PIK3CA and neoplasm: We found that palbociclib plus alpelisib led to the highest degree of synergism in inhibiting tumor cell growth of the three combinations (average ExcessHSA score: − 213.24; Fig. 5a), with significantly higher ExcessHSA scores observed in PIK3CA mut/amp cell lines than that of PIK3CA WT lines (P = 0.0253, Fig. 5b).