, ERK8, GSK3α/β, PIM1/3, AAK1, IRAK1, DYRK1-3, CSNK2α3