PIK3CA and breast neoplasm: The administration of B7‐H3 CAR‐T cells to NOD severe combined immunodeficiency gamma mice bearing a human hepatoma or PIK3CA‐mutated breast tumor can significantly inhibit the tumor growth after the induction of tumor hyperthermia by the nanocomposites and promote the secretion of serum cytokines, including IL‐2, IFN‐γ, and TNF‐α.