To investigate whether blocking the PI3K/5‐LOX/LTB4 axis can inhibit the growth of PIK3CAmut LBC and synergize with ICB therapy in vivo, we applied alpelisib, LY255283 (10 mg/kg/day) and an anti‐PD‐1 mAb (10 mg/kg/day) alone or in combination after PIK3CAmut xenografts were established (Figure 7F). Here, PIK3CA is linked to CDH1-related diffuse gastric and lobular breast cancer syndrome.