Furthermore, MDSCs isolated from PIK3CAmut tumours in the alpelisib‐treated group induced less inhibition of T‐cell proliferation (Figure 7D) and IFN‐γ secretion (Figure 7E) than those in the other groups, which indicated that the suppressive TIME in PIK3CAmut LBC xenografts was attenuated by the PI3K inhibitor alpelisib. This evidence concerns the gene PIK3CA and CDH1-related diffuse gastric and lobular breast cancer syndrome.