Fig. 6.

HER2⁺PIK3CA tumors are resistant to dual blockade of HER2. (A) Mice with established HER2⁺PIK3CA tumor transplants were randomized to receive vehicle control, BKM120, trastuzumab + lapatinib ± BKM120 (T + L ± B), or trastuzumab + pertuzumab ± BKM120 (T + P ± B) as described in SI Materials and Methods. Each data point represents the mean tumor volume in mm³ ± SEM. P values were calculated by Student t test. ** or ***, relative to vehicle control; #, relative to BKM120. (B) Tumor lysates harvested at the study endpoint were probed with the indicated antibodies. β-Actin was used as a loading control.