CD4 and cancer: Regulatory immune cells including myeloid-derived suppressor cells (MDSCs), M2-like tumor-associated macrophages (TAMs), and CD4+CD25highFoxP3+ regulatory T cells (Tregs) contribute to the inhibition of cytotoxic CD8+T cells and tumor progression.10 11 Although the effect of PI3K inhibitors on cancer cells has been extensively studied, their effect on cancer-associated immunity remains largely unknown.