PIK3CA and breast cancer: In addition, studies have confirmed that p110γ, one of the catalytic subunits of PI3K, plays an important role in immunosuppressive function of M2-type macrophages in tumor microenvironment, and by inhibiting M2-type macrophages, PI3Kγ inhibitors can restore drug resistance of breast cancer cells to immunotherapy, such as PD-1 and CTLA-4.