IL2 and breast neoplasm: Through a series of in vitro and in vivo experiments, including the use of NSG mice engrafted with a Hep3B liver tumor or an MDA‐MB‐231 PIK3CA‐mutated breast tumor as the animal models, we have demonstrated that these nanocomposites can induce mild hyperthermia upon laser irradiation (at 808 nm), and this effect can boost the therapeutic effect of B7‐H3 CAR‐T cells and prolong the survival of the animals through promoting the infiltration of the CAR‐T cells and the secretion of serum cytokines, including IL‐2, IFN‐γ, and TNF‐α.