Fig. 4

Targeting CDK4/6 overcomes acquired resistance to PI3K inhibition in ER+/HER2− breast cancer. a, b ZR751 and MCF7 xenografts treated with fulvestrant or alpelisib monotherapy or the combination (8 mice per arm, mean tumor volume ± SEM). c ZR751 xenografts treated with fulvestrant/alpelisib combination therapy until progression followed by the addition of ribociclib to the combination. Growth curves for 3 individual combination-treated mice are depicted. For all experiments, the following dose schedule was used: ribociclib 75 mg/kg PO QD, alpelisib 35 mg/kg PO QD, and fulvestrant 5 mg/mouse QW by subcutaneous injection. *Statistically significant difference compared to vehicle control; P < 0.05